Page 2 of 2

Re: Transfer Filter / Neumann HT75 Replacement

Posted: Thu Feb 25, 2021 8:49 pm
by Gold
mediatechnology wrote: Thu Feb 25, 2021 7:37 pm 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?

Re: Transfer Filter / Neumann HT75 Replacement

Posted: Thu Feb 25, 2021 8:52 pm
by mediatechnology
I measured the slope on mine at 18 dB/octave.
My reference points were a little farther outside the pass band than 2xFc and Fc/2.
Its a Butterworth alignment so the initial rolloff isn't as steep as the outer skirts.

Re: Transfer Filter / Neumann HT75 Replacement

Posted: Fri Feb 26, 2021 5:58 pm
by Gold
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 like most of the rest of them.

Re: Transfer Filter / Neumann HT75 Replacement

Posted: Mon Mar 01, 2021 2:47 pm
by Gold
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.

Image

Image

The faceplates are getting neater. This one has some mistakes but I'm happy with the overall look. I did the stripe down the middle on the micro mill. It's the first time I've tried something like this. I like the way it looks.

Image

There is a lot of wiring. There are separate power supplies for Preview and Modulation. This is all eight channels.

Image

The power distribution is done with these DIN rail terminal blocks. I had to diode isolate the Relay Common's so they didn't talk to each other through the return path. Luckily I've been through that already and knew what to do.

Image

Installed in the console. Now it's time to master a record and cut a couple of sides.

Image

Re: Transfer Filter / Neumann HT75 Replacement

Posted: Mon Mar 01, 2021 3:29 pm
by mediatechnology
Now it's time to master a record and cut a couple of sides.
Yea!

Re: Transfer Filter / Neumann HT75 Replacement

Posted: Mon Mar 01, 2021 3:51 pm
by Gold
I can't thank you enough Wayne. You saved my butt. The console sounds better already.