[eric343]

Download the Zipfile of pics here

Well, I finished my function-generator kit today, and decided to play around with it. Soo... I hauled out my original, unmodified Cmoy (that uses OPA134s, IIRC) and hooked it up to my oscilloscope. I used the function generator as an input, and took some photos, which are in the zipfile linked to above.

Just for comparison, I also included pics of a cheap Rat Shack amplifier, hooked to the exact same setup; and a pic of the whole setup I used to test the amplifiers with.

 

[eric343]

You know, I was looking at these results a bit more, and I think I can see why IC amps have a 'harshness' as opposed to tube amps. In many of the pictures, I was running the (cmoy) amp off of a sine wave, which sounds like a 'pure' tone. The square wave sounds harsher, because it's "square, not round." So I wonder- do tube amps output sine (or triangle) waves instead of square waves?


Just some 11 o'clock ramblings... I'm probably totally off the mark.

 

[paulb]

Amps are supposed to output a larger version of whatever they are fed with. Tube amps may sound 'warmer' because they introduce more even harmonic distortion. With a good tube or op-amp based amplifier, you should not be able to see the difference on your scope once you correct for gain.

 

[eric343]

Well, if Tyll/Danny/Todd would send me a Max or a BlockHead, I'd be happy to test it out, see if that's right

 

[RMSzero]

Hell, if someone sends me some samples of their handiwork, I would be more than willing to haul them up to one of the undergrad labs some night and create some gain vs frequency graphs with a computer controlled FG/DO setup. I'd have to do some programming but it's a snap in Igor, I've done it before (and I learned why cheap op-amps do NOT make good audio amplifiers).

 

[danny]

eric343 said

Quote:

Well, if Tyll/Danny/Todd would send me a Max or a BlockHead,I'd be happy to test it out, see if that's right

eric, I ran your idea past Todd, and he said it was fine with him, as long as you sent him a good credit card

 

[eric343]

Well then I may as well *buy* it, and that ruins the whole point

(well knowing you, if I did what you suggest I may as well buy it, an Orpheus, and that Krell CD player you guys use as the high-end source on the traveling rig

)

 

[danny]

works for me

 

[Redwoood]

can't download the pics eric.