Thomas Henry CEM3340 VCO

col2 · Posted: Tue Dec 20, 2016 1:28 pm Post subject: Thomas Henry CEM3340 VCO

I think I read somewhere that TH's favorite VCO chip is the CEM3340. Now that the CEM3340 has been re-manufactured and is within grasp of the SDIY community ($15 each). I wonder if Thomas is contemplating one of his minimalist designs?

elmegil · Posted: Tue Dec 20, 2016 10:29 pm Post subject:

Not a new one, but check out the "Deluxe VCO" in "Build a Better Music Synthesizer".

You should be able to find copies at reasonable prices on the used market.

(3 chips, no waiting Wink

The CEM3340, a Quad Op Amp, and a 4013 for a sub octave generator)

col2 · Posted: Wed Dec 21, 2016 1:02 pm Post subject:

Hi Elmegil,

That sounds Interesting, is it 3 voice polyphonic? I can see a few copies of the book available. Is there any images that could scanned/used to etch a PCB in the book? I don't have the skills to translate circuit diagrams to PCB layouts. I can etch a board though Wink

edit: opps, 3 chips including the opamp and the 4013. I guess not 3-voice polyphonic Smile

cheers,
col.

elmegil · Posted: Wed Dec 21, 2016 2:28 pm Post subject:

Nope, not polyphonic Very Happy

There are schematics but no foil, unfortunately.

col2 · Posted: Wed Dec 21, 2016 3:34 pm Post subject:

I can see the TH books on lulu.com but not "Build a Better Music Synthesizer". I like the idea of the 4013 sub octave generator Smile

>There are schematics but no foil, unfortunately.

Maybe Fonik will pick up the idea Very Happy

elmegil · Posted: Wed Dec 21, 2016 4:40 pm Post subject:

This is an older book, out of print. You can buy them used, but not from Lulu.

https://www.amazon.com/Build-Better-Music-Synthesizer-Thomas/dp/0830602550/ref=tmm_hrd_swatch_0?_encoding=UTF8&qid=1482363548&sr=8-1

brock · Joined: May 26, 2011 Posts: 112 Location: Canada

The design originally appeared in the Nov/Dec 1981 issue of Polyphony. Back issues are still available from PAIA for $5.00. http://www.paia.com/Articles/polyphny.htm

Thomas_Henry · Posted: Sat Feb 11, 2017 1:57 am Post subject:

Hi Guys,

Stay away from the VCO Deluxe; it's a stink bomb. But what can I say? I had only been designing for a year or so in 1981!

However, hold onto your hats, for the VCO Maximus is on my breadboard at this very moment. Thanks to new availability of the CEM3340 (I bought ten right away) we are ready to re-enter the golden age of VCOs.

-- no thermistor or matched pair needed
-- three chips (two if you don't need the sine)
-- multi-polarity hard sync
-- soft sync
-- triangle, ramp, pulse and sine
-- elegant buffering throughout
-- linear and exponential FM
-- PWM
-- huge range, from sub-audio to supersonic

The testing is going well. Tonight was first-sound, and I hit 10 octaves of perfect tuning in less than a minute. The only thing left is to test the soft sync and then hopefully engage my colleagues to check for chip-to-chip variation, etc.

I'll post the schem for the VCO Maximus here shortly.

Thomas Henry

wackelpeter · Posted: Sat Feb 11, 2017 3:12 am Post subject:

That sounds really interesting... having already 10 VCO's which i never use at the same time i think it wouldn't hurt to have another few VCO's Wink

One thing i'm still curious is what These CEM3340 IC's would cost... a quick search on eBay gave a Price range from above 30 Euro up to 85 Euro and i believe it was MatrixSynth wrote that up to 499 pieces they would maybe cost 15$US...

Can you tell us how much you spent on your chips and what source you got them from, Thomas?

Cheers Bastian

Thomas_Henry · Posted: Sat Feb 11, 2017 3:32 am Post subject:

Hello Bastian,

Getting the chips was really easy here in the United States, even though we no longer have a rational government. I ordered on a Thursday and had the parts on Monday. I bought ten at $15 apiece, and after shipping and the PayPal charge, they came in at $16 apiece. Accounting for inflation, this is not far off from what I paid 35 years ago. However, I suspect shipping to Europe might be bad for small orders. Perhaps you can call together colleagues to make a joint order.

Anyway, I started by writing to Susan at:

susanonchip@covad.net

and she very courteously provided all the ordering information. Like I say, everything went like clockwork, and Susan was a delight to deal with.

Hope that helps.

Thomas Henry

wackelpeter · Posted: Sat Feb 11, 2017 5:16 am Post subject:

Hi Thomas,

thank you for your really fast reply.
Well 15$US isn't something i couldn't effort. Seems a good price to me...

Maybe i'll check/ask if they have some european distributors as i guess here on the other side of the atlantic there are enough potentially interested buyers too...

Ordering as single person maybe would be a bit too expensive as the shipping charges from the USA increased a lot over the years from what i experienced over years of buying records from the USA... Also our customs especially here in Germany take their work more seriously and this add's taxes as well to the total payment...

Regarding your government, you're not that alone... Even here in Europe there's a greater tendency in the politics and public opinion in favour of those people who promise some simple solutions for complex problems..
Hopefully it didn't end in a complete mess and changes within time some minds to some not that short-sighted reactions...

Cheers Bastian

philpeery · Joined: Nov 08, 2006 Posts: 137 Location: new jersey, usa

A new CEM3340 VCO from TH? Too cool for words! I can't wait to see the design, and I will definitely build two for me and a few for a small modular that I am putting together for a good friend. I am curious to see how they sound next to the pair of VCO-555's that I just finished.

I actually have two copies of the VCO Deluxe in my system that I built way back in the mid 80's. They sound great, and are used side by side with my MOTM-300 VCO's. Never did use the sub feature much but the sync is super!

I am hoping that CEM3340's of the 1980's vintage will work too. Please? I've got a bunch I want to use!

BIG fan of Mr. Henry! Keep knocking these great designs out!

StephenGiles · Joined: Apr 17, 2006 Posts: 507 Location: England

A new circuit from Thomas Henry has always been a delight to behold, ever since the pre internet days of the 1980's, when once a month a copy of Polyphony would drop through my letterbox!

Back in the days when post was delivered by 8am then a second delivery late morning. Now we are lucky to have one delivery by 2pm!"

Thomas_Henry · Posted: Mon Feb 27, 2017 6:20 pm Post subject:

Why thank you, chaps!

Yes, we have a small coterie shaking down a new design at this very moment. It's promising to be quite elegant!

Thomas Henry

Scott Stites · Posted: Tue Feb 28, 2017 6:52 pm Post subject:

Where is this public directory I hear tell about?

Thomas_Henry · Posted: Tue Feb 28, 2017 8:41 pm Post subject:

Scott: http://electro-music.com/forum/topic-68068.html

Scott Stites · Posted: Wed Mar 01, 2017 7:29 pm Post subject:

Tanks!

YashN · Joined: Jun 27, 2011 Posts: 104 Location: Canada

And a million thanks for the articles, Thomas, looking forward to reading them and prototyping some of the circuits! props

col2 · Posted: Sun May 21, 2017 3:49 am Post subject:

Been away from the SDIY for a bit travelling, great to look in the forum and see such great news! Just reading the birthofasynth pages now. I'll hold out for the Foniktronik PCB/Panel kit. Can't wait! Very Happy

Ayab · Joined: Oct 27, 2015 Posts: 186 Location: London, UK

Dear Thomas Henry

Another thank you for kindly making these very interesting articles and designs available.

Looking forward to your new CEM33440 VCO design!

Very Happy

Thomas_Henry · Posted: Tue May 23, 2017 5:19 pm Post subject:

Well, thank-you!

Scott posted all the VCO Maximus plans several months ago. So, just scroll down a bit to find the thread here.

Thomas Henry

Ayab · Joined: Oct 27, 2015 Posts: 186 Location: London, UK

Hi Thomas

Thanks so much for letting me know; exciting - will take a look!!

Btw do you know anywhere that may have an Ami S-2566 rythm chip as used in your Rhythm Generation article?

col2 · Posted: Sun Dec 17, 2017 3:24 pm Post subject: VCO MAXIMUS

Almost exactly one year from when I started this topic, just ordered a VCO MAXIMUS PCB/Panel set and a CEM3340 from Thonk. Very Happy

philpeery · Joined: Nov 08, 2006 Posts: 137 Location: new jersey, usa

Since SynthCube doesn't seem to have the PCB's yet, I just ordered a few from Thonk! I'm going to build one or two with my NOS 3340's of 1980's vintage, and the others with revG chips. Should make a good comparison test. Can't wait!

Best Regards,
Phil