The sound of the vacuum tube amplifier is determined by its damping factor!!

[fpitas]

I’m feeling unenlightened so far in this thread, apart from learning about the ideological stance at AsR that approaches the appeal of tube amplifiers with a kind of huffy, impatient, generally pejorative reductiveness that refuses to contemplate any sympathetic hypothesis around legitimate technical explanations for enjoying tube sound, whatever that actually is.

Is it something more interesting and intelligible than just bad measurements and impedance mismatches and euphonic distortion and nostalgia, all the stuff that make listeners who seek out and enjoy that sound bad people in this corner of the internet? Damned if I know.

I'm old enough to have heard good tube amps, back before there was magic associated with them. Good ones sounded pretty much alike, and clean, like today's good SS amps.

 

[NTTY]

I’m feeling unenlightened so far in this thread, apart from learning about the ideological stance at AsR that approaches the appeal of tube amplifiers with a kind of huffy, impatient, generally pejorative reductiveness that refuses to contemplate any sympathetic hypothesis around legitimate technical explanations for enjoying tube sound, whatever that actually is.

Is it something more interesting and intelligible than just bad measurements and impedance matches and euphonic distortion and nostalgia, all the stuff that make listeners who seek out and enjoy that sound bad deluded people in this corner of the internet? Damned if I know.

Gonna go watch Erin’s video and see if that helps.

And you read that from the above?
I might be completely lost in translation, but really I read quite the opposite.

 

[MaxwellsEq]

I’m feeling unenlightened so far in this thread, apart from learning about the ideological stance at AsR that approaches the appeal of tube amplifiers with a kind of huffy, impatient, generally pejorative reductiveness that refuses to contemplate any sympathetic hypothesis around legitimate technical explanations for enjoying tube sound, whatever that actually is.

Is it something more interesting and intelligible than just bad measurements and impedance matches and euphonic distortion and nostalgia, all the stuff that make listeners who seek out and enjoy that sound bad deluded people in this corner of the internet? Damned if I know.

Gonna go watch Erin’s video and see if that helps.

What!

Not a single post above your post had any pejorative comments. Just facts about output impedance, damping factor, negative* feedback and the challenges inherent in output transformers.

*(Perhaps you thought people were being negative about feedback, but "negative feedback" is an engineering capability)

I've heard excellent tube preamplifiers. They just were no better than the solid state preamplifiers I've heard. And they were hot.

I've also heard tube power amplifiers that sounded OK. They just cost a lot per Watt and were hot.

So, if you do not want room heaters and want to ensure you are getting best cost-per-Watt, tube amplifiers are probably not for you...

 

[fpitas]

I've also heard tube power amplifiers that sounded OK. They just cost a lot per Watt and were hot.

So, if you do not want room heaters and want to ensure you are getting best cost-per-Watt, tube amplifiers are probably not for you...

They were also beastly heavy from the good transformers used. And the output tubes needed replacing frequently if you cared about SQ. You had to re-bias them, too.

 

[Mart68]

Negative feedback reduces gain, but increases bandwidth. I'm guessing that if you widen BW beyond human hearing, more distortion harmonics will be allowed at the output. Unless you are referring to some masking effect or IMD, I can't see the assertion being true, BUT early transistor amplifiers likely needed as much gain as possible to keep component costs down.

Yes, masking. Higher order HD is masked by lower order HD. Remove the lower order HD with negative feedback and the higher orders become audible. If you don't use enough feedback. That was the theory being postulated, anyway.

 

[HalSF]

What!

Not a single post above your post had any pejorative comments. Just facts about output impedance, damping factor, negative* feedback and the challenges inherent in output transformers.

*(Perhaps you thought people were being negative about feedback, but "negative feedback" is an engineering capability)

I've heard excellent tube preamplifiers. They just were no better than the solid state preamplifiers I've heard. And they were hot.

I've also heard tube power amplifiers that sounded OK. They just cost a lot per Watt and were hot.

So, if you do not want room heaters and want to ensure you are getting best cost-per-Watt, tube amplifiers are probably not for you...

Yes, I admit I may be reacting more with a general perception I have about ASR discourse about “tube sound” than to this thread. I definitely read the thread title as techno-reductive, however,, along with the overall focus on pinning down what tube amplifiers do to simple explanatory spec factors of various kinds.

Your characterization of tube amplifiers as at best equal to solid state amplifiers, plus wicked hot, is successfully humorous, but possibly sidesteps consideration of any reasonable aesthetic pleasure-based case for tube amp sound. Maybe there is no such non-Luddite case, but I’m still curious to find out.

 

[Cbdb2]

Yes, masking. Higher order HD is masked by lower order HD. Remove the lower order HD with negative feedback and the higher orders become audible. If you don't use enough feedback. That was the theory being postulated, anyway.

Its called re-entrant distortion. Feedback under 20db can create HD. Those results have people wrongly thinking all feedback is bad.

From
https://www.diyaudio.com › community › attachments › the-f-word-bruno-putzeys-pdf.1140285

"The story of re-entrant distortion has an unambiguous conclusion: there simply is no such thing as
“too much” feedback. There is only something as not enough feedback and it happens to be exactly
what so-called moderate audio designers call “modest amounts” of feedback"

 

[Speedskater]

There is not a single "tube sound", there are lots of different tube sounds.
Some are accurate and some have (lets be nice) euphonic colorations.
Different euphonic amps have different sounds and many of these sounds change with different loudspeakers.

 

[smygolf]

I used different tube amps and high sensitive speakers way back
The speakers was WLM Aura Active, so an active filter with the possibility to tune the sound depending on the tubes used
Worked as a charm and with 98dB sensitivity 10-20W was enough and Duo 18 sub played straight down to 20hz

Unfortunately the company went broke and the current WLM line up is totaly different

 

[MaxwellsEq]

Your characterization of tube amplifiers as at best equal to solid state amplifiers, plus wicked hot, is successfully humorous

I was not attempting to be humorous. Where I live is too @#&##ing hot at the moment. I have no air conditioning. So despite having solid state amplifiers, I can't actually listen to music at the moment because my room is too hot to enjoy it! I don't want to waste watts unnecessarily heating my room. The electricity where I live is also very expensive, so I don't want to waste audio watts on unnecessary heat! If you can get high quality sound with low heat you should, it's just economic sense!

but possibly sidesteps consideration of any reasonable aesthetic pleasure-based case for tube amp sound.

There should be NO tube sound when amplifiers are designed to work correctly within their design envelope. Thermionic valves, bipolar transistors, MOSFETS etc have NO intrinsic audio characteristics. It is possible to mess up the design and add noise and distortion. We know some people have a preference for added noise and distortion. But of course that's not high fidelity to the recorded material.

 

[Mart68]

Its called re-entrant distortion. Feedback under 20db can create HD. Those results have people wrongly thinking all feedback is bad.

From
https://www.diyaudio.com › community › attachments › the-f-word-bruno-putzeys-pdf.1140285

"The story of re-entrant distortion has an unambiguous conclusion: there simply is no such thing as
“too much” feedback. There is only something as not enough feedback and it happens to be exactly
what so-called moderate audio designers call “modest amounts” of feedback"

Thanks. Some of that is above my pay grade but I think I understand a little more now.

 

[fpitas]

High fidelity amplifiers are not supposed to add some kind of audio magic, so inevitably a good tube amp will at best sound like a good SS amp. If you degrade the fidelity, it's quite possible someone will like it, but that is no longer high-fidelity, but special effects.

 

[HalSF]

I was not attempting to be humorous. Where I live is too @#&##ing hot at the moment. I have no air conditioning. So despite having solid state amplifiers, I can't actually listen to music at the moment because my room is too hot to enjoy it! I don't want to waste watts unnecessarily heating my room. The electricity where I live is also very expensive, so I don't want to waste audio watts on unnecessary heat! If you can get high quality sound with low heat you should, it's just economic sense!

There should be NO tube sound when amplifiers are designed to work correctly within their design envelope. Thermionic valves, bipolar transistors, MOSFETS etc have NO intrinsic audio characteristics. It is possible to mess up the design and add noise and distortion. We know some people have a preference for added noise and distortion. But of course that's not high fidelity to the recorded material.

I should cry uncle right about now. You’re making excellent points. But you’re also kinda sorta a little bit also making *my* point about the stern, near-zero lack of sympathy for the attractions of tube amps around here, even just for the sake of argument or to extend a bit of steelmanning give-the-devil-his-due on behalf of tube aficionados even if you think they have no good reason to like dirty sound that betrays true fidelity.

 

[fpitas]

This site is pretty much dedicated to studying the art of high-fidelity, so it should be no surprise that special-effects boxes (especially expensive one) are frowned on.

 

[MaxBuck]

I'm still not convinced that the primary attraction of tube amps isn't primarily the glowing tubes.

When I bought my system 7 years ago, I bought stuff based solely on measurements, like KEF R11s, NAD C298 amp and Topping D30Pro DAC-preamp. Except, that is, for my $300 power center. That, I bought primarily for all its pretty blue lights.

 

[MaxwellsEq]

I should cry uncle right about now. You’re making excellent points. But you’re also kinda sorta a little bit also making *my* point about the stern, near-zero lack of sympathy for the attractions of tube amps around here, even just for the sake of argument or to extend a bit of steelmanning give-the-devil-his-due on behalf of tube aficionados even if you think they have no good reason to like dirty sound that betrays true fidelity.

I'm just being myself: an Electronic Engineer that has designed, built and repaired audio electronic devices for decades including in recording studios.

When I was a teenager with no money, almost all the stuff I tinkered with was tube-based. It was cheap or free because people were replacing old or broken tube gear with solid state, so pretty much everyone had something they wanted to dump. Lots of interesting stuff could be found at landfill sites.

As a practical engineer I have no romance about any technology. But I also have no value judgement against tubes. Dollar for dollar a solid state amplifier is better value. In terms of support, a solid state amplifier requires less maintenance. It's tricky, but not impossible to build "blameless" tube preamplifiers. It's expensive and harder but not completely impossible to build "blameless" tube power amplifiers (working within their design envelope).

I'm into audio so that I can get as close as possible to the music, not to have a romantic engagement with the tin.

 

[popej]

Probably the experts are already well aware of this

It is over 40 years since Carver challenge, it should be a public knowledge

The Carver Challenge | Stereophile.com

Is it possible to make a $700 "mainstream-audio" power amplifier sound exactly like a high-priced perfectionist amplifier? Bob Carver, of Carver Corporation, seemed to think he could, so we challenged him to prove it. The question posed above seems laughable. If it were possible to make an...

www.stereophile.com

 

[PirateQuinn]

Its called re-entrant distortion. Feedback under 20db can create HD. Those results have people wrongly thinking all feedback is bad.

From
https://www.diyaudio.com › community › attachments › the-f-word-bruno-putzeys-pdf.1140285

"The story of re-entrant distortion has an unambiguous conclusion: there simply is no such thing as
“too much” feedback. There is only something as not enough feedback and it happens to be exactly
what so-called moderate audio designers call “modest amounts” of feedback"

IIRC this is not true except under quite overdriven conditions. Who listens to hifi amplifiers in this manner? There's no question that going from 0db to 20db negative feedback progressively lowers distortion. There isn't an area where it gets worse then better as you approach this 20db magic number. The people pushing this nonsense are voodoo hifi designers selling a story to justify the existence objectively incompetent amplifiers.

 

[HalSF]

It is over 40 years since Carver challenge, it should be a public knowledge

The Carver Challenge | Stereophile.com

Is it possible to make a $700 "mainstream-audio" power amplifier sound exactly like a high-priced perfectionist amplifier? Bob Carver, of Carver Corporation, seemed to think he could, so we challenged him to prove it. The question posed above seems laughable. If it were possible to make an...

www.stereophile.com

The Carver Challenge haunts me..

Does anyone reading this know the current state of digital plug-ins or EQ presets that simulate euphonious “tube sound”? It seems like the greatest trolling of what people love about tubes would be successfully making music playing through a Benchmark AHB2 or inexpensive Class D amp sound like it was coming out of some exquisite SET amp or McIntosh tube beast.

 

[Mart68]

The Carver Challenge haunts me..

Does anyone reading this know the current state of digital plug-ins or EQ presets that simulate euphonious “tube sound”? It seems like the greatest trolling of what people love about tubes would be successfully making music playing through a Benchmark AHB2 or inexpensive Class D amp sound like it was coming out of some exquisite SET amp or McIntosh tube beast.

I think since it in part depends on how rubbish or not the output transformers are and what the impedance curve of the speakers are then it can't really be simulated there's too many variables.

At a meet we stuck a Radford STA15 on some Tannoy Cheviots after having something solid state (forget what) on them. Right away bloomy bass and severe top end roll off. Then we put it on some QUAD ESL and it sounded very fine indeed.