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Tubes vs Transistors: An Audible Difference?
cgenman writes "Are those vaccuum tubes worth the extra price? This paper, a transcript of a speech to the Audio Engineering Society of New York, indicates so, though the reason is surprising: Overloaded tubes behave better.
While the speech itself is from the early 70's, the paper takes on new importance with the recent trend in louder is better music."
Bob Carver did this already. If I remember correctly, it's the increaed resistance from a tube amp using output transformers that creates the 'soft' sound that characterizes glass audio.
Carver created a solid state amp which pretty much mimicked a $10K tube amp and no one could tell the differencec in blind tests.
I am shocked that this old crap has no annotation from the 1990s when phychology tests proved tubes sound more appealing than solid state op-amps.
The reason ?
Odd harmonics vs EVEN Harmonics !!!!
Odd harmonic overtones sound HARSH to human brains and are an unwelcome side effect of all solid state electronic amplification.
That was new data in the 90's that this ancient speech being discussed had no idea about.
Valve amps (the original name for tube amplifiers) are basically voltage driven, so when they distort, even-order harmonics are produced (2nd, 4th, 6th, etc...) while transistor amps are current driven and produce odd-order harmonics (3rd, 5th, 7th, etc....)
I cannot believe at the time i posted this i am still the only one to point this out.
All those years of subscription to The Absolute Sound taght me at least why tubes were better and an oscilloscope visibly points out the harmonics.
The problem with this is you end up with horrible range that you can't do much with. Loud sounds end up clipped so that the softer sounds can sound 'louder'. Here's why it sucks: You lose a lot of the music's quality. When I turn up this song, my stereo dac becomes the limiting factor. When you turn up crap like this, the sound waves are already clipped. The jokes on them.
People like tube amps because they add a little bit of harmonics that sounds nicer to our ears. Tubes sound 'warm' and they fail gracefully when overdriven. It's an old battle that no one will win, but most muscians go with tube amps so they can't all be wrong
[Fuck Beta]
o0t!
This whole phenomenon is well understood today. You can buy a little "tube amp emulator", with emulations for famous tube amps. Choose your own harmonic distortion. There are product lines of amp modellers.
Most of the trouble in audio today is not tube vs. transistor vs. digital. It's from artifacts introduced during compression of the dynamic range. The real problem is the car audio listening environment, which is noisy. Radio stations need to sound good in cars. This led radio stations to compress their audio into a narrow dynamic range. People got used to this. Then, when cars got CD players, CD mixes began to be compressed like car audio. ("You don't want your record to be the softest one in the changer"). Now, most popular music is so compressed that musicians have totally lost the musical use of volume. You can't have a soft passage; it will be pumped up. Sharp attacks are clipped, so that tool has been taken away. The end result is popular music that has no texture. Background music.
It's not that the loud parts are clipped, rather they are compressed. Yes, audio hardware/software compressors while they can be a godsend at times, their overuse has makes things sound flat, loud, and boring. (Wouldn't it be great if everytime someone whispered to you, your brain instead cranked that whispering up to the equivalent shouting db level? That's what compressors do - so that the music is always shouting).
A compressor is a device that says when the music reaches a certain decibel level, reduce the volume by X (X=compression ratio). So with a compressor you can take a song and crank it up super loud, without fear of ever actually clipping the signal or the system (it hovers right below 0db).
The result of this is that if you looked at a compressed waveform, they are no dynamics in it at all. The peaks and values of the entire wav are all maxed out. While this is louder, you have almost no dynamic range. Compression comes at a cost - most engineers these days don't seen to realize this.
CDs aren't actually recorded like this. The recordings are fine - it's when they go in to get the whole song (and CD) mastered that this happens. Audio Engineers are under increasing pressure to make the CD "sound louder" by the PHBs.
What is interesting to me is the cult status that tube amplifiers have achieved. Some forty-odd years ago vacuum tube engineers (my father was one) jumped on the transistor bandwagon because of the numerous advantages it conferred over tubes. Now, for some unaccountable reason we look back at the heyday of the pentode in some twisted nostalgic fashion making unprovable claims about the wonders of the good old days. Fact is, all they were is old.
Some people like the sound of the tube amp better, others don't see any significant difference, and there are those that don't like it at all. Put it like this: what is an amplifier supposed to do? Why, it is supposed to amplify, of course, and the more precisely, predictably and accurately it does that is a good measure of the quality of the amplifier. The closer you come to achieving a one-to-one correspondence between the input waveform and the signal presented to your speakers the better your amplifier. Conversely, an amplifier that modifies, distorts or otherwise results in significant variation between the input and output waveforms is a worst a lousy amplifier and at best functioning as a signal processor in its own right.
What it comes down to is that the extremely-hard-to-model non-linear responses of a bewildering variety of kinds that you describe indicate that the tube amplifier is not faithfully reproducing the original recording and is distorting it in complex and unpredictable ways. Yes, it may do so in a pleasing manner and one may very well prefer the modified sound, I have no problem accepting that. But that is not intrinsically different from saying that I like what my 20-band equalizer or my Alesis effects processor does to the sound. And given the decades-long controversy on the subject, the presumption by tube amp afficionados that their sound is inherently "superior" is a bit hard to swallow, particularly as we are talking about one of the most subjective experiences that human beings can share. Personally, I like the sound of some of the tube systems I've heard, but for my part I wouldn't say that they are, under all circumstances, simply "better."
The higher the technology, the sharper that two-edged sword.