Copper Gherkins (KT150s) [Archive] - The Art of Sound Forum

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The Black Adder

15-01-2016, 15:50

Spot the difference.

http://i457.photobucket.com/albums/qq295/musical_submarine/Tannoyista%20System/Tannoyista%20system%20update%202015/DSC00945.jpg

http://i457.photobucket.com/albums/qq295/musical_submarine/Tannoyista%20System/Tannoyista%20system%20update%202015/DSC00961.jpg

As you can see, I recently updated from the superb KT120's to the KT150's in my copper amp and I have to say it's a superb upgrade. :eek:

A lot has been said about the KT150's. From the off the midrange is much more lucid, slightly less shouty in comparison with the KT120's with an increase in air around instruments and more top end definition. On the lower registers the sound is much more organic sounding with much more texture.

Very happy with them so far and they still have plenty of loosening up to do... Job's a good un.

:)

trio leo

15-01-2016, 16:11

what a beauty,the glowy things on the L/R are a different shape? nice 124 there.

Enjoy your music :)

cheers Al

struth

15-01-2016, 16:34

not seen 150's in a amp b4... look good, and very 50's si-fi

Marco

15-01-2016, 17:08

TheMooN

15-01-2016, 18:45

Told Y'all ;)

The Black Adder

15-01-2016, 19:35

Ah, now that's very interesting, Jo! I had been contemplating getting a set of KT150s for a while, but had held off because Anthony didn't rate them... Maybe he just got a duff set? :scratch:

Anyway, if you reckon that they're a good upgrade over the 120s, I'll give some a go. The good news is that our Copper amps can take 150s no problem.

Where did you get yours from - got a linky? :)

Marco.

Sure. I got them from HotRox. Anthony recommended them to me:
http://www.hotroxuk.com/tungsol-kt150.html

I'm going to give these a few more weeks to open up but all I can say is they are certainly a nice upgrade from the KT120's.

The reasoning behind the difference could be the shape, apparently they have reduced microphonics due to the envelope has no straight edges.

I'm not sure what Anthony didn't like though but of course different components, rooms etc could be the reason but I know Anthony is now using some in his single ended amps.

The Black Adder

15-01-2016, 19:39

Some more pics:

http://i457.photobucket.com/albums/qq295/musical_submarine/Tannoyista%20System/Tannoyista%20system%20update%202015/KT150%20-%202016/DSC00981.jpg

http://i457.photobucket.com/albums/qq295/musical_submarine/Tannoyista%20System/Tannoyista%20system%20update%202015/KT150%20-%202016/DSC00962.jpg

http://i457.photobucket.com/albums/qq295/musical_submarine/Tannoyista%20System/Tannoyista%20system%20update%202015/KT150%20-%202016/DSC00976.jpg

http://i457.photobucket.com/albums/qq295/musical_submarine/Tannoyista%20System/Tannoyista%20system%20update%202015/KT150%20-%202016/DSC00982.jpg

Marco

15-01-2016, 19:53

Sure. I got them from HotRox. Anthony recommended them to me:
http://www.hotroxuk.com/tungsol-kt150.html

I'm going to give these a few more weeks to open up but all I can say is they are certainly a nice upgrade from the KT120's.

The reasoning behind the difference could be the shape, apparently they have reduced microphonics due to the envelope has no straight edges.

I'm not sure what Anthony didn't like though but of course different components, rooms etc could be the reason but I know Anthony is now using some in his single ended amps.

Ok, cool. I thought it might've been Hot Rox. Did Anthony tell you to get low-output [or a term similar to that] matched ones? Apparently, it's necessary with the Copper amp.

Marco.

P.S Great pics, as usual! :)

The Black Adder

15-01-2016, 20:00

Thanks Marco.

Yes, sorry... Low to Medium current draw.

Marco

15-01-2016, 20:04

Yeah, I thought it was summat like that!

So did Hot Rox sort that out ok and mark the measurements on the boxes? :)

You'd had to have known the correct plug-in order....

Marco.

The Black Adder

15-01-2016, 20:07

Yes, they sorted it all out fine. They write the readings on each box. All the readings measure the same so they simply plug in.

Marco

15-01-2016, 20:15

Ok, mate. Cool... Just wanted to check before I order some! :thumbsup:

Marco.

Ali Tait

15-01-2016, 20:33

Hotrox are good and give reliable service in my experience. Use with confidence.

Marco

15-01-2016, 21:33

Yup, mate, so I've heard. I'm just deciding on where to get the 150s from, there or from my usual source in the States, where they also Cryo-treat the valves. That's where I got my KT-120s from.

Here, in fact: http://www.upscaleaudio.com/tung-sol-kt-150/

The cryo treatment, in my experience, makes a notable difference to how they sound.

Marco.

User211

16-01-2016, 09:14

I was told by a metallurgy expert the obvious. That cryo is likely to do a lot more harm than good.

Any tonal changes are likely to be a result of damage e.g. loss of vacuum etc...

He is also seriously into hi-fi.

User211

16-01-2016, 09:51

To elucidate what he said was the expansion/contraction of glass versus metal is very likely to matter at such low temperatures and cause leaks. The same is true for any differing material types inside the valve e.g. carbon versus metal etc.

I had and still have 4 cryo'd Mullard E88CC equivs and they are all, without exception, microphonic. They came with my current preamp wot I got off ebay.

Marco

16-01-2016, 10:32

Hi Justin,

I can't really argue against that, as I'm no expert; merely comment on my experience to date (having had numerous cryo'd valves and compared them with the same types, non-cryo'd), and the former always, without exception, sounded better - and measured better too, in Anthony's valve tester! ;)

He's taken a set of valves (KT88s in this instance), measured them beforehand (noting down their various parameters), then sent them off to Frozen Solid to have them cryo'd, and measured them again when they came back. The aforementioned parameters always change for the better on return. Plus the valves always perform better, sonically.

Therefore, on that basis, when possible, I'll be sticking with using cryo-treated valves :)

Marco.

walpurgis

16-01-2016, 10:34

To elucidate what he said was the expansion/contraction of glass versus metal is very likely to matter at such low temperatures and cause leaks. The same is true for any differing material types inside the valve e.g. carbon versus metal etc.

I agree. That has to be the case. Also the physical stresses involved are considerable. Expanding and contracting solids can produce an amazing amount of force.

Marco

16-01-2016, 10:36

Well...... See my above post! ;)

Also, I would add, any cryo-treated valves I've used have never 'leaked', and to boot, have lasted LONGER than non-cryo'd ones.

Marco.

User211

16-01-2016, 10:43

It's hi-fi. Go with your hunches!:)

struth

16-01-2016, 10:44

Metal coefficient is 1.4 that of glass i think so it will expand more ...thats how you get a stuck lid of a jamjar.

Marco

16-01-2016, 11:14

It's hi-fi. Go with your hunches!:)

Yup, but in this case it's not just hunches. My opinion on this is based on about six years experience of using various cryo-treated valves, and listening to the 'before & after' results. Also, Anthony's measurements on his AVO professional valve tester don't lie... ;)

Furthermore, it's not just valves I've heard benefit sonically from cryo-treatment, but cables and other stuff, too!

Marco.

The Black Adder

16-01-2016, 11:31

I was tempted to get them from Upscale but I didn't want to pay extra on the back of an experiment.

I've never had cryo valves and never had a problem with leaking or premature failure.

Marco

16-01-2016, 11:36

I was tempted to get them from Upscale but I didn't want to pay extra on the back of an experiment.

Neither did I, but since you've been the 'guinea pig' this time, I don't mind! :D

;)

Marco.

The Black Adder

16-01-2016, 13:04

well, yes.. naturally. :)

Marco

16-01-2016, 13:07

We could also compare both of our sets of KT150s in the same amp and system, one cryo'd and the other not, and analyse for any sonic differences ;)

That's something we should do here when you visit - and talking of which, it's something we really need to nail down in terms of a date! :cool:

Marco.

The Black Adder

16-01-2016, 13:10

Oh yes... lol

How time flies. Yes, let's do that. I'll PM you.

That would be interesting because if these burn in well it Ii could always get another set and keep these as spares.

Marco

16-01-2016, 13:13

Presaktly! Yup, get yer diary out and PM me with a proposed date :cool:

Marco.

TheMooN

16-01-2016, 14:18

Wooohhhh there! I am having a very hard time getting my head around any mechanism by which the main measurement characteristics of a vacuum tube , Mu (voltage gain), Gm (transconductance) and Rp (plate resistance) might be physically altered by this process?

***Please note that I make no comment on, or reference to, any subjectively held belief of any change in any form in the audible domain.***

User211

16-01-2016, 14:20

Yup he's gotta be telling porkies!

The Black Adder

16-01-2016, 14:23

Well, I've got no idea how it works. Some say it's a great thing to do sonically of which I must admit, it would be interesting to know how it works.

These are fine for me though for now at least... very happy with them.

Marco

16-01-2016, 14:24

Yup he's gotta be telling porkies!

Yes, of course, that'll be it ;)

Marco.

Marco

16-01-2016, 14:42

Well, I've got no idea how it works. Some say it's a great thing to do sonically of which I must admit, it would be interesting to know how it works.

Read here: https://www.watfordvalves.com/products.asp?ID=10&man=110

I'm not saying that what's stated there is 'indisputably correct' or even 'scientifically provable', but it certainly matches with my (considerable) experience of using cryo-treated tubes.

Also, a company such as Watford Valves, who've been trading for years and have an excellent reputation, simply wouldn't entertain the idea if a) they didn't think it worked, and b) the process of cryogenic treatment caused reliability issues with the valves that they sold.

Marco.

The Black Adder

16-01-2016, 14:58

Thanks, Marco.

Interesting... over my heed but interesting... lol

I'd be interested in trying some cryo valves but maybe the 6SN7's or the 5U4G's for starters. Incidentally, which 5U4G's do you recommend?

Marco

16-01-2016, 15:01

RCAs or Mullards, dude. I have the latter (rebranded as Zaerix) in at the moment, and they're superb :)

Marco.

The Black Adder

16-01-2016, 15:02

what a beauty,the glowy things on the L/R are a different shape? nice 124 there.

Enjoy your music :)

cheers Al

Sorry, Al.

lol... Yes, they are KT150's. Thanks for the compliment, and yes... enjoying the music is what it's all about.

Spectral Morn

16-01-2016, 20:37

YNWaN

16-01-2016, 20:57

Lovely looking valve amp :).

Marco

16-01-2016, 21:36

Indeed, and mine is rather similar:

http://imagizer.imageshack.us/v2/1024x768q90/909/501cde.jpg

http://imagizer.imageshack.us/v2/1024x768q90/539/f306a8.jpg

:cool:

Marco.

The Black Adder

17-01-2016, 08:12

Aye... a proper bit of kit.

AlfaGTV

17-01-2016, 09:14

Quite like the look of theese! Not too bling, but not your run of the mill garden shed design either.

I suppose they work in a push-pull pentode config? Power output ca?

And the 150's look like "suppositories from hell"! :D

Marco

17-01-2016, 12:10

Quite like the look of theese! Not too bling, but not your run of the mill garden shed design either.

Are you referring to the Copper amps? If so, you can order one for £5k ;)

Marco.

anthonyTD

17-01-2016, 12:55

Hi All,
Good to hear you have had good results with the KT150's in your copper amp Josie, my own trials with them were in my Soul 30 watt mono-blocks, and in those I preferred the KT120's over the 150's, However, I have since tried them in an old conventional single ended design I built back in the 1990's, and in that amp, they seem to work very well indeed, so, after that experiment, and your results in your copper amp, i am warming to them.
Now, a little bit about Cryo-treating, and my own findings with the results, and the process involved.
Cryo treating valves is a very, very risky business indeed, and due to the extreme nature of it, it will weed out the weak valves in the process, leaving only the best, and most robust valves intact after the process has completed.
It is true that I was amongst the first in the UK to experiment with the process on valves, and speak of my findings with the results. the first thing I had to do was find an independent source that I trusted to carry out the process, next, I hand picked a pair of KT88's that I had thoroughly tested, and also listened to in an amp I knew well. I then gave them to the company that carried out the process, and stated that I would only require them to treat one out of the tested pair, and when they were ready, I requested that they put on each valve identification markings that would only make sense to them as to which one of the pair had been treated, that way, when I got them back, I would have no idea by physically examining them which one was which.
When I got them back, the first thing I did was re-test both of them, to see if there were any differences in their characteristics from the last time I tested them, sure enough, one did indeed test different, I then went on to listen extensively to each valve in turn in the original mono amplifier I had used them in before sending them off, again, the one that tested differently, also sounded different, quite markedly i might add, with a seemingly more effortless, and somewhat extended frequency extreme, at both ends of the scale, also, the midrange seemed more liquid, and effortless. I then went on to explain my findings to one of the afore mentioned valve suppliers, who having known me for some time, and that I was not one for being involved in Foo, quickly decided to do his own investigation into Cryo-treatment, and now carries quite a large selection.
Now, I agree, the process is a very harsh thing to do to an item such as a Vacuum valve, which is why the process has to be done right, but as stated earlier, failures are to be expected.
Also, I am not saying that all valves need to be treated; I am only going on my own experiences, and experiments with certain types of audio valves that I have come to know the sonic properties, and failings of over the years I have been in this business.
One valve that went on to become a huge success was made by the original Tesla plant before it finally closed its doors in the early 2000’s, this valve went on to become one of EAT’s best sellers, I actually still own some of the original Tesla versions, and I have sold and tested many of the EAT versions, All I will say on the matter is; this valve would not have been the success it was/is, without the Cryo-treating process!
Anthony,TD…

Firebottle

17-01-2016, 13:40

Good post Anthony, very interesting :thumbsup:

User211

17-01-2016, 13:51

One valve that went on to become a huge success was made by the original Tesla plant before it finally closed its doors in the early 2000’s, this valve went on to become one of EAT’s best sellers, I actually still own some of the original Tesla versions, and I have sold and tested many of the EAT versions, All I will say on the matter is; this valve would not have been the success it was/is, without the Cryo-treating process!
Anthony,TD…

Which one was it?

TheMooN

17-01-2016, 14:00

Anthony....If you can recall, might you expand a little on exactly which characteristic(s) of that particular 88 measured differently post Cryo, and by how much?

The Black Adder

17-01-2016, 14:12

Anthony, can valves be cryo'ed here in the UK then? If so, I would be very interested in having these done if possible. Is it an expensive thing to do? It would be great to compare before and after.

anthonyTD

17-01-2016, 19:36

Hi Roger,
The GM, or MA/V had changed, and also, the current draw had changed, both measured higher after the treatment.
Hope this helps.
A...
Anthony....If you can recall, might you expand a little on exactly which characteristic(s) of that particular 88 measured differently post Cryo, and by how much?

anthonyTD

17-01-2016, 19:39

Hi Josie,
Yes, Frozen Solid is one company that will do them,However, they would probably advise you of a waiting period, obviously they will not want to put a few valves in at a time.
A...
Anthony, can valves be cryo'ed here in the UK then? If so, I would be very interested in having these done if possible. Is it an expensive thing to do? It would be great to compare before and after.

anthonyTD

17-01-2016, 19:40

The KT88!
Which one was it?

anthonyTD

17-01-2016, 19:42

:)
Good post Anthony, very interesting :thumbsup:

Marco

17-01-2016, 21:04

User211

17-01-2016, 21:39

The KT88!

Well, IMHO that was the best sounding KT88 I ever tried by leaps and bounds. And I tried quite a few NOS and new types. I've documented it before here as some will know.

It was also super-unreliable. I went through quite a few before giving up on them. A crying shame they really did sound superb.

Now I know why.

User211

17-01-2016, 21:43

So so far all cryo'd valves I have tried have had serious issues. Marco I think you have been lucky.

Marco

17-01-2016, 22:02

Lol... Me and no doubt 100s of others, who've reported similar things. A couple of my mates, for example, who use valve amps, have had the same experiences as me with cryo'd valves. I guess they were lucky, too ;)

Perhaps the sellers you bought from didn't carry out the process correctly? Who knows... Like Anthony says, it has to be done right :)

Marco.

User211

18-01-2016, 08:25

They just put yours in the freezer for a few days. Mine obviously hit absolute zero.;)

Marco

18-01-2016, 10:48

:lolsign:

Joking aside though, one key point that risks being buried amongst the 'froth', but that shouldn't be forgotten, is that Anthony successfully measured key electrical differences between both cryo'd and non-cryo'd tubes (KT88s), noting in the process that the Cryo'd tubes measured better afterwards, as a result of the treatment, so that should all but put an end to the 'dissers', who consider the use of cryogenic treatment in audio as 'foo'! ;)

The interesting thing here too, is that he was able to do that because he had the necessary equipment allowing him to carry out those measurements, and thus show said improvements. I'm convinced that similar sonic (and electrical) benefits result in the cryogenic treatment of cables, but unfortunately, unlike with valves, as far as I'm aware, we currently don't have the required apparatus allowing us to measure the 'before & after' electrical benefits with cables.

This shows that, as ever, any effect in audio, which is genuinely heard, can ALWAYS be measured, *providing* that we have the correct tools for the job! Therefore, it's simply a matter of science catching up with what our ears clearly tell us :exactly:

Marco.

anthonyTD

18-01-2016, 10:50

Hi Justin,
Unfortunately, the original Tesla valve that was used suffered from poor heater to cathode insulation, thus failure rates were high, i will explain briefly why this came to be; Tesla, in their wisdom decided some time around the 1980's that Audio valves were old hat, and not worth producing anymore, and so decided to cease production of them, and concentrate on the production of transmitter types, unfortunately, by doing so, they had to let go a number of individuals that were very experienced in certain key processes that were absolutely crucial to specific types of Audio valve production, eg, Cathode coating etc, after a while, they realised their mistake,and decided that Audio valve production was still quite lucrative, and thus re-started the production line of common Audio types, ie;ECC81, ECC82, ECC83, KT88, etc, etc, however, they quickly realised that they had lost employees that were key to certain processes involved in making some of these valves,Hence the failure rates, even after going to great lengths, re-tooling, and building certain machines again from scratch, they finally gave up around 2003, and closed their doors for good.The story of how EAT ended up with the stock is not for me to tell, safe to say, i agree with your findings, the EAT KT88 was/is amongst the very best performing [sonicaly] KT88's on the planet!
A...
Well, IMHO that was the best sounding KT88 I ever tried by leaps and bounds. And I tried quite a few NOS and new types. I've documented it before here as some will know.

It was also super-unreliable. I went through quite a few before giving up on them. A crying shame they really did sound superb.

Now I know why.

TheMooN

18-01-2016, 11:41

In the interest of balance folks,

http://blog.thetubestore.com/cryogenic-treatment-of-tubes-an-engineers-perspective/

http://blog.thetubestore.com/cryo-tube-controversy-the-chilling-truth/

Marco

18-01-2016, 11:43

Why not just try it for yourself and see - or have you done that already? Theory is all well and good, but it can never replace practical experience :)

Marco.

anthonyTD

18-01-2016, 12:26

Roger, and others have every right to be sceptical, i was, and for many of the reasons given in those links, which is why i went to great lengths in getting test samples done by someone i could trust, only then could i be sure that i was actually testing and evaluating the processes effect on an audio valve i knew well. For me the effect was obvious, we can argue why the process changes the sonic quality of the valves treated until the cows come home, but there really isnt any conclusive reason that i can think of, or have found over the years that totally, without doubt explains why this effect happens with vacuum valves, and as i have stated in an earlier post, the effect may not be as obvious, or in fact a positive one with some types.
A...
In the interest of balance folks,

http://blog.thetubestore.com/cryogenic-treatment-of-tubes-an-engineers-perspective/

http://blog.thetubestore.com/cryo-tube-controversy-the-chilling-truth/

TheMooN

18-01-2016, 12:53

Pretty much what I am getting at Anthony, I would very much like to see the test data results from ideally 100, or at least 20 control units, pre stress tested and identically matched by valve characteristics, measured before and then after cryogenic treatment.
The point being in order to establish whether the results of the procedure, as measured, are quantifiable and repeatable (within reasonable % control discrepancy)

User211

18-01-2016, 13:09

Roger, and others have every right to be sceptical, i was, and for many of the reasons given in those links, which is why i went to great lengths in getting test samples done by someone i could trust, only then could i be sure that i was actualy testing and evaluating the processes affect on an audio valve i knew well. For me the affect was obvious, we can argue why the process changes the sonic quality of the valves treated untill the cows come home, but there realy isnt any conclusive reason that i can think of, or have found over the years that totaly, without doubt explains why this affect happens with vacuum valves, and as i have stated in an earlier post, the Affect may not be as obvious, or infact a positive one with some types.
A...

The fact that some readings may change doesn't actually mean they change for the better. In fact it may just mean the valve is pushed outside of its production tolerances, especially if it was marginal in the first place.

Also, changes in electrical measurements won't always result in an audible change. Though if one is heard I concur with Marco it should be measurable by some means.

Oh the Tesla story - yeah I had heard that before. Sure it will interest some, though.

Marco

18-01-2016, 13:25

I would very much like to see the test data results from ideally 100, or at least 20 control units, pre stress tested and identically matched by valve characteristics, measured before and then after cryogenic treatment.
The point being in order to establish whether the results of the procedure, as measured, are quantifiable and repeatable (within reasonable % control discrepancy)

[Yawn] Lol... Yes, let's all bore ourselves silly and lose the will to live! My wife makes rather nice knitted blindfolds too, if you'd like one in pink? ;)

Marco.

Marco

18-01-2016, 13:26

The fact that some readings may change doesn't actually mean they change for the better.

It does, if to your ears, after extensive listening, it results in a better sound! ;)

I think we're starting to move from being sceptical to cynical, in this discussion...

Marco.

anthonyTD

18-01-2016, 13:54

The fact that the physical test parameters after treatment had changed, was the first indication that something had indeed occurred in the process, i must stress, this alone was not reason enough to state that what ever change had occurred' was in any way going to make the valve sound better, the proof of that was in the listening!
Also, i might add, every batch [bar one] that i had treated, when re-tested, all indicated different test parameters before and after. There was however' one batch that came back that didn’t, i later found out that this particular batch had not been treated!

The fact that some readings may change doesn't actually mean they change for the better. In fact it may just mean the valve is pushed outside of its production tolerances, especially if it was marginal in the first place.

Also, changes in electrical measurements won't always result in an audible change. Though if one is heard I concur with Marco it should be measurable by some means.

Oh the Tesla story - yeah I had heard that before. Sure it will interest some, though.

Marco

18-01-2016, 13:59

Interesting observations, Anthony. However, I'm afraid that probably still won't be good enough for the doubting Thomas' in our midst.... :doh:

Marco.

anthonyTD

18-01-2016, 14:29

Well, thats fine, the facilities are there for anyone who is genuinely interested in giving it a go! :)
I have not had anything treated for some time now, as the valve that i found mostly benefited from the process [the original winged C KT88] is no longer available.:(
Interesting observations, Anthony. However, I'm afraid that probably still won't be good enough for some people.... :doh:

Marco.

Marco

18-01-2016, 14:34

Yeah, sad to see the demise of those. I enjoyed using them for quite a while in the Copper amp, before we all upgraded to 120s. However, it'll be interesting hearing what cryo'd KT-150s are like :)

Marco.

TheMooN

18-01-2016, 17:15

The fact that some readings may change doesn't actually mean they change for the better. In fact it may just mean the valve is pushed outside of its production tolerances, especially if it was marginal in the first place.

Additional current draw in particular.

anthonyTD

18-01-2016, 18:39

It could of course indicate that the valve has become more efficient within its design parameters. :eyebrows:
Let me be clear here,The differences in Current change and GM I measured were not huge, But enough to indicate that something had indeed changed.
Additional current draw in particular.

User211

18-01-2016, 19:59

A much more interesting test is system frequency response changes TBH. I can see that change with every valve roll I do.

Mark Grant

18-01-2016, 21:25

http://i457.photobucket.com/albums/qq295/musical_submarine/Tannoyista%20System/Tannoyista%20system%20update%202015/DSC00961.jpg

As you can see, I recently updated from the superb KT120's to the KT150's in my copper amp and I have to say it's a superb upgrade. :eek:

That looks wonderful, valves with curves in all the right places :)

Great picture and no dust.

AlfaGTV

18-01-2016, 21:58

Are you referring to the Copper amps? If so, you can order one for £5k ;)

Marco.

Yes, they are very pretty! I am hopelessly a solid state guy though.. ;)

Josie, whats the expected output with the 150's?
Balanced construction?

/Mike

Marco

18-01-2016, 23:08

Yes, they are very pretty! I am hopelessly a solid state guy though.. ;)

Why? Best to keep your options open, IMO! :)

Marco.

The Black Adder

19-01-2016, 08:57

Many thanks, Mark. :) - Yep, I have to agree. The sound it produces is spectacular too.

Thanks Mike... To be honest I don't know.. lol

I'll let Anthony fill us both in on that one, or Marco might know?

Guys?

The Black Adder

19-01-2016, 09:44

If you do cryo to valves, can they be done to used ones too? Is there any difference in results I wonder?

anthonyTD

19-01-2016, 10:42

The power output from the copper amps, with the KT150's fitted shouldnt realy change much, it will depend mostly on how much current they are drawing compared to the KT120's for the same given bias etc, and also how well they match the impedance of the output transformers, but i would say around 45, to 50 watts class A...
Josie, as for Cryo-treating used valves, personaly, i wouldnt bother, unless they have had very little use etc.
A...

TheMooN

19-01-2016, 12:19

Anthony, I would be interested in a general ( Non proprietary disclosure) topology of your amplifier, Did you mean up to 50 Watts overall enriched Class A/B say 200 deg waveform ? Or Are both pairs of output devices per channel operating a full 360 deg waveform?

The Black Adder

19-01-2016, 13:16

Thanks Anthony. :)

Tempted... lol - Well they have only had a few 'full' days on them. Is that still ok do you think?

An update in sound from these.

I couldn't quite put my finger on how the bass is different to the KT120's but I think they are certainly more focused, the bass is very tight and strong.

anthonyTD

19-01-2016, 15:49

Hi Roger,
All the copper amps were designed to produce most of their power in class A, ie; the output valves are biased to draw the maximum current needed to produce the stated output power in Class A, However, in conventional valve amplifiers, unless dedicated current sources are fitted, [like in the Soul Series] there is always the posibilty of the driver stage being able to push the output valves outside of their set current, so in that respect, they are very close at full output to 360 degrees, but not perfect to absolute full output power.
I hope this helps.
A...

Anthony, I would be interested in a general ( Non proprietary disclosure) topology of your amplifier, Did you mean up to 50 Watts overall enriched Class A/B say 200 deg waveform ? Or Are both pairs of output devices per channel operating a full 360 deg waveform?

anthonyTD

19-01-2016, 15:51

Thats interesting Josie,
I would try some in my big Copper amp, but as you know, i would need eight for that beast!:eek:
Thanks Anthony. :)

Tempted... lol - Well they have only had a few 'full' days on them. Is that still ok do you think?

An update in sound from these.

I couldn't quite put my finger on how the bass is different to the KT120's but I think they are certainly more focused, the bass is very tight and strong.

TheMooN

20-01-2016, 11:51

Anthony...Would that be 50Watts *per channel* at 'close' to 360deg Class A?

anthonyTD

20-01-2016, 12:42

Hi Roger,
In Josie's amp, 40 watts.
A...
Anthony...Would that be 50Watts *per channel* at 'close' to 360deg Class A?

The Black Adder

20-01-2016, 13:29

Thats interesting Josie,
I would try some in my big Copper amp, but as you know, i would need eight for that beast!:eek:

Now THAT is something I really want to hear! - Sounds bonkers.

anthonyTD

20-01-2016, 13:50

:lol:
Now THAT is something I really want to hear! - Sounds bonkers.

Marco

10-02-2016, 19:24

After being told by Hot Rox that it will be 2 weeks until they receive more stock of KT150s, enabling them to make up matched quads, I've bitten the bullet and ordered a cryo'd matched quad from Upscale Audio in the US, who have them in stock.

Should be here within the week, after which there will be a full (detailed) report on this one, and a comparison with my usual KT120s! :cool:

Marco.

The Black Adder

10-02-2016, 19:36

Sounds ace, Marco.

I can tell you now though that the sound has changed somewhat since I got them in. They have pretty much been run in every day since for most of the day.

The bass is now more loose, better definition and the space is becoming deeper. Sounding so good though. I honestly think you will be very happy with them.

Marco

10-02-2016, 20:03

Nice one, mate. Glad that they're still hitting the spot :)

I actually phoned up Kevin Deal (the boss from Upscale), and had a good chat with him on the phone, as when importing stuff like this, I prefer dealing directly with a human being, to ensure that everything goes smoothly.

He was saying that they've been having rejects and failures with a lot of KT150s, and they sell more than pretty much anyone else does on the planet (supplying Audio Research and McIntosh, etc), so they've had to operate a very strict testing and selection process, and now only supply them cryo'd, in order to sift out the duds!

Therefore, he assured me that mine would be throughly tested and hand-selected by him, for low to medium emission, so that sounds good :cool:

There's a detailed explanation here of the benefits of their cryo-treating process (click on the Cryogenic Treatment tab): http://www.upscaleaudio.com/6550-kt88-kt120-kt150/tung-sol-kt-150/#null

They cost me $466.20, all-in, shipped - so not cheap! The f*ckers better be good, lol ;)

Marco.

Marco

10-02-2016, 20:25

I also like the way he outlines the quality control process here:

Every power tube is different. This applies especially to power tubes like EL34, 6550, KT88’s, etc. Two tubes can be brand new in the original box, with one testing at [as an example] 6500 micromhos, the next one at 8600 micromhos. Both tubes would be considered "new" by the factory, and not defective. While the weaker tube isn’t "defective," it will certainly have a shorter life. So if you pay 10% less, you might get a tube with a significantly shorter life. The big lie from manufacturers of tube equipment and tube dealers themselves is that they “reject” these tubes. It’s not true. You can imagine the nightmare that would create for the tube factory if people are sending back 50% - 80% of the tubes that get shipped, coming back in all kinds of condition.

As the owner of Upscale Audio, a company that has supplied tubes into over 50,000 components, and someone obsessed with treating your amp like it’s my amp, I can tell you in no uncertain terms the factory doesn’t take them back. The only tubes they will take back are tubes that have shorts, gas, or measure BELOW the minimum number they assign for that tube type (it varies from type to type, so don’t bother trying to figure that out).

I’ve overcome that issue for you. I can say with calm assurance that we pay the factories more for our tubes than any other tube seller, and we ensure that we receive the absolute cream of the crop. This flies against the logic of how to run a business: The way you make money is to pay less for the goods you sell! That’s what most ANY business owner will tell you. We also don’t sell certain brands of tubes because while they might be cheap and sometimes good, they can be more trouble than they're worth. We pass on a lot of money as a result.

Upscale Audio is the only dealer that does what we do on a grand scale, and have a deep understanding of high end tube electronics. We’re the only dealer that manufacturers give a thumbs-up to, and recommend to their customers. And I promise you only the best.

Sounds reassuring! He certainly sounded like a very knowledgeable and helpful chap on the phone, plus as I've said, I used Upscale before, when I got my 120s :cool:

Marco.

The Black Adder

10-02-2016, 20:36

Yes.. indeed although I've not heard of many (in fact, any) of the latest crop failing. Obviously it doesn't mean that any didn't but I did my detective work and I wouldn't have bought them if I heard of any failing. If you read on the net the early ones certainly had problems.

Regardless, I really like them and they seem to be bedding in nicely. Can't wait to read your verdict. :)

Marco

10-02-2016, 20:40

Cool... How would you say that the bass compares with KT120s? :)

Marco.

The Black Adder

10-02-2016, 20:44

More focused and a little less bloated. Certainly not leaner, more wholesome I'd say with a more cleaner sound throughout the midrange too.

The sound is certainly developing as time goes on. I've read that they need quite a few hours on them before they really start to bloom so it's nice to know that the sound has plenty of headroom to envelop.

Marco

10-02-2016, 20:48

Sounds good, mate! :cool:

Marco.

User211

10-02-2016, 21:45

Sounds reassuring! He certainly sounded like a very knowledgeable and helpful chap on the phone, plus as I've said, I used Upscale before, when I got my 120s :cool:

Marco.

Well after all that he is going to seem like a complete prune if what you get turns out to have some sort of issue.

I do like him, though. The "use a transistor, go to jail" ad used to really make me smile.

Marco

10-02-2016, 21:52

I do like him, though. The "use a transistor, go to jail" ad used to really make me smile.

Missed that one... Got any links? :)

Marco.

User211

10-02-2016, 22:31

Missed that one... Got any links? :)

Marco.

No. The ads used to be in Stereophile a few years ago.

Amazed I can't find the ad online somewhere though. Brownie points to a member that can!

Marco

10-02-2016, 22:43

Ah, did he used to advertise in Stereophile? Don't read it. Certainly comes across as a genuine enthusiast, which I like :)

Marco.

User211

11-02-2016, 01:23

No I don't read it either. However I did used to buy the Recommended Components issue once a year for a few years. But there are WAY too many recommended components at silly price tags that aren't worth it so I stopped.

Marco

11-02-2016, 07:43

But there are WAY too many recommended components at silly price tags that aren't worth it so I stopped.

Indeed, and that's precisely why I never started! ;)

I'm completely against that type of showy 'badge-fi', and consider that it's a major reason why the industry is in the state that it's in. There needs to be more focus on SPPV, and realistically priced equipment aimed at genuine enthusiasts, instead of key-jangling oneupmanship merchants, with more money than sense.

Marco.

jandl100

11-02-2016, 07:44

Marco

11-02-2016, 07:49

Ha - quality! :D

Never seen that before... Nice one, Jerry :thumbsup:

Marco.

Firebottle

11-02-2016, 08:04

Brilliant! I know the phrase but haven't seen the ad before.

Also quite like the 'and get ready for a spanking' :spank:, and 'with even the whackiest amps'. He'd fit right in here :thumbsup:

Marco

11-02-2016, 08:10

Lol... Yeah, he sounded like it on the phone: quite 'quirky', confident and opinionated, but not arrogant. My sort of guy, and certainly of the ilk we like to encourage joining AoS :)

Marco.

The Black Adder

11-02-2016, 09:04

lol... that's ace Jerry. Thanks for posting that.

User211

11-02-2016, 09:11

Indeed, and that's precisely why I never started! ;)

I'm completely against that type of showy 'badge-fi', and consider that it's a major reason why the industry is in the state that it's in. There needs to be more focus on SPPV, and realistically priced equipment aimed at genuine enthusiasts, instead of key-jangling oneupmanship merchants, with more money than sense.

Marco.

I just thought it was interesting to spy on the American market. The digital subscriptions are so ridiculously cheap it doesn't cost much to get an entire year of American foo should you so desire. That is if you can stand the prolific advertising and verbal BS. Very little ever gets a bad review.

Marco

23-02-2016, 23:03

Well, my "Copper Gherkins" are currently with Customs, so we'll see how much I get skinned for! :rolleyes:

Good news is that they'll be chez-moi very shortly :)

Marco.

struth

23-02-2016, 23:15

ooooo, I'd say 60 notes may cover it ...ouch ... still boys must have their toys :D

User211

24-02-2016, 09:05

I have a whole load of back issues from when I subbed Stereophile ...

http://i262.photobucket.com/albums/ii114/jandl100/DSCF6691_zpsrv9ezgcb.jpg (http://s262.photobucket.com/user/jandl100/media/DSCF6691_zpsrv9ezgcb.jpg.html)

Brownies++.

I might be wrong but I also remember a black & white cartoon version too.

Ironically, I now need to be sent to jail, after years of using valve amps... well, OK I still use a valve DAC and pre. But I'm still guilty:D

Anway, I have now had it verified by quite a few people (including two hi-fi kit reviewer's - one working for a very serious hi-fi mag) that the Accuphase amps do indeed work exceptionally well. Appreciably better than the almost myriad of contemporary SS designs tried including even higher powered efforts.

anthonyTD

24-02-2016, 12:41

The Black Adder

24-02-2016, 13:08

Marco

24-02-2016, 16:05

Hi Marco,
When you get them, leave them in a nice warm room to re-adjust to normal temp after being in transit, and after fitting them, leave the amp in standby mode for at least 15 to 20 minutes before switching on the HT, this will give the valves internals the best chance to stabilise slowly after being bumped, and knocked about in transit.
Let me know how you get on, i will write a bit about my personal thoughts on the KT150 at a later date.

Hi Anthony,

Cheers for that info... TBH, I wouldn't even have considered any of that! Will let you know what I think when they arrive (still stuck in customs at the moment) :)

Btw, do you know any of the guys at Hot Rox? I spoke to someone there called Mark (on 4th Feb), who was supposed to phone me back when he had taken delivery of more KT150s, which he said was in two weeks (from 4th Feb).

It's now 24th Feb, and I've heard zilchoid from him. Not that it matters now, as I've bought the KT150s from the States, but it shows you how some places just can't be arsed/aren't organised properly to follow up customer enquiries! Not what I'd call good service... :doh:

I guess they must not need the business!! :rolleyes:

Marco.

anthonyTD

25-02-2016, 11:57

Hi Marco,
I have dealt with Mark at Hotrox many times over the years, i think the work load there is probably to blame, they are very busy these days.
But also understand from a customer point of view, the frustration of not knowing, or being informed etc.
A...
Hi Anthony,

Cheers for that info... TBH, I wouldn't even have considered any of that! Will let you know what I think when they arrive (still stuck in customs at the moment) :)

Btw, do you know any of the guys at Hot Rox? I spoke to someone there called Mark (on 4th Feb), who was supposed to phone me back when he had taken delivery of more KT150s, which he said was in two weeks (from 4th Feb).

It's now 24th Feb, and I've heard zilchoid from him. Not that it matters now, as I've bought the KT150s from the States, but it shows you how some places just can't be arsed/aren't organised properly to follow up customer enquiries! Not what I'd call good service... :doh:

I guess they must not need the business!! :rolleyes:

Marco.

The Black Adder

25-02-2016, 12:07

They were fine with me... They took 3 days to arrive. They were a little slow on answering my emails though.

No excuse to not keep you informed though.

Marco

25-02-2016, 12:08

Indeed (on both counts), and I appreciate the work load aspect. However, it would be interesting to phone up Mark now, after the suggested 2 week waiting period has elapsed, and find out if any progress has been made on the KT150 front, or whether my enquiry has simply been 'filed away and forgotten about'...

In the interests of gauging their standards of customer service, I shall do that and report the outcome. Next time you speak to Mark, however, you should mention the experience I've had (and my position of influence here, both as forum owner and as a serious buyer, not a time waster), and see what he says ;)

As an aside, any idea why Watford Valves (whom I know you're also friendly with) don't stock KT150s. Why is it that Hot Rox are the only UK stockists? :hmm:

Marco.

Marco

25-02-2016, 12:10

They were fine with me... They took 3 days to arrive.

Yes, you were lucky because the required valves were in stock :)

Otherwise, it's piss-poor if other folks, living in the UK, want to order a matched quad of KT150s, and have to wait goodness knows how long to get them! Or be like me, forced to import them from the States, with all that that entails.

Marco.

struth

25-02-2016, 12:18

Guess its the old story of were the only stockists so we dont have to work on our customer service... May not be foremost in their minds but it can creep in if your not careful

Marco

25-02-2016, 12:23

Yup, in business, being 'too busy' to handle a sale that might seem like 'small beer', can quickly turn into times when you'd only be too grateful for such a sale! ;)

Marco.

anthonyTD

25-02-2016, 13:07

Hi Marco,
I will indeed mention the frustration experienced by potential customers next time i speak with him!
As for Derek not stocking the KT150, i guess its something he doesent want to get into at the moment, i think it was only due to me explaining my findings in a conversation i had with him, why he decided on stocking the KT120's.
Indeed (on both counts), and I appreciate the work load aspect. However, it would be interesting to phone up Mark now, after the suggested 2 week waiting period has elapsed, and find out if any progress has been made on the KT150 front, or whether my enquiry has simply been 'filed away and forgotten about'...

In the interests of gauging their standards of customer service, I shall do that and report the outcome. Next time you speak to Mark, however, you should mention the experience I've had (and my position of influence here, both as forum owner and as a serious buyer, not a time waster), and see what he says ;)

As an aside, any idea why Watford Valves (whom I know you're also friendly with) don't stock KT150s. Why is it that Hot Rox are the only UK stockists? :hmm:

Marco.

Marco

25-02-2016, 14:46

Ok, I've just phoned Hot Rox, and spoken to a lady there who was most helpful, who informed me that they've received more stock of KT150s, now enabling them to supply both matched pairs and quads, also even in the low to medium emission variety I would've required for the Copper amp. In that respect, they have pairs in the high 70s, and quads in the high 80s...

Still, it would've been nice to have been contacted, as promised, although I guess it could've slipped Mark's mind (we're all human). Anyway, if anyone else is looking to obtain matched pairs or quads of KT150s, now's the time! :cool:

Marco.

anthonyTD

25-02-2016, 15:20

You probably spoke with Toni, yes, its quite posible it slipped Marks mind.
Ok, I've just phoned Hot Rox, and spoken to a lady there who was most helpful, who informed me that they've received more stock of KT150s, now enabling them to supply both matched pairs and quads, also even in the low to medium emission variety I would've required for the Copper amp. In that respect, they have pairs in the high 70s, and quads in the high 80s...

Still, it would've been nice to have been contacted, as promised, although I guess it could've slipped Mark's mind (we're all human). Anyway, if anyone else is looking to obtain matched pairs or quads of KT150s, now's the time! :cool:

Marco.

Marco

25-02-2016, 15:26

Yeah, no harm done. Both were certainly very helpful and friendly on the phone, so no complaints there :)

Marco.

Marco

26-02-2016, 09:03

Ok, latest update on the KT150s is that they're on the way from the Parcelforce national hub to my local Parcelforce depot in Shrewsbury, where they should arrive there tomorrow, and I'll go and collect them, so I should have them chez-moi for the weekend :yay:

Customs charges were £72.08, which is around what I was expecting. Full report will be posted once they've arrived, allowed to have warmed up and settled, and then plugged in and listened to! :cool:

Marco.

The Black Adder

26-02-2016, 10:00

£72.08 :eek:

anthonyTD

26-02-2016, 10:33

Great!.
Yes, the dreaded customs charges.:rolleyes:
Ok, latest update on the KT150s is that they're on the way from the Parcelforce national hub to my local Parcelforce depot in Shrewsbury, where they should arrive there tomorrow, and I'll go and collect them, so I should have them chez-moi for the weekend :yay:

Customs charges were £72.08, which is around what I was expecting. Full report will be posted once they've arrived, allowed to have warmed up and settled, and then plugged in and listened to! :cool:

Marco.

Marco

26-02-2016, 10:54

£72.08 :eek:

I know... The valves, including cryo-treatment and shipping, came to $466.20, which works out at roughly £334.00 (or £83.50 a valve), so with the tax and import duty included, it comes to a total of £406.08.

Not cheap, so the fuckers better be good!! :eyebrows:

Marco.

Marco

26-02-2016, 11:04

Great!.
Yes, the dreaded customs charges.:rolleyes:

I know, but given what I paid for the valves, I was expecting something around that amount.

I guess that I could've waited the two weeks and got them from Hot Rox, and saved some dosh, but there wasn't any real guarantee that new stock would've arrived within that timescale, and of course the valves wouldn't have been Cryo'd, or (I suspect) tested quite as thoroughly as Kevin has done.

To minimise any risk of failures, I'm going to give them a full 24 hours to 'acclimatise' themselves and come up to room temperature, and then leave them on stand-by mode, for half an hour, before activating the HT on the amp, so it'll be Sunday before I give them a proper listen.

Best to have some patience and do things right! :cool:

Marco.

anthonyTD

26-02-2016, 13:06

Quite Agree!
A...

To minimise any risk of failures, I'm going to give them a full 24 hours to 'acclimatise' themselves and come up to room temperature, and then leave them on stand-by mode, for half an hour, before activating the HT on the amp, so it'll be Sunday before I give them a proper listen.

Best to have some patience and do things right! :cool:

Marco.

The Black Adder

26-02-2016, 14:55

Sounds good... :)

Ali Tait

26-02-2016, 15:09

I know... The valves, including cryo-treatment and shipping, came to $466.20, which works out at roughly £334.00 (or £83.50 a valve), so with the tax and import duty included, it comes to a total of £406.08.

Not cheap, so the fuckers better be good!! :eyebrows:

Marco.

Not that bad if you consider the cost of premium 300b's Marco.

tubehunter

26-02-2016, 16:16

I'd say a bit expensive, compared to

http://uk.farnell.com/multicomp/mj15003/transistor-npn-to-3/dp/1165909?ost=1165909&mckv=sxHrJatVj_dc%7Cpcrid%7C77666563808%7Ckword%7C mj15003%7Cmatch%7Cp%7Cplid%7C&selectedCategoryId=&CMP=KNC-GUK-FUK-GEN-SKU-MDC&gclid=CPLpvsfolcsCFUHkwgodb24IIg&gross_price=true

and these will last a hell of a lot longer

happy days :)

Ali Tait

26-02-2016, 16:17

struth

26-02-2016, 16:19

anthonyTD

26-02-2016, 16:21

Yea, but they dont look as nice, especialy when they get hot! ;)
I'd say a bit expensive, compared to

http://uk.farnell.com/multicomp/mj15003/transistor-npn-to-3/dp/1165909?ost=1165909&mckv=sxHrJatVj_dc%7Cpcrid%7C77666563808%7Ckword%7C mj15003%7Cmatch%7Cp%7Cplid%7C&selectedCategoryId=&CMP=KNC-GUK-FUK-GEN-SKU-MDC&gclid=CPLpvsfolcsCFUHkwgodb24IIg&gross_price=true

and these will last a hell of a lot longer

happy days :)

Marco

26-02-2016, 16:29

Sounds good... :)

Churz. It will be good when I go tomorrow to the Parcelforce depot and pick them up. Toys to play with at the weekend! :D

I always do it that way (by monitoring the tracking info and 'intercepting' their arrival at the depot), rather than waiting an extra day or so for important stuff to be delivered. 1) because I'm an impatient bastid (other than when it's really necessary), and 2) to negate another journey via courier, where the valves could get damaged in transit... One journey less in the back of a truck is good! :exactly:

Handy too, when the local depot is open on a Saturday to facilitate such things :cool:

Marco.

Marco

26-02-2016, 16:31

Not that bad if you consider the cost of premium 300b's Marco.

Aye, good point! Small change in comparison....

Marco.

tubehunter

26-02-2016, 16:35

Can you cryo them ?;)

Of course, I always give them the full 24 hours @ -18c before installing.
:)

http://i514.photobucket.com/albums/t350/halx00/434AEB5F-D311-404F-8CAB-EFAEDD0E31E6_zps2l1meplk.jpg (http://s514.photobucket.com/user/halx00/media/434AEB5F-D311-404F-8CAB-EFAEDD0E31E6_zps2l1meplk.jpg.html)

Marco

26-02-2016, 16:55

Heh-heh.... :lolsign:

I know where I'll shove that next time I see you! :eyebrows:

Marco.

Marco

27-02-2016, 14:40

Well, the KT150s were collected earlier from Parcelforce, then we had a nice spot of lunch at the nearby Mytton and Mermaid (highly recommended, btw, if you're ever in the Shropshire area): http://www.myttonandmermaid.co.uk/index.php Food here: http://www.myttonandmermaid.co.uk/dining.php

...and now home to relax. Box has been duly opened (superb packaging as usual from Upscale), and all seems well. Next will be to 'acclimatise' the valves overnight, and then tomorrow after a short warm up in the amp, minus the HT, have a good listen to these babies! :cool:

Marco.

anthonyTD

27-02-2016, 14:48

:)
Well, the KT150s were collected earlier from Parcelforce, then we had a nice spot of lunch at the nearby Mytton and Mermaid (highly recommended, btw, if you're ever in the Shropshire area): http://www.myttonandmermaid.co.uk/index.php Food here: http://www.myttonandmermaid.co.uk/dining.php

...and now home. Box has been duly opened (superb packaging as usual from Upscale), and all seems well. Now to 'acclimatise' the valves overnight, and then tomorrow after a short warm up in the amp, minus the HT, have a good listen! :cool:

Marco.

The Black Adder

27-02-2016, 16:01

Great stuff... Whack em in tomorrow and enjoy da tooz. They do take a while to open up though.

The Black Adder

28-02-2016, 09:34

Bond, stand aside for today is.... 'The Day of the Gherkin's' :eek: lol

Marco

28-02-2016, 12:04

Lol... I'm just running them in the amp now, with the HT off, ready for all systems GO! :eyebrows:

Marco.

Marco

28-02-2016, 12:53

Ok, HT now on, and all is well so far! :thumbsup:

Now just to sit down and do some proper listening... I'm not going to rush this, or jump to any immediate conclusions, so I'll refrain from making any comments on their sonic performance until I've gotten a proper handle on what they're doing.

Just one immediate thing, they don't appear to have as much 'gain'/loudness, or whatever is the correct term is, as my KT120s, and consequently I've had to turn the preamp up a notch from normal, in order to achieve the same listening levels. That's not an issue, though.

Anthony, I presume that's because these valves are low to medium emission? Jo did you also notice that? :)

I can also hear what you mean about the lack of a 'shouty' quality, in comparison with the KT120s. Even this early on, the KT150s appear to sound 'cleaner', and more 'unforced' and natural.

I *suspect* that could be a by-product of the reduced microphonic effect, due to how their glass envelope has been constructed ('gherkin shape'), and thus the 'shoutiness' (or superficially perceived 'brighter' or more forward sound) of the KT120s, in comparison, is simply down to a form of coloration, as there is no lack of genuine openness or top-end extension I can detect so far - but we shall see!

More (much) later.... :cool:

Marco.

The Black Adder

28-02-2016, 13:06

Cool.. :)

I can't say I noticed a reduction in volume but then my room is different to yours, I'm pretty certain your room is more precise than mine. What you might be hearing a less straining (shouty sound) in the midrange, though. Another thing I'm sure you will notice straight away is the air around the midrange.

Yes, initial impressions are not to be officially noted I think as you need time to re-adjust. I had mine running for a few days before I went in to the details. But initial impressions were certainly good. After a few weeks the sound gradually starts to open up more and become more fluid/lucid.

The Black Adder

28-02-2016, 13:13

Ok, HT now on, and all is well so far! :thumbsup:

Now just to sit down and do some proper listening... I'm not going to rush this, or jump to any immediate conclusions, so I'll refrain from making any comments on their sonic performance until I've gotten a proper handle on what they're doing.

Just one immediate thing, they don't appear to have as much 'gain'/loudness, or whatever is the correct term is, as my KT120s, and consequently I've had to turn the preamp up a notch from normal, in order to achieve the same listening levels. That's not an issue, though.

Anthony, I presume that's because these valves are low to medium emission? Jo did you also notice that? :)

I can also hear what you mean about the lack of a 'shouty' quality, in comparison with the KT120s. Even this early on, the KT150s appear to sound more 'natural'.

I *suspect* that could be a by-product of the reduced microphonic effect, due to how their glass envelope has been constructed ('gherkin' shape), and the 'shoutiness' of the KT120s, in comparison, is simply down to a form of coloration, as there is no lack of genuine openness or treble extension - but we shall see!

More (much) later.... :cool:

Marco.

Yes, I put the midrange improvement on the design of the envelope, lot's have commented on this.

Glad it's all going well... Sit back and get some tunes groovin' :)

User211

28-02-2016, 13:33

I reckon if you crank the volume right up to max with no source playing, flick a valve pretty hard (but not too hard - be careful), and you hear nothing through the speakers, you don't really have ANY appreciable microphony issues. So if you hear a difference i.e. less noise with KT150 doing that you are onto a cleaner sounding valve in all likelihood. Whether you like that or not is another issue.;)

anthonyTD

29-02-2016, 09:53

Hi Marco,
Good to hear they arrived intact, and seem to be working fine.
There are some genuine reasons why the KT150 sound diffrent to the KT120's in the same circuit, and being run at the same parameters.
The clues are in the data sheets, but i have my suspicions on whether the info on them is correct, perhaps Nick [Lurcher] could have a look, and comment when he gets a chance.
Anyway, all good so far! :)
A...

Marco

29-02-2016, 13:58

Ok, having now had an extended listen to the KT150s, I can confidently confirm that, in the context of my amp and system, they are a 'no brainer' upgrade over KT120s. Quite simply, if the former work efficaciously in your system, then there's no way you'd return to using the latter...! :nono:

The sonic differences between both are fairly profound, especially in the midrange and bass. I emailed Ian (Walker) yesterday and told him that, in terms of 'electrostatic-like' midrange openness and lucidity, the KT150s were now making my 15" Tannoy Golds sound like Monitor Reds!!

Bass, with the KT150s, is also incredibly tight and 'driven', with massive grip/headroom, extension and ZERO flab. In all honesty, it feels and sounds (in a good way) like I've substituted my Copper amp for a behemoth 500W Krell/300B hybrid.....! :eek:

All the renowned sonic traits of the Copper amp remain in place (in spades), such as its beautiful layering of voices and instruments, portraying them with the requisite amount of 'air' and 'texture', in order to sound lifelike, together with its dynamic alacrity/rhythmic acuity, and ability to 'propel' music along with an infectious élan, thus ensuring the requisite 'grin factor' is conveyed with all music which is meant to be fun to listen to.

However, added to that, with the KT150s in situ, is the most solid and controlled deep bass I've ever heard produced from a valve amp, where here it is veritably solid-state in nature, with its vice-like grip, ensuring that the large 15" cones of my Tannoy DCs were kept in total control, with no hint whatsoever of any looseness or tendency to boom, as can occasionally happen in my smallish room, if one listens beyond a certain volume with certain material.

With the KT150s at the helm, it was as if someone had secretly installed a power supply inside the amp twice as big as the one that was in it, such was the sheer effortlessness of its musical delivery, consequently as you turn up the volume, the sound just gets bigger and bolder, with no sense of strain or sign that the amplifier was being driven beyond its limits. The effect is akin to driving a car with a 3.5-litre engine, cruising along on the motorway at 60mph, and then putting your foot down to see what happens!

Well HUGE and UNADULTERATED FUN is what happens, when you're behind the wheel in such a car, and its the same in my system, when behind the volume control of the Croft, with KT150s powering the Copper amp - it simply allows the Tannoys to reproduce music at truly frightening sound pressure levels, whilst both the amp and speakers stay in total control - and so playing guitar-driven heavy rock music, for example, truly is a pant-wetting riot! :D

However, with KT150s it's not simply all about 'balls-out' fun and dynamics. They are also easily capable of single-ended valve degrees of subtlety, finesse and overall musical communication, and in the midrange they possess all the 'phat' juicy liquidity of 300Bs, but with also serious control at the bottom end. Furthermore, in terms of the underlying noise-floor present, KT150s make 120s sound positively like obstreperous teenagers, such is the solid-state levels of 'blackness behind the music', delivered by the KT150s.

When installing them, the first most notable aspect of this was now how much quieter the background was. A falsely lit 'electronic background' appears to have been replaced with a realistic facsimile of the ambience of a concert hall. When listening to a favourite 1984 LP recording of Mahler's 4th, and with eyes closed, there was nary a hint of speakers present in the room. What was before me instead was a vividly clear sonic picture of the orchestra, almost like being in an actual concert hall, whilst sitting midway back in the stalls.

The physical space portrayed by the recording was practically 'visible'. Each instrument was more accurately represented, in terms of its characteristic tone, colour and dynamic range, and also where it was within a three dimensional space. The musical performance I was experiencing, in that respect, was both proportional and in perspective. The other improvement with the KT150s was in respect of timing and flow. The music flowed more naturally, with more energy and life, than with KT120s, making the listening pleasure both more intense and overall more convincing and 'lifelike'.

Downsides? None that I can now detect. Initially, when swapping over from KT120s, the 150s can sound a little 'subdued' in comparison, and seemingly not as open or 'dynamic' as KT120s. However, with prolonged listening, and particularly as the 150s start to settle/'burn-in' and open up, it becomes quite clear that the KT120s somewhat 'brightly lit' characteristics, in comparison, is false and results from coloration, perhaps derived from the increased microphonic nature of its sub-optimally constructed glass envelope, in comparison with the notably less microphonic nature of the 150s, clearly evident when gently tapping the valves during playback.

The 150s, in my system, also have considerably tightened up the bass, which is a good thing when you're using huge speakers in a relatively small room, making the bass of the 120s in comparison sound somewhat 'heavy' and sloppy, which is not a trait I was aware of before. However, the vice-like grip provided by the KT150s simply shows it up as such, but without making the bass hard or lacking in extension. It's still really 'bouncy' and tuneful; just MUCH more controlled, possessing greater 'kick', such that when low notes exist on recordings, you *really* feel it in your chest!

The KT150, for me, is an altogether cleaner sounding and, arguably, more 'accurate' valve, than the KT120. Whether that or any of the above is due to, as Anthony says, genuine electrical reasons, then I can only surmise, and of course be educated in accordingly. In terms of that, here are the respective specifications for both the KT120 and KT150, taken from the New Sensor website:

KT-120

Plate resistance - 3000 ohms
Heater characteristics - 1.70 to 1.95 A
Plate current – 135 to 165 mA
Plate dissipation –60 watts

KT-150

Plate resistance - 3000 ohms
Heater characteristics - 1.70 to 2.00 A
Plate current – 150 to 180 mA
Plate dissipation –70 watts

You will see that the plate current and dissipation is where the main differences are, so if that's what Anthony is referring to, then I can understand what may have been responsible for what I've heard. However, I really don't know if the increase in plate dissipation current, or plate current draw, is electrically significant. Perhaps Anthony or Nick could weigh in here?

It's also said that the KT150 has a life span of 4000 hours, which is twice the suggested limit for KT120s, and that alone, for some, may make the extra expense worth it. However, I found an interesting piece on the Net about what may be responsible for the sonic differences claimed by many who've tried KT150s, a relevant snippet of which is as follows:

I received an interesting question today about using the new Tung-Sol KT150 in our KT88 designed amps. Besides being arguably one of the ugliest looking new tubes I've seen in quite a while, this tube does specify a pretty heft filament current.

Out of curiosity, I contacted the manufacturer and they confirm that the KT150 typically pulls 1.75A, for a quartet total of 7A, or an increased load of about 9% over a typical KT88 (6.4A) . That shouldn't present a problem, but it's nice to know what the actual outcome will be.

Here's why:

A high filament voltage will make the tube sound brighter than a low one, so if the KT150 causes the 6.3 volt supply to drop 9% (5.78V), you might conclude that the KT150 is "softer sounding" than the stock KT88.

The only way to know for sure how the KT150 really behaves compared to the KT88 is to run them under identical conditions. Since that's not something the end user can do, your conclusion is going to be based an amalgam of circumstances beyond your ability to compensate for. Because our power transformers are of a robust design, a full 9% voltage drop is probably unlikely, but we'll never know until we measure it.

So, if you're buying the Tung-Sols for any reason other than that they remind you of the thingie you used in prison to store your valuables, it's probably worth looking into their affect on the filament voltage supply.

Perhaps the key to their main differences, in comparison with KT120s, lie in their effect on the filament voltage supply?

In that respect, I'm wondering whether my Copper amp could be further optimised, in order to bring out the best of the KT150s, and take full advantage of their 70-watt plate dissipation rating, as I suspect that there *could* be even more to come! Anthony can answer that one for me in due course... ;)

Anyway, I'm certainly very much enjoying what the KT150s are doing in my system, sonically and musically. As such, I would thoroughly recommend them to anyone who owns a quality (large) push-pull valve amp, able to accommodate their electrical demands, as they do raise the bar quite significantly, compared with what's possible from either KT88s or KT120s. Quite simply, this is another league entirely. The 150s aren't cheap, especially when cryo'd, but IMO, the overall gains are worth it in a system able to exploit their rather remarkable talents.

Right, I'm off to get some lunch - more later! :cool:

Marco.

The Black Adder

29-02-2016, 14:18

Great write up, Marco... I have a draft write up in waiting but you have pretty much summed it up... Now, just wait for a month in... ooooooooh boyo! - More of pretty much that's good now is to come.... I found mine open up after a good week or two, from then they just seem to grip the MG's with white knuckles.

I've had nothing but The Chemical Brothers on today and I'm pinned to the freaking wall....! I just don't want to move from my seat. :)

So, as Marco said... If your amp can eat Gherkins, you should feed it some.

:yesbruv::yay:

Marco

29-02-2016, 14:38

There are some genuine reasons why the KT150 sound diffrent to the KT120's in the same circuit, and being run at the same parameters.
The clues are in the data sheets, but i have my suspicions on whether the info on them is correct, perhaps Nick [Lurcher] could have a look, and comment when he gets a chance.

Cheers, mate. In terms of that, see my last (long) post :)

Marco.

struth

29-02-2016, 14:46

Looks like your a happy bunny Marco... Nice one!

Marco

29-02-2016, 14:46

Great write up, Marco... I have a draft write up in waiting but you have pretty much summed it up... Now, just wait for a month in... ooooooooh boyo! - More of pretty much that's good now is to come.... I found mine open up after a good week or two, from then they just seem to grip the MG's with white knuckles.

Sounds great, Jo, so I shall look forward to that! :cool:

I think what we've reported pretty much ties in with what others who've tried them are saying all over the Net, with rather different systems from ours too, so I guess there must be something in it.

Marco.

Marco

29-02-2016, 14:47

Looks like your a happy bunny Marco... Nice one!

Cheers, mate. Yes, it's another punt that's luckily (and happily) paid off! :)

Marco.

anthonyTD

29-02-2016, 16:28

Hi All,
Nice write up Marco,
Glad the wait paid off. :)
Ok, now just reading your data sheet figures on both tubes, i had to re-look at the data sheet myself, and i see that it now seems to have been ammended! :scratch:
The original Anode/plate resistance figure for the KT150 was 9k, which seemed very odd to me, as the 150 had an even higher Anode dissipation figure than the 120's, which usualy evaluates to a lower plate resistance, not higher, this threw me for a while, but as stated, i see now that that figure has been ammended!
When i first got hold of some, [around a year ago now] as you know, i started experimenting with them, and comparing them with the KT120's, The first time i put them in my Soul single ended hybrid amps, i wasnt sure about them at all, having just replaced my KT120's that i had been using in them for a number of years, and therefore, i was not taken with them from the off.
However, i gave them another try in a more conventional single ended amp that i built many years ago, and is now used mostly as an ornament!
In there, they realy seemed to shine, so, i will re-visit the situation with them in my Soul amps, and give them a bit more time, and see if they grow on me, and report back.
Most folk who have used them in push-pull amps seem to be in agreement though, and that is; that they are a definate improvement over the KT120's, which in my opinion, they should be, when examining the two side by side. Although the insides of both have a much greater mass than the KT88, hence the higher power disapation potential, if not supported properly this can be a serious dis-adavantage. Physicaly Comparing the two, the structure inside the 150's are much more rigid, and solid compared to the 120's, therefore, they should have a much lower noise/microphonic nature than the 120's.
This is IMHO something that is a major factor in the way these two great power valves portray music.
Its not that all KT120's are loose inside, but the consistency doesent seem to be there, like it is with the KT150's, I think the manufacturers learnt some great lessons from the KT120, [which by the way' is still a great valve] and just made the new KT range with the 150 at the helm, even better.
A...

TheMooN

29-02-2016, 17:24

Aught to have listened to me months ago Marco! Now where is that smug emoticon when you need it :D

Marco

29-02-2016, 17:26

Lol... Remind me, Roger, what was it you said months ago? So many things get said or recommended here, I lose track! :)

Marco.

Marco

29-02-2016, 17:31

Hi Anthony,

Interesting about the apparent 'looseness' of construction inside KT120s. I had no idea about that... What about this bit here then, which I addressed to you:

Perhaps the key to their main differences, in comparison with KT120s, lie in their effect on the filament voltage supply?

In that respect, I'm wondering whether my Copper amp could be further optimised, in order to bring out the best of the KT150s, and take full advantage of their 70-watt plate dissipation rating, as I suspect that there *could* be even more to come! Anthony can answer that one for me in due course... ;)

See key bit blue....

Could anything be done, in that respect, or it is already as good as it'll get? I'd like to ensure that I'm getting the *most* out of the 150s. I like the sound of these tubes so much, I'd be willing to spend a bit more on optimising my amp to them, if it would be possible and/or worthwhile :)

Marco.

TheMooN

29-02-2016, 18:22

Lol... Remind me, Roger, what was it you said months ago? So many things get said or recommended here, I lose track! :)

Marco.

http://theartofsound.net/forum/showthread.php?42167-Wanted-4-KT120-valves&p=714711&highlight=Kt150#post714711

Marco

29-02-2016, 18:28

Lol... Well done for finding that, amongst many 100s of new threads posted since then in the classifieds section! :eyebrows:

Still, I was right:

Interesting, Roger. I've not yet tried 150s, but Anthony has, and he didn't like them, which has put me off investing in some. No doubt the curiosity factor we get me at some point, though!

And it certainly did - thank goodness! ;)

Looking at that old thread has reminded me of something I wanted to post earlier, showing the differences between the various 8-pin pentode and tetrode valves, all of which I've tried at one point or another:

http://imagizer.imageshack.us/v2/xq90/923/pktaI3.jpg (https://imageshack.com/i/pnpktaI3j)

The KT150 makes the KT88, which I used to think was big, look like a toy!

Marco.

The Black Adder

01-03-2016, 08:55

I missed that too, Roger. Sorry... That's cool, though.. they really are superb.

I feel that they are really getting in to the groove now. I was pretty astonished with the 120's and are still excellent but these.... another league.

anthonyTD

01-03-2016, 12:55

I have now re-fitted them in my Soul mono-blocks, I will let you know my findings, after i have given them more time to work their magic!:)
Initial signs are good, i am not too sure what the reason was for them not sounding as good as they do today, the first time round, :scratch: may have been room temperature, or something else, I have racked my brain this morning, but cant for the life of me remember, anyway, i will give them a decent amount of time in the Soul's this time, before giving my final comments on them.:)
A...

Marco

02-03-2016, 08:44

Interesting one, mate. Perhaps you just didn't give them enough time before? :)

I have to admit that at first I wasn't sure myself, as they sounded a little 'subdued', compared with my KT120s. However, as they gradually warmed up and burnt in, that changed, blossoming into the sound I've described in my review.

Having lived with them now for a few days, for me there's no doubt that KT150s are the cleaner/more neutral sounding tubes, exhibiting the least coloration/distortion. That's not to say that some folk, depending on the system, might still prefer KT120s (or even KT88s), as at the end of the day it's all about the sound that's most pleasing to yer own lugs!

However, one consideration is that if you're tuned your system (and cable choices in particular) to the slightly more forward sonic signature of KT120s, then some adjustments may be needed in order to compensate for the difference in presentation, offered by KT150s. I've already done that by adjusting the feedback a little on the Copper amp.

That done, there's simply no way now I'd go back to using KT120s, as when you get it right, they just have more going from them sonically, and indeed musically :cool:

Marco.

anthonyTD

02-03-2016, 11:03

Hi Marco,
Yes, posibly a bad day when i first tried them, and maybe i should have just left them in until another day, we all do things in haste from time to time.
Thats not to say, that i am totaly convinced yet on the merits of KT150's, over the 120's, or indeed Good KT88's. however, with these new valves, we at least have good alternatives to experiment with.
I will report further on my findings, when i have given them a decent amount of time in my system.
As for something you asked about in an earlier post, regarding optomising your amp further, to fully take advantage of the KT150's, yes, as far as power output is concerned, there is more to be gained, however, to acheive this, you would need to at least change output transformers, and mains transformer, and as we know, its not all about power, you already have more than enough on tap as it is :eyebrows: so' in my opinion, anyone using KT150's in their copper amps, i would continue using them as is, and just enjoy the seemingly impressive merits you have gained from them so far, at least until i come up with something i personaly feel would be worth doing, without compromising the sonic qualities of the copper amps.
I hope this helps.
A...

The Black Adder

24-03-2016, 16:29

So, Marco... How are the KT-150's bedding in?

Marco

28-03-2016, 08:28

Sorry, Jo. Just seen this! Yeah, they're great, mate. Can't say I've noticed them changing too much, sonically, as they've bedded in. However, in my amp, they're an unquestionable no-brainer upgrade over KT120s.

The only thing I want to do now (but it won't be right away) is max-out the Copper amp, so that I can get the absolute most out of the KT150s, in terms of their power output and sonic characteristics. Watch this space for that one! ;)

Marco.

BTH K10A

28-03-2016, 10:05

Marco

28-03-2016, 10:52

BTH K10A

28-03-2016, 11:42

Hi Andy,

You mean in terms of rectifier valves? Yes, both Jo and I use 5U4Gs. In my case Mullards, and in Jo's, I think, Tung Sol. We both prefer them to the GZ34s that were originally fitted to the Copper amps :)

Marco.

Yes, my PE1/100 amp uses a rectifier from that family and when using 5U4G;s I've found the Cossor and Marconi Osram versions to be noticeably better than the rest. Incidentally some Mullard 5U4G's are rebadged MO U52's

User211

28-03-2016, 13:20

The only thing that has stopped me trying U52s is the price. Nay cheap.

I did try Brimar 5U4Gs and I felt they sucked quite badly. I never have any luck with Brimar, as a rule.

EDIT: of course that does NOT mean 5U4Gs are bad. It just means I didn't like the Brimar's.

BTH K10A

28-03-2016, 14:02

Some Brimar's are rebranded MO U52's and should be good.

The prices for U52's KU53's and seem to have gone crazy over the last couple of years but nowhere near as crazy as 274B'S

GZ33 & 37's are another option but it's worth checking that the input capacitance is OK

User211

28-03-2016, 14:39

I just sold some EML 274Bs. I actually prefer the TJ 274B that EML so obviously hate (punched plates as opposed to true mesh). The EMLs look really well made. In my system, they were ultimately too clean i.e. too much to cope with in terms of resolution.

I need to try more NOS options really.

DSJR

28-03-2016, 14:56

The only thing I want to do now (but it won't be right away) is max-out the Copper amp, so that I can get the absolute most out of the KT150s, in terms of their power output and sonic characteristics. Watch this space for that one! ;)

Marco.

Isn't it time the Coper Amp was retired in favour of a new amp, built from the ground up with proper transformers fully able to work with the new valves you like? Otherwise your existing amp is going to be well overstretched and may need physical surgery to accommodate all the new gubbins you'll want to fit. It's a bit like trying to turn a Ford Focus ST into a big-car racer - you can do it, but it's a damned cut-n-shut compromise and will cost loads of money better put to the real thing...

BTH K10A

28-03-2016, 15:50

I was referring to the Western Electric 274B's which cost a small fortune. The modern ones are definitely not the same.

I had a couple of STC 4274A's which I used with a 5 to 4 pin adaptor. There was little to choose between them and some Marconi U52's I have so I sold them. I found another one not long ago for a couple of pounds at the Audiojumble. It that had no print left on it but it had the painted code on the glass pinch inside and the right shape anode structure so I had a good idea it was.

A friend in Germany has my old adaptors and uses them with 5Z3's in his Audio Note amps as he prefers the lower voltage drop. He picks them up quite cheaply and I must admit they sound really good.

As I've not looked for a while I've just checked out pricing on U52's. This ones ridiculous http://www.ebay.com/itm/1x-MARCONI-GEC-OSRAM-U52-CV1071-5U4G-274B-black-base-Cup-getter-Tube-NOS-NIB-212-/291359410430 :mental:

Marco

28-03-2016, 16:42

Isn't it time the Coper Amp was retired in favour of a new amp, built from the ground up with proper transformers fully able to work with the new valves you like? Otherwise your existing amp is going to be well overstretched and may need physical surgery to accommodate all the new gubbins you'll want to fit. It's a bit like trying to turn a Ford Focus ST into a big-car racer - you can do it, but it's a damned cut-n-shut compromise and will cost loads of money better put to the real thing...

Funny you say that, Dave, as that's exactly what'll be happening! Essentially, we'll be starting again with another Copper chassis, as to do it right will require the use of new mains and output transformers. Still, a nice wee project for next year! :cool:

Marco.

User211

28-03-2016, 16:51

I was referring to the Western Electric 274B's which cost a small fortune. The modern ones are definitely not the same.

Yup I thought you were. The TJ is definitely brilliant in my preamp compared to EML and Brimar 5U4G. I quite like their 2A3 too. I tried another NOS 5U4G but I can't remember what it was (I borrowed the Brimar's and whatever it was).

This TJ 274B (/n/+) variant makes me smile. Look at the height of the thing:) Might buy a pair for laughs. But I bet it sounds good, too.

http://g02.a.alicdn.com/kf/HTB1x8d.KFXXXXaMXVXXq6xXFXXXd/1-PC-TJ-FULLMUSIC-274B-n--daya-penyearah-tabung-menggantikan-5U4G-FR-antik-Audio-Amp.jpg_640x640.jpg

Various old NOS jobs will have their own tone, no doubt, and may well better the TJ. No question about that in my mind.

BTH K10A

28-03-2016, 18:28

Yup I thought you were. The TJ is definitely brilliant in my preamp compared to EML and Brimar 5U4G. I quite like their 2A3 too. I tried another NOS 5U4G but I can't remember what it was (I borrowed the Brimar's and whatever it was).

This TJ 274B (/n/+) variant makes me smile. Look at the height of the thing:) Might buy a pair for laughs. But I bet it sounds good, too.

http://g02.a.alicdn.com/kf/HTB1x8d.KFXXXXaMXVXXq6xXFXXXd/1-PC-TJ-FULLMUSIC-274B-n--daya-penyearah-tabung-menggantikan-5U4G-FR-antik-Audio-Amp.jpg_640x640.jpg

Various old NOS jobs will have their own tone, no doubt, and may well better the TJ. No question about that in my mind.

Not as sexy looking as your TJ but a bit of a hidden gem both price and sound wise is the Australian manufactured 5AS4 made by Amalgamated Wireless Valve Co and were branded Super Radiotron, Miniwatt or Mullard. It looks very plain but is a bit of a super tube but you nee to be able to accommodate a current draw of 3 amps.

User211

28-03-2016, 22:06

Cryo'd, not expensive. Will check it out in greater depth.

http://www.ebay.co.uk/itm/5AS4-AWV-Amalgamated-Wireless-Valve-Australia-60s-NIB-NOS-5U4G-Cryo-Vacuum-Tube-/331651344691

BTH K10A

28-03-2016, 22:23

Here's another possible source

http://www.members.westnet.com.au/tubeguru/5V-Rectifiers.html

User211

30-03-2016, 18:59

Since 5U4G is 3A and the pre ran without complaint for hours I might (will) get some.

If the trannies can't supply the current you know about it e.g. sticking a 5V 2A tube in my Lampizator DAC - obvious break up sonically.

User211

30-03-2016, 19:01

Now back to Gherkins - though this is copper amp relevant.