Pro Audio Design Forum

I found the 1/f component to be quite high in a number of caps I tested even with the input terminated in 150R and Rbias at 1k. These samples were Panasonic SU-series so as you often say YMMV. For new never-before-powered caps it took them 30 minutes or more to get "quiet." I did find the ...

John - Thank you for bringing that to my attention. I think the comment made was for a topology that didn't provide correction of differential offsets from mic-induced errors. I saw that problem from the get-go and the posts here deal with that issue in great detail. I wrote early on: 7) Because DC ...

Thanks Paul! Yes, they're in. Note that postage is going up Mother's Day and all rate bets are off. I hope to have an early BOM posted here soon and there are those schematics to get drawn for Roger to tidy up. Here's the link: http://www.ka-electronics.com/kaelectronics/MS_Matrix/MS_Matrix.htm Rath...

Have you looked at this one? No input or Cgain caps. http://www.picocompressorforum.com/forum/php/viewtopic.php?f=6&t=14 I would do the offset servo differently now and change a couple of things but it's passed the proof-of-concept stage and works. Roger sent me some AT3525s to try with it. The ...

So I'll be OK using the two 3.3k resistors and 22k for the center resistor? Yes, to make my rather long story short that should work fine. :ugeek: Without coupling caps however that extra resistor doesn't bring much to the party. Have you considered using a 1512? It would drop in the same socket an...

Using the T-bias scheme, what impedance will a mic see? I'm concerned about loading dynamic and ribbon mics. I have built a preamp around the 1510 using two 3.3k resistors to ground using the rule of thumb that the input impedance should be 10x the mic impedance (I do have a 600-ohm mic, AT804, and...

Here's one way to operate and bias a THAT1646 for single supply operation: https://www.ka-electronics.com/images/jpg/THAT1646_Single_Supply.jpg Image courtesy of THAT Corporation If the input is at or near the same DC potential as Vref (the one-half Vcc potential at the output of U2A) then C2 and R1...

raf wrote:I need to re-pitch the output device pads... I used 0.1" thinking they were TO220, they are, what TO126?

They are an insulated TO-126 on a 2.28 mm pitch. 0.1" may be close enough.

Thanks Roger and Doug.

I had a chance to check the PC board a few weeks ago and run a few measurements. The output Vos was <5mV. The orginal slew rate was thought to be ~4V/us but when re-measured turned out to be ~8V/us. This is consistent with the THAT1646 when driven in the "common mode" configuration. The RM...

What was the harmonic content of the fields? Could it be an issue of core saturation?