bernbrue

Re: [BUILD] NU FEDERAL AM-864 PCB OFFICIAL BUILD & HELP THREAD
« Reply #200 on: August 30, 2019, 03:12:43 AM »
Huh, now you’ve got me. It’s more than 10 years ago :-)
Bernd


scott2000

Re: [BUILD] NU FEDERAL AM-864 PCB OFFICIAL BUILD & HELP THREAD
« Reply #201 on: August 30, 2019, 06:48:16 AM »
Quote

What would happen with a stereo unit if I used one B+ supply for both sides?

Collins 26U-2 has a similar thing as well I believe....

Mmt50816

Re: [BUILD] NU FEDERAL AM-864 PCB OFFICIAL BUILD & HELP THREAD
« Reply #202 on: November 21, 2019, 01:55:33 PM »
Im just starting my build. I am slightly confused as to the wiring of the Attack, Release and Meter trim pots. are the two terminals CW and W or CCW and W?
Thanks

bernbrue

Re: [BUILD] NU FEDERAL AM-864 PCB OFFICIAL BUILD & HELP THREAD
« Reply #203 on: November 21, 2019, 02:11:05 PM »
Honestly, I can’t remember anymore. Best think is to try out and change later if it’s wrong. It won’t do any harm. Good luck with your new compressor.
Bernd

Mmt50816

Re: [BUILD] NU FEDERAL AM-864 PCB OFFICIAL BUILD & HELP THREAD
« Reply #204 on: December 11, 2019, 04:10:54 PM »
I am attempting to wire up the power transformer. I got the Don Audio Toroid with 2x 180v, 2x 6.3 and 9v. I am guessing that one each of the 6.3v goes to the " Fil AC", but then do I wire up the 2x 180v in parallel to the B+ AC on one of the boards? Also, which values for R1 and R2 should I try?
Thanks

madreza

Re: [BUILD] NU FEDERAL AM-864 PCB OFFICIAL BUILD & HELP THREAD
« Reply #205 on: April 17, 2020, 07:56:42 PM »
Hi guys.
What voltage for C9 C10 and C11 ?
Thanks
Knight 1: We are now no longer the Knights who say Ni.
Knight 2: NI.
Other Knights: Shh...
Knight 1: We are now the Knights who say... "Ekki-Ekki-Ekki-Ekki-PTANG. Zoom-Boing. Z'nourrwringmm.

bernbrue

Re: [BUILD] NU FEDERAL AM-864 PCB OFFICIAL BUILD & HELP THREAD
« Reply #206 on: April 18, 2020, 09:40:32 AM »
35V or more.
Bernd

shot

Re: [BUILD] NU FEDERAL AM-864 PCB OFFICIAL BUILD & HELP THREAD
« Reply #207 on: April 19, 2020, 01:51:57 PM »
Fortunately, my over a year long voyage with this build is finally over!
I a mysterious problem with the unit not compressing and barely reacting to anything. In the process, I went through checking all the things I could think of. I even found mislabeled resistor numbers on the input pad part of the pcb.
Since this corona s**t got me with too much time to spare, I went back to troubleshoot the unit.
Finally I've found that there was a broken trace from triode grid of the 6AV6 (pin 1) and wiper pin of the current control pot. Since I've been checking wiring if it was faulty and it always checked fine, I didn't go through testing what is going on on the pcb. Well, problem of my unit was actually on the board itself. How that happened I don't know! Probably I overheated it when stuffing components, since I doubt it was manufactured with this error. I fixed it with a wire link and it works now!

I also made a few modifications. I've lowered C16 to 0.5uF and R12 to 500k. Those two values sped up the release. And also I lowered R13 to around 5k to speed up the attack time. I've tried many combinations of those three values and this is what I most liked. They all depend on each other so it's not possible to modify attack without affecting the release and vice versa.

I'm happy now! It is packed and ready to be installed in studio rack!

:)

Luka

bernbrue

Re: [BUILD] NU FEDERAL AM-864 PCB OFFICIAL BUILD & HELP THREAD
« Reply #208 on: April 19, 2020, 01:56:39 PM »
Glad to hear that you finally sorted out the problem. Enjoy the compressor.
Bernd

Re: [BUILD] NU FEDERAL AM-864 PCB OFFICIAL BUILD & HELP THREAD
« Reply #209 on: April 30, 2020, 07:05:02 AM »
Hi,

This looks like an interesting build! I have to try something like this.

I've been studying the stereo link on vari-mu units like this. I'm trying to read the schematic, and is the stereo link on this unit simply a matter of connecting the center taps together on input transfomers' secondaries ?

Cheers!


bernbrue

Re: [BUILD] NU FEDERAL AM-864 PCB OFFICIAL BUILD & HELP THREAD
« Reply #210 on: April 30, 2020, 07:16:15 AM »
Hi,
linking the sidechains of both channels at the input secondaries ensures that both channels have the same time constants. You still need to match the input/output levels on both channels.
This project quite complex and certainly not a tube beginners project. All in all it’s worth the time and effort you have to put in this project.
Bernd

dribro

Re: [BUILD] NU FEDERAL AM-864 PCB OFFICIAL BUILD & HELP THREAD
« Reply #211 on: July 27, 2020, 01:57:41 PM »
Hi there

Can I use this trafo for a Stereo version ?

https://www.tube-town.net/ttstore/toroidal-62va.html

Using only one psu?

Or is it better to go with recommended DonAudio trafo?

Although I have the feeling im answering myself...
« Last Edit: August 01, 2020, 05:00:54 AM by dribro »

Mmt50816

Re: [BUILD] NU FEDERAL AM-864 PCB OFFICIAL BUILD & HELP THREAD
« Reply #212 on: October 16, 2020, 11:07:06 AM »
So I have been messing with this thing a lot lately.
It seems to me that the input pot is not input volume but rather a balance between the two 6BA6 tubes. There is only one position for the input pot that doesnt sound like crap. is that how everyone elses units work?
Also, R9 doesnt do anything for my meter. The meter trim pot gets it in the right range though. What is the purpose of R9?
Lastly, my voltages at E and F are 1.7v while everything else is matched to the recommended voltage. Is that ok?


 

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