DIY ARP-2600 Modular Synthesizer

THeff

Oops,

The MP3 didn't get attached...so here it is.

-Tim

Midnight Express.mp3

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rjd2 · Joined: Sep 02, 2007 Posts: 232 Location: philly

this is too damned rad. great job dude!

vtl5c3 · Posted: Fri Feb 26, 2010 10:39 am Post subject:

Quite impressive! Thank you for the 4027 PCB artwork. Building a trio of those has been on my wish list for some time.

R.

emdot_ambient · Joined: Nov 22, 2009 Posts: 669 Location: Frederick, MD

Wow, that's......obsessive. But very, very cool! Wink

bennethos · Joined: Apr 18, 2009 Posts: 31 Location: Belgium

Very nice and inspiring work ! I find the arp2600 the mother of all synths, it's ideal to start learning about synths in an academic way.

The things that are holding me back most is making pcb's & frontpanels... I hope there will be more pcb's available in the near future.

congratz !

loydb · Joined: Feb 04, 2010 Posts: 369 Location: Providence, RI

Yeah, I'd love some PCBs. I'm pretty sure I can handle the front panel portion.

rjd2 · Joined: Sep 02, 2007 Posts: 232 Location: philly

yea, i'd really love a pcb. considering how small it is, i'd probably go for 8-16 of these. im pretty busy the first half of this year, but if it doesnt pop up by summer, i might be interested in funding a run.

Jaba · Joined: Feb 27, 2009 Posts: 47 Location: Genova, Italy

Hello Tim,
great job on both the modular and the demos, really amazing!
you once wrote that you used the 40235 pcb for the VCF;
I have one 40235 PCB currently being populated on my desk.
would you please share your suggestions, modifications, anything about this board ?
I am founding it rather crowded, and I also discovered that I am no good at making double sided PCBs, so I am almost sure it is not going to work at first attempt; so any help will be very welcome
thank you
Paolo (Jaba)

THeff · Posted: Thu Oct 07, 2010 6:38 pm Post subject: 40235 pcb

Hi Jaba,

Sorry for the delayed response, I have not been on the forum very much lately. Making double sided PCBs at home is painful and tedious!

I have made two of the 40235 filter PCBs successfully. On the first one I built both the 2 pole and 4 pole sections (4023 & 4035), on the second one I only built the 4035 section for the ARP 2600 clone.

To make the 2 sided boards I usually take the artwork for the top and bottom, hold them up to a light for alignment and staple them together along one edge. I then slide the pre-sensitized PCB in between the artwork films and scotch tape in place. This pretty much guarantees that both sides will stay in alignment when exposed. Another trick someone showed me is to take a small strip of copper clad PCB material (about 1/2" wide), scotch tape the top and bottom artwork films to the PCB strip with the correct alignment. When you slide the pre-sensitized PCB in between the artwork films it makes a nice level package for exposing. You still need to scotch tape the artwork films to the PCB on the top and bottom to prevent movement when you flip it over for each exposure.

The only thing I remember about the making the 40235 PCBs that was a little tricky was that I had to solder the ICs in place first because it was hard to get the soldering iron next to the IC pins on the top side because the surrounding components were very close.

Since making those PCBs I have made several of the 4035 PCBs from this thread: http://www.electro-music.com/forum/topic-29447 and they are much easier to populate. AndyR1960 did a great job on these little boards and they don't require any additional circuitry to create a standalone filter like the 40235.

Hope this helps a little,

-Tim

Jaba · Joined: Feb 27, 2009 Posts: 47 Location: Genova, Italy

Hello THeff,
thank you for your help

good to know that you built the 40235 with success, so I may hope to be able to do the same

I already made the PCB, and actually used some tricks very similar to what you suggested;
another detail not to be forgotten is that many components must be soldered on both sides of the PCB (no metalized holes) and some request that you think about it in advance and mount those components first, before other components make them unreachable.

btw, the 4035 pcb from AndyR1960 is doublesided too

But I think you are right, AndyR1960 did a great job. And you did too.

thank you
Paolo(Jaba)

pdman1 · Posted: Thu Mar 24, 2011 2:19 pm Post subject:

Been off the board for a while and saw this thread, simply fantastic!!

Anyways I was wondering if anyone made a run of the VCO PCBs for sale?

Again a totally fantastic build and job.

THeff · Last edited by THeff on Thu Dec 27, 2012 12:23 pm; edited 1 time in total

It's been a while since I have worked with my DIY ARP-2600 synthesizer, so I thought I would try to record a seasonal Mannheim Steamroller hit. The "Good King Wenceslas" MIDI file was created by Larry Soprano and all of the voices in the MP3 are from the DIY ARP-2600, except the drums and a little piano.

Regards,

Theff

** I re-master the recording after I noticed the original had amplitude problems once it was normalized with a cheap audio editor. I have uploaded a new one and I believe the 2nd file sounds much better. **

Theff 12-27-2012

Good King Wenceslas DIY ARP-2600 #2.mp3

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elmegil · Posted: Sat Dec 22, 2012 7:13 pm Post subject:

Very nice

StephenGiles · Joined: Apr 17, 2006 Posts: 481 Location: England

What a wonderful sound and arrangement.

When I was a boy I always thought his name was King Wenceslascameout - and also kept asking "where is Orientare"!!

LFLab · Posted: Mon Dec 24, 2012 1:21 am Post subject:

Saw this old thread drift to the top again, amazing how good the graphics look. Very tight, considering it's a laminated paper print, which is secured by spray adhesive. You'd expect unevenness, but not so, very nice!
Built the AXXE VCO this week, might give this 2600 vco a try as well (and then the Odyssey VCO), collect them all!

THeff · Posted: Mon Dec 24, 2012 7:18 am Post subject:

Thanks guys,

It sure is easier to make a recording like this compared to when the when the Moog and Arp synths first came out. With desktop multitrack recording, and MIDI, the only real critical step is tuning your VCO's. My first exposure to synths was Walter Carlos (Wendy) and "Switched On Bach" on LP. It's impressive to see what was done with no MIDI/CV and only magnetic tape recording machines.

Regards,

Theff

zayance · Joined: Dec 24, 2012 Posts: 4 Location: France

Hi There,

This is my first post here, so hi to everyone, been on another DIY forum for a while, called GroupDIY, with same nickname.

I was wondering if you would mind sharing just the Eagle brd file or the project file you've used for the VCO?
I'd like to build myslef one of these, it would be for personal use only of course, and would like modify a little the file for a better etching process, because by default the resistor pads are made for double sided boards, and so Thru hole plating, for home etched board i always tought they were too thin, and the Ground plan Thermal pads are super tin as well, and i think it would be best to fatten those thermals a little, would save some troubleshooting.

Anyway hope you're not taking this as an offense on your work, it's absolutly not my intention, and i think it's a great build and very inspiring, since it got me to finally think about building myself a Analog Synth.
I'm not a pro in PCB designing, but i've worked a lot with Eagle, and know my ways around the software, creating parts, modifying them etc...;
Anyway i could use the Jpeg, and Corel or whatever and rectify all pads one by one, that would be ok also, but i was just dropping a line.
I would share this modded file here as well of course.

Thanks in advance.

T.

zayance · Joined: Dec 24, 2012 Posts: 4 Location: France

Nevermind, i actually modded going from the existing Jpeg.
For me this file would be easier to etch, and cleaner at the end, well sort of, importing/exporting is not helping but anyway, drilling will leave more copper than before, and i think it's always better, Thermal pads for Gnd Plane are a little more thicker also.
Disconnected the 100K Resistor from the Gnd Plane, so to hardwire to -15V as you've noted.

pdf attached for if curious.

Now lets see what's needed next to start rolling with my first Analog synth Cool

Thanks again.

T.

ARP VCO.pdf

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steffensen · Joined: Jul 11, 2012 Posts: 85 Location: Sweden

zayance · Joined: Dec 24, 2012 Posts: 4 Location: France

THeff · Posted: Sat Dec 29, 2012 10:06 am Post subject:

Hi Zayance,

Glad you were able to make the PCB the way you wanted it. I have not gone back and compared the schematic against the PCB lately, but I can tell you that I have made four of these PCBs (3 VCO, and 1 VCLFO) and they work fine. The only issue was the resistor to the -15V supply rather than ground, which I noted. All of the recordings on this thread were made with those PCBs.

Regards,

Theff

zayance · Joined: Dec 24, 2012 Posts: 4 Location: France

pdman1 · Posted: Thu Jan 03, 2013 11:42 am Post subject:

What a great job!! Totally Impressive, deserving of an award!
I'm looking to try and build the oscillators. Any plans on perhaps selling etched PCBs? It would be a timesaver for me and others.
Again, just a superb build!

lucid · Joined: Dec 03, 2012 Posts: 19 Location: Slovakia, EU

Wow, great job
definitely will add this one to my DIY wish list.

THeff · Posted: Sat Jan 05, 2013 12:35 pm Post subject:

Thanks pdman1 & lucid,

I do emusic strickly as a hobby and I am not interested in selling anything. My real job (and my wife) keeps me pretty busy and makes my hobby time very valuable and protected! Wink

I would personally encourage everyone to try and make their own PCBs...at least once. I think you would be surprised at how easy it really it is. The best thing to do is create a process that works for you and stick to that process. This will lead to great consistency. Circuit Specialists is a great resource for pre-sensitized boards. With those blank boards and a laser printed transparency you are good to go. To me there is nothing better than creating a design, making a PCB, and building it all in one day...instant gratification!

Regards,

Theff