Search found 290 matches

by terkio
Fri Jan 22, 2021 2:50 pm
Forum: Pro Audio Design
Topic: Super Low Distortion Ultra Pure Audio Oscillators Revisited
Replies: 132
Views: 176002

Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

I do not understand about J1 J2.
I see a balanced-only configuration as a underpopulated board, no J1 no J2 no VR2 but a strap, four caps become one.
by terkio
Thu Jan 21, 2021 9:20 pm
Forum: Pro Audio Design
Topic: Super Low Distortion Ultra Pure Audio Oscillators Revisited
Replies: 132
Views: 176002

Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

Yes. A link given by mediatechnology in a previous post. http://www.janascard.cz/PDF/An%20ultra%20low%20distortion%20oscillator%20with%20THD%20below%20-140%20dB.pdf Very informative, a key source. With: Resistors are preferably 0.1%, 15 ppm/K through-hole types, capacitors are preferably polystyrene...
by terkio
Wed Jan 20, 2021 5:47 pm
Forum: Pro Audio Design
Topic: Super Low Distortion Ultra Pure Audio Oscillators Revisited
Replies: 132
Views: 176002

Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

I was amazed to see very good notch depth despite a +/- 10% capacitor. Thanks to the two trimmers adjusted in SE mode to accurately get Fc 1KHz, I get -96dB notch depth on the 6 cases I simulated. The trimmed 15.9k range is: 14.5k to 17.7k. The trimmed 15.9k/2 range is: 7.4k to 8.6k. So, I think you...
by terkio
Wed Jan 20, 2021 2:46 pm
Forum: Pro Audio Design
Topic: Super Low Distortion Ultra Pure Audio Oscillators Revisited
Replies: 132
Views: 176002

Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

I have done more work about the two ways to build a balanced notch filter. This is about J1 and J2. What is best two jumpers or one jumper. I had thought a twin H was better rather than a double Twin T. It looks good and can be built with all equal capacitors. Then I realized that this was not a rat...
by terkio
Tue Jan 19, 2021 5:57 am
Forum: The Peabody Lounge
Topic: digital thermometers.... arghhh
Replies: 21
Views: 33435

Re: digital thermometers.... arghhh

mediatechnology wrote:
Tue Jan 19, 2021 5:43 am
You need a "cotton region" shelter for your outdoor instruments...

https://proaudiodesignforum.com/forum/p ... f=12&t=476
Definitely. This is the real thing and it would look great in JR backyard. 😀
by terkio
Thu Jan 14, 2021 5:33 pm
Forum: Pro Audio Design
Topic: Super Low Distortion Ultra Pure Audio Oscillators Revisited
Replies: 132
Views: 176002

Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

So far, with simulations I found no difference. Virtual grounds connected or not, no difference detected. The unbalances, I tried: inputs amplitudes 0.25 0.75 ( iso 0.5 0.5 ) input resistance 1K 2K ( iso 1K 1K ) With or without differential output load 100K. Interesting. I found the same thing on t...
by terkio
Thu Jan 14, 2021 1:38 pm
Forum: The Peabody Lounge
Topic: Entropy
Replies: 1296
Views: 603733

Re: Entropy

I cannot resist to tell a most stupid mistake of my own. That was with a battery charger. A cheapo. I set the charger near the car battery, checked I had an ok voltage at the battery, so far so good. A couple of hours later, I came back to check. From a clumsy move, the charger tumbled down, while i...
by terkio
Thu Jan 14, 2021 9:04 am
Forum: Pro Audio Design
Topic: Super Low Distortion Ultra Pure Audio Oscillators Revisited
Replies: 132
Views: 176002

Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

So far, with simulations I found no difference. Virtual grounds connected or not, no difference detected. The unbalances, I tried: inputs amplitudes 0.25 0.75 ( iso 0.5 0.5 ) input resistance 1K 2K ( iso 1K 1K ) With or without differential output load 100K. I then thought I should try with non idea...
by terkio
Wed Jan 13, 2021 6:48 pm
Forum: Pro Audio Design
Topic: Super Low Distortion Ultra Pure Audio Oscillators Revisited
Replies: 132
Views: 176002

Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

Extremely brain warping. When fully balanced, indeed both are at 0V so no current in between. So it should make no difference to split or not to split. But I am not sure, I feel some pit fall here. Assuming fully balanced inputs ( same level, same impedance ) and fully balanced output ( same load ) ...
by terkio
Wed Jan 13, 2021 6:03 pm
Forum: Pro Audio Design
Topic: Super Low Distortion Ultra Pure Audio Oscillators Revisited
Replies: 132
Views: 176002

Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

All that has to be done to switch the filter topology from Left/Right to balanced is to float where VR2/C3/C4 on both channels would common to ground and switching R7 from ground to the other channel's R7 to make the SE 40 dB gain stages a 40 dB INA. It only takes two switch poles I think you need ...