Do tubes do anything well in circuits?

[mhardy6647]

I was still running a HD widescreen CRT up until 5 years ago and still have a few CRT monitors put aside just in case... I do prefer to watch my tubes and not listen to them though. I suppose CRT's can have that high pitched whine... which is not noticeable with age and a glass of wine.



JSmith

I cannot hear the horizontal oscillator squeal in a CRT TV any more

We still have several big (and I mean BIG) CRT computer monitors here, but no longer in service.
My son is a big fan of a paricular Dell (maybe(?) Philips OEM) that is actually his... but for some reason it's in our basement.

If I had a little extra useless cash and space, I would love to have an all vacuum tube color TV like the RCA CTC-15 that I grew up with . Actually, I'd rather have a CTC-16; but we never had one of those.

 

[levimax]

Tubes are to audio what automatic self-winding mechanisms are to timepieces.

I thought it was LP's and TT's

 

[restorer-john]

Even I retired our 1983 vintage Toshiba CRT TV... albeit just a couple of months ago.

My father still has the 26" General floorstanding colour TV bought in 1981/2. Apart from a cleanout inside and a slight focus adjustment I performed about 12 years ago, I has never put a foot wrong. Has the best sound I've heard from a television too. It is rarely used these days as I gave him a number of flatscreens over the years, but we will never get rid of it.

 

[MakeMineVinyl]

I thought it was LP's and TT's

Any proper equalizer MUST use inductors. That much should be obvious to any rational person. Gyrators are sent by the devil.

 

[Doodski]

My father still has the 26" General floorstanding colour TV bought in 1981/2. Apart from a cleanout inside and a slight focus adjustment I performed about 12 years ago, I has never put a foot wrong. Has the best sound I've heard from a television too. It is rarely used these days as I gave him a number of flatscreens over the years, but we will never get rid of it.

The quantity of 26" cathedral styled console TVs I sold in the early to mid 80s is mind blowing and they where predominantly to Italian families. The city I was in had a large quantity of Italian immigrants that all had extended families and they where the glue of the city there. It was most always the same routine. A sale included a delivery and setup of the TV, drink some homemade grappa, red wine or both, sit at the kitchen table for awhile, admire the furniture, have a delicious snack, some more grappa or red wine apologize for needing to return to the store for business, have some more red wine and chat more etc etc. We all loved doing Italian family deliveries. Sometimes I should not have been operating a motor vehicle after the delivery but things where what they where in those days. We lost one delivery person in action for a entire afternoon due to him having lunch and dinner with the customers, playing guitar there, drinking too much and being too impaired to return to the store.

 

[LeftCoastTim]

...distortion down to 0.0000x% levels. Still, distortion in well designed circuits can be at inaudible levels...

So what's inaudible distortion? -70dB? -94dB? -120dB?

ASR thinks it's >16 bits or 96dB. Is there a tube amp that measures that well?

 

[restorer-john]

So what's inaudible distortion? -70dB? -94dB? -120dB?

ASR thinks it's >16 bits or 96dB. Is there a tube amp that measures that well?

My number is -80dB or 0.01% for THD. Not saying it's audible, but any amplification, source or component in the reproduction chain at that number or lower makes for a pretty darn good level of fidelity.

16bit CD came to market in 1983 with most players advertising ~0.0025% THD, dynamic range >90dB, separation of >90dB, flat response within +/-0.5dB. The design goals were all met and 16bit has served us well.

 

[MakeMineVinyl]

So what's inaudible distortion? -70dB? -94dB? -120dB?

ASR thinks it's >16 bits or 96dB. Is there a tube amp that measures that well?

It really depends on the spectra of the distortion. If we're talking about low order 2nd and perhaps 3rd order distortion, the audible threshold could be much higher than if we're talking about >= 5th order. I would bet that you wouldn't be able to hear 2nd order distortion as high as 1% or maybe higher since this is harmonically an octave above the fundamental frequency and thus musically related. Also, the presence of low order distortion, especially 2nd order, tends to cover up the presence of higher orders of distortion. Its more complex than a single number, and this is the crux of the debate on tube amplifiers vs solid state. Tube amplifiers typically produce low order distortion (this is a generalization!), where a typical solid state push-pull amplifier will eliminate (if it is a 'perfect' stage) the low-order-even-order distortion components and leave only the odd harmonics (a 'perfect' tube push-pull stage will do this too, but the earlier stages won't - same goes for non-balanced SS stages!). It gets really complex, really fast and doesn't lend itself to one 'single golden threshold' of audibility of distortion.

 

[LeftCoastTim]

It really depends on the spectra of the distortion. If we're talking about low order 2nd and perhaps 3rd order distortion, the audible threshold could be much higher than if we're talking about >= 5th order. I would bet that you wouldn't be able to hear 2nd order distortion as high as 1% or maybe higher since this is harmonically an octave above the fundamental frequency and thus musically related. Also, the presence of low order distortion, especially 2nd order, tends to cover up the presence of higher orders of distortion. Its more complex than a single number, and this is the crux of the debate on tube amplifiers vs solid state. Tube amplifiers typically produce low order distortion (this is a generalization!), where a typical solid state push-pull amplifier will eliminate (if it is a 'perfect' stage) the low-order-even-order distortion components and leave only the odd harmonics (a 'perfect' tube push-pull stage will do this too, but the earlier stages won't - same goes for non-balanced SS stages!). It gets really complex, really fast and doesn't lend itself to one 'single golden threshold' of audibility of distortion.

All of these "n order" distortions have amplitudes attached to them. I'm only talking about amplitude.

Please provide a number that would be acceptably "transparent".

 

[MakeMineVinyl]

All of these "n order" distortions have amplitudes attached to them. I'm only talking about amplitude.

Please provide a number that would be acceptably "transparent".

My last post was an attempt to explain that it is impossible to provide one definitive number to quantify the audibility of distortion. Really, I'm serious, it is a complex subject which is dependent on the moving target which is the human auditory system. If it seems like a subject you wish to devote a huge amount of your life to in researching it, have at it! Me, I'm only concerned with what brand of beer (IPA please) I wish to consume.

 

[Jim Shaw]

One factor that often gets overlooked in these discussions is tube aging. From their first time in use, tubes age and change character. The effects may be slow and insidious (cathode disintegration, interelement spacing changes due to heat/shock) or they may happen rather quickly (burnouts, gas infiltration, shorting). But their characteristics will at least change over time and use, most often resulting in biasing and operating points that weren't intended. Vacuum tubes in high-temperature operating circumstances like power output circuits are especially subject to aging and failure. Vacuum tubes are entirely unsuitable for switching and therefore digital applications. Then there are tubes' long rise times and interelement capacitance.

One could conclude that vacuum tubes (or valves for those with stiff upper lips) are unsuitable for consumer equipment and less so for professional equipment. One would be correct.

Most fundamentally, as it were, in a world of Teslas, electric locomotives, or the internet, tubes are the horse and buggy and the telegraph. Use them if it makes you feel nostalgic and fuzzy, but there's a reason hardly any companies make them anymore.

"Audiophiles" and microwave ovens are some of the last holdouts. What can we say? Some people want hot sauce on their baked apple.

 

[Doodski]

If the rise time of a tube amp is limited when compared to a transistor amp what would the upper cutoff frequency be for a average audio tube amplifier?

 

[LeftCoastTim]

My last post was an attempt to explain that it is impossible to provide one definitive number to quantify the audibility of distortion. Really, I'm serious, it is a complex subject which is dependent on the moving target which is the human auditory system. If it seems like a subject you wish to devote a huge amount of your life to in researching it, have at it! Me, I'm only concerned with what brand of beer (IPA please) I wish to consume.

So weaseling out of any actual claims. I'm not surprised.

To the OP: Tube amps are like mechanical jeweled watches. They art pieces of art. Actual timekeeping is secondary. A $1 quartz watch will beat the pants out any jeweled mechanical watch.

 

[MakeMineVinyl]

So weaseling out of any actual claims. I'm not surprised.

OK, if you insist on a firm number, it is -78.93547dBu.

 

[pma]

It really depends on the spectra of the distortion. If we're talking about low order 2nd and perhaps 3rd order distortion, the audible threshold could be much higher than if we're talking about >= 5th order. I would bet that you wouldn't be able to hear 2nd order distortion as high as 1% or maybe higher since this is harmonically an octave above the fundamental frequency and thus musically related.

Yes. And it depends on the signal we listen to. The threshold for pure sine is much lower than for any music signal. And even for the sine it depends on frequency and level, exactly according to masking curves. I can only repeat that I posted two tests here so anybody can try in ABX what distortion he is able to hear with music.

https://www.audiosciencereview.com/...tortion-test-about-5-on-a-music-sample.18217/
https://www.audiosciencereview.com/...-world-tube-preamplifier-about-2-7-thd.18392/

The distortion as shown below can be perceived on a sine tone with proper level (below the level when ear inherent nonlinearity masks it) but never on the music.

 

[pkane]

Yes. And it depends on the signal we listen to. The threshold for pure sine is much lower than for any music signal. And even for the sine it depends on frequency and level, exactly according to masking curves. I can only repeat that I posted two tests here so anybody can try in ABX what distortion he is able to hear with music.

https://www.audiosciencereview.com/...tortion-test-about-5-on-a-music-sample.18217/
https://www.audiosciencereview.com/...-world-tube-preamplifier-about-2-7-thd.18392/

The distortion as shown below can be perceived on a sine tone with proper level (below the level when ear inherent nonlinearity masks it) but never on the music.

View attachment 151210

Easy to try this with music. Apply any amount of harmonic distortion you want using PKHarmonic VST plugin and hear it with your music in real time:

 

[dfuller]

So weaseling out of any actual claims. I'm not surprised.

A few reasons @MakeMineVinyl won't give you a hard number:
1. Every person's hearing is different. What might be audible to you may not be to me, and vice versa.
2. It depends on which harmonic/nonharmonic (in the case of IMD) we're talking about - as you get further from the fundamental they're masked less and less, and nonharmonic info is also masked less (so IMD is in a lot of cases somewhat more offensive than harmonic distortion).
3. It depends on listening level. Distortion is less apparent at high volumes because our ears themselves have some intrinsic distortion.
4. It depends on frequency. LF distortion is way less noticeable than distortion in the midrange and presence region - as in, 10% THD for a signal around 40hz is probably juuuuust barely audible, but 1% arouind 1-2k is probably pretty audible.

 

[egellings]

NeuralDSP Quad Cortex does not glow in the dark, and a home constructor will most likely not be able to make one. As for sound quality, the DSP can emulate the sound of any amplifier, but again, the thrill is gone for those who, for one reason or another, like tubes.

 

[MCH]

I bet more sooner than later the only reason to have an amplifier as we know it today will be, if any, decorative, so maybe tubes have a future... like people having a jukebox at home, but with a smaller footprint

 

[MakeMineVinyl]

I bet more sooner than later the only reason to have an amplifier as we know it today will be, if any, decorative, so maybe tubes have a future... like people having a jukebox at home, but with a smaller footprint

I think the more likely reason would be that the whole audio hobby will whither and die off, being replaced by 'lifestyle' components which are heard but not seen.