Single-ended Triode Discussion

[greg788]

Face it, it was doomed from the start.

jeff

I enjoy this site but, yah, I should have seen this coming. There are far too many on this forum who, apparently out of sheer boredom or misguided anger at the world, feel compelled to argue or proselytize about everything.

I find it amusing that we all spend inordinate amounts of money on audio gear and then feel compelled to argue about various aspects thereof: cables are bad, your preferred type of speaker is bad, your preferred mode of amplification is bad. And on and on and on. Really? It's like sport bike guys bagging on Harley guys and visa-versa. It never gets anywhere.

 

[paskinn]

Of course it never gets anywhere! That's perhaps the point....

 

[Errol]

Absolutely agree. If a Wavac amplifer has any sort of following, I don't want to have anything to do with a hobby that's so misguideded
S.

Misguided? If one can afford it, why not a Wavac? Just as if one can afford a Aston Martin why not?

Mr Ed.

 

[lindsayt]

The Wavac reaches a minimum at 0.15%. The first solid state power amp on the list at Stereophile betters this at similar powers by an order of magnitude.

http://www.stereophile.com/content/mbl-reference-9011-monoblock-amplifier-measurements

An absurd choice for a very efficient speaker system.

Paul

The $53,000 MBL is one of the best solid state power amps in the Stereophile listings from a THD+N point of view. Most of them have higher THD+N at 100 milliwatts.

The MBL will start producing more than 0.15% THD+N at somewhere betweeen 0.1 and 1 milliwatt at 1khz if we extrapolate the graph. But we are taking a guess on these figures by extrapolating into unmeasured territory. Extrapolation is difficult as at 0.12 watts on the 8 ohm graph there's a kink. We don't know how many more kinks there would be in this graph if it went below 100 milliwatts. Also we don't know if the MBL uses an excessive amount of negative feedback in order to achieve these distortion figures with any sonic trade-offs as a result.

Also if you look at the THD+N vs frequency graph for the MBL, this indicates that it will start producing more than 0.15% THD+N at around 1 milliwatt at 4khz.

So no the MBL is not better than the Wavac by an order of magnitude above 4khz and below 1 milliwatt, or below 0.1 milliwatts at 1khz.

 

[greg788]

The $53,000 MBL is one of the best solid state power amps in the Stereophile listings from a THD+N point of view. Most of them have higher THD+N at 100 milliwatts.

The MBL will start producing more than 0.15% THD+N at somewhere betweeen 0.1 and 1 milliwatt at 1khz if we extrapolate the graph. But we are taking a guess on these figures by extrapolating into unmeasured territory. Extrapolation is difficult as at 0.12 watts on the 8 ohm graph there's a kink. We don't know how many more kinks there would be in this graph if it went below 100 milliwatts. Also we don't know if the MBL uses an excessive amount of negative feedback in order to achieve these distortion figures with any sonic trade-offs as a result.

Also if you look at the THD+N vs frequency graph for the MBL, this indicates that it will start producing more than 0.15% THD+N at around 1 milliwatt at 4khz.

So no the MBL is not better than the Wavac by an order of magnitude above 4khz and below 1 milliwatt, or below 0.1 milliwatts at 1khz.

And I do know that the MBL has a significant amount of negative feedback. I don't recall where I read it but it uses a bunch -- more than average, let's say

 

[sergeauckland]

The $53,000 MBL is one of the best solid state power amps in the Stereophile listings from a THD+N point of view. Most of them have higher THD+N at 100 milliwatts.

The MBL will start producing more than 0.15% THD+N at somewhere betweeen 0.1 and 1 milliwatt at 1khz if we extrapolate the graph. But we are taking a guess on these figures by extrapolating into unmeasured territory. Extrapolation is difficult as at 0.12 watts on the 8 ohm graph there's a kink. We don't know how many more kinks there would be in this graph if it went below 100 milliwatts. Also we don't know if the MBL uses an excessive amount of negative feedback in order to achieve these distortion figures with any sonic trade-offs as a result.

Also if you look at the THD+N vs frequency graph for the MBL, this indicates that it will start producing more than 0.15% THD+N at around 1 milliwatt at 4khz.

So no the MBL is not better than the Wavac by an order of magnitude above 4khz and below 1 milliwatt, or below 0.1 milliwatts at 1khz.

The problem with measuring THD+N figures for low powers is the +N. As the power reduces, the +N figure, which is fixed, becomes increasingly significant.

An amplifier with a 90dB S/N ratio will measure a THD+N figure of 0.01% just due to the N, and that's at full power.

To measure lower values of THD, requires the distortion analyser to be of the wave-analyser sort, that takes an FFT of the output and adds the powers of the harmonics. This is then a true THD figure, not a THD+N.

Using conventional notch-filter analysers, which actually measure THD+N, it's not possible to measure distortions much below 0.001% just due to the N.

S.

 

[Dik Dolan]

I just re-did the tests on my glasshouse, using better connections with decent shielded cables and battery power on the netbook, and the thd figure dropped by a tiny percentage- probably insignificant, but the thd+n dropped by a fair margin to <1.2% Biggest change was to the FR plot though. All other test settings were the same.

Just posting this for completeness more than anything. The original FR test shows a significant roll off at the bottom end, this new one doesn't. Only change was to the cabling- from croc clips to decent leads. cables make a difference, who'd have thunked it=)

 

[EddieV]

I'm just curious -- who here uses a single ended triode amplifier (or something similar like single ended pentode)? I'm looking for an open discussion about different amps, tubes (especially NOS), etc. I don't recall ever seeing a thread specifically about this at PFM.

Having once been strictly a solid state person, I recently began exploring valves. .....

Hello Greg,

I 'built' my first tube amp in 1969, actually I took the amplifier part (with one ECL86 tube) out of an old radio. At that time solid state amplifiers were restricted to portable radio's.

In the 1990's I bought an Audio Innovations First (2A3 push-pull), highly regarded at that time. But I switched to single ended with an Audio Note Kit One (300B). If you want more information, see http://www.phys.tue.nl/EPG/veldhuizen/hobbies.htm. I definitely preferred single ended.

In 2007 I was stimulated to test a Tripath TA2020 (I started with an AMP6-basic from 41Hz, price 35 Euro). Shortly after that I sold all my tube stuff! I switched to the TA2021B later. These tiny amps have, to my ear, much less distorsion than tube amps, however they do not combine nicely with every speaker.


Kind regards,
Eddie

 

[paskinn]

The truth always comes down to the same point....opinions are so comically split, and individual preferences so wide, that you can only learn through your own experience.This, of course, is far easier said than done. All I can suggest is that you arrange to pop round to people who have various types of amps, and have a chat and a listen.
As for all the flat-earth 'spec' stuff; this is about your perceptions, not test meters.The whole 'spec' stuff is just one long wind-up by people who think your consciousness is copy of a test instrument. Just listen, decide on what you hear.Don't be bullied into adopting someone else's view of the world.

 

[Dik Dolan]

Paskinn, sorry to you and anyone else if my recent posts have got in the way. I've only recently acquired the adc/dac to enable me to take these measurements, and I thought someone might be interested. I remain a listener rather than a measurer, I still hear differences I can,t measure. I only posted originally because there was talk of SET amp distortion at low outputs and I was in a position to measure mine. I thought that was relevant.

 

[Mescalito]

The truth always comes down to the same point....opinions are so comically split, and individual preferences so wide, that you can only learn through your own experience.This, of course, is far easier said than done. All I can suggest is that you arrange to pop round to people who have various types of amps, and have a chat and a listen.
As for all the flat-earth 'spec' stuff; this is about your perceptions, not test meters.The whole 'spec' stuff is just one long wind-up by people who think your consciousness is copy of a test instrument. Just listen, decide on what you hear.Don't be bullied into adopting someone else's view of the world.

The spec stuff, as you put it merely acts as a quality filter. If the amp beats some not-very-difficult-to-beat-nowadays criteria, you are free to choose it on criteria other than sound quality. Appearance, features, bling, bragging rights, WAF.

Of course you should audition it, but really, it's not strictly necessary.

I wouldn't personally consider a SET for this reason. And yes, the SETs I have heard simply sound wrong to me.

Now this maybe "reverse expectation bias", but if it is, there's little I can do about it, other than go to the bother of blind testing, & I really can't be arsed to do that.

Chris

Chris

 

[Robert]

Can you, or Robert or Serge please find me a solid state amp in the Stereophile measurements pages with lower THD+N measurements into an 8 ohm load at power levels below 1 to 10 milliwatts?

IMO the epitome of what is wrong with solid state amplifiers.

My old Quad 405 beats it, perhaps partly because at power of up to a few watts it's Class A.

Serge makes a good point about 'N' which skews results at very low output levels.

However in defence of SETS (what am I saying.....) they are known to produce distortion which is less subjectively annoying. If you offered me a SET and SS amp both with 1% THD I'd likely take the SET since SS distortion at those levels is rarely nice.

The question is does all this become moot when you can push everything down to extremely low levels these days. I'd argue that takes the problem away.

I think you can get good sound from SETS but you have to match very carefully to the loudspeaker, and I think if done correctly you can get situation where two wrongs make a right.

 

[pure sound]

The question is does all this become moot when you can push everything down to extremely low levels these days. I'd argue that takes the problem away.

You also (more significantly) reduce the unwanted contribution of wayward speaker drivers. Heavy diaphragms, heavy voice coils, large magnet gaps, weedy magnets. Not a great combination.

 

[CJ14]

I recall building a JLH Class A many moons ago. It did sound pleasant for an SS amp but if truth be told, wasn't really up to the standard of even a pretty basic EL84 PP design. I'd hope this latest Colin Wonfor design was a good deal better.

Well you do loose the sound of "Breaking Glass" when dropped.
The TQ design is nothing like the JLH design, and later this month there will be a 40W version out.
Did anybody see the TOCA 300W SECA designs?

 

[les24preludes]

I came across this thread while doing a search and as a long time SET user it seemed interesting, though more so at the start than later.

My news is that the 2a3, or the 6.3v versions 6B4G and Soviet 6C4C, are not just output valves - they make stonkingly good line stages. I've just completed one for a guy who needs a low gain, low output impedance DHT line stage to feed a 10K input impedance amp. It sounds so addictively good - neutral, smooth, detailed, dynamic - that I'm building another one for myself as fast as possible. There are some 2a3 based preamps about, but driven by a 6SN7 which makes no sense to me - it's not needed or wanted. There was the Tram 2 2a3 preamp which gets a glowing review here. But it's a rare beast. It's not too difficult to build a 6B4G/6C4C line stage and it's a keeper for sure.

Diy HiFi Supply Tram Mk2 DHT OTL Preamplifier Take the direct route to the heart and soul of your music. Review By Clive Meakins

Diy HiFi Supply Tram Mk2 DHT OTL Preamplifier Take the direct route to the heart and soul of your music. Review By Clive Meakins - Enjoy the Music.com Review Magazine

www.enjoythemusic.com

 

[martin clark]

I came across this thread while doing a search and as a long time SET user it seemed interesting, though more so at the start than later.

My news is that the 2a3, or the 6.3v versions 6B4G and Soviet 6C4C, are not just output valves - they make stonkingly good line stages. I've just completed one for a guy who needs a low gain, low output impedance DHT line stage to feed a 10K input impedance amp. It sounds so addictively good - neutral, smooth, detailed, dynamic - that I'm building another one for myself as fast as possible. There are some 2a3 based preamps about, but driven by a 6SN7 which makes no sense to me - it's not needed or wanted. There was the Tram 2 2a3 preamp which gets a glowing review here. But it's a rare beast. It's not too difficult to build a 6B4G/6C4C line stage and it's a keeper for sure.

Diy HiFi Supply Tram Mk2 DHT OTL Preamplifier Take the direct route to the heart and soul of your music. Review By Clive Meakins

Diy HiFi Supply Tram Mk2 DHT OTL Preamplifier Take the direct route to the heart and soul of your music. Review By Clive Meakins - Enjoy the Music.com Review Magazine

www.enjoythemusic.com

This isn't my area of interest at all, but it'd be lovely if you share some of your approach & experience to such, over in the DIY area - perhaps as a new thread/ example project - only if it suits you, obvs.

pfm is a very broad church, and such good experience in DIY Valve stuff, does seem a bit under-represented.

ATB!

 

[jtgofish]

I am not a fan of the really big Tannoys.

Probably because you have never heard them with the right amp.A lot of people use SETs with them and they can't control them properly.The worst amp I have heard was an Audio Note 300B SET-a big loose soggy mess.Push pull valve amps do a better job but I am yet to hear a push pull that is high enough resolution to get the best out of the compression drivers.You need a medium output impedance no negative feedback SS amp to get the best out of them.A Dartzeel NHB 108 or a Bakoon for example.People underestimate how revealing the compression drivers are in them.Some people say they do not like the treble but it is not the speaker it is the amp.That is where the low distortion quality of a good SS amp is needed.

 

[jtgofish]

I came across this thread while doing a search and as a long time SET user it seemed interesting, though more so at the start than later.

My news is that the 2a3, or the 6.3v versions 6B4G and Soviet 6C4C, are not just output valves - they make stonkingly good line stages. I've just completed one for a guy who needs a low gain, low output impedance DHT line stage to feed a 10K input impedance amp. It sounds so addictively good - neutral, smooth, detailed, dynamic - that I'm building another one for myself as fast as possible. There are some 2a3 based preamps about, but driven by a 6SN7 which makes no sense to me - it's not needed or wanted. There was the Tram 2 2a3 preamp which gets a glowing review here. But it's a rare beast. It's not too difficult to build a 6B4G/6C4C line stage and it's a keeper for sure.

Diy HiFi Supply Tram Mk2 DHT OTL Preamplifier Take the direct route to the heart and soul of your music. Review By Clive Meakins

Diy HiFi Supply Tram Mk2 DHT OTL Preamplifier Take the direct route to the heart and soul of your music. Review By Clive Meakins - Enjoy the Music.com Review Magazine

www.enjoythemusic.com

Friends have owned the Tram preamp.Yes they are very good but can sound a bit relentless.Very fast and clean sounding but we all preferred the more composed and finessed sound of our Suprateks.

 

[Filian]

So leave the thread alone then. You've made your point (twice). It shouldn't be any further concern of yours unless you are in 'saviour' mode.

Saviour mode; I like that. Easier than typing projection, technical ignorance, cloth ears, and hubris every time they crap a thread.

 

[chiily]

You need a medium output impedance no negative feedback SS amp to get the best out of them.

Could you explain please the reason for needing an amp with no negative feedback for compression drivers?