IN STOCK: Hi-quality Quad VCA-Mixer (THAT2181 based)

L-1 · Last edited by L-1 on Tue Feb 07, 2012 3:13 pm; edited 4 times in total

Build docs are here http://greenexpo.by/synth

I have designed PCB for hi-quality Quad VCA-Mixer. This is really workhorse for every modular system. I was needed several hi-quality VCA's with mixing possibilities for my system. Now I going to order PCB's. I need to estimate quantity of PCB's to order. Please PM me who are in and quantity needed.
Boards have some SMD parts which will be already installed (I will order smd-components insertion).
Installed parts: 4 x BC847BS dual transistors, 4 x 2K TEMPCO resistors, 14 x 0,1 mkF decoupling caps.
Price 45$ per board with installed SMD-parts; and airmail shipping about 5$ anywhere.
FEATURES:
- Eurorackers are welcome! PCB size 105 x 70 mm, have EURO, MOTM, Dotcom power connecton possibilities (12V version differs from 15V version with two resistor values).
- VCA's design based on THAT Corp. design notes and uses maybe the best available VCA chip THAT2181.
- VCA's have tempco CV inputs as suggested in THAT Corp. design notes for more accurate results.
- it's possible to mixing channels in pairs and all together.
- all connectors have on board ground pads for shielded cables.
- I used hi-quality OPA2604 opamps at VCA's outputs but regular TL072 will fit too.

Estimated start of sales - february 2012.
I will make web-page with detailed assembly instructions.
Please PM me about quantity with contact info, I will contact you when boards will be ready.

This is discussion on MUFF's http://www.muffwiggler.com/forum/topic-48476.html

L-1 QUAD VCA-MIXER 1.JPG

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roman_f · Posted: Wed Dec 14, 2011 6:31 am Post subject:

i'm in for 10 boards, alex :)

Mongo1 · Joined: Aug 11, 2011 Posts: 411 Location: Raleigh NC

I'd probably like 2 - what are the SUM+ and SUM- jacks for ?

Thanks
Gary

L-1 · Posted: Wed Dec 14, 2011 8:18 am Post subject:

This is inverted and non-inverted outs for all 4 channels.

Mongo1 · Joined: Aug 11, 2011 Posts: 411 Location: Raleigh NC

Perfect - then I'd definitely like 2 of these. { edit - lets make that 4 }

I was actually just thinking about buying a couple of Ray Wilsons MFOS VCAs, and building mixers into the front end of them. Sort of 180 degrees away from what you've done. I think your solution will be better though.

If there's sufficient interest perhaps we can get a group buy together for the front panels. I'm so tired of making my own panels Mad

Thanks
Gary

L-1 · Posted: Wed Dec 14, 2011 8:37 am Post subject:

I can't spend much money for front panels therefore make DIY with acceptable results. I will make web-page with detailed instructions for board and frontpanel assembly. Here is example foto of my 3U module.

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Mongo1 · Joined: Aug 11, 2011 Posts: 411 Location: Raleigh NC

Very nice!

I've been trying to do my panel work as cheaply as possible, and it hasn't really met my expectations yet. I've been trying to do some stuff with laminated artwork on sheet metal, but I keep running into problems getting holes to line up between those two layers, and the angled aluminum stock I use as my PC board mount.

I'm working on developing some jigs for my drill press that may improve accuracy. Hopefully that will help.

Gary

L-1 · Posted: Wed Dec 14, 2011 9:18 am Post subject:

Technology I use is not the best but very cheap and strong. This is rack without power rails.

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Mongo1 · Joined: Aug 11, 2011 Posts: 411 Location: Raleigh NC

Wow - that is really nice stuff. I love that inductor! Did you wind that yourself or buy it ready-made?

L-1 · Posted: Wed Dec 14, 2011 9:33 am Post subject:

I only ordered laser-cutted aluminium plates, it's not expensive, because I tried to cut at home without required precision. All other is DIY include huge 250VA trans.

Mongo1 · Joined: Aug 11, 2011 Posts: 411 Location: Raleigh NC

That's great work - I think one thing I may do is start buying the pre-cut panels as you suggest. The thicker material would help me with mounting issues, and would help stiffen the panel so it feels more secure.

Gary

rosch · Joined: Oct 03, 2009 Posts: 164 Location: germany

i'll take 2 at least

telbonic · Joined: Jan 08, 2010 Posts: 39 Location: uk

I would like one board please Smile

janvanvolt · Joined: Nov 24, 2005 Posts: 285 Location: Mainz, Germany

Two boards please.

unterbit · Posted: Tue Jan 03, 2012 5:57 am Post subject:

Happy New Year!
One VCA.MIX pcb like this would appreciate in my backlog!
Все правильно напечатал? Вообщем одна штука. Очень рад был повстречать близких людей

L-1 · Posted: Wed Jan 25, 2012 8:24 pm Post subject:

First device is assembled and tested, works good. Start PCB's sales in two weeks.

marvkaye · Joined: Mar 14, 2011 Posts: 225 Location: Fla

Count me in for 2 as well. Anyone know of US source for the THAT2181?

<marv>

L-1 · Posted: Fri Feb 03, 2012 4:14 pm Post subject:

Ok, better buy 2180, they are a bit more expensive, but you can eliminate distortion trimming. Farnell have in stock.

marvkaye · Joined: Mar 14, 2011 Posts: 225 Location: Fla

Thanks for the tip about the 2180... Mouser has them, yippee!! I'm definitely in for the two boards now. Looks like a really nice project, can't wait to start. Thanks for doing this.

<marv>

unterbit · Posted: Thu Feb 09, 2012 8:55 am Post subject:

PM sent for 2 boards.

guitarfool · Posted: Tue Feb 14, 2012 9:05 pm Post subject:

unterbit · Posted: Mon Feb 20, 2012 3:03 am Post subject:

Boards are here,with lovely soldered smd's.Thank you Aleksey!