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Radford Revival
21-01-2018, 16:24
As well as some other STA100s that are quite a bit further ahead than this, montesquieu has sent in his STA100 for full restoration

As far as original STA100s go his wasn't in too bad nick as it had previously had been serviced to a good standard, though the intention was to always have it rebuilt and improved in a few areas. While the STA100 is a good amp there are many sensible ways it can be improved in terms of reliability.

Flying leads are visible in the 2nd pic due to output transformer development - Tom's amp was a convenient guinea pig ;)

http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2018/01/DSC_1156.NEF_.jpg

http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2018/01/DSC_1157.NEF_.jpg

http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2018/01/DSC_1158.NEF_.jpg

Oops. This explains why one valve wasn't biasing up at all!
http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2018/01/DSC_1179.NEF_.jpg

Radford Revival
21-01-2018, 16:30
First thing I needed to do was strip down the amp.

Sadly someone had punched some large holes in the chassis where the binding posts go, so this had to be rectified. Luckily I know a friendly local engineer who did me a favour here! Some plates were welded in and ground flush (it's flatter than it looks). All that is needed is holes drills for binding posts. Clearly the whole chassis will be blasted clean and powder coated, I don't think Tom would be too pleased with the current finish ;)

http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2018/01/DSC_1321.NEF_.jpg

http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2018/01/DSC_1322.NEF_.jpg

http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2018/01/DSC_1323.NEF_.jpg

struth
21-01-2018, 16:43
na, thats fine for Tom;)

Radford Revival
21-01-2018, 16:44
na, thats fine for Tom;)

Noted ;) Should save a few quid :D

montesquieu
21-01-2018, 21:08
na, thats fine for Tom;)

Cheeky bugger.:ner:

Nice to see it all coming together Will.

montesquieu
14-02-2018, 19:01
:sofa:

farflungstar
14-02-2018, 20:54
:sofa:Someone's gonna be very happy. Looking good Tom.

Radford Revival
04-07-2018, 21:46
Random progress pics :)

http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2018/07/DSC_1389.NEF_.jpg

http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2018/07/DSC_1403.NEF_.jpg

http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2018/07/DSC_1404.NEF_.jpg

http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2018/07/DSC_1405.NEF_.jpg

http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2018/07/DSC_1406.NEF_.jpg

http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2018/07/DSC_1407.NEF_.jpg

http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2018/07/DSC_1408.NEF_.jpg

http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2018/07/DSC_1436.NEF_.jpg

http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2018/07/DSC_1437.NEF_.jpg

http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2018/07/DSC_1438.NEF_.jpg

http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2018/07/DSC_1439.NEF_.jpg

http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2018/07/DSC_1440.NEF_.jpg

http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2018/07/DSC_1442.NEF_.jpg

http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2018/07/DSC_1444.NEF_.jpg

walpurgis
04-07-2018, 22:06
Looking very good! :thumbsup:

montesquieu
04-07-2018, 22:50
Looking forward to this :)

Radford Revival
04-07-2018, 22:54
Looking forward to this :)

Shouldn't be too bad ;)

Firebottle
05-07-2018, 07:19
Ooh, shiny or what. Super job.

User211
05-07-2018, 12:01
When this returns and you are happy with it I'll bring the Lampi round Tom.

Mind you I am putting more foo in the Lampi like WBT RCA, Teflon sockets and upgraded resistors. Won't happen til August, though. Audio Note do a good UX4 socket but it isn't made of Teflon and I like the idea of Teflon.

The sockets do need replacing otherwise I wouldn't bother with the other foo.

Radford Revival
05-07-2018, 12:11
Tom's amp and all amps built by me are certified Foo Free™ :D (Not that there's anything wrong with experimenting but that's my preferred way to do things)

walpurgis
05-07-2018, 12:20
Tom's amp and all amps built by me are certified Foo Free™ :D)

Do they come with a sticker that says that? :D

montesquieu
05-07-2018, 12:53
When this returns and you are happy with it I'll bring the Lampi round Tom.


I look forward to that. I'll warn the neighbours this time though :)


Tom's amp and all amps built by me are certified Foo Free™

... otherwise you wouldn't get the lid on!

User211
05-07-2018, 14:19
Tom's amp and all amps built by me are certified Foo Free[emoji769] :D (Not that there's anything wrong with experimenting but that's my preferred way to do things)A bit of foo here and there never hurt anyone apart from their wallet.

The use of it can lead to questions of sanity when you look at the prices of some of it.

Still , it's a hobby and people spend money on hobbies. For questionable return in the eyes of others. Especially non-hi-fi types.

Radford Revival
05-07-2018, 18:40
Getting there... ;)

http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2018/07/DSC_1445.NEF_.jpg

Clive
05-07-2018, 19:43
I dread to think what such a beautiful job costs!

REXTON
05-07-2018, 20:03
I dread to think what such a beautiful job costs!

A lot! :eyebrows: But it's probably your final amp destination, certainly will be for me when mine arrives.

Radford Revival
05-07-2018, 21:27
A lot! :eyebrows: But it's probably your final amp destination, certainly will be for me when mine arrives.

:)



In case anyone was wondering, the amp has been power coated Slate Grey which of course wasn't a standard Radford colour, but works nicely.

montesquieu
05-07-2018, 22:08
:)



In case anyone was wondering, the amp has been power coated Slate Grey which of course wasn't a standard Radford colour, but works nicely.

Yes the colour decision was challenging. The original grey is a bit unexciting ... Will offered me the choice of any RAL colour so I bought a swatch and swithered between Mad Scientist's Laboratory Green, assorted coppery / orangey colours, various silvers/champagnes and even lipstick red. All this in flat, metallic or even two-tone with the lid being darker or lighter depending.

Sent me quietly mental for weeks before I settled on a mid-grey sort of colour, neither a dark grey/ shiny near black nor the original flat grey, but something more neutral but still a bit stronger than the original colour, I'm pretty happy with the pics so far it seems to have worked out.

walpurgis
05-07-2018, 22:17
Hmm. Purple 'metalflake' with orange highlights could have been interesting! :lol:

montesquieu
05-07-2018, 22:18
Hmm. Purple 'metalflake' with orange highlights could have been interesting! :lol:

Option number #234 on the spreadsheet as I recall :mental:

walpurgis
05-07-2018, 22:21
:lolsign:

Edward
06-07-2018, 07:36
Hope to have a listen soon.

Tom, hope you still up for having a side by side shoot out with my Sugden amp.

WESTLOWER
06-07-2018, 08:31
Yes the colour decision was challenging. The original grey is a bit unexciting ... Will offered me the choice of any RAL colour so I bought a swatch and swithered between Mad Scientist's Laboratory Green, assorted coppery / orangey colours, various silvers/champagnes and even lipstick red. All this in flat, metallic or even two-tone with the lid being darker or lighter depending.

Sent me quietly mental for weeks before I settled on a mid-grey sort of colour, neither a dark grey/ shiny near black nor the original flat grey, but something more neutral but still a bit stronger than the original colour, I'm pretty happy with the pics so far it seems to have worked out.

what about clad in Green Leather, to match the Thorens TD124 MkII ?

montesquieu
06-07-2018, 10:10
Hope to have a listen soon.

Tom, hope you still up for having a side by side shoot out with my Sugden amp.

Of course. Having had a couple of quality solid state amps up against it I have a reasonable idea what to expect - one of the strengths of the STA100 is that it has most of the attributes of a solid state amp in terms of frequency response and distortion (measuring as good as or better than many solid state amps) while at the same time retaining the musical capabilities of a pentode valve amp. I would expect the Sugden - which comes at things the other way round - to run it close, but the Radford will be more enjoyable into the Tannoys.

User211
06-07-2018, 14:13
I could arrive armed with my Lampi AND 211s and give this Radford a spanking... or maybe not.

It would be interesting I have no doubt.

montesquieu
06-07-2018, 14:26
I could arrive armed with my Lampi AND 211s and give this Radford a spanking... or maybe not.

It would be interesting I have no doubt.

Would be interesting Justin.

Radford Revival
06-07-2018, 18:42
Small update, all the voltage rails are confirmed as working OK!

montesquieu
22-07-2018, 19:07
Quick update and a fuller report to follow ... I picked this up from Will's place yesterday. Bit of a schlep to North Cornwall but definitely worth it to avoid trusting it to a courier. (Also lovely to meet Will and Steve at last). Petrat made the trip too picking up his amp. and no doubt he'll be along to report findings in due course ...

Anyway I'm sure I'll do a more lengthy write-up at some stage, and it's early days with a brand new set of tubes (Sophia Electric KT88s - which I'm reliably informed are identical in their internal design to more mundane Shuguangs, despite their attractive blue glass envelope - though claimed to be some premium iteration of the design, which may still be possible of course). But I thought I'd quickly summarise early findings.

The STA100 was already the best amp I'd heard with my Tannoys, that's including £10k's worth of Leben 1000P which spent some time here, as have quite a few other high-end valve and solid state amplifiers from EAR, Pass, C-J and others. (The Leben ran it pretty close though I have to say).

Initial impressions mainly comprised relief that Will's efforts haven't let out the magic fairly dust. It still sounds like the superbly musical amp I handed over for renovation. Phew for that - first hurdle cleared.

Second thing that jumped out at me was a sense that the already rock solid bottom end - which always sounded as resolute as a solid state amp - is even more textured, defined and articulated than it was before. Will had showed us a few things on his oscilloscope before we got away yesterday but the stand-out one was approx 0.2 distortion at full power at 1kz ... followed by a demonstration that distortion was barely any higher (0.3%) at 40hz .. an astonishing performance for a valve amp.

Will also noted that the work he has done has also significantly improved the high frequency performance and I think this is what lay behind what I was hearing when noting my third main impression, which was the amp's fantastic ability in presenting a sense of the venue in which the recording too place. This isn't in any way to denigrate the STA25 which is a wonderful amp with Tannoys and with Monitor HPDs in particular (which are a bit harder to drive than earlier Monitor Silvers, Golds or Reds), but the STA100 does seem to kick things up a level. Not just the 3D sense with stereo recordings, or a superbly dimensional 2D presentation with mono, but an incredibly real live sense of the recording space acoustic.

I had a brief moment wobble in the evening after some hours listening when one of the NOS ECC88s I had given Will to use in the refurbished amp went crackly on me in the left channel ... I really have terrible luck with NOS valves ... but luckily I had some Brimars to hand - all good. Phew.

Interestingly replacing a £30 / 2m interconnect I bought from ebay because my RFC cable was too short to reach with the STA25 in place also made a significant difference. I'm not the biggest cable believer but the RFC Mercury really lifted musicality up even further.

Anyway I'm absolutely delighted with Will's work on this - I now have an heirloom quality piece of kit that not only sounds great but comes with the peace of mind of having been restored effectively to brand new, by a true craftsman.

I intend to try out some KT90s (which is what I was using previously) though being a Radford I wouldn't expect a massive difference in flavour.

User211
22-07-2018, 19:17
Excellent news Tom. Enjoy. Looking forward to more audiophile rantings so typical of us types when we get something new;):lol:

montesquieu
22-07-2018, 19:24
Excellent news Tom. Enjoy. Looking forward to more audiophile rantings so typical of us types when we get something new;):lol:

Looking forward to hearing the Lampi with it.:D

User211
22-07-2018, 19:28
Looking forward to hearing the Lampi with it.:D

In about a month plus you are on...

User211
22-07-2018, 19:48
I think we all need a pic of the finished product in situ...???

montesquieu
22-07-2018, 20:33
I think we all need a pic of the finished product in situ...???

Dark now. I'll take one tomorrow.

Radford Revival
22-07-2018, 21:23
Here's some pictures ;)

http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2018/07/frontcoveron2.jpg.jpg


http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2018/07/frontsidecoveron2.jpg.jpg


http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2018/07/frontsidetwo3small.jpg.jpg


http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2018/07/sidefront2.jpg.jpg


http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2018/07/toponbiasside2.jpg.jpg


http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2018/07/zoomsideextra2.jpg.jpg

Radford Revival
22-07-2018, 21:27
Missed a few!

http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2018/07/bottom2small.jpg.jpg

http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2018/07/biasside3.jpg.jpg

http://www.radfordrevival.co.uk/wordpress/wp-content/uploads/2018/07/bias2.jpg.jpg

walpurgis
22-07-2018, 21:28
Cor. Looks a treat! :D

Barry
22-07-2018, 21:31
Beautiful work! Well done . :)

Radford Revival
22-07-2018, 21:34
Cor. Looks a treat! :D


Beautiful work! Well done . :)

Many thanks :D

Marco
22-07-2018, 21:36
Awesome stuff as usual, Will. Bet that kept you busy for a wee while! :eyebrows:

Marco.

Radford Revival
22-07-2018, 21:47
Awesome stuff as usual, Will. Bet that kept you busy for a wee while! :eyebrows:

Marco.

Definitely, feels like I need to sleep for a week after finishing that lot!!

Edward
22-07-2018, 21:57
Your workmanship Will is not only first class it is bordering on genius art. Looking forward to listening to this beauty.

User211
22-07-2018, 22:52
Tis very nice - the grey really looks good. Nice, fooless job.;):)

AD Audio
23-07-2018, 16:46
Great job Will and Tom! Hope to hear these beauties at some point!
David

The Black Adder
23-07-2018, 16:49
Looks smashing, Tom.

I bet your well pleased. :)

Groovy! :)

montesquieu
23-07-2018, 16:51
Had my wife in floods last night listening to some Rameau (one of her favourites from the clavecin pieces).

Ultimately, measurement and technical specifications are just a means to an end ... this is what it's all about.

montesquieu
23-07-2018, 18:06
Great job Will and Tom! Hope to hear these beauties at some point!
David

Don't think you are that far from me David (Richmond? Twickenham?) I'm only 5 mins off the M3 at J4/Camberley. You would be most welcome of course.



Looks smashing, Tom.

I bet your well pleased. :)

Groovy! :)

Thanks Josie, indeed I am!

AD Audio
23-07-2018, 18:24
Hi Tom,
I'll definitely take you up on that! I'm in Wimbledon, so yes, not so far. Unfortunately next Sat is sacrosanct (wife's birthday:() otherwise I'd be round like a rabbit being chased by a hunting pack!
David

The Black Adder
23-07-2018, 18:40
Hehe... I bet it sounds great.

Your last amplifier?

Sent from my 9001X using Tapatalk

montesquieu
23-07-2018, 20:27
Hehe... I bet it sounds great.

Your last amplifier?



Undoubtedly the last one in the main system. It's been a fixture since I got it about 3 years ago (or was it four?), seen off all sorts in that time, it's just wonderful to have it back.

That's not to say I won't have a play with other bits for the system in the study ....

Edward
23-07-2018, 20:42
Undoubtedly the last one in the main system. ...

Nah Tom, you will soon want another STA100 and get Will to monoblock them.

Or get 4 altogether and implement vertical and horizontal amping.

At that point you can cancel your central heating.

:lol:

User211
23-07-2018, 20:49
Nah he has the power. You can tell one someone really likes somerhing.

I've been trying to beat my 211s for 10 years odd now despite trying about 30 odd amps. Only one got closeish but it used 20 KT150s. Absurd!

montesquieu
23-07-2018, 20:51
Nah Tom, you will soon want another STA100 and get Will to monoblock them.

Or get 4 altogether and implement vertical and horizontal amping.

At that point you can cancel your central heating.

:lol:

Actually I did have four Audion push pull 300b monoblocks at one point and an active crossover arrangement (into 15in Golds). It looked quite impressive, a long line of 300b amps!

But it while there was more detail active, it sounded more musical and together - just more enjoyable - with the passive crossover in place, and I went back to normal arrangement.



Nah he has the power. You can tell one someone really likes somerhing.

I've been trying to beat my 211s for 10 years odd now despite trying about 30 odd amps. Only one got closeish but it used 20 KT150s. Absurd!


Indeed Justin - I've refined this system to the point where it just sounds 'right' to my ears. Anything that's not a perfect a fit doesn't stay. Seems to me you are the same with your 211s (which I've heard and are truly fab with the Apogees).

Edward
23-07-2018, 21:42
Nah he has the power. You can tell one someone really likes somerhing.

I've been trying to beat my 211s for 10 years odd now despite trying about 30 odd amps. Only one got closeish but it used 20 KT150s. Absurd!

It will be interesting to see if Tom's STA100 gets near your 211s. Or should that be the other way around?

20 KT150s. Sheesh. That must have been a sight. Any pic/link?

Tom and I have a plan for me to come over to his place and have a listen to his STA100. I'll be taking a recently fettled Sugden for a listen on his Tannoys. It will be an interesting comparison - chalk and cheese mind you with the Sugden being SS.

User211
23-07-2018, 22:16
It will be interesting to see if Tom's STA100 gets near your 211s. Or should that be the other way around?

20 KT150s. Sheesh. That must have been a sight. Any pic/link?

Tom and I have a plan for me to come over to his place and have a listen to his STA100. I'll be taking a recently fettled Sugden for a listen on his Tannoys. It will be an interesting comparison - chalk and cheese mind you with the Sugden being SS.

https://9sgbqq.ch.files.1drv.com/y4mkPkpNG35C_IgXc_XU1dD8WnzqvZyfKg_38kZaP2d85uLHw0 Jw4K_XCEMZXotkrLX0Jq_KBI5vedaBtL4iUxpqawlth_lvS-226FkB_Y6-3EVa3cefYledifIH-eXx4MN1NN5yHQm3mu6tfSwonqMBkl-VhJhgr2JXDtVuwP3DRL26MUXZGytF9wEELWIpEBDW8han3KQJ5 uVLRMrKuofNg?width=1600&height=900&cropmode=none

https://9siv1g.ch.files.1drv.com/y4mxOak4EordmtTZkRBALi5vtMhA8RKBUWPlHXRyfxkfONbVwb Qti7Ljrvwb4aYnWMsA9UnbhkS_RHaTPYMIlbkos9JTRd2rgKYE FN6iEhJYQt3K2ZMiB3P5cr-sfPVm6fI0uhWGdp28RsfTb0Swg_d3PPBgDuwvA_uulJWQOhywd b0kzqXFDufi0TcHHUOBZyMDzJitmK5KuSVKUbwkLXfPA?width =1600&height=900&cropmode=none

They did sound good. 400 Watts in Pentode and 250 Watts in triode. Trouble is, they kept shutting down in triode mode. On the 4 Ohm taps in pentode they were fine.

But they weighed stupid amounts - about 8 KG more than the 211s at about 50G each. Oddly the 20 KT150s emitted much less heat than 4 211s. Or seemed to.

A Diva owner tried them - and - they kept shutting down in triode mode. He's using ARC 250 Watt monos with no issues.

Refined sound, no question. Not as alive as the 211s but a great sound nonetheless.

Edward
23-07-2018, 22:21
:stalks: :drool:

User211
23-07-2018, 22:30
:stalks: :drool:

Ah its only looks. Looks are bullshit*.


*repeat after me:)

guero
24-07-2018, 20:20
What a wonderful looking amp- can I ask how it differs in performance to an Sta 25? I would imagine it has even more control and authority than the Sta25..

smangus
24-07-2018, 21:08
It does look lovely, would you consider making them from scratch? Not that I can afford one lol. Bet it would look good in British Racing Green.

montesquieu
24-07-2018, 22:13
What a wonderful looking amp- can I ask how it differs in performance to an Sta 25? I would imagine it has even more control and authority than the Sta25..

In many ways it's very similar to an STA25 and with some speakers you might not hear a massive difference I suspect ... The 35w STA25 is superb with Tannoys generally but to really get the most out of HPDs - which though harder to dive than earlier variants in the Monitor series are capable not just of stunning treble performance but stonking bass as well (the specs for the 12in HPD are similar to 15in Golds in terms of bass response, though with less risk of cone break-up at the crossover point) you need an amp that is more robust at the bottom end and simply has more power available.

The other difference in this amp is its clarity in the treble, not that the STA25 is in any way inadequate in this regard but it just seems that bit more capable at presenting room ambience - I suspect this is where the vanishingly low distortion figures come into play.

But as I say with some music there's not a great deal of difference, it's only at the extremes where the extra capability becomes apprent in any obvious way.

guero
25-07-2018, 05:32
Thanks for describing the two amps, very informative.

nickbaba
27-07-2018, 21:53
Congratulations, Tom - I was waiting to see when you would post about this. I saw David Coe today and he mentioned you had collected it. Very happy for you that it's everything you hoped for after such a long wait. It sure is a beauty!

User211
28-07-2018, 08:59
The KR KT88 is reasonably priced. 596 Euro plus VAT for a quad from Best300B.

My bet is they'll be worth every penny and will transform the amp for the better.

nickbaba
28-07-2018, 09:32
Would be fun to hear the TT100 alongside the STA100 sometime - I'd be curious to hear if there's a big difference or not.

REXTON
28-07-2018, 10:59
Would be fun to hear the TT100 alongside the STA100 sometime - I'd be curious to hear if there's a big difference or not.

I will probably be making similar comparisons with the sta100 against my sondeX s100 at some point in the year.

nickbaba
28-07-2018, 11:57
Yes, that would be interesting! I would imagine the Sondex, being all valve, would be closer to the STA100 in sound... I'm curious to hear what, if any, difference the FET solid-state inputs make to the sound, seeing as the rest of the TT circuit is very similar to the STA100.
Also, to quote a post here "the output transformers in the TT100 were wound for 4-8 ohms - much more sensible for modern speaker loads than the 8-16 ohm/100v setup of the original STA100" - but I'm not sure if that applies to Tom's RR STA100 anymore, as I guess it's been somewhat modernized?

nickbaba
28-07-2018, 11:59
However, it's clear that the (new) STA100 is far more beautiful to behold than my TT100, which is a basically huge black metal box!

montesquieu
28-07-2018, 12:16
Yes, that would be interesting! I would imagine the Sondex, being all valve, would be closer to the STA100 in sound... I'm curious to hear what, if any, difference the FET solid-state inputs make to the sound, seeing as the rest of the TT circuit is very similar to the STA100.
Also, to quote a post here "the output transformers in the TT100 were wound for 4-8 ohms - much more sensible for modern speaker loads than the 8-16 ohm/100v setup of the original STA100" - but I'm not sure if that applies to Tom's RR STA100 anymore, as I guess it's been somewhat modernized?

Yes indeed Will had new transformers wound which I believe were based on the TT100 transformers - I never heard it with the original 100v line transformers as one was found to be slightly faulty and I had them replaced at the outset when it was originally serviced.

David is coming round on Thursday so he may be able to give a view, though different sources and speakers so it may be hard to discern quite what is doing what.


The KR KT88 is reasonably priced. 596 Euro plus VAT for a quad from Best300B.

My bet is they'll be worth every penny and will transform the amp for the better.

Thanks Justin I thought they were more expensive than that I'll investigate.

User211
28-07-2018, 13:28
I really think they will be worth a go, Tom. All the KR valves I have tried have been nice.

I think they have priced it right since amps that use KT88s generally use at least a quad of them. And they want a chunk of that US power amp tendency to use a lot more than that!

I firmly believe that a large part of the difference between a good valve power amp and an appreciably better one is down to the output valve quality.

AD Audio
28-07-2018, 13:32
Hi All,
Will told me he wound /winds the new transformers with only a 6 ohm tap. That still gives max power at 8ohms and works better with modern speakers.

Yes, I'm looking forward to some early impressions on Thursday and happy to host a bake off at a later date.
David

Sent from my ONEPLUS A5000 using Tapatalk

Radford Revival
28-07-2018, 13:35
The transformers in Tom's and Peter's amp are my own special design and can be set for 4, 8, or 16 ohms (though maximum power transfer happens around 3, 6 and 12 ohms) but are an absolute nightmare to wire up!

"4", "8", and "16" ohms is really a rough terminology, usually it means that the said impedance reflects the design centre impedance / often a datasheed suggested value on the anodes. Normally I aim for a slightly lower than the stated value to take into account "difficult" 8 ohm loads etc

nickbaba
28-07-2018, 13:48
Thanks for the info, Will - excellent work!


Will had new transformers wound which I believe were based on the TT100 transformers

Interesting... so that should place the STA/TT sound even closer overall, and all things being equal the difference between the valve and FET input stages, if any, should be easier to hear.

Radford Revival
28-07-2018, 13:56
Thanks for the info, Will - excellent work!



Interesting... so that should place the STA/TT sound even closer overall, and all things being equal the difference between the valve and FET input stages, if any, should be easier to hear.

They shouldn't sound a million miles apart, given in any well designed amp using valves in its output stage, any residual distortion should be dominated by said output stage and linearised with the use of feedback

nickbaba
28-07-2018, 14:16
That's great to know Will, thank you.

My TT100 sounds fantastic to me, that's for sure, and soundwise beats my previous amp, an EAR 890 (hence currently for sale on AoS!).

Edward
29-07-2018, 11:20
Tom kindly invited Adam and I over yesterday and we had a wonderful time listening to the STA100.

So after a lovely lunch (thanks Tom! - you should open a restaurant) we sat down and had a few hours with different things. All three of us are familiar with the unique Tannoy/Radford STA25 marriage so were ideally placed to detect the difference the STA100 is able to give. In a word - awesome. Another word - effortless. Last year I had a mini listen to a part finished STA100 at Will's place driving his RFC Raptors so I knew I was in for something special.

The STA100 lift things altogether to another level. It simply breathes music in a totally uncompressed and unrestrained manner. No matter what Tom threw at it the STA100 just picks it up and presents it in a totally natural and open way.

The STA100 is able to take the most delicate or thunderous tracks and present it cleanly without fuss or fanfare. Notes start exactly where they should and stop with natural decay. Huge dynamic passage are almost frightening to the listener but the STA100 just sails through it - never complaining. All obviously helped by the Tannoy setup Tom has. The STA100 has a vice like grip on the Tannoys.

One thing that Tom demonstrated which I don't think I have ever experienced before is playing a mono LP (Cannonball Adderley etc - Somethin' Else) via a mono cartridge and mono SUT. This was completely captivating. The ease and naturalness that was heard completely drew me in and made me feel I was there. Who wants stereo when one can have this incredible sound.

Tom played around with various SUTs and also played some CDs. Vinyl rocks!

Tom wired in my Sugden amp (35w pure class a) and we all agreed that the Sugden played wonderfully and held the Tannoys incredibly well - but alas the STA100 and its valve sound won the day.

Thanks Tom for taking the time and being such a great host.

Radford Revival
29-07-2018, 11:47
Very happy to hear the amp is doing its job - many thanks for the positive review of it sounding good in Tom's system ;) Credit for the sound is of course also due to Paul / RFC for his Canterbury cabinets and crossovers.

nickbaba
29-07-2018, 14:41
100w Radfords Rule!! :fingers:

WESTLOWER
29-07-2018, 22:30
Yes well said Edward. The synergy Tom has put together to get the most from the music he collects and loves is the key here. Every element is thoughtfully introduced and if it isnít of the required standard it goes. The Radford STA100 is an endpoint for any system but for Tomís brew itís perfect. Perfect is a big word in this game and one should utter it with care, but in this system the word fits. I had my doubts Iíd be able to really agree on the justification of extra power the STA100 delivers over the smaller stablemate, the STA25. I have the STA25 feeding Tannoy Monitor Gold 12Ē in RFC custom cabinets, and quite frankly it just works so well.

The STA100 delivers music, as said by Edward, with ease and feels so effortless and in control, not that the STA25 doesnít but this is just something else, something different which is hard to articulate. I said on the day it feels like one of those New big arsed Rolls Royce cars, classsy, big, luxurious with all that power to pull away, and plenty in reserve.
I havenít even touched on the looks, which are beautiful in an industrial sort of way but finished with a delicious paint job
But looks ainít what itís about. Itís a special amplifier, and if you have thoughts on big Tannoy cabinets with current hungry drivers, then the STA100 should be on your radar.
Top restoration job Will, you should be proud, Tom is!

montesquieu
03-08-2018, 16:50
Yes well said Edward. The synergy Tom has put together to get the most from the music he collects and loves is the key here. Every element is thoughtfully introduced and if it isn’t of the required standard it goes. The Radford STA100 is an endpoint for any system but for Tom’s brew it’s perfect. Perfect is a big word in this game and one should utter it with care, but in this system the word fits. I had my doubts I’d be able to really agree on the justification of extra power the STA100 delivers over the smaller stablemate, the STA25. I have the STA25 feeding Tannoy Monitor Gold 12” in RFC custom cabinets, and quite frankly it just works so well.

The STA100 delivers music, as said by Edward, with ease and feels so effortless and in control, not that the STA25 doesn’t but this is just something else, something different which is hard to articulate. I said on the day it feels like one of those New big arsed Rolls Royce cars, classsy, big, luxurious with all that power to pull away, and plenty in reserve.
I haven’t even touched on the looks, which are beautiful in an industrial sort of way but finished with a delicious paint job
But looks ain’t what it’s about. It’s a special amplifier, and if you have thoughts on big Tannoy cabinets with current hungry drivers, then the STA100 should be on your radar.
Top restoration job Will, you should be proud, Tom is!


Thanks Adam, yes with the benefit of a bit of miles on the clock the grin on my face just gets bigger ... in so many ways it's the same amp that was send down for restoration, the sound is still as clean and powerful and 'right' as it was before. And yet the improvement is palpable, the atmospherics are something else, the bass just that bit more defined, the detail that bit more perceptible, all without losing that relaxed effortlessness and snappy agility when it comes to timing.

Indeed - very happy.

Herrmann
24-12-2018, 08:07
Hi.

I realize this is an old thread, but I have a question:
Is the restored STA100 still running the output valves in Ultra Linear mode at 600 Volts?

Torben

AD Audio
24-12-2018, 10:35
The answer is yes. If you look at the TT100 restoration thread you will see that KR100s wouldn't work with the same anode / screen volts whilst Genalex and GE ones were perfectly happy. But why the question?

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Herrmann
24-12-2018, 15:16
I am interested because I own an STA100. I got it from my teenage brother in 1982. It destroyed Gold Lions one after another until I set the current a lot lower and used GE6550A's instead. It has stayed in service with another family member for nearly 30 years but is now back with me. I was told, that it had started to distort (that is all I know so I will have to take a look at it). I would feel more comfortable with a somewhat lower B+. These valves are quite expensive.
I will have a look at the TT100 thread. Thanks.

montesquieu
24-12-2018, 16:26
I am interested because I own an STA100. I got it from my teenage brother in 1982. It destroyed Gold Lions one after another until I set the current a lot lower and used GE6550A's instead. It has stayed in service with another family member for nearly 30 years but is now back with me. I was told, that it had started to distort (that is all I know so I will have to take a look at it). I would feel more comfortable with a somewhat lower B+. These valves are quite expensive.
I will have a look at the TT100 thread. Thanks.

Yes the STA100 was known for putting stress on KT88s especially modern ones. But I ran mine very happily unmodified with KT90s for several years before it went to Will for restoration - prior to that it had only had some fresh wiring in a couple of key places, a few electrolytics changed, and the big caps carefully reformed after some years of reuse. It ran fine at the full voltage. There are some tricks getting the splitters balanced though.

Talk to Will at Radford revival he may be able to bring yours back to life he has just completed ground up restoration of five of these including mine and I’m sure would turn yours around quickly. It cost me £100 shipped from Finland on a pallet when I first got it so in the grand scheme shipping isn’t a barrier.

AD Audio
24-12-2018, 17:24
Hi Hermann
Out of interest what did you lower the bias to? The standard setting of 2v or 60ma is not unusual for modern kt88s.My Leben runs KR88s at the same bias point and the Cannonball amps I build run them harder in Class A. When you change tubes on the Radford you should rebalance the output tubes with the internal pot for each channel. It's not that difficult if you've got an oscilloscope and dummy load, but if you're not teccy of course it's a bit complex and you need to take the bottom cover off, exposing high voltages.
Cheers
David

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Herrmann
24-12-2018, 21:28
Hi
I lowered the current to 50 mA corresponding to a total dissipation of 30 W.

I know the purpose of the balance pots, and I do have access to all the necessary equipment.
When I get the time (may be a while) I will power it up carefully. I am not convinced there is anything wrong with it at all.

Torben

AD Audio
25-12-2018, 10:49
I'm sure it's not the overall dissipation at 60ma that's the issue. I think it's the high screen voltage. If it was my amp I would do two things:
1. Add the choke in as per the tt100 power supply which will lower HT slightly
2. Add an additional heater supply for two of the output valves and run the higher rated (and to my ears sweeter sounding) KT120s (or even kt150s if they'll fit!)

I've never tried kt90s but from the spec are higher rated and would do the job very well. The Radford design tends to minimise the impact of the tube sound anyway.

Happy Christmas!
David


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