Search found 643 matches

by Gold
Fri Feb 26, 2021 6:58 pm
Forum: Build
Topic: Transfer Filter / Neumann HT75 Replacement
Replies: 12
Views: 1249

Re: Transfer Filter / Neumann HT75 Replacement

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...
by Gold
Thu Feb 25, 2021 9:49 pm
Forum: Build
Topic: Transfer Filter / Neumann HT75 Replacement
Replies: 12
Views: 1249

Re: Transfer Filter / Neumann HT75 Replacement

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?
by Gold
Thu Feb 25, 2021 7:59 pm
Forum: Build
Topic: Transfer Filter / Neumann HT75 Replacement
Replies: 12
Views: 1249

Re: Transfer Filter / Neumann HT75 Replacement

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...
by Gold
Thu Feb 25, 2021 4:16 pm
Forum: Build
Topic: Transfer Filter / Neumann HT75 Replacement
Replies: 12
Views: 1249

Re: Transfer Filter / Neumann HT75 Replacement

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...
by Gold
Thu Feb 25, 2021 3:32 pm
Forum: Build
Topic: Transfer Filter / Neumann HT75 Replacement
Replies: 12
Views: 1249

Re: Transfer Filter / Neumann HT75 Replacement

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...
by Gold
Wed Feb 17, 2021 3:59 pm
Forum: Build
Topic: Transfer Filter / Neumann HT75 Replacement
Replies: 12
Views: 1249

Re: Transfer Filter / Neumann HT75 Replacement

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...
by Gold
Tue Feb 09, 2021 3:05 pm
Forum: Build
Topic: Transfer Filter / Neumann HT75 Replacement
Replies: 12
Views: 1249

Re: Transfer Filter / Neumann HT75 Replacement

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.
by Gold
Thu Jan 21, 2021 1:59 pm
Forum: Pro Audio Design
Topic: Super Low Distortion Ultra Pure Audio Oscillators Revisited
Replies: 118
Views: 81137

Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

terkio wrote:
Wed Jan 20, 2021 5:47 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.
by Gold
Sat Jan 16, 2021 7:28 pm
Forum: Build
Topic: Mid Side M-S Matrix Construction Information
Replies: 121
Views: 265283

Re: Mid Side M-S Matrix Construction Information

What is the wrench in the top right-hand corner of the first frame? I have one of those in the garage that was my Dad's. I have a letter and number punch set similar to yours that I inherited from either my Dad or brother. The wrench in the drawer is for a Foredom rotary tool. I think that particul...
by Gold
Sat Jan 16, 2021 6:22 pm
Forum: Build
Topic: Mid Side M-S Matrix Construction Information
Replies: 121
Views: 265283

Re: Mid Side M-S Matrix Construction Information

Nice! Did you CNC those dimples with one of your tools or did you have someone else do it? Do you mean the marks? That is all hand done. I had templates made for the dots and used hand stamps for the text. http://www.saltmastering.com/Console/FaceplateFab_Stamp-8.JPG http://www.saltmastering.com/Co...