The AM Forum

Will you believe Electronic Design?

http://electronicdesign.com/article/analog-and-mixed-signal/-House-of-Fire-Firebottles-And-Groove-Tubes-Versus-Devices-That-Find-Their-Origins-in-Sand-Part-1-.aspx

              _-_-bear

What's to believe?

These sorts of discussions (and often bitter arguments) have been published for over 40 years. 

bill

No real audiophool stuff there, just well-known engineering practice.  I don't see any nonsense regarding "high end" fuses, power cords, or speaker cables either, so I don't know what your point is when you're asking "Will you believe Electronic Design".

hi John et al .... I think Bear is referring to a cuss and discussion on the forum a couple of years ago about if electronic parts could affect the sound in an audio system ... an emotion based exchange is hard to avoid until all parties understand the ground rules

So ur ok with all the assertions?

Like audibility of information at -130dB?
How small a phase shift at bass freqs did he say?
Audible differences in resistors and capacitors?
Carbon pots?

But not the non-linearity of fuses?

But without regard to the fuse issue, imo NO ONE would have accepted MOST of the things in the article in the 1970s, and very few in the 1980s. Not sure all that many in the 1990s... and still a lot not today. Which I think is the whole point... it's a case of peeling the onion...

                      _-_-bear

The section titled "Our hearing" contains many claims about our ears but not one reference to where these claims come from.

Does anyone know where these claims come from ?

I too have reservations about some of his statements... I think one can ask the author, and certainly one can register at ED and post a comment... the references may come at the end of the series... perhaps.

                    _-_-bear

The Audio Engineering Society (of which I used to be a member) was publishing quite a bit of laudable research on "Psycho-acoustics" in the late 70's and 80's.  Much of the claims mentioned in ED article sound quite familiar to me regarding various double-blind "subjective" test results.  I've long known of our extreme sensitivity to phase differences; and used that much to my advantage in much of my work.  And those differences can certainly be detected even 100dB (or more) apart.  

For example: In listening to various types of RF filters for SSB we hear, for a given complex tone, many harmonically related components. When components become phase (time) shifted we hear that as a wishy-washy sound. We AMer's would typically describe this as not sounding "life-like".  How many dB apart are those components?  Quite a bit. Now raise that single tone, single channel example an order of magnitude to a complex stereo music signal with a multitude of possible aberrants.  Ask any acoustician who tunes performance venues with damping panels about how many dB separation we can hear on minute sound components arriving at the "wrong" time.

Yes, I believe we can hear things we may have difficulty measuring. This is largely because our measurement techniques classically focused too narrowly on small bandwidths and "pure" signals. Digital analysis of more complex waveforms now make such (more "subjective") measurements feasible, although I've yet to see any test results or that sort yet; but I know they're out there.  

On the other hand, I also believe the human brain lacks in certain sensitivities; like harmonic distortion.  Seems we can tolerate quite a bit of waveform reshaping without being bothered. That's probably why we don't (generally speaking) hear "fuse" non-linearity. Just don't time shift it.  

I think the article made good sense of a senseless argument. Only true audio-phools (and I DO mean FOOLS) would scoff at the science presented in lieu of some sensory superiority imbued by the bundle of money they just forked over for that $1,500 EIC AC power cord. :)

His conclusions, IMHO, were spot on, and likely nothing new to those of us who have worked with tubes and wideband audio.  It comes down to the sound of highly damped low-impedance sources (alomost curent sources) versus lightly damped, "high"(er) impedance voltage sources.  The comment that any SS amp can sound like a tube amp by inserting a series resistance in the output... PRECIOUS.  It's not likely the audio-phools will be sending the author any Christmas card this year. LOL

He neglected to get into the discussion of distortion components being different when driven to excess but again, we all know the results there as well.   

Thanks for the heads up Bear. An interesting read from ED to be sure.

Regards,
Mark

"It comes down to the sound of highly damped low-impedance sources (almost curent sources) versus lightly damped, "high"(er) impedance voltage sources"


I once made nearly the same comment on that other AM site and was told what an idiot that I was and that solid state amps had no characteristics of current sources.  I don't go there anymore.

My opinion is that most of the way an amp "sounds" is due to the above.  That, and to the characteristics of the harmonic distortion that is generated by solid state versus tube.

Tubes driven into hard distortion don't sound as bad as a solid state device due to the order of harmonics generated.

Guitar amps are distortion generators by design. That is why tubes are still manufactured. A solid state guitar amp just doesn't sound very good and anyone can hear the difference.  Solid state guitar amps work well and are popular for use where there is little distortion as in steel guitar use or amplifying acoustic guitars but when you plug in a Fender Stratocaster - solid state just fails miserably.

Bass amps went to solid state quickly years ago because of the high power solid state made available.

Me neither. 

Some folks just cannot accept an explanation which exceeds their comprehension. A hostile rebuke is not uncommon if the "herd" is of like mind.
Audio-phoolery is a good example of such mentality.

"Any sufficiently advanced technology presented to a less advanced civilization is synonymous with magic." - H.C. Clark

After reading it all, seems the best thing to do (my opinion only) is use what you like, and listen to what you like. No one will ever change another's opinion of tubes vs transistors much less triode/pentode/beam/bipolar/FET/IGBT (indeed, IGBTs for audio - it works but..). I just hope that certain favorite tubes are made for the forseeable future.

I like the way good sounding audio equipment sounds!

I have both kinds and the tube amps have a cool factor because no one else has them anymore. And they do have a warm sound - it may not be what the recording souded like - but it does sound good to an old fart that used to love the sound from an old juke box or the sound of the monitor speaker at the local AM station.

To skip the definition of "current source" vs. "voltage source" and focus on the output impedance of an amp is sufficient. Bad news, putting a resistor in series with a low DF (damping factor, or low output Z) amp will absolutely NOT make it sound like a tube amp. It will however cause the frequency response at LF, where DF plays a role in the response to be similar to the response that would be found with a higher DF, less damped.

However the spectra of distortion, not at clipping, will be decidedly different between amps. Better stated, IF the spectra of distortion, NOT the ABSOLUTE VALUE of distortion is similar it turns out that we hear the amps as sounding quite similar - without regard to if they are toobe or solid state.
This is the interesting part of it.

Refer to the work of D.E.L Shorter and recently Dr. Earl Geddes (the GedLee Metric) for more on this.

Of course getting the spectra to be similar between tubes and solid state is not so simple. And furthermore there are tube amps with nasty spectra of distortion, just as there are solid state amps.

This explains why many report that solid state amps with O.001% THD do not sound good.  And why many report that tube amps with 0.1% distortion do sound good. The relationship between sounding good to the ears and distortion does not correspond to simple distortion levels.

Of course this is contrary to the orthodoxy of many years standing and common sense.

All of which serves to illustrate that when it comes to human perception, it's not easy to measure and correlate to perception.

                          _-_-bear