Sensitivity to crossover distortion

[angel]

Has anyone here got information on what frequency segments appear to suffer the most/least from crossover distortion and/or magnetic hysteresis distortion?

It would be interesting to know, in these biamped days.

[Sch3mat1c]

Uh.. it's an odd harmonic distortion, so anything below 20/3 = about 7kHz should sound different when distorted as such.

It's far easier to see on the scope than to hear it, I think. Haven't played around with it much.

Lemme see... I don't have 7 12AT7s up here to plug into Hept'AU7 so I'll try Frankenhouse... goes down to... -35V on 6V6s at 350Vs, which is 14mA at the cathode. Sounds just the same, so it's still not even into class B yet. I have -56V available so I can try more bias and get back to 'ya. But right now I have to use the bathroom

Tim

[angel]

Originally posted by Sch3mat1c
Uh.. it's an odd harmonic distortion, so anything below 20/3 = about 7kHz should sound different when distorted as such.

Yes. And even 7kHz would probably cause phenomenon related to spatial clues. I'm just wondering what ranges are most sensitive.

It's far easier to see on the scope than to hear it, I think. Haven't played around with it much.

I suspect as much, as I have a class B amplifier here which has no noticeable harshness or artifacts to its sound. It does lack detail, though, and I expect that can be attributed to crossover distortion.

not even into class B yet. I have -56V available so I can try more bias and get back to 'ya.

That would be nice.

[Sch3mat1c]

...After some calculations and poking in a hot chassis it seems the bias supply is 138kohms impedance (that is, it acts as a -500V voltage source with 138k source impedance in series), so only gained but 2V when I shorted the top resistor (4.7k.. below it is 2x10k bias pots in parallel, followed by another 4.7k, then ground). Seems 6V6s don't lose much Gm despite being biased at 15mA! Although, it does have an NFB loop which is going to hide the nasties, as it's supposed to.

I could bring it to the bench and do some more exhaustive studies but I can't help you with audiophilogical persuits, as everyone has their own take on it.

Tim