Search found 4604 matches

by mediatechnology
Sat Nov 28, 2020 5:36 am
Forum: The Peabody Lounge
Topic: The Corona Virus Hoax of 2020
Replies: 297
Views: 25246

John Hopkins Study: A closer look at U.S. deaths due to COVID-19

John Hopkins Study: A closer look at U.S. deaths due to COVID-19 Cached copy: https://waynekirkwood.com/images/pdf/A_Closer_Look_At_US_Deaths_Due_To_COVID-19_The_Johns_Hopkins_News_Letter.pdf Retrieved from: https://web.archive.org/web/20201126163323/https://www.jhunewsletter.com/article/2020/11/a-...
by mediatechnology
Fri Nov 27, 2020 9:48 am
Forum: Pro Audio Design
Topic: Super Low Distortion Ultra Pure Audio Oscillators Revisited
Replies: 62
Views: 49478

Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

Here's the schematic of the notch filter I've been using borrowed from "Janasek."

Image
"Nacho" 1kHz Notch Filter

"Nacho's" insertion loss at 2 kHz is about -9dB; at 3 kHz the loss is about -5 dB.
by mediatechnology
Thu Nov 26, 2020 9:20 pm
Forum: Pro Audio Design
Topic: Super Low Distortion Ultra Pure Audio Oscillators Revisited
Replies: 62
Views: 49478

Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

The converter and output stage for a NCO/DDS is still the weak link. With all the hardware and advanced math shown in the ADI document to generate a sinewave the best performance they can come up with is only equal to a high quality Soundcard or outboard converter. The analog oscillator is so much b...
by mediatechnology
Thu Nov 26, 2020 8:53 pm
Forum: Pro Audio Design
Topic: variable gain amplifier using analog optoisolators
Replies: 5
Views: 90

Re: variable gain amplifier using analog optoisolators

The Tesla "Vactrols" are very interesting. I hope they come out with a VTL 5C3 replacement. I would keep going with your project though I'm not sure you'll find an CdS-based photocell to be fast enough for peak limiting. You might want to consider a hybrid approach using both an Opto and a FET. The ...
by mediatechnology
Thu Nov 26, 2020 11:49 am
Forum: Pro Audio Design
Topic: Super Low Distortion Ultra Pure Audio Oscillators Revisited
Replies: 62
Views: 49478

Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

I don't have a commerically-made DAC that can even come close to this low a level of THD. The THD and purity of this oscillator, or other analog solutions is at least an order of magnitude - maybe two orders of magnitude - better. It can be used to check A/D distortion and it's notch filter used to ...
by mediatechnology
Wed Nov 25, 2020 11:12 am
Forum: Pro Audio Design
Topic: Super Low Distortion Ultra Pure Audio Oscillators Revisited
Replies: 62
Views: 49478

Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

I still have some minor tweaking to do but the Ultra Low Distortion Oscillator looks pretty much like this: Oscillator schematic: https://proaudiodesignforum.com/images/png/ULDO_Ultra_Low_Distortion_Oscillator_Schematic_Cropped.png "ULDO" Ultra Low Distortion Oscillator Schematic Large format schem...
by mediatechnology
Wed Nov 25, 2020 8:19 am
Forum: Pro Audio Design
Topic: variable gain amplifier using analog optoisolators
Replies: 5
Views: 90

Re: variable gain amplifier using analog optoisolators

I purchased the fastest optos available, the Tesla 3WK160
Hi, thanks for your post.
Do you have a data sheet link for the opto?
by mediatechnology
Wed Nov 25, 2020 7:26 am
Forum: Pro Audio Design
Topic: Super Low Distortion Ultra Pure Audio Oscillators Revisited
Replies: 62
Views: 49478

Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

3) The third source is the output stage when heavily loaded at high levels. Working on it. Unloaded the second order is in the noise floor. The above appears to be PSRR related. I need to add bypass for the front end transistors and use shunt regulators for the whole oscillator similar to Vicktor's...