The single-ended Nature of things

[SumTingsBurning]

I want to do more tests on this. Does anyone know of a circuit that can be use to create 2nd or 3rd order distortion. Ideally it would have a pot to adjust the level and the distortion would increase with increasing audio signal (like a speaker).

[Steve Eddy]

Originally posted by SumTingsBurning
I want to do more tests on this. Does anyone know of a circuit that can be use to create 2nd or 3rd order distortion. Ideally it would have a pot to adjust the level and the distortion would increase with increasing audio signal (like a speaker).

You could use an audio transformer and run some current through either the primary or secondary. Make the current adjustable and voila...

se

[Nelson Pass]

You can work up some serious adjustable effects with
Germanium diodes, chosen for the sloppiness of their
conduction curve.

Put level pots on the input and output and use 1 diode (for 2nd)
or 2 in reverse/parallel (for 3rd harmonic) to ground and adjust
the input and output pots to get the effect.

I have played with this at length years ago, as have many
others, and the result is that introducing such distortion into a
circuit only partially accounts for the sound of tubes or simple
solid state circuits. As far as I'm concerned, it's a dead end.

[Steve Eddy]

Originally posted by Nelson Pass
I have played with this at length years ago, as have many
others, and the result is that introducing such distortion into a
circuit only partially accounts for the sound of tubes or simple
solid state circuits. As far as I'm concerned, it's a dead end.

Yeah, but the context here really hasn't anything to do with emulating the sound of tubes but rather using distortion as a means of ultimately reducing total system distortion by producing distortion in the amplifier which is effectively complimentary to the distortion produced by the loudspeaker.

se

[Nelson Pass]

Well, you're right.

[pr]

Hi guys
thank you for this great thread. Never before I found all this information so compact.
But one thing I'm missing here which might be of interest: the reason why high order distortion is not desirable.
The higher the level of higher order harmonics the more energy is contained in them. For example when softly knocking with a wooden stick and with a steel stick on a table it's easy to distinguish between them. But when hitting strong, the sounds become more similar like a sharp bang, because the higher order harmonics rise in relation to the first harmonic and from the spectrum it's not easy to tell anymore which stick was used. It sounds more threatening, like a warning for danger. Similar with singing and scream. In addition, high order distortions are not masked by the 1. harmonic so there are audible in very small dosis.

I think (that means I don't know) that's the reason why so many cheap amplifier sound only up to a few watts (a little) acceptable although they are able to deliver 100 watts permanent at 1 percent distortion. On more than 1 to 5 watts output they tend to "scream". Can anybody confirm this guess?

Another question:
Will a single ended design allways lead to the desired spectrum (low order harmonics greater than high order harmonics and harmonics increasing with output power)? I guess it's also necessary to use as few stages as possible.
Can anybody shed a light on?

[fdegrove]

Hi,

But one thing I'm missing here which might be of interest: the reason why high order distortion is not desirable

I am baffled by this question...

It should be common knowledge that odd order harmonic distortion tends to sound unleasant to the human hearing system whereas even order ones are still distortion but much more acceptable to the hearing.

Whereas musical instruments contain both types of overtones, the composition and amount of these overtones allows us to distinguish one instrument from the other.

If an amplifier contains predominantly odd order harmonic distortion it tends to sound unpleasant, shrill, thin whatever way you want to describe it but certainly not something you'd call pleasant to listen to for a prolonged period of time.

Amplifier topologies tend to have a tendency to throw up a harmonic distortion spectrum that either supreeses even harmonics, leaving whatever odd order harmonic distortion that the device created (PP stages for instances) or, conversely do not suppress the even harmonics with subdued odd harmonics still present.

Most people tend to prefer lowish distortion with a spectrum tending to the latter hence the success of SE amps nowadays.

This is an ongoing topic and I'll leave whatever wisdom I and other old faithfuls have acquired over the years but for the time being I'd just say it's the harmonic content that matters most not quite the amount of the distortion, at least IMHO.

Cheers,

[pr]

I am baffled by this question...

I was not talking about odd or even order but HIGH order harmonics and the reason why they sound unpleasant. And it was not a question, it was a statement. But I have 2 questions for you in my previous post. Mayby you like to answer them?

[fdegrove]

Hi,

I was not talking about odd or even order but HIGH order harmonics and the reason why they sound unpleasant. And it was not a question, it was a statement.

O.K., and what explanation would you actually want for that?
Hasn't that been explained before scientifically and as such is accepted as an actual fact?

But I have 2 questions for you in my previous post. Mayby you like to answer them?

Which are?

Cheers,