Valve power - feel the force!

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Originally Posted by Marco

I don't hear any "clipping", and so don't need to "pay attention", JC. The bottom line is my valve amps sound simply wonderful - better to my ears than any solid-state designs at any price I've owned or heard, and this is all that matters to me. I really couldn’t give a monkey’s about anything else! :)

Marco.

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Ahem, the clipping is there, you are in denial. :eyebrows: ;)

You have become accustomed to that particular distortion and to you, it sounds "right" and "musical".

Another listener would be able to identify that phenomenon and in my opinion if the ss amp were sufficiently powerful would correctly identify it as "superior".

This situation is usually glibly resolved by saying, everyones opinion is valid and it simply boils down to personal preference.

Please allow me that preference without telling me only your ears are a criterium. :)

There has been a considerable amount or informed research on this topic, I expect Ashley has reminded you of it.

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Originally Posted by jcbrum

Please allow me that preference without telling me only your ears are a criterium. :)

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Criterion.

Now playing:

'Shit Arm, Bad Tattoo' by Half Man Half Biscuit.

"If you must quote from The Book of Revelation
Don't keep calling it The Book of Revelations
There's no s, it's the Book of Revelation
As revealed to Saint John the Divine
(See also Mary Hopkin, she must despair)"

'Upon Westminster Bridge'

"Oh help me Mrs Medlicott
I don't know what to do
I've only got three bullets
And there's four of Motley Crue"

I don't give a toss about "informed research", JC. Why should I? I'm not a manufacturer. It's my system and I'm delighted with it, so therefore my ears are the most important arbiter, not Ashley's!

My current valve amps sound better than any solid-state amps I've heard or owned - simple.

I see your pal's bottled out of the meeting again, incidentally.

Marco.

P.S Iain - nicely corrected. I was going to point out JC's error myself but felt it somewhat cruel ;)

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Originally Posted by jcbrum

...you are in denial...

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There's only one person in denial here, and it ain't Marco!

Precisely, mate! :eyebrows:

Have you completed your erudite appraisal yet of those ADM9s you had the pleasure of hearing?

Marco.

A CRITERIUM is a combination of CRITERION and CREMATORIUM

How's that for a red-hot established standard ?

Obviously burnt at the altar of conventional audio by J.C.Brum

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Originally Posted by Marco

P.S Iain - nicely corrected. I was going to point out JC's error myself but felt it somewhat cruel ;)

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I agonised for a while before posting; are ears a criterion, or must they, being plural, be criteria? But even my pedantry has its limits!

J.C.,why all the talk about clipping? 0.5w per channel output power is ample if your speakers are sensitive enough.Witness Steve Sheils open baffle speakers at Owstfest,driven by his amp at around 1.5 watts,effortlessly filling what is a very large room(compared to the average living-room).High-power amps are common because there are so many poorly designed commercial speakers around,with insensitive drivers and complicated crossovers sapping the current available from the amp.If they were designed correctly in the first place,300w or so per channel would never be needed!

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Originally Posted by Mike Reed

A CRITERIUM is a combination of CRITERION and CREMATORIUM

How's that for a red-hot established standard ?

Obviously burnt at the altar of conventional audio by J.C.Brum

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Hilarious! :D

:dynamite:

Marco.

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Originally Posted by Iain Sinclair

Criterion.

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Well spotted Iain, I didn't notice my spell checker alter my post.

Bet you don't know what a criterium is without looking it up ? :)

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Originally Posted by jcbrum

Well spotted Iain, I didn't notice my spell checker alter my post.

Bet you don't know what a criterium is without looking it up ? :)

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A place where criters live?

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Originally Posted by jcbrum

Bet you don't know what a criterium is without looking it up ? :)

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Bike race.....

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Originally Posted by Ali Tait

J.C.,why all the talk about clipping?

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Well having just heard Marco's bad news, it's perhaps not the best time to elaborate this thread. However Marco described his amp as 60w, whereas I suspect that if fed a continuous duty signal at high level, such as I use to test my amps, then it would struggle to sustain 30w. This is only my estimation based on his description of the components.

Marco said he listened at a very high level on sp100's. A combination of a knowledge of electronic circuit modeling, and experience with that type of amp and those speakers suggest that under those operating conditions, clipping is unavoidable.

This is reinforced by Marco's suggestion that to his ears, his amp sounds better than any other amp he has heard, particularly ss ones, and is exceptionally "musical".

Conclusion: His amp is almost certainly clipping and he likes the effect so much that he thinks its better than anything else he's heard.

For my purposes, therefore his ears are unsatisfactory, although I accept he is very attached to them. :)

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Originally Posted by Shian7

Bike race.....

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:):):):):):) Well done Mike ! :):):):):):)

(did you look it up ?)

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Originally Posted by Iain Sinclair

A place where criters live?

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vg :lolsign:

Bollocks, JC! I suggest you come and listen before writing such ill-informed nonsense. You haven't heard my system so you don't have a clue what you're talking about, amigo! Stick to your little computer speakers and give me peace :lol:

What "bad news"? Ashley's bottling out of our meeting yet again? It was highly predictable!

Marco.

Marco,what is the quoted sensitivity of the Spendors?

90db, mate, and an easy 8ohms load. The Yaqin drives them to serious levels, believe me, and there is no (audible) clipping!

Marco.

Ok Marco I'll listen to them, just to please you. :)

I thought you were looking forward to going to AVI ? what happened ? :(

p.s. I have heard lots of valve amps you know as well as owning them myself in the sixties and seventies, and I do know what sp100's sound like, but I'll accept I haven't heard yours. :)

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I thought you were looking forward to going to AVI ? what happened ?

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I was, but Ashley read my account of listening to my valve amp with dance music at rather naughty levels and has concluded that I'm somewhat too uncouth to appreciate ADM9s! :lol:

I'm glad you're coming to have a listen. Prepare to have your misguided preconceptions rudely readjusted! :eyebrows:

Marco.

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Originally Posted by lurcher

Just pointing out that the presense of the output transformer does slight alter the equivilance your analogy requires.

Though I wonder if the transformer is responsible for valve amps having seemingly effortless dynamics, the transformer itself is a store of energy (in its flux), so its a simpiler process for that to be dumped into the speaker. The output stage of a SS amp contains no sources of stored energy, and merely allow the energy stored in the power supply caps to flow towards the speakers. And then of course the flow of that current is restricted by the ESR and other problems that plague large caps.

And that another difference, to store the same energy the size of a cap in valve amplifier the cap can be smaller, as the stored energy is proportional to the square of the voltage, but directly proportional to the capacitance.

Hmm, maybe that was what you were trying to show with your anaolgy, I will get my coat...

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quite right,
and i agree about the output transformer playing a big part in this, after-all, they have to reflect a relitively high impedence/high voltage/low current primary into a low impedence/low voltage[in comparison to the primary] high current capable secondary in order to drive the loudspeaker! as i stated in my original post i tried to simplfy things to get my point across to most of the folk on here, wether they be technicaly minded or not, it would seem i didnt go into things quite enough for some, but thats ok, and i am glad that you expanded the explanation. the point jc is missing with solid state amps is this,the reason they clip so violently and need huge amounts of power to overcome this problem is because of the amount of feedback involved in their circuitry used to linearise the devices used.
anthony...

He's trying to slither his way around that, though, Anthony.

Marco.

My favorite nosh is a small baguette, or two slices of a medium loaf "rustic crusty" variety, with a thin slice of "parma" type ham, any air dried is ok., with black pepper and lemon juice on it., and a large mug of tea, minimum milk, and a tbsp of Irish W.

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Originally Posted by Marco

He's trying to slither his way around that, though, Anthony.

Marco.

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wtf are you on about ?

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My favorite nosh is a small baguette, or two slices of a medium loaf "rustic crusty" variety, with a thin slice of "parma" type ham, any air dried is ok., with black pepper and lemon juice on it., and a large mug of tea, minimum milk, and a tbsp of Irish W.

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I shall mention it to my chef :smoking:

Marco.

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Originally Posted by jcbrum

wtf are you on about ?

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Read Anthony's last post and attempt to discredit it, then, particularly this bit:

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the point jc is missing with solid state amps is this,the reason they clip so violently and need huge amounts of power to overcome this problem is because of the amount of feedback involved in their circuitry used to linearise the devices used.

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Marco.

Plenty power for those then Marco.I still have a pair of B&W P5's that I used to use as my main speakers.These are 90dB,and I've driven them with an original wooden-sleeved Sugden A21(7 watts per channel with a tail-wind) to some pretty high SPL's.

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Originally Posted by anthonyTD

quite right,
and i agree about the output transformer playing a big part in this, after-all, they have to reflect a relitively high impedence/high voltage/low current primary into a low impedence/low voltage[in comparison to the primary] high current capable secondary in order to drive the loudspeaker! as i stated in my original post i tried to simplfy things to get my point across to most of the folk on here, wether they be technicaly minded or not, it would seem i didnt go into things quite enough for some, but thats ok, and i am glad that you expanded the explanation. the point jc is missing with solid state amps is this,the reason they clip so violently and need huge amounts of power to overcome this problem is because of the amount of feedback involved in their circuitry used to linearise the devices used.
anthony...

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I (respectfully for anthony only, as a fellow engineer) disagree entirely. Feedback has nothing to do with it, that simply sets the gain. The reason is that the rise times are MUCH faster in a ss amp, therfore allowing it to emulate a square wave much more readily. This is what produces the prodigious harmonics.

Because a valve amp has it's output transformer in circuit, that has considerable inductance which modifies the wave form to approximate a sinusoidal one rather than a square wave.
This is the whole problem with output transformer design, to allow a small enough inductive effect to pass the higher frequencies accurately, rather than suffer HF fall-off, which incidentally, since it's on Chinese transformers, Marco's amp probably suffers from as well.
Therefore the output from a transformer coupled valve amp clips in a "sinusoidal" fashion and produces "musical" harmonics.
Whereas the ss amp clips in a much more flat topped fashion, more approximating to a square wave, with horrible sounding harmonics.

BUT, if you make the ss amp very powerful so that it doesn't clip then it sounds the best of all. (providing you haven't got to like the sound of valves clipping and confuse it with "musicality").

p.s. all this is very easy to see on a scope and that is the way you can "educate" your ears ! :)

Perhaps so,but as I said earlier,if your speakers are sensitive enough,clipping will not occur.

Indeed, Ali. I know all too well what clipping sounds like and there was none at the levels I was listening to Tiesto at last night! The system just rocked in a very brutish and uncouth (but non-distorted) way, which is perfect for dance music, but maybe not so for those with more delicate sensibilities! :lol:

Marco.

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Originally Posted by jcbrum

I (respectfully for anthony only, as a fellow engineer) disagree entirely. Feedback has nothing to do with it, that simply sets the gain. The reason is that the rise times are MUCH faster in a ss amp, therfore allowing it to emulate a square wave much more readily. This is what produces the prodigious harmonics.

Because a valve amp has it's output transformer in circuit, that has considerable inductance which modifies the wave form to approximate a sinusoidal one rather than a square wave.
This is the whole problem with output transformer design, to allow a small enough inductive effect to pass the higher frequencies accurately, rather than suffer HF fall-off, which incidentally, since it's on Chinese transformers, Marco's amp probably suffers from as well.
Therefore the output from a transformer coupled valve amp clips in a "sinusoidal" fashion and produces "musical" harmonics.
Whereas the ss amp clips in a much more flat topped fashion, more approximating to a square wave, with horrible sounding harmonics.

BUT, if you make the ss amp very powerful so that it doesn't clip then it sounds the best of all. (providing you haven't got to like the sound of valves clipping and confuse it with "musicality").

p.s. all this is very easy to see on a scope and that is the way you can "educate" your ears ! :)

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jc,
i use signal generators and scopes to test all the equipment that comes through my workshops, and i am quite aware of what an amplifier looks like when clipped, i also test them for frequency response at diffrent levels of power output. marco's amp tested well, it gave a true 60 watt RMS output into a constant 6.8 ohm load, at 1khz. its frequency response was flat from 7 hz to 100khz tested at half power!
the best solid state amplifiers i have heard are the simple ones, ie, using the minimum amount of devices, with the least amount of feedback, but sadly only producing around 10 watts. also, the first transistor amplifiers which by the way sounded pretty good when using gemanium [spellin] transistors were transformer coupled, like valves!
you hit the nail on the head when you said about using feedback sets the gain, feedback does various things when used in amplifier designs but the main three things it does are, reduce distortion,[ by linearising] increase damping factor, and de-crease gain!
anthony...

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Originally Posted by anthonyTD

marco's amp tested well, it gave a true 60 watt RMS output into a constant 6.8 ohm load, at 1khz. its frequency response was flat from 7 hz to 100khz tested at half power!

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As they say in Scotland, JC, GET IT RIGHT UP YE! :ner:

Read and weep, sweety, and stick yer "30W" bollocks up your ample-sized bottom, haha...

Marco.

Ali, Well ok ish, but it really depends how far you turn up the gain.

For those of a practical nature, it might amuse you to hear that the amps I use have no external gain controls, and are set to full volume without clipping all the time. therefore I know that they cannot clip till the drive voltage exceeds 2v peak.

Once was more than enough! ;)

Marco.

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Originally Posted by jcbrum

Well ok ish, but it really depends how far you turn up the gain.

For those of a practical nature, it might amuse you to hear that the amps I use have no external gain controls, and are set to full volume without clipping all the time. therefore I know that they cannot clip till the drive voltage exceeds 2v peak.

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most valve amplifiers usually run their driver stages wide open, and are easily capable of receiving a 2v peak to peak signal without a hint of clipping!
some valve grounded grid pre-amplifiers i have made over the years will except many times that without clipping!
anthony...:)

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Originally Posted by jcbrum

(did you look it up ?)

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Erm... Yes. :(

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Originally Posted by anthonyTD

jc,
i use signal generators and scopes to test all the equipment that comes through my workshops, and i am quite aware of what an amplifier looks like when clipped, i also test them for frequency response at diffrent levels of power output. marco's amp tested well, it gave a true 60 watt RMS output into a constant 6.8 ohm load, at 1khz. its frequency response was flat from 7 hz to 100khz tested at half power!
the best solid state amplifiers i have heard are the simple ones, ie, using the minimum amount of devices, with the least amount of feedback, but sadly only producing around 10 watts. also, the first transistor amplifiers which by the way sounded pretty good when using gemanium [spellin] transistors were transformer coupled, like valves!
you hit the nail on the head when you said about using feedback sets the gain, feedback does various things when used in amplifier designs but the main three things it does are, reduce distortion,[ by linearising] increase damping factor, and de-crease gain!
anthony...

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I have some early transformer coupled amps in my collection. :) I bought them new in 1967 I think.

So Marco's amp is only flat at 30w, that's what I expected. I wouldn't like to guarantee how long it would deliver 60w on a warm day !

Have I got this wrong or am I right in recalling Marco's amp has 2x KT88 per channel ?

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Originally Posted by anthonyTD

most valve amplifiers usually run their driver stages wide open, and are easily capable of receiving a 2v peak to peak signal without a hint of clipping!
some valve grounded grid pre-amplifiers i have made over the years will except many times that without clipping!
anthony...:)

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Yeah sure, but will they deliver 500w at that setting ? :)

Have I got this wrong or am I right in recalling Marco's amp has 2x KT88 per channel ?[/QUOTE]

yes, two KT88's in push pull run in AB will give 100 watts.
in marcos amp they are run in the warm side of AB1.
anthony...

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Originally Posted by jcbrum

So Marco's amp is only flat at 30w, that's what I expected. I wouldn't like to guarantee how long it would deliver 60w on a warm day !

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More unsubstantiated waffle. Is that like the way you wouldn't guarantee how long the transport mech in my Sony will last? It'll outlast you, that's for sure! ;)

Marco.

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Originally Posted by Shian7

Erm... Yes. :(

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Well done, ;) so did I :lolsign:

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Originally Posted by jcbrum

I have some early transformer coupled amps in my collection. :) I bought them new in 1967 I think.

So Marco's amp is only flat at 30w, that's what I expected. I wouldn't like to guarantee how long it would deliver 60w on a warm day !

Have I got this wrong or am I right in recalling Marco's amp has 2x KT88 per channel ?

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example,
kt88's were used in for example, loss testers in the steel industry, they drove huge triode valves flat out for months at a time!:)

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Originally Posted by anthonyTD

Have I got this wrong or am I right in recalling Marco's amp has 2x KT88 per channel ?

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Originally Posted by anthonyTD

, two KT88's in push pull run in AB will give 100 watts.
in marcos amp they are run in the warm side of AB1.
anthony...

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100w is a "catalogue" figure, at that level the distortion would be awful and they would go bang v quickly. Don't you agree ? :)

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Originally Posted by jcbrum

[/B]



100w is a "catalogue" figure, at that level the distortion would be awful and they would go bang v quickly. Don't you agree ? :)

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no,
i dont agree, the distortion figures are relatively high [10%] at that power without feedback, but the 100 watt power output is feasible, and definitely achievable, and with sufficient cooling, sustainable!:)

off to bed now folks...
anthony...;)

Ok, matey. You've well and truly kicked JC's ass now anyway! Nighty night :smoking:

Marco.

The limiting factor with most valves is the anode dissipation of heat, which is mainly controlled by the bias setting, not the output power.

In class A, KT88's might provide 10w out, in AB 30w, in class C 60w, in class D 100w.

It is therefore misleading to talk in terms of output power and anyway 60w is only 3db louder than 30w (v small difference)

To exceed double the volume (spl) you'd probably need to go from 30w to 300w.

In an attempt to do that in a push pull design the crossover distortion would be enormous >10% and clipping would be absolutely inevitable, but some do regard this as "involving musicality" and even get to like the sound.

Marco has already set fire to his amplifier once :) I rather think this "mythical" 100w from a pair of 88's in ab push pull will provide an even bigger bang eventually. :lol:

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Originally Posted by jcbrum

To exceed double the volume (spl) you'd probably need to go from 30w to 300w.

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More like 900W :eyebrows: