Name for this sort of distortion ?

Asymmetry is the term that springs to mind ...

Arfa

rectification

no Like you have the term clipping distortion for being driven into the DC rails, of course Googling for something like gets nowhere

Half wave?

Ron(UK)

If the audio voltage is "low level" -- under 1 volt peak, and the amplifier output is a push-pull type especially class B, then it is probably crossover distortion.

If the audio voltage you see is well over 1 volt peak (with no negative voltage swing), then what the other guys above said is correct, but there is no standard term for that kind of distortion I can think of other than "rectification".

If one half cycle was missing, you couldn`t have crossover distortion as there wouldn`t be any crossover.

Half wave rectification maybe, tho it`s not being 'rectified', it`s just missing.

Ron(UK)

and

I'll call it complementary output failure half-wave distortion, but as its a specific and recognisable sort of distortion that it had a specific name. Just writing up a Laney R4 repair brief.

I've asked this one before but is anyone aware of a collection of audio file snippets with simulated or actual named distortions to point non-technical owners of equipment to to help diagnosis of intermittant faults.

Crossover distortion is a very specific type of distortion that results from incorrect bias in a class B output stage. That incorrect bias causes the 'handover' from one output device to the other, to not take place in a smooth manner, due to one or other of the devices not being lifted off the non-linear part of the bottom end of its curve at the zero drive point. It does not result in one half of the signal being missing.

When one half of the signal is going missing, due to either an output or drive fault, I suppose at a pinch, you could apply the term 'rectification' on the grounds that the resulting waveform would look like it had been passed through a single diode, but to make this connection between a faulty amplifier, and what is normally associated with being a power supply function, is tenuous at best, and downright misleading at worst. I still say that the only term that I have seen applied to this type of distortion occuring in an amplifier, is asymmetry.

Arfa

On Tue, 16 Jan 2007 12:41:12 +0000, N Cook Has Frothed:

Unisymetricalnon-modularhyperbolichalfsinetoriodalimbalance?

I suppose you could call it a level-shifted clip if you don't like rectification. Asymmetry seems a bit broad to me.

Broad ? Where do you get "broad" from ? Two definitions from dictionary.com a·sym·me·try (a-sim'i-tre) n. Lack of balance or symmetry.

and

a·sym·me·try (-sm-tr) n. Disproportion between two or more like parts; lack of symmetry.

Seems to pretty much cover the condition to me. I would also contest that we are talking clipping here. Again, like crossover distortion, clipping is a very specific form of ( sometimes intentional ) distortion, and tends to be characterised by being symmetrical, although I will accept that it can be asymmetric. The condition that is being discussed here is probably not even strictly speaking "distortion" - rather, it's a severe corruption of the intended performance, by virtue of a fault condition. I also don't follow "level shifted". The reference level surely remains fixed at zero ?

I think that we're all in danger of over-complicating a straightforward situation here ... :~)

Arfa

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This unbalance would be caused by failure of on half of a push pull amplifier. It would become a single ended class B amplifier.

No. That's symmetrical.

Graham

Correct !!

Arfa

Not really (IMO) because the waveform would have half cycle long periods at 0 volts, the output would be chopped

Ron(UK)