An Improved Servo for the THAT1510 and THAT1512

Where we discuss new analog design ideas for Pro Audio and modern spins on vintage ones.
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JR.
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Re: An Improved Servo for the THAT1510 and THAT1512

Post by JR. » Wed Feb 15, 2012 5:14 pm

A few uA of leakage sounds high, while the data sheet spec is even more than that, I don't recall it being that much or a problem in practice.

Regarding noise from that leakage, it is terminated by a couple hundred ohms of microphone at audio frequencies so rarely an issue. I recall exactly one production incident when a new model electrolytic cap, got flagged by the factory QA people for noise. My speculation is that, this cap manufacturer made their new improved part too small and cheap to work in that particular application.

So generally not a problem but there are problem parts out there so trust but verify.

JR
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mediatechnology
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Re: An Improved Servo for the THAT1510 and THAT1512

Post by mediatechnology » Wed Feb 15, 2012 6:43 pm

I think the best thing you can do is anticipate the need for phantom and allow things to settle for 5-15 minutes before you actually use the preamp for a take.

One of the other issues is that after turn-on, the differential DC offset can be quite large as the C pair charges unequally.
If there is no Cgain capacitor (there was probably a Cgain used in the low-cost realm) the servo has to correct that constantly-changing error for the first minute or two.

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https://ka-electronics.com

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mediatechnology
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Re: An Improved Servo for the THAT1510 and THAT1512

Post by mediatechnology » Mon Jul 09, 2012 8:36 pm

Take a look at the "improved" improved servo here: viewtopic.php?f=6&t=14&start=114
https://ka-electronics.com

"States Ordered To Fraudulently Inflate COVID-19 Cases 15 Times Actual Rate"
https://banned.video/watch?id=5efab695672706002f367a0a
"Plandemic/Doctors In Black" https://proaudiodesignforum.com/content/Plandemic.mp4

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