Super Low Distortion Ultra Pure Audio Oscillators Revisited

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fredbloggstwo
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Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

Post by fredbloggstwo » Mon May 17, 2021 8:43 am

mediatechnology wrote:
Thu May 13, 2021 3:44 pm
Thanks George and Mike!
To answer your question George I have a couple of extra boards.
So where do I sign up - can't see them in your store? :)

Do you have a BOM as well?

Thanks

Mike

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mediatechnology
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Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

Post by mediatechnology » Mon May 17, 2021 9:13 am

MIke - I sent you a PM. Thanks for your interest.
I hope to have a BOM later today and will then start on some assembly instructions.
I've spent the last few days testing the board pretty extensively - the 1M pt 10 sample FFTs take quite awhile to run.
https://ka-electronics.com

“Diet, injections, and injunctions will combine, from a very early age, to produce the sort of character and the sort of beliefs that the authorities consider desirable, and any serious criticism of the powers that be will become psychologically impossible.” – The Impact of Science on Society (1953) by Bertrand Russell, p.50

Dr. Sherri Tenpenny Exposes 10 Deadly Dangers of Pzifer/Johnson & Johnson Covid-19 Vaccines: "This is a well-designed killing tool." https://waynekirkwood.com/content/Docto ... accine.mp4
Plandemic Series: "Pland3mic - Indoctornation" https://waynekirkwood.com/content/Pland ... nation.mp4
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mediatechnology
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Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

Post by mediatechnology » Mon Jun 14, 2021 9:28 am

Here's a link to the THD calculator I use to interpret ULDO/Nacho's FFTs.

https://proaudiodesignforum.com/calcula ... ulator.xls

I plugged in some typical measurement data into the xls.
The gray cells are for measurements and test conditions.

Image
https://ka-electronics.com

“Diet, injections, and injunctions will combine, from a very early age, to produce the sort of character and the sort of beliefs that the authorities consider desirable, and any serious criticism of the powers that be will become psychologically impossible.” – The Impact of Science on Society (1953) by Bertrand Russell, p.50

Dr. Sherri Tenpenny Exposes 10 Deadly Dangers of Pzifer/Johnson & Johnson Covid-19 Vaccines: "This is a well-designed killing tool." https://waynekirkwood.com/content/Docto ... accine.mp4
Plandemic Series: "Pland3mic - Indoctornation" https://waynekirkwood.com/content/Pland ... nation.mp4
Plandemic Series: "Plandemic - Doctors In Black" https://waynekirkwood.com/content/Plandemic.mp4

fredbloggstwo
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Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

Post by fredbloggstwo » Tue Jun 22, 2021 3:36 pm

Hi Wayne

thanks for posting the calculator. I'll give it a try in a day or so.

I have got mine working after a little finger trouble on my part :-) and also found what I think are a couple of minor errors in the build guide/testing section.

The building was straight forward and I followed your build guide to the letter but double checked against my own BOM at the same time.

I found that IC8, the Notch filter 5532 amp (both sections of the 40dB post filter amp) has a d.c. offset of about 1.5 volts and is not a about 10mV volts as suggested in the guide. I tried some cherry picking on my Signetics 5532 and that was the lowest I could get it. So I put a LM4562 in instead which brought it down to a few 10s of mV. I might have a play with some alternative low noise FET opamps in that position.

I am out for a few days so I will post some photos for the scrap book when I get back.

Best regards

Mike

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mediatechnology
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Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

Post by mediatechnology » Tue Jun 22, 2021 5:23 pm

Mike you're right about the output offset. That 10mV number was from cut and paste. The 1.5V that does develop shouldn't be too much of a problem since the output is AC coupled and the INA doesn't see much level due to the preceeding notch filter. I actually anticipated that and AC coupled it for that reason.

I haven't tried an OPA2134 there it may be quiet enough. An LME49720/LM4562 should work ok and not latch up at 30V with a 100K bias resistor.

You may have noticed I also forgot to tell the reader to install VR2-5.

Thanks for the feedback. I'm about to build a second one based on my instructions so I may find more errors.
https://ka-electronics.com

“Diet, injections, and injunctions will combine, from a very early age, to produce the sort of character and the sort of beliefs that the authorities consider desirable, and any serious criticism of the powers that be will become psychologically impossible.” – The Impact of Science on Society (1953) by Bertrand Russell, p.50

Dr. Sherri Tenpenny Exposes 10 Deadly Dangers of Pzifer/Johnson & Johnson Covid-19 Vaccines: "This is a well-designed killing tool." https://waynekirkwood.com/content/Docto ... accine.mp4
Plandemic Series: "Pland3mic - Indoctornation" https://waynekirkwood.com/content/Pland ... nation.mp4
Plandemic Series: "Plandemic - Doctors In Black" https://waynekirkwood.com/content/Plandemic.mp4

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Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

Post by mediatechnology » Wed Jun 23, 2021 1:09 pm

Using a 5532 I just checked the output offset on the first PC board and it's about -1.8V with the notch filter unbalanced and about -130 mV with the jumpers set to balanced.
That offset is primarily due to Ib*100KΩ*Gain.

I made Rbias large to allow a lowish value polypropylene film cap and let the offset develop to avoid an electrolytic anywhere in the notch filter.
The offset doesn't significantly reduce DR since the output would rarely be outputting a signal higher than -10 dBu.

The coupling caps for the VCA input and notch filter are a lot larger than they need to be for 1 kHz but I wanted to leave the door open to make a 100 Hz version without resizing them.
All the signal path caps on the BOM are polypropylene except the output coupling caps/1246 input caps which are polyester.

When I get a chance I'll drop an OPA2134 in the notch filter and see how it affects the filter output noise.
https://ka-electronics.com

“Diet, injections, and injunctions will combine, from a very early age, to produce the sort of character and the sort of beliefs that the authorities consider desirable, and any serious criticism of the powers that be will become psychologically impossible.” – The Impact of Science on Society (1953) by Bertrand Russell, p.50

Dr. Sherri Tenpenny Exposes 10 Deadly Dangers of Pzifer/Johnson & Johnson Covid-19 Vaccines: "This is a well-designed killing tool." https://waynekirkwood.com/content/Docto ... accine.mp4
Plandemic Series: "Pland3mic - Indoctornation" https://waynekirkwood.com/content/Pland ... nation.mp4
Plandemic Series: "Plandemic - Doctors In Black" https://waynekirkwood.com/content/Plandemic.mp4

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