Pro Audio Design Forum

MM carts are sensitive to termination capacitance. High and low capacitance cables, and length, should be considered when going for a target termination. I used to sell a kit 4 station dip switch and PCB with 24pF, 47pf, 100pF and 200pf polystyrene caps to cover a wide range of terminations. There ...

It's done. It of course took much longer than I thought. That's kind of a good thing. If I accurately could estimate time I probably wouldn't have started in the first place. http://www.saltmastering.com/Console/EE-FilterSet-1.JPG http://www.saltmastering.com/Console/EE-FilterSet-3.JPG The faceplate...

I fixed the response of Pre B LPF. It was all of my own doing as usual. Yesterday I fixed the Pre B HPF section which of course wasn't broken... I took another look at it today. I had the 680p and the 10n capacitor positions swapped on the right channel. Now it matches to a few hundredths of a dB li...

Yes, that's about as close to 16 kHz as we can get on the LPF with E6-series capacitors. Great. I’ve never measured the HT75’s. I hope I’m not coming across as nit picking. I’m trying to learn. Do the same component tolerances account for the roll off being -14dB at an octave out instead of -18dB?

It looks like the error in the Pre B HPF is an errant resistor. I went back and found better capacitor matches. It helped a little but not much. I'll have to go through the resistors again. I have a couple of questions though. I tried to use exact specified values for the capacitors and resistors. I...

That's excellent Paul! The only one that was significantly different was: Pre B HPF Left: -14.00dB HPF Right: -13.04dB Yeah, I ran out of very tightly matched sets. I was selecting for absolute value as well as relative matching. That's why the gains also match from board to board. I could get a be...

I have all four boards working and tested. Hopefully I can finish up the unit on Saturday. Since it's going in the case with the EE's the wiring shouldn't be too bad. I can recycle some of the wiring already in place. http://www.saltmastering.com/Console/Filter-3.JPG http://www.saltmastering.com/Con...

Because of the weather my Mouser shipment was delayed. I've done a bunch of work on the boards so it hopefully won't be too much work to get them installed . I've stuffed and soldered one board to make sure it works. I've stuffed and soldered most of the other boards except for the tuning capacitors...

Thanks Wayne! I am the one with the limping HT75's. Hopefully I'll be able to get them built and installed in the next week or so. I can't wait decommission the HT75's for a few reasons. I will be able to locate the PCB's in the same chassis as the EE. This will free up 2RU for future expansion.

terkio wrote: ↑Wed Jan 20, 2021 4:47 pm So, I think you do not need accurate costly capacitors, trimming will fix this like wonder. Very good TempCo seems more important than accuracy.

What about a C0G ceramic? They have very stable TempCo and are very linear.