Best measuring tube amp

[mhardy6647]

Stereophile did:
...
I don't believe that it is in the running for "best measuring tube amp".

Jim

Well, in this case, the root cause's clear, right?
Not nearly enough tubes in that model.

vs.

c'mon -- this is science.

 

[lashto]

Stereophile did:

AudioValve Baldur 70 monoblock power amplifier Measurements

Sidebar 3: Measurements

www.stereophile.com

I don't believe that it is in the running for "best measuring tube amp".

Jim

It was only meant as an example of the 'busiest' tube amps. The Challenger ~looks like a crate of beer bottles

The measurements seem to be ~standard for a tube amp. And IIRC, those aren't even pure tube amps but some sort of hybrid circuit which includes opamps

 

[lashto]

Talking about best measuring, the Sonic Frontiers SFS-80 looks like a good candidate. The noise floor is a bit high and 'busy' but that is a 20+ years old device. A thorough refresh (e.g. replace 'expired' caps) might clean up the graphs quite a bit.

And from the same thread a McIntosh MC3500 which measures into SS range at ~80 SINAD. 350W of power is quite a lot for a tube amp. Are those Macs using pure tube circuits or some sort of hybrid amplification?

Also this DIY effort looks pretty solid

 

[mhardy6647]

Talking about best measuring, the Sonic Frontiers SFS-80 looks like a good candidate. The noise floor is a bit high and 'busy' but that is a 20+ years old device. A thorough refresh (e.g. replace 'expired' caps) might clean up the graphs quite a bit.

And from the same thread a McIntosh MC3500 which measures into SS range at ~80 SINAD. 350W of power is quite a lot for a tube amp. Are those Macs using pure tube circuits or some sort of hybrid amplification?

Also this DIY effort looks pretty solid

The MC-3500 is all tube except the P/S HV rectification, AFAIK.
Check that. A few soiled state devices lurking elsewhere in the amplifier.

source: http://www.oestex.com/tubes/Circuits/mc3500.JPG

Not very "pure tube circuit", though - at least not from an audiophile point of view - using TV horizontal sweep tubes for outputs!

 

[lashto]

The MC-3500 is all tube except the P/S HV rectification, AFAIK.
Check that. A few soiled state devices lurking elsewhere in the amplifier.

source: http://www.oestex.com/tubes/Circuits/mc3500.JPG

Not very "pure tube circuit", though - at least not from an audiophile point of view - using TV horizontal sweep tubes for outputs!

As long as there is no SS component that actually amplifies the signal, it's 'pure' enough for me. Can't pretend that I can read circuit diagrams but there are quite a few transistors in there..

Anyway, this amp won't ever be on my list because they did hide the tubes. Don't understand why some designers do that. For me, the tube amps are also a visual experience. Hide the tubes and I'll hide my wallet..

 

[lashto]

Talking about 'impure' tube amps, the Acuhorn OTLs should have very good measurements. Some modern ICs used for power delivery and supposedly lots of NFB.

A pretty original/different look too (the above link also has internal pics, looks pretty tidy)

 

[mhardy6647]

As long as there is no SS component that actually amplifies the signal, it's 'pure' enough for me. Can't pretend that I can read circuit diagrams but there are quite a few transistors in there..

Anyway, this amp won't ever be on my list because they did hide the tubes. Don't understand why some designers do that. For me, the tube amps are also a visual experience. Hide the tubes and I'll hide my wallet..

There are diodes in the active part of the amp, and (of course) the PS. Mac ditched vacuum tube HV recifiers earlier than some other (US) hifi companies.
I do see a transistor - maybe a regulator(?) - in the P/S. The only other transistors I see are in the meter drive circuit. I didn't look hard at the schematic, either.
... and I think they covered the tubes to help keep their customers alive.

My "pure" riposte was meant only to poke fun at using (relatively) cheap and (then) plentiful, nigh-on indestructable color TV horizontal output tubes as audio(phile) outputs. How un-audiophile. As an aside, the world's supplies of tubes like those (e.g., the US 6JE6 and its cousins and siblings) has dwindled due mostly to their use in linear (RF) amplifiers for CB radio and other such suitably elegant transmitter applications.

 

[lashto]

There are diodes in the active part of the amp, and (of course) the PS. Mac ditched vacuum tube HV recifiers earlier than some other (US) hifi companies.
I do see a transistor - maybe a regulator(?) - in the P/S. The only other transistors I see are in the meter drive circuit. I didn't look hard at the schematic, either.
... and I think they covered the tubes to help keep their customers alive.

My "pure" riposte was meant only to poke fun at using (relatively) cheap and (then) plentiful, nigh-on indestructable color TV horizontal output tubes as audio(phile) outputs. How un-audiophile. As an aside, the world's supplies of tubes like those (e.g., the US 6JE6 and its cousins and siblings) has dwindled due mostly to their use in linear (RF) amplifiers for CB radio and other such suitably elegant transmitter applications.

just a cage would be ok-ish but the latest version actually has the tubes 'hidden' on the back side. Guess we are supposed to look at the giant mc-branded VU meter in the front. As much as I like those, my tubes rule is: no tube glow, no money flow

 

[valve_integrator]

t's like having a classic Triumph or Austin-Healy; you need to be proficient with tools to keep them running properly.

So if you're not a tube amp design maven, there's two choices: a well-restored classic amp like the old Macs or H-K or similar, or build from a proven kit like Pete Millet's Engineer's Amp.

There is no inexpensive, no-hassle way to do tubes well in 2022. It is unfortunate, but it's true. Money or hassle, you're doing fetish objects, not electronics.

Sad, I read this tosh & ignorance.
I work on both as it happens.

The old Triumphs can be truly wonderful if you know how to rebuild the transmission and engine to modern standards.
(Many of those old classics can leave a modern in the dust after doubling the power output)!
eg. The much maligned Triumph stag V8 can be made 100% reliable not struggling to do 115-120bhp, but a ferrari style genuine 230-240 totally reliably.

The guff about valve amps seems to be very common nowadays.
I would welcome you to a shoot out between the "fetish object" and the truly dreadful sterile sounding valve based MACs or some of the awful sounding high NFB designs with transistors in.

Like all good cuisine, you don't look in a cook book when you want to make a delicious meal, you take some well known classics and good wine, and make it up as you go along without coming out with prejudice and nonsense.

Indeed the following statement would be far truer "there is no inexpensive, no-hassle way" to do good cooking unless you happen to live in Italy or France, and have access to the best raw materials, and have learnt how to cook without screwing it up or burning the meat and veg, or buying wine you know nothing about that doesn't go with it.

Electronics, particularly building stuff with the very finest from the mid 60s to mid 70s when the technology reached a very impressive peak, is not to be knocked unless you have tried it, while not regurgitating the same mantras time and again.

 

[SIY]

Sad, I read this tosh & ignorance.
I work on both as it happens.

The old Triumphs can be truly wonderful if you know how to rebuild the transmission and engine to modern standards.
(Many of those old classics can leave a modern in the dust after doubling the power output)!
eg. The much maligned Triumph stag V8 can be made 100% reliable not struggling to do 115-120bhp, but a ferrari style genuine 230-240 totally reliably.

The guff about valve amps seems to be very common nowadays.
I would welcome you to a shoot out between the "fetish object" and the truly dreadful sterile sounding valve based MACs or some of the awful sounding high NFB designs with transistors in.

Like all good cuisine, you don't look in a cook book when you want to make a delicious meal, you take some well known classics and good wine, and make it up as you go along without coming out with prejudice and nonsense.

Indeed the following statement would be far truer "there is no inexpensive, no-hassle way" to do good cooking unless you happen to live in Italy or France, and have access to the best raw materials, and have learnt how to cook without screwing it up or burning the meat and veg, or buying wine you know nothing about that doesn't go with it.

Electronics, particularly building stuff with the very finest from the mid 60s to mid 70s when the technology reached a very impressive peak, is not to be knocked unless you have tried it, while not regurgitating the same mantras time and again.

Heh, I apparently missed a couple of the tropes. Thanks for filling in the gaps.

 

[fpitas]

Is there a consensus as to which type of tube amp is the best measuring? e.g. OTL, SET, SEP, Pentodes in push-pull, triodes in push-pull?

The gold standard back when engineers designed things was triodes in push-pull. Some modern OTLs like from Atmasphere are pretty good, too.

 

[BDWoody]

Sad, I read this tosh & ignorance.

There's a lot of that being displayed in your posts.

Electronics, particularly building stuff with the very finest from the mid 60s to mid 70s when the technology reached a very impressive peak, is not to be knocked unless you have tried it, while not regurgitating the same mantras time and again.

I'm going to give you a little time off so you can (hopefully) get a better feel for where you are and who you are talking to before coming back in with your guns blazing.

 

[fpitas]

Heh, I apparently missed a couple of the tropes. Thanks for filling in the gaps.

What an odd coincidence he showed up just recently to give us his wisdom.

 

[anmpr1]

The old Triumphs can be truly wonderful if you know how to rebuild the transmission and engine to modern standards.
(Many of those old classics can leave a modern in the dust after doubling the power output)!
eg. The much maligned Triumph stag V8 can be made 100% reliable not struggling to do 115-120bhp, but a ferrari style genuine 230-240 totally reliably.

As an erstwhile owner of two MGs (A and Midge) I would argue a bit differently. Sure, you can 'upgrade' or mod the parts. But then you don't have an MG (or a Triumph, or whatever). Part of the 'wonderfulness' of those originals is keeping them as original as possible, and then reflecting upon how things have changed. Usually for the better, but not always. That might seem counterintuitive.

There's a guy in Scandinavia (I think) who has posted on-line much DIY information on how to turn your JBL L100 into a 'modern' speaker, with better specs and all that. He's put a lot of effort into it. And I'm sure the finished product is worthy. But then you don't have an L100. Do you?

Now, part of the 'fun' of old gear (hi-fi or cars) is modding. I admit that. But if I wanted a 'modern' MGA, I would buy a Caterham. Just like I wouldn't 'upgrade' an L100 in order to make it sound 'modern'. YMMV

BTW: I keep a '70s era system in my study. L100, Dynaco tube amps, SL-1100a record player, Pickering XV 1200e/Denon 103/Shure V15 III. The only thing 'new' is my hand built pre, which looks like a PAS, but uses modern boards with different tube circuits (along with VFET phono stage). Listening reminds me of how things were, and how things have changed. Much different, but I like it as much as my Benchmark system.

If I was younger and wanted 'that automobile experience', I'd locate a '70s era Pininfarina Fiat 124 Spider--an ergonomic step up from MG for sure, but just as quirky, just as unreliable, and just as fun. However, not now. Being older, I'm not willing to crawl under a car in order to replace something. Old hi-fi gear being much easier to fix when it breaks.

 

[Tom C]

Sad, I read this tosh & ignorance.
I work on both as it happens.

The old Triumphs can be truly wonderful if you know how to rebuild the transmission and engine to modern standards.
(Many of those old classics can leave a modern in the dust after doubling the power output)!
eg. The much maligned Triumph stag V8 can be made 100% reliable not struggling to do 115-120bhp, but a ferrari style genuine 230-240 totally reliably.

The guff about valve amps seems to be very common nowadays.
I would welcome you to a shoot out between the "fetish object" and the truly dreadful sterile sounding valve based MACs or some of the awful sounding high NFB designs with transistors in.

Like all good cuisine, you don't look in a cook book when you want to make a delicious meal, you take some well known classics and good wine, and make it up as you go along without coming out with prejudice and nonsense.

Indeed the following statement would be far truer "there is no inexpensive, no-hassle way" to do good cooking unless you happen to live in Italy or France, and have access to the best raw materials, and have learnt how to cook without screwing it up or burning the meat and veg, or buying wine you know nothing about that doesn't go with it.

Electronics, particularly building stuff with the very finest from the mid 60s to mid 70s when the technology reached a very impressive peak, is not to be knocked unless you have tried it, while not regurgitating the same mantras time and again.

Aside from being complete balderdash, this is about as self serving a mantra regurge as I’ve ever seen.

 

[fpitas]

Aside from being complete balderdash, this is about as self serving a mantra regurge as I’ve ever seen.

I'm sure that contributed to his being cast into the outer darkness. Where he is probably wailing and gnashing his teeth as we speak.

 

[mhardy6647]

... or listening to the accordions and the banjos (or is that banjoes?).

 

[Nicknack]

Couple of things not mentioned here about the better designed tube amps
(1) some tube amps have very low order distortion 2nd and 3rd and virtually nothing after that ie minuscule by orders of magnitude after the 3rd harmonic.
(2) very low ie of the order of 0.01 or less distortion from 1w or less across 30Hz to 35kHz and the distortion falls even more as at power levels of ~ 100mW
Amps having both (1) and (2) with little to no global negative feedback and driving good high impedance load like a 300 ohm headphone or well behaved efficient 16+ ohm speakers have that magical clarity.
(3) power supplies must be extremely good ie line regulation and supply noise must be well suppressed. Lots of filtering.

 

[SIY]

have that magical clarity.

You mean that they then sound no different than any other amp with moderately low distortion.

power supplies must be extremely good ie line regulation and supply noise must be well suppressed. Lots of filtering.

Maybe. The other side of the coin is designing circuitry with high power supply rejection. This takes a LOT of onus off the power supply.

 

[sophie smith]

Decware publishes some of the measurements on their website, under individual amps. Torii has some measurements posted. .
It would be nice to test independently. Frenzel has been in business for over 50 years. Could not find any measurements at all.