Distortion measurements

[premiumplus]

Hi guys,
First off, Happy Veteran's Day, and a big THANK YOU for your service to any and all of our service veterans out there...I can't thank you enough.

On the subject of "The only stupid question is the one that is not asked"...
Is there a way that I can get any meaningful distortion measurement without a distortion meter?
I have a nice HP function generator, a Tek 220D 2 channel scope, and a couple of 2 channel analog scopes. Also an old HP boat anchor audio generator that supplies nice clean tube powered sine waves.
I'm thinking that if I use square waves at various frequencies I can get a fair idea of how the amp tracks by comparing the input from the function generator on one channel to the output from the amplifier on the other.
Have any of you tried something like this, and did you get useful data from it?
Dave

 

[Skywavebe]

As far as I know the Audio Amp is not happy working with square waves and the only thing measured with square waves is transient response or rise time of a amp. They most likely will get rounded off some of the way. The distortion analyzers are looking for harmonics of the third order from off the fundamental frequency and that is a matter of filtering, weighting and comparative value of the waveforms. If you don't have the right equipment some of these computer plug in programs might o the job cheaper than getting a HP Distortion analyser.

 

[laatsch55]

Getting useful distortion specs from only com,paring in/out sinewaves is problematic. When you are talking less than 1% the resolution is not there. Google "Daqarta". It's a sound card based suite of audio testing, fairly cheap with free yearly updates...

 

[laatsch55]

Or an ATS-1DD as Sam also has.

 

[laatsch55]

That's a pretty Pre-amp in the Avatar!

 

[premiumplus]

That's a pretty Pre-amp in the Avatar!

Thank you sir, that's my Luxman 350. The cab was trashed when I got it, it had water glass marks all over it...but with lots of sanding and 3 coats of tung oil, it looks gorgeous. We're going to find out how good it is later in the week when I get my PL400 updated with dc protection.