Comparing the Nonlinearity of a Triode and a Bipolar Junction Transistor

[Mike Sulzer]

Mike, I see Maria cat 5 is heading your way. What a hurricane season! Stay safe.

Thanks. It has currently shifted a bit north east and should destroy just part of PR rather than the whole island tomorrow.

[SoulFetish]

Thanks. It has currently shifted a bit north east and should destroy just part of PR rather than the whole island tomorrow.

The reports coming out of PR look very dire! I Mike and his close ones are all safe!
(Latest news is that Puerto Rico could be out of power for months, so it may be a while till we hear)

[Mike Sulzer]

The reports coming out of PR look very dire! I Mike and his close ones are all safe!
(Latest news is that Puerto Rico could be out of power for months, so it may be a while till we hear)

Thanks for your concern! We have limited internet at the Arecibo Observatory now (none at home still). (microwave link into the central hills and back out to the coast) No power, of course, but you can get gasoline and diesel now, and so generators are useful. The observatory is supplying thousands of gallons of water a day to the local community from its very deep and good well (and that includes me for drinking water only as long as my tanks hold out (for washing dishes, etc,) and pool (buckets hauled inside for the toilet). If the diesel supply goes, so goes the well pump, and there will be no more processed water out here for anybody. You would just have to collect rain. Fema has flown some water here, not realizing that we have an unlimited supply as long as we have fuel. The military folks said they could fly in 1000 gallons of diesel at time in a Sikorsky equipped with a bladder, but trucks are more effective now that the roads are passable. As far as I can see the guys are doing a great job putting power lines back up, and we might have power here in less than two weeks. (The problem with many other areas of the island is that some of the main high voltage distribution lines are down, and that is a tough problem through the central hills.)

[nickb]

Thanks for the update. Good to know you made it.

[Dave H]

3rd harmonic is extremely close to a note which forms the C Major chord.

That note is G isn't it? It's an octave of a 5th interval. The 5th is in both the Major and minor chords. Omit the 3rd from the maj/minor chords and you have a "power" chord which works in either major or minor keys. People seem to only want even order harmonics in their guitar amps but there's nothing wrong with the 3rd harmonic.

[d95err]

When discussing the evolution of guitar amps I think we must keep in mind that in most cases, the primary design goal was cost. Engineers had to deliver sufficient output volume at as low cost as possible. Engineers quickly found out that they could get away with simple solutions even if they did distort a bit.

If tone had been more important than cost, we would have seen more complex designs with much less warmth and distortion.

[Enzo]

REminds me of Madman Muntz, who sold TVs in the 1950s. His ads were on the TV and radio ALL THE TIME. I can still sing his jingle 60 plus years later.

He was famous for eliminating just everything in a TV that wasn't absolutely necessary, to reduce cost. His TVs were cheap, and crappy.

https://en.wikipedia.org/wiki/Madman_Muntz

[teemuk]

People seem to only want even order harmonics in their guitar amps but there's nothing wrong with the 3rd harmonic.

Absolutely not. I think the whole idea is ridiculous, it's those higher order harmonics we need to worry about more.

Push-pull power stages inherently produce mainly odd order distortion, and many people regard power amp as the most important -tubed- part of the circuit. That alone sinks the whole theory.

Then, when we think about -asymmetric- clipping, which produces those "musical" even order harmonics, we need to remember that in just about every practical application that very same asymmetric clipping ALSO produces significant amount of odd order harmonic distortion. So we don't get just one, we get both. The theory sinks even deeper...

Factor in intermodulation distortion, which is VERY relevant factor because guitar's don't produce pure sinewaves, and we quickly realize that with complex signals IMD will undoubtedly produce plenty of harmonics which are "odd" in respect to fundamental frequency of the note(s). Effect of IMD will be more drastic with asymmetric distortion because we get intermodulation of both even AND odd harmonic frequencies.

[pdf64]

Where did that 'even harmonics sound nice' and the 'tube amps generate mainly even harmonics, solid state generate mainly odd harmonics' nonsense come from? It seems to have been the received wisdom since maybe the 70s.

[Dave H]

Where did that 'even harmonics sound nice' and the 'tube amps generate mainly even harmonics, solid state generate mainly odd harmonics' nonsense come from? It seems to have been the received wisdom since maybe the 70s.

I've no idea where it came from. It wasn't from looking at a spectrum that's for sure. Here's my 2 x EL84 amp at 500Hz, 5% distortion. There's more 3rd and 5th harmonics than 2nd and 4th.

[g1]

I had thought it was maybe an Aspen Pittmn thing, but that would have been later.

[Justin Thomas]

I think that's actually where I read about it first, g1 - and I think the first edition of The Tube Amp Book came out in 1981? It was either there or in Gerald Weber's, which I believe was early 90s. But I think it was Pittman's, and since he didn't do a whole lot of updating as much as "putting in more stuff," because he would have been a primary pusher for the superiority of tubes at the time.

Justin

[Dave H]

I think that's actually where I read about it first, g1 - and I think the first edition of The Tube Amp Book came out in 1981?

I have The Tube Amp Book. It was before the internet. I bought it for the schematics, honest. I've just looked it up and in the Tubes, Transistors and Distortion section it says -

"When a transistor amp clips it produced more odd order harmonics (and in its worst case can sound hollow and dry), whereas tube distortion produces even order harmonics. Tube distortion generally sounds warmer."

I guess we can blame Pitman then.

[g1]

We can probably blame him for the spread of the misinformation, but I don't think he came up with many ideas. He was probably just repeating something one of his "gurus" told him. Now we can all take a guess as to who.

[J M Fahey]

That idea has various sources, which I donīt straight call *wrong* , but many are missing important points.
Wonīt pontificate against them, on the contrary I am *grateful* they felt curious and investigated.

One of the most influential and being constantly quoted even today, is a paper by RUSSELL O. HAMM, from Sear Sound Studios, New York, N. Y.
Clearly he knew what he was doing, with one foot firmly into Engineering, the other on practical Studio experience.

This is one upload of his work, which merits reading ... and rereading:
http://www.guitars-of-love.com/pdfs/TbsVsTrans.pdf

to spoil the Mystery movie, he was comparing Mic preamps, both measuring and by ear, very well made.

His only error was that he attributed most of what he found to "Tubes vs. Transistors" while he was actually comparing:
Single ended, Triode and Pentode Preamps to Symmetrical/Push Pull High to Very High NFB Transistor and Op Amp ones , and heavily overdriving them.

If he had compared all Tube stuff but with above noted *structure* difference, he would have found the same results he attributed to Transistors

Same if he had compare all SS but different structure types.

FWIW old Neve mixers, specially "input strips" which include the microphone input are much cherished, ( some carry a spare channel strip everywhere they go ).
A friend of mine cloned and sold many of them.

The Line Out stage is made out of a single 2N3055 driving an output transformer.

According to buyers, it blows most modern mixers out of the water with its unique sound ... now you can imagine why.