MATRIXSYNTH: Curtis Electro Music

Showing posts with label Curtis Electro Music. Show all posts
Showing posts with label Curtis Electro Music. Show all posts

Wednesday, May 29, 2024

AS3394: exponential versus linear filter modulation:

video upload by Ultratroninator 3000

"The AS3394 (Curtis 3394 clone) synth-on-a-chip has a linear filter modulation that is somewhat unique. The chip's triangle output from the VCO can be routed to filter modulation in a linear manner. At maximum modulation the filter cutoff will go from close to very to about 2x the unmodulated frequency. Comparatively, exponential modulation tends to increase the pitch."

See the Zoxnoxious label below for more.

Wednesday, August 09, 2023

The Story of SSM and Curtis Electromusic. The soul within the sound of the 80s

video upload by Johnny Morgan Synth Dreams

"A mini-doc on two companies that changed the way synthesizers were designed in the 80s. Both had a incredible impact on the electronic music industry and the sound of music created during that time."

Sunday, July 29, 2018

Synth Voltage Controlled Oscillator 1v/oct tracked DIY how to.

Published on Jul 29, 2018 LOOK MUM NO COMPUTER

"DIY HOW TO make a proper synth oscillator, with temperature compensation 1v/oct and all that jazz! using the CEM 3340.

Im giving away 5 component packs, and a DIY modular furby i built on a livestream a week ago, on my patreon next week! so if you want any of that go check that out!
Patreon :-
Where there will also be updates on the progression of this project before it goes up anywhere else! All the funds goes straight back into Look mum machines :)

more info on this project over here :-"

Follow-up to Build A DIY Case And Power Supply For A Modular Synth CHEAP.

Wednesday, March 14, 2018

New CEM and SSM Chip Clones

A few new CEM and SSM chips for the DIYers out there.

First we have Latvian CEM Synth IC clones from ALFA:

AS3310 Voltage Controlled Envelope Generator. CEM3310 pin-to-pin compatible
AS3320 Voltage controlled filter. Improved CEM3320 pin-to-pin compatible
AS3330 Dual Voltage Controled Amplifier (VCA). Improved CEM3330 replacement.
AS3340, AS3345 Voltage Controlled Oscillator (VCO). CEM3340, CEM3345 pin-to-pin compatible
AS3360 Dual Voltage Controled Amplifier (VCA). CEM3360 pin-to-pin compatible
AS16M1 Serial Controlled, 16-Channel SPCO Switch

Next, Coolaudio [Behringer] announced they are working on new SSM chip clones (news via Soviet Space Child):

"Now that we have successfully cloned the famous Curtis 3340 and 3320 synth chips, we are now looking into reviving the great sounding SSM2044 and SSM2033 chips."

Sound Semiconductor recently announced the SSI2164 QUAD VCA.

And last, but definitely not least, considering, Curtis Electro Music announced the CEM3340 VCO re-issue in 2016.

For a list of CEM and SSM chips in synthesizers see Wikipedia here.

For previous posts including some with demos, see the corresponding labels below.

This post, like all posts, is an FYI that this all exists. It's up to makers and DIYers to decide where they get their chips. This post is worth reading.

Wednesday, January 03, 2018

Genuine Curtis CEM3340 Chips at Thonk

via @thonk_synth

"We have temporarily cut the price of genuine CEM3340 chips by 25%"

You can find them here.

"These are BRAND NEW chips, the real thing as manufactured by Curtis Electromusic with the full blessing of the late Doug Curtis’s family. These are not clones."

Monday, March 20, 2017

Latest News from Behringer & A Response From The Curtis Family

The next chapter in Behringer synth development is in. We already know Uli Behringer announced plans to re-create classic synths. Behringer will be making new innovative synths as well, and we now have some numbers:

“We have 4 synthesizer development teams simultaneously working on 20 synths, drum machines etc..

We’ll be creating both innovative new synths as well as reviving classics.

We’re all in and the teams are on fire.'"

On reproducing vintage chips for the classics:

"We just received the first batch of our 3340 VCO chip.

It is a 100% exact replica of the Curtis CEM3340 which even includes the 40 year old, 8 micron manufacturing process. It was a difficult and expensive undertaking but we are very pleased with the result as this VCO is considered one of the best sounding oscillators.

We are continuing to invest in reviving other legacy Curtis and SSM semiconductors which will allow us to bring back classic synths - all in the most authentic way. We have also reissued the 3320 filter chip which should be arriving in a few months.


It's worth noting the Curtis CEM 3340 has already been re-introduced by OnChip Systems, formerly Curtis Electromusic, and is currently available for makers. Behringer's 3340 appears to bypass Curtis Electromusic and is being manufactured by Behringer (via Coolaudio) directly. SSM chips and the CEM 3320, however, are not yet available. Although the chips will obviously be re-issued for use in Behringer synths, it does appear that some if not all may become available to the Synth DIY community as well. More info on that further below, but first a response on the re-creation of Curtis chips from the Curtis family:

"Many of you who are active on synth forums have recently contacted us regarding another company's claim of producing VCO chips that are the equivalent to the CEM3340 that was used in many legendary synthesizers.

To avoid any confusion, please know that there is only one manufacturer of the authentic CEM3340 designed by my late husband, Doug Curtis. Any claims, use of this product designation, and use of the name Curtis Electromusic by other companies are made without permission from OnChip Systems (our current company name) or the Curtis Family.

As much as Doug would be humbled and so very happy about the legacy his products enjoy, we can assure you that as a person of the highest integrity he would be deeply saddened by the attempt of others to trade on his name and to make unsubstantiated claims of equivalency to his original inventions.

In his loving memory and gratitude for the community of musicians and synthesizer enthusiasts, Doug's family is committed to making his authentic designs available as demand presents itself. Thank you for your continued support of Doug's analog synthesizer legacy.

Mary Curtis and our daughters, Ashley and Julia"

It's worth noting that many Dave Smith Instruments synths use Curtis chips and do so with permission from the Curtis family. Dave Smith was friends with Doug Curtis and has been buying parts from OnChip for over 15 years. OnChip was Doug Curtis' company and is now his wife Mary Curtis's company. These chips were used in the Evolver line, the Prophet '08, MoPho line, and the Prophet 12. The Pro 2, Prophet-6, and OB-6 use discrete designs.

The following is from another thread from Uli in German, translated into Googlish:

"Something clearer. Patent rights are generally 20 years, whereby the technology is freely available for everyone. This allows the inventor, on the one hand, to harvest the fruits of his invention, but also to ensure that no monopoly arises and, after the expiry of the protection, everyone has free access to the technology - without a bad conscience.

In the case of the Curtis or SSM chips, the patent rights of these 40-year-old components have run out for a long time and everyone can reproduce them today. Why this no longer companies do is simply because the mask costs are very high (6-digit USD range per chip) and on the other hand the minimum edition is about 300,000 - 500,000 pieces.

Curtis has registered the name rights for Curtis and CEM, but on the number 3340 etc. there is no protection. Therefore, there are other vendors who have revived these old chips:

Http:// ... er-as3320 /

Or look at how many manufacturers. The 074 Opamp.

Why are these 40 year old chips being rebuilt? Anyone who once belonged to an old Oberheim OB-Xa or a Prophet 5 will agree with me that the sounds of these Curtis and SSM chips are absolutely unsurpassed in their sound qualities. This specific sound is not easy to replicate with discrete technology and since we have an immense passion for analog synthesizers and believe that customers will appreciate these components, we are taking the financial risk of reviving these chips. Coolaudio has just produced the 3340 VCO successfully and the 3320 filter chip is now also under development - further building blocks will follow.

For more than ten years, the company, which is affiliated with us, has specialized in restoring expired components. On the one hand the company produces the coveted BBD chips from the Panasonic times, but also VCA's, OTA's, Optocoupler, etc.

Our intention is to focus on the old Curtis and SSM chips, as we want to use them in our future synthesizers. At the same time, Coolaudio will also offer them for sale, which allows other competitors to build analog instruments as well as help people repair old synths. Many of the Coolaudio chips are already used today by our competitors and we are happy if we can make a contribution to the fact that these analogue components are made of music.

I personally consider VA for eyewash because this is ultimately digital technology. No digital synthesizer will ever be able to reproduce the 'unpredictability' and 'inaccuracy' of an analog synthesizer - no matter how much marketing is operated. Anyone who listens to analogue and digital synthesizers in comparison can easily find out. That is exactly why we will be specializing in analogue synths.

Perhaps our desire for analogue technology is simply that we humans are knitted by themselves analogously and the emotions associated with it determine our existence.



This one spotted and sent in via Soviet Space Child.

Update: And another update just in via Soviet Space Child:

Originally Posted by Uli Behringer:

"Allow me to share a thought.

Dave Smith Instruments (DSI) is using our SSM clones (V2164).
homemade polysynth — A quick tour of the Prophet 6 voice card

Elektron are using Coolaudio parts as well.

Many other leading manufacturers are using Coolaudio chips and by using these parts obviously have no concerns with cloning in general and with using our chips in their products.

If our competitors are not concerned then why should customers be?


The difference of course is currently available vs. not currently available.  The CEM3340 is currently available from Curtis Electromusic, and the Minimoog Model D is currently available from Moog Music.   You be the judge for yourself.

Tuesday, September 06, 2016

cem3340 1st try

Published on Sep 6, 2016 cirtcele

"This is a proto-type of a CEM3340 based VCO. Just pleased it was working well so recorded a minute of it.
The production version will have a 2mm white panel with ENIG gold labelling."

As many of you know the CEM3340 VCO has been re-issued.

Thursday, July 07, 2016

New vs. Old Curtis CEM3340 Rev G Comparison

Published on Jul 4, 2016 Gregory Cox

"This video is a demonstration of the newly manufactured Curtis Electromusic CEM3340 oscillator IC. A comparison is achieved using the Oberheim OB-8 with half of its 3340s replaced and setting the keyboard in dual mode. Voices 1-4 are the original CEM3340s and 5-8 are the Revision Gs. By assigning the same sound to both splits in dual mode, a comparison can be made by fading between both sounds using the program balance knob.

The signal chain is OB-8 / Neutrik patch bay / Apogee Symphony / Headphone Output / Canon 5D mkiii mic input."

Follow-up to this post.

This one in via Soviet Space Child.

Friday, June 03, 2016

Curtis CEM3340 VCO Chips Re-Issued

The Curtis CEM3340 VCO has been reissued by Curtis Electromusic. Note the Rev G in the image. That is the new chip. This is pretty big news. If the info below is correct you will be able to order a single chip for $15, or less in bulk.

The CEM3340 was responsible for the main VCO used in quite a few classic synths including the Oberheim OB-Xa, OB-Sx & OB-8, the Voyetra 8, Roland SH-101, MC-202, Jupiter-6, and early model MKS-80, The Sequential Circuits Prophet-5 Rev 3, Prophet-10, Prophet-600, Pro-One, and Prophet T8, Moog Memorymoog, Banana Polysynth, Crumar Spirit, Digisound 80 VCO modules, the Synton Syrinx, Steiner Parker EVI, Doepfer's A-111-1 High End VCO and more.

Image by David Rudolph Smith.

I saw mention that Dave Smith might have been involved with the re-issue. This would make sense as Dave Smith was close to Doug Curtis and DSI uses a later revision of Curtis chips in many DSI synths, however, I checked with DSI and they let me know: “DSI wasn’t involved in the reissue and if anyone would like to find out more about it, they should contact directly.” More info including price follows.

"Founded in 1979, Curtis Electromusic Specialties created a line of signal processing chips for electronic musical instruments and accessories.

Curtis Electromusic currently offers the sought after CEM3340 VCO, a rework of the original design."

And via johnny83 on the Muff Wiggler Forum including contact info, price, and availability.

"Dear all, I've been speaking with onchip for the last 3 months and they have already produced a new batch of CEM 3340. They are available for $15 each! We have tested them and they are revision G and pass our tests on the original Curtis test boards and also various synths we tried them in.

The person to contact is, she has been remarkably helpful and can process your order. Please be aware that revision G has meant the following:

"After reviewing the prior specifications I did decide to change the minimum VCC spec. The old VCC min. was +10V and the new VCC min. is +11V. This is based on my own bench experience with several versions of the device. Many devices will work with a VCC of +10V and others won’t. Devices that won’t work at +10V should easily work at +11V or higher. This is the only specification that we’ve changed" John Borg (Onchip Engineer)

Additionally they have no plans to release the 3310, 3320 and 3360 yet but I think if they see the success of the 3340 it may be apparent the market needs them. I am in communication with them and will continue to push for the other chips to be brought back but to be honest the release of the 3340 is great news as that was the most common curtis chip used.

Here are the price breaks for anyone wanting to get more than a handful:
1 - 499 = $ 15.00
500 - 999 = 12.82
1000 - 4999 = 9.64
5000+ = 7.46

Postage is in addition to this.

I hope you enjoy and spread the word!!"

Update: I don't have official confirmation but I heard they are also re-issuing the CEM3320 filter.  Do a search on 3320 on wikipedia here to see what synths it was used on.


New vs. Old Curtis CEM3340 Rev G Comparison

Published on Jul 4, 2016 Gregory Cox

"This video is a demonstration of the newly manufactured Curtis Electromusic CEM3340 oscillator IC. A comparison is achieved using the Oberheim OB-8 with half of its 3340s replaced and setting the keyboard in dual mode. Voices 1-4 are the original CEM3340s and 5-8 are the Revision Gs. By assigning the same sound to both splits in dual mode, a comparison can be made by fading between both sounds using the program balance knob.

The signal chain is OB-8 / Neutrik patch bay / Apogee Symphony / Headphone Output / Canon 5D mkiii mic input."

This one in via Soviet Space Child.

Switched On Make Synthesizer Evolution Vintage Synthesizers Creating Sound Fundlementals of Synthesizer Programming Kraftwerk

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