HK Square Wave Analysis of Audio Perform.

[GeneT]

Attached is the scanned HK Square Wave Analysis of Audio Amplifier Performance from approximately 1975. This is an assessment of the performance and importance of square wave processing for the 430, 730 A401 and Citation 12 receivers / amplifiers (possibly more). I had to zip up 2 or 3 of the .jpg's at a time into .zip format to get them inside of the forum file size limit. If anyone needs this as a single PDF format drop me a note with an email address and I can send it along, or if you have public storage for easier sharing, I can upload the pdf file there. Gene

 

[Jim H B]

Very cool of you to scan that Gene, thanks. Interesting reading too.

Jim

 

[GeneT]

No problem

It speaks to the quality of vintage audio that that 25 year old literature is more that just history. Gene

 

[Proconsul]

Five years since the last post, I've just come across this excellent article -- thanks, GeneT. I've often wondered about how to fully interpret square waves, and this article has helped. I often see SW results for tube amps that exhibit much more tilt than the HK amps in this article, which I suppose reflects that transformer-coupled amps have a more difficult time controlling the bass drivers and the back EMF generated.

 

[SoCal Sam]

Excellent article. Only the most confident of manufacturers will publish SW results. The others will market using the "listen for yourself" angle which to me is code for poor objective performance. The explanation of the importance of rise time as it relates to transients is the reason why fast amps are better at reproducing the inner details of instruments. Sound is vibration and in real time (live), rise time is perfect. Sound is also a stream of vibrations which will blur if rise time is not vertical because the the previous vibration has not completed when the next vibration occurs. There is absolutely no reason to accept anything less in a solid state amplifier.

The relationship between objective performance and perceived SQ in tube amps is less clear to me. Rise time and DF in tube amps imply they are slow and should sound muddy but IME, tube amp SQ is not degraded in anyway. IMO, tube amps sound BETTER than the vast majority of solid state amps which would imply that objective performance rules are different for tubes and ss. I'd like to understand this paradox better. I think it has to do with the odd order harmonics of ss vs. the even order harmonics of tube amps.

 

[richiem46]

Just read this article today. Very interesting for sure!