Bruce Hofer (AP) has been mentioned many times here and reference made to his and his companies expertise. His article, Designing for Ultra-Low THD+N v1.0 , originally written for AudioExpress is being re-distributed on the AP site, AP High Performance Audio Analyzer & Audio Test Instruments : Downloads
Cheers
Alan
Cheers
Alan
Bruce is a great guy. I've known him since his Tektronix days, before he co-founded AP with Rich Cabot. His AES paper on the state variable oscillator used in the SG505 is what inspired me to get into using state variable approaches for the oscillator and analyzer in my THD analyzer.
Cheers,
Bob
Didn't look closely at topology but another old-timer has a nice osc and amps etc on his site: www.renardson-audio.com/index.html
Thx-RNMarsh
Thx-RNMarsh
I made a significant performance improvement on my Shibasoku 725; http://www.diyaudio.com/forums/equi...matic-distortion-analyzer-17.html#post3847749 Its interesting how much the opamp after the filter affects the performance. Next step will be the Shibasoku Oscillator.
Hi,
My new oscillator design is getting closer and closer, but it will still take a while until it's finished and ready for publication.
I intended to make an earlier work of mine on low distortion oscillator design available at this point. Triggered by some personal communications I thought that it might be time to advance this, so here we go:
low_distortion_oscillator_design.pdf
low_distortion_oscillator_design_schematics.pdf
The oscillator I'm now working on is a redesign of the above thesis. It will have better performance and lower cost/complexity. My understanding of oscillator design issues (particularly WRT leveling loop dynamics) is much better now, and there are a few shortcomings with regard to contents in the text. But perhaps it is of interest to some of you nonetheless.
Samuel
My new oscillator design is getting closer and closer, but it will still take a while until it's finished and ready for publication.
I intended to make an earlier work of mine on low distortion oscillator design available at this point. Triggered by some personal communications I thought that it might be time to advance this, so here we go:
low_distortion_oscillator_design.pdf
low_distortion_oscillator_design_schematics.pdf
The oscillator I'm now working on is a redesign of the above thesis. It will have better performance and lower cost/complexity. My understanding of oscillator design issues (particularly WRT leveling loop dynamics) is much better now, and there are a few shortcomings with regard to contents in the text. But perhaps it is of interest to some of you nonetheless.
Samuel
I am very, VERY surprised by the author's admonition against using metal foil resistors. This needs more study; what am I missing?
Otherwise this is an interesting read that confirms some long-held opinions on passive component quality and linearity becoming increasingly important as noise/distortion becomes extremely low by design: the littler things start to become significant.