CP3PLUS Mixer (by FEEDBACK) [REV2.0 PCB UPDATE]

From circuitbending to homebrew stompboxes & synths, keep the DIY spirit alive!

Moderators: Joe., luketeaford, lisa, Kent

User avatar
strat-1
Veteran Wiggler
Posts: 515
Joined: Wed Jun 03, 2015 8:58 am
Location: Romania
Contact:

CP3PLUS Mixer (by FEEDBACK) [REV2.0 PCB UPDATE]

Post by strat-1 » Sat Mar 26, 2016 4:36 am

www.feedbackmodules.com

[UPDATE}
We updated the PCB to REV2.0 with the following changes :
Turned the pots to vertical, so D shaft knobs can be fitted.
The trimmer is now on the top of the pcb (90dgrs trimmer), so it there is no danger anymore to damage the trimmer.

Image

The CP3PLUS is an accurate recreation in Eurorack format of one of the most appreciated vintage mixer for it's rich and beautiful sound.

We know that there are already available projects based on the same famous mixer so probably the question is why we did it. We are musicians and synth DIYers and already built before variations on this theme, but practical experience showed us that there are a few things we wanted to do different to improve it:

- There were many situation we found the 3 inputs were not enough so we decided for four inputs (like the original).

- Previous projects didn't offer both inverted and non inverted polarity outs but a crossfade between the two outs. This has two drawbacks, you don't have access to both outs at the same time (which could be very useful in some patches). Also the distortion pattern is not the same because the harmonic structure of the distortion is affected by the position of the output croossfade pot. We decided for both outputs and to have a similar distortion pattern like in the original mixer.

- Another addition is a four jack multiple (like in the original mixer). It is a very good idea to have a multi close to the mixer. Let's say you want to mix three oscillators for a rich sound and you want to drive them from the same CV source. Having a multi close to the mixer makes easy to distribute CV to all three oscillators.

- Another improvement was to make the module as simple to build as possible without the need of wires. You only need to solder the parts and that's it.

- The last improvement is related to ergonomics. We understand that many modular users try to make compact setups for live performance, so weight and module HP are a big concern. But we find all the crowded modules kill the ergonomics making access to pots and jacks a struggle. So we decided that we will make a version of this mixer that has a good compromise between ergonomics and panel dimensions. Look at this mixer like a module mostly made for your non portable studio modular setup.

This is a comprehensive build document for our CP3PLUS project and we hope it will make soldering and assembling this project an easy task.
We tried to make the whole experience as easy as possible and give as much information as needed to avoid confusion. We also provide additional documents like BOM lists
(PDF and XLS), images with part values, and photos of the construction in various stages. Feel free to download the whole pack and have fun.

This document assumes that you have a decent knowledge about electronics, soldering, using tools and measurement instruments.
The CP3PLUS is an easy project so we recommend it even if you are relativelly new to electronics.
We built some modules from this construction manual so we are confident we ironed out any errors, but we are human and if you discover any problem, feel free to give us a feedback.

Project is available in 2 KITs :

KIT1 : PCB + Panel
KIT2 : PCB + Panel + 79L06, Pots, miniJacks + matched pair 3904 and 3906

PLEASE READ THE MANUAL FIRST AND LOOK AT THE PROJECT.

Image
Image
Image
Image
Image

FEEDBACK projects you can build :

CP3+ Mixer :
viewtopic.php?t=158439
SmArTT verter :
viewtopic.php?t=158691
106 Chorus :
viewtopic.php?t=158257
PRE CR :
viewtopic.php?t=163228
PRE BX :
viewtopic.php?t=163224
PRE KM :
viewtopic.php?t=163227
106 Chorus :
viewtopic.php?t=158257
You do not have the required permissions to view the files attached to this post.
Last edited by strat-1 on Sat Apr 04, 2020 8:06 am, edited 15 times in total.

User avatar
strat-1
Veteran Wiggler
Posts: 515
Joined: Wed Jun 03, 2015 8:58 am
Location: Romania
Contact:

Post by strat-1 » Sat Mar 26, 2016 4:38 am

KIT 1 :


Image


KIT 2:


Image

BARE BONES
Wiggling with Experience
Posts: 289
Joined: Sun Aug 10, 2014 5:15 pm
Location: Bath

Post by BARE BONES » Sat Mar 26, 2016 9:54 am

Kit 1 with postage to the UK please! :)

User avatar
Bamboombaps
Wiggling with Experience
Posts: 404
Joined: Wed Sep 16, 2015 7:14 am
Location: Glasgow

Post by Bamboombaps » Sat Mar 26, 2016 10:12 am

Yah man kit 1 and uk shipping

DJBRUTAL
Common Wiggler
Posts: 191
Joined: Wed Jan 29, 2014 12:08 am

Post by DJBRUTAL » Sat Mar 26, 2016 10:27 am

PM sent for 1x kit 1 with shipping to the USA.

User avatar
strat-1
Veteran Wiggler
Posts: 515
Joined: Wed Jun 03, 2015 8:58 am
Location: Romania
Contact:

Post by strat-1 » Mon Mar 28, 2016 7:32 am

There's a print error on the silkscreen, I forgot to mention in the main text. R7 is printed twice, R12 is printed twice.
All the build files are correct, so this print error have no impact in the build.

sammy123
Super Deluxe Wiggler
Posts: 1216
Joined: Sun Mar 24, 2013 12:36 pm

Post by sammy123 » Mon Mar 28, 2016 9:01 am

I'd like a kit 1 please.

Stides
Wiggling with Experience
Posts: 267
Joined: Fri Feb 08, 2013 11:26 pm
Location: Pittsburgh

Post by Stides » Mon Mar 28, 2016 9:12 pm

Pm'd for kit 1. :yay:

User avatar
yan6
Ultra Wiggler
Posts: 967
Joined: Sat Jun 15, 2013 7:14 pm
Location: Ontario, Canada

Post by yan6 » Mon Mar 28, 2016 11:01 pm

1 x Kit 1 for me please, shipped to Canada

acilator
Learning to Wiggle
Posts: 50
Joined: Thu Dec 12, 2013 3:39 am

Post by acilator » Tue Mar 29, 2016 12:30 am

One KIT1 for me, shipping to The netherlands

User avatar
Zaibach
Common Wiggler
Posts: 202
Joined: Sat Jul 26, 2014 2:13 pm
Location: Germany

Post by Zaibach » Fri Apr 01, 2016 3:23 pm

I'd like a KIT 1, please! Shipping to Germany.

User avatar
strat-1
Veteran Wiggler
Posts: 515
Joined: Wed Jun 03, 2015 8:58 am
Location: Romania
Contact:

Post by strat-1 » Tue Apr 26, 2016 1:34 pm

I recorded some demos for the CP3PLUS project.

In the first track I change continuously the mix between 3 waveforms from 3 System-X VCO's. Saw, Square and Sine.
When I raise one channel near the maximum you can hear the characteristic sound of CP3 mixers, the transistors starts to add harmonics to the sound. You can here it especially on sine waveform.
The setup is basic vco's to CP3PLUS to vca.

https://soundcloud.com/strat1/cp3plus-capabilities

In the second demo I play again with the waveforms volume, but the mixer is patched to a vcf>vca>chorus 106.

https://soundcloud.com/strat1/cp3-to-106-noodle

User avatar
spneca
Common Wiggler
Posts: 182
Joined: Wed Apr 24, 2013 2:47 pm
Location: Brooklyn, NY

Post by spneca » Tue Apr 26, 2016 2:15 pm

I would like a Kit 2, please. Shipping to USA.

Styrofoam
Learning to Wiggle
Posts: 28
Joined: Mon May 23, 2011 4:49 pm
Location: Antwerp, Belgium

Post by Styrofoam » Tue Apr 26, 2016 3:02 pm

Kit 2 please, shipped to Belgium (I sent you a PM).

User avatar
pix
Veteran Wiggler
Posts: 680
Joined: Fri Jul 31, 2009 2:40 pm

Post by pix » Mon May 02, 2016 12:43 pm

I got a dual gang pot from mouser but the shaft is too large and doesn't fit the panel hole.

Now I'm in a dilemma, either I try to enlarge the hole (with very high changes to F it up) or try and source another pot.

Has anyone found a pot that works well?

User avatar
strat-1
Veteran Wiggler
Posts: 515
Joined: Wed Jun 03, 2015 8:58 am
Location: Romania
Contact:

Post by strat-1 » Tue May 03, 2016 2:35 am

pix wrote:I got a dual gang pot from mouser but the shaft is too large and doesn't fit the panel hole.

Now I'm in a dilemma, either I try to enlarge the hole (with very high changes to F it up) or try and source another pot.

Has anyone found a pot that works well?
As I specified in the manual you have to enlarge the hole. You have pictures also of the making process in the zip file.

User avatar
pix
Veteran Wiggler
Posts: 680
Joined: Fri Jul 31, 2009 2:40 pm

Post by pix » Tue May 03, 2016 9:48 am

As usual...RTFM!

thanks!

User avatar
strat-1
Veteran Wiggler
Posts: 515
Joined: Wed Jun 03, 2015 8:58 am
Location: Romania
Contact:

Post by strat-1 » Thu May 05, 2016 12:11 am

I had some time to spent and I sawed to size the double gang pots
with professional tools. So the last kits I sent had already prepared pots :).

User avatar
HipDestroyer
Wiggling with Experience
Posts: 416
Joined: Tue Nov 10, 2015 4:19 am

Post by HipDestroyer » Wed May 11, 2016 11:44 am

I've been a naughty boy: I used film caps for this build.

Anyways, it sounds amazing. To be honest, when I ordered it I wasn't 100% sure the "characteristics" mentioned would be audible but the harmonics are definitely there and sound beautiful. :yay:

Image
Image

User avatar
InfraXpert
Common Wiggler
Posts: 200
Joined: Tue Apr 03, 2012 3:33 pm
Location: Denmark

Post by InfraXpert » Mon May 23, 2016 3:28 am

2 x Kit 2 for me please, shipped to Denmark
Really good music starts with a solder iron

purple_elk
Learning to Wiggle
Posts: 36
Joined: Thu Jan 28, 2016 5:26 am
Location: Manchester, England

Post by purple_elk » Wed May 25, 2016 6:24 pm

Hi,
Could I order kit 2 to the UK please?

User avatar
squarewavesurfer
Wiggling with Experience
Posts: 255
Joined: Tue Jan 27, 2015 2:43 pm
Location: Canada

Post by squarewavesurfer » Sat May 28, 2016 10:50 am

pm'd for two of the CP3+ mixer kit 2

kashmir
Common Wiggler
Posts: 65
Joined: Fri Apr 01, 2016 6:07 am

Post by kashmir » Sun May 29, 2016 2:58 am

Hi, PM'd for one CP3 kit 1

User avatar
strat-1
Veteran Wiggler
Posts: 515
Joined: Wed Jun 03, 2015 8:58 am
Location: Romania
Contact:

Post by strat-1 » Fri Jul 22, 2016 4:34 am

UPDATE : KIT2 WILL INCLUDE MATCHED PAIR 3904, 3906 TRANSISTORS AT NO CHANGE IN KIT COST.

User avatar
Addam
Wiggling with Experience
Posts: 347
Joined: Thu Apr 28, 2016 4:40 pm
Location: Hudson Valley

Post by Addam » Fri Jul 22, 2016 9:10 am

Any info on that two59 waveshaper? :hyper:

Post Reply

Return to “Music Tech DIY”