So what in solder "sounds" bad, and what can be done about it?

[Mike Sulzer]

[QUOTE=Alan0354;234362]

Even in clean setting, the second harmonics of the tube should still drown out the little distortion from the CC resistor. Point is the major thing about the tube circuit that has a plate resistor generate a lot of second harmonics and even harmonics.

Except it is odd harmonics from plate resistors because the total voltage has only one sign.

[RedHouse]

(yawn)

[J M Fahey]

As the audio signal swings one way, we are increasing the voltage across the resistor. When the audio signal goes the other way, the voltage across the plate resistor decreases. This produces odd harmonics.

Only if the resistor (or whatever element is said voltage applied to) is non linear.

Meaning I/V varies with applied voltage, which should be clearly visible on a graph or plot of one value against the other.
I´m not prejudiced one way or the other, being quite open minded, but I know that doesn´t happen on carbon or metal film resistors, at least to a measurable/detectable degree.

Does it happen on CC resistors? ... Don´t know. Maybe. Why not? They are *terrible* in so many aspects so why not misbehave in just *another* area? Their "police record" is already bad enough.

Did anybody trace a few and produce some curves? Would *love* to see them.

Would I accept "testimony" as proof? (as in "this 1969 JTM45 full of CC resistors sounds so much better than the 1998 re-edition, full of carbon or metal films")
Sorry but definitely not, because of the zillion *other* variables which can´t be factored in, too many to even mention.

[Steve Conner]

There's a VI curve for a carbon comp resistor in The Art Of Electronics. The resistance changes so many percent per volt, so the VI curve has a V squared term, which produces second harmonic distortion.

A SECRET UNDERGROUND LAB SOMEWHERE IN PUERTO RICO
Mike Sulzer: So which guitar do you prefer, A or B, and if you have a preference how would you describe the difference.

Me: I've been playing the damn solo from Little Wing over and over for 3 months now. My fingers are bleeding. Please can I go home?

Mike Sulzer: No, we still have 381 variables in guitar design left to investigate.

Me: Cries into blindfold

Narrator: This, folks, is why you should never work with children, animals, or try to do scientific experiments without some sort of Hewlett Packard gizmo that measures the actual quantity you're interested in.

[Mike Sulzer]

Only if the resistor (or whatever element is said voltage applied to) is non linear.

At that point in the discussion, what I wrote was contingent upon just such distortion. The only thing in question was the nature of the distortion: odd or even?

You want to question what Keene wrote about the existence of the effect, but hat looks pretty solid to me.

[SpareRibs]

Amplifiers

Hello,
I was playing my 63 Stratocaster thru my Fender Blackface, I inadvertently set a bottle of lime Gatorade on top of the amp and noticed a drop in the out put immediately. I removed the Gatorade and the output went back to normal. It perplexed me to no end. I checked the capacitance, and the inductance of the Gatorade and could not get a very high reading. I think the electrolytes in the Gatorade are lining up in parallel with the output side of the transformer I am at this point going to the store to buy some grape flavor to see if it has the same effect. I don't know what the next step could be. Maybe copper shielding on the bottles!!!

Update-I was getting up from the chair to go to the store and poked myself in the eye with
my slide rule. I will have to post more on the results later.

[SpareRibs]

Amplifiers

Hello,
I was playing my 63 Stratocaster thru my Fender Blackface, I inadvertently set a bottle of lime Gatorade on top of the amp and noticed a drop in the out put immediately. I removed the Gatorade and the output went back to normal. It perplexed me to no end. I checked the capacitance, and the inductance of the Gatorade and could not get a very high reading. I think the electrolytes in the Gatorade are lining up in parallel with the output side of the transformer I am at this point going to the store to buy some grape flavor to see if it has the same effect. I don't know what the next step could be. Maybe copper shielding on the bottles!!!

Update- I was getting up from the chair to go to the store and poked myself in the eye with
my slide rule. I will get back with results as soon as possible

[big_teee]

Hello,
I was playing my 63 Stratocaster thru my Fender Blackface, I inadvertently set a bottle of lime Gatorade on top of the amp and noticed a drop in the out put immediately. I removed the Gatorade and the output went back to normal. It perplexed me to no end. I checked the capacitance, and the inductance of the Gatorade and could not get a very high reading. I think the electrolytes in the Gatorade are lining up in parallel with the output side of the transformer I am at this point going to the store to buy some grape flavor to see if it has the same effect. I don't know what the next step could be. Maybe copper shielding on the bottles!!!

Update-I was getting up from the chair to go to the store and poked myself in the eye with
my slide rule. I will have to post more on the results later.

That surely beats my Two Pair!
B_T

[salvarsan]

re: carbon composition resistors "CC" types

Makers of new CC resistors actually spec them for Resistance vs. dV/dT or "voltage coefficient of resistance (dR/dV) at 10% and 100% rated voltage", or with something that links resistance change to applied voltages.

Under these conditions, CC resistors generate 2nd harmonic distortion that gets amplified into low audibility, and older NOS CC resistors were an order of magnitude worse than new ones.

They make a sonic difference if they are used in a tube circuit that subjects them to a large enough delta-V and dV/dT, usually attached to the plate in the 2nd and 3rd preamp stages of a vacuum tube amp.

As we ought to know by now, 2nd harmonics are sonic sweetening as audible artifacts go.

[J M Fahey]

You want to question what Keene wrote

Dear Mark, you are putting words in my mouth I didn´t utter.
Besides that minor point, you seem to try to counteract something I´m curious about (obviously only blind faith counts; meaning doubt = heresy) with the Logical fallacy called "reference to Authority" instead of showing actual data which proves or disproves what I want to know.
Incredibly, it´s *you* (not me) who publicly doubts Keene

Thinking about this some more, I am not convinced that it is nearly all even harmonics as Keen implies, or actually mostly second harmonic as he writes.

Oh well.
I much prefer Steve´s and salvarsan´s approach of referring to a table or graphic or formula showing exactly that.

By the way, the copies of "The Art of Electronics" by Horowitz (which, not casually, was one of my Gurus , a long long time ago) which I happened to download, are lobotomized in that none (so far) has the first chapter, which should be the one including such table.
Would somebody be so kind as to post a copy of such table or graphic (or a link to it).

Dear salvarsan, could you link to some datasheet which you are referring to?

Thanks in advance.

[Mike Sulzer]

re: carbon composition resistors "CC" types

Makers of new CC resistors actually spec them for Resistance vs. dV/dT or "voltage coefficient of resistance (dR/dV) at 10% and 100% rated voltage", or with something that links resistance change to applied voltages.

Under these conditions, CC resistors generate 2nd harmonic distortion that gets amplified into low audibility, and older NOS CC resistors were an order of magnitude worse than new ones.

They make a sonic difference if they are used in a tube circuit that subjects them to a large enough delta-V and dV/dT, usually attached to the plate in the 2nd and 3rd preamp stages of a vacuum tube amp.

As we ought to know by now, 2nd harmonics are sonic sweetening as audible artifacts go.

OK, so there are two effects, one related to how fast the voltage is changing (T is time, not temperature, right?), and the other to the voltage itself.

But is it really the voltage itself (a signed quantity) or the magnitude of the voltage that counts? (if the latter, then the derivatives would be written
d|V|/dT and dR/d|V|.)

This matters for the symmetry of the distortion. I suspect that it is the magnitude that counts, and so it is backwards from what I wrote earlier: it is second harmonic for a (biased) plate resistor, and 3rd harmonic for an unbiased resistor, like a load resistor coupled to the plate by a capacitor.

[FunkyKikuchiyo]

Here's a stupid question for the resident empiricists... how exactly do you measure harmonic content for even order vs. odd order, which harmonic, and whether it is distorted or not? I feel like I'm missing something.

(before you jump on me, bear in mind I prefaced it saying that it was a stupid question)

[David Schwab]

Are ya sure ya wanna be quoting RG Keen? he's kinda the Mike Sulzer of the DIYStompbox forum (no offence to Mike) and, well, we already have Mike here (no offense to RG).

I think we have RG here as well, or at least in the effects section.

[Alan0354]

OK, so there are two effects, one related to how fast the voltage is changing (T is time, not temperature, right?), and the other to the voltage itself.

But is it really the voltage itself (a signed quantity) or the magnitude of the voltage that counts? (if the latter, then the derivatives would be written
d|V|/dT and dR/d|V|.)

This matters for the symmetry of the distortion. I suspect that it is the magnitude that counts, and so it is backwards from what I wrote earlier: it is second harmonic for a (biased) plate resistor, and 3rd harmonic for an unbiased resistor, like a load resistor coupled to the plate by a capacitor.

I think dR/dV is the important part. Still under the change of the plate voltage, there is an inherent second harmonics from the tube that should dominant the effect no matter you use metal film or CC. This hold true for JFET or MOSFET where you can see the slope of the drain curve are quite steep like the tubes.

I think BJT would be bad for guitar amp in this sense because the collector curves are very flat implies dI/dV is very small ( early voltage is very high). You won't get much second harmonics out of the BJT.

[Mike Sulzer]

I think dR/dV is the important part. Still under the change of the plate voltage, there is an inherent second harmonics from the tube that should dominant the effect no matter you use metal film or CC. This hold true for JFET or MOSFET where you can see the slope of the drain curve are quite steep like the tubes.

I think BJT would be bad for guitar amp in this sense because the collector curves are very flat implies dI/dV is very small ( early voltage is very high). You won't get much second harmonics out of the BJT.

But does the sign of the dR/dV matter? Could it add to the second harmonic produced by the tube with one sign, and subtract with the other?