[BUILD] NU VARIMU 436 build & help thread

[rock soderstrom]

In my excitement about this project, I've been tinkering with Inkscape and have mocked up a meter insert which more or less reproduces the original Altec design. Fonts aren't perfect, though I'd say it's pretty close. I've sized it to match the Honeywell meters I've got set aside for the project - as far as I can tell, these are the same style & model used on the 436. 

Attached as an SVG - hopefully it will be useful to somebody (you'll need to trim and resize to fit what you're working with).

Thanks a lot! Cheers

 

[dogvoid]

First I made the gate sta level, then the federal nu 864.

waiting for good news about this project.

I love you

 

[mhbunch]

Very excited for this. Any idea when pcbs will be available?

 

[etheory]

I'm in when boards are available.

 

[bernbrue]

We have a prototype running and do various tests right now.  The circuit is working fine so far, a few things need to be checked again before we can release the pcb.  Stay tuned.
Bernd

 

[vitopower]

Again with the vari-mu..this looks like a great project 8)

 

[bernbrue]

Updated first post. Made a short video of the working prototype .
Cheers
Bernd

 

[Neko Neko]

In for a set once they are ready. Been wanting to build a vari mu for a while 

 

[TwentyTrees]

Ditto!  ;D

 

[bernbrue]

PCBs available right now!!!
See first post or go directly to Zayance white market thread
https://groupdiy.com/index.php?topic=53011.0

 

[groselicain]

Forgive me if this is a dumb question—is this a stereo unit? I noticed in the BOM that there's only a single input and output transformer listed but it looks like there are two input transformers on the PCB.

 

[mysticmerlin]

Yes Its stereo. I ordered the sowters. Watch the video maybe

 

[brndvnrdn]

Looks really nice this project 

 

[bernbrue]

In fact it is! I’ll upload additional files (schematic, BOM, frontpanel, etc.) soon. I’m a bit busy right now but won’t forget you.
Stay tuned!
Bernd

 

[etheory]

My PCBs have arrived safely and look beautiful. Thank you so much! Looking forward to getting stuck into this build.

 

[bernbrue]

full schematic and universal frontpanel design added. (2nd and 3rd post)
Cheers
Bernd

 

[TwentyTrees]

Thanks Bernd!

full schematic and universal frontpanel design added. (2nd and 3rd post)
Cheers
Bernd

 

[etheory]

Hi all,

This is awesome. Thanks for the schematics, but could you additionally please make some comments about:

1.) The choice of input transformers. There are 1:1 and 1:4 suggestions, under which circumstances would you suggest using those options? (i.e. for use as a line-input tracking/mastering compressor vs a mic-amp or whatever).

2.) The choice of output transformers (even if you just provide, as a suggestion, what you built it with so we have a starting position).

3.) The choice of tubes. On the schematic, the tubes aren't labelled, even though they are for the heater schematic (it'd be great for completeness to add that to the .pdf schematic in the first few posts). I'm curious about the choices, when on one of the "original" threads, the 6ES8 was suggested for the input/gain tube, and the 6CG7 for the output. You guys have clearly suggested other tubes, but is this for reasons of availability, or do we need to modify the other parts for different tube choices?

Thanks!

 

[bernbrue]

Unfortunately, we can’t give any recommendations concerning specific brands. It’s up to your personal taste and of cause to your budget, which tube brand you want to use.  Same applies to the choice of transformers. Any decent 1:1 input transformer with center tap will work fine. The output transformer from Sowter is certainly  first choice in terms of quality and availability.  I used  transformers from AVD Audio. He is a member of this forum and makes decent transformers. Search in the white market.

I suggest you to build the NU Varimu 436 with easily available parts. Later you can tweak the unit and test various tube and also transformer brands according to your personal taste.
Cheers
Bernd

 

[Unit-8]

Hi Bernd,

I found an error on Motherboard  + Control board  components list where R10A-B and R11A-B the value is 10k while on schematic is 18k.
Also R10, R11, R13 has the same Mouser ref code.
Could you please double check on MB + CB list, PSU list and schematics?

Thank you!