Where can i get Curtis filters from?

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Re: Where can i get Curtis filters from?

Post by Synthacon » Mon Aug 04, 2008 9:42 pm

They are real Curtis chips, made by "Mr Curtis" who passed away recently I understand.

The question has to be asked though if the demand from the Vintage buying people is so high why has nobody remade stuff before??

I know I would love to go out and by a synth with SSM 2040 VCF's!!!!
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Re: Where can i get Curtis filters from?

Post by Solderman » Mon Aug 04, 2008 9:59 pm

minime123 wrote:did you know that even when CEMs were current, they had different production runs and that an unmatched set of chips could perform slightly differently than a matched set? theres variability in most chips (even in a matched set) but we often dont detect the subtle differences.
Just wanted to chime in with an anecdote: I had to replace the CEM3320 filter IC in my Pro~One some years back, using stock from synthtech. I had no problems with installation, but did notice the tonal character to not be as pleasing as it was before. It also changed the range position of the filter cutoff pot, and I had to do a basic mod just to get anything below a setting of 100hz.
I am no longer in pursuit of vintage synths. The generally absurd inflation from demand versus practical use and maintenance costs is no longer viable. The internet has suffocated and vanquished yet another wonderful hobby. Too bad.
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Re: Where can i get Curtis filters from?

Post by steveman » Mon Aug 04, 2008 10:09 pm

Synthacon wrote:They are real Curtis chips, made by "Mr Curtis" who passed away recently I understand.

The question has to be asked though if the demand from the Vintage buying people is so high why has nobody remade stuff before??

I know I would love to go out and by a synth with SSM 2040 VCF's!!!!
So would I...

The answer's simple - cost, prolly cost a 7 figure sum to get someone to refab these chips, how many people are there really in the vintage synth market? less than a 1000 I'd guess, and most of them are on here :wink:
In terms of demand for a chip to be fabricated, demand is in fact minute.

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Re: Where can i get Curtis filters from?

Post by Synthacon » Tue Aug 05, 2008 12:34 am

steveman wrote:The answer's simple - cost, prolly cost a 7 figure sum to get someone to refab these chips, how many people are there really in the vintage synth market? less than a 1000 I'd guess, and most of them are on here :wink:
In terms of demand for a chip to be fabricated, demand is in fact minute.
I totally agree, but I do think there are alot of people who think it will happen and that chips will always be available.
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Re: Where can i get Curtis filters from?

Post by carbon111 » Tue Aug 05, 2008 12:55 am

Solderman wrote: Just wanted to chime in with an anecdote: I had to replace the CEM3320 filter IC in my Pro~One some years back, using stock from synthtech. I had no problems with installation, but did notice the tonal character to not be as pleasing as it was before. It also changed the range position of the filter cutoff pot, and I had to do a basic mod just to get anything below a setting of 100hz.
That's exactly the way my Rev1 Pro-One is. According to a former SCI employee I know, that's "normal". :!:
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Re: Where can i get Curtis filters from?

Post by rhino » Tue Aug 05, 2008 1:37 pm

not much of an answer, but my 2 cents:

it can be done. Korgs CX hammond clones had custom chips that failed, killing the organ. some private company began making 'emulators' using stock chips on a pc board.. messy, and a bit $$$$, but htey saved many of these old 'boards.

what i,m saying (i'm not smart enought to do it) is could these filters be replicated in discrete form?

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Re: Where can i get Curtis filters from?

Post by pricklyrobot » Tue Aug 05, 2008 2:57 pm

The main problem with hoping the chips we be re-made at some point due to demand from the vintage synth market is, as others have pointed out already, that it's not a large enough market to justify a massive production run (which is the only kind of run most of these chip companies do).

I think it would take someone specifically starting up an independent re-issue chip company, licensing the rights from the owners and making the chips on a small scale (a few hundred or thousands at a time, instead of tens of thousands). Kind of like licensing obscure old major-label records and putting them out on an independent label. I'm not sure if the technology actually exists to make this feasible with chips, but it's the only way I see it happening business-wise.
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Re: Where can i get Curtis filters from?

Post by Altitude » Tue Aug 12, 2008 5:07 pm

Philly Stress wrote:I'm thinking about building a midibox like this.

Does anyone know where I can get low pass curtis filters to go in it?
I hope you realize what is involved to do that. the MB6582 does not have discrete filter chips, everything is on the SID chips. To add CEM's you will need a CV board not to mention a whole DIY'ed board for the CEM chips themselves for each SID pair and a new power supply since those chips and the CV unit require bipolar 12V rails

I am working on adding SSM filters to mine and the order for the boards wrapped up last week but it will be a massive undertaking.

Here is the link:

http://www.midibox.org/dokuwiki/ssm2044_pcb

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Re: Where can i get Curtis filters from?

Post by etcetera » Tue Aug 12, 2008 6:25 pm

I just wonder, do we even have the diagrams for those chips anymore? I seem to remember that the diagrams have been lost on some SSM circuits, making them very hard to reengineer.

Second, as these chips are usually analog, they are really just miniaturized analog boards. With the diagram at hand, maybe in some cases it would be possible to device do-it-yourself electronic kits that can replace the missing chips?

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Re: Where can i get Curtis filters from?

Post by Altitude » Wed Aug 13, 2008 12:30 pm

etcetera wrote:I just wonder, do we even have the diagrams for those chips anymore? I seem to remember that the diagrams have been lost on some SSM circuits, making them very hard to reengineer.

Second, as these chips are usually analog, they are really just miniaturized analog boards. With the diagram at hand, maybe in some cases it would be possible to device do-it-yourself electronic kits that can replace the missing chips?
http://www.synthtech.com/cem/cemdata.html

I dont see what the point of DIYing a discrete clone of a CEM. There are tons of designs that a far superior to the curtis stuff, The appeal of these chips was the size, cost, and features, how they sounded was a distant fourth.

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Re: Where can i get Curtis filters from?

Post by Tiitu » Thu Aug 14, 2008 2:46 am

Yes, but NOW this sound is what ALL vintage lovers are after!!

In addition, I would quess that they want to get original equipment, not so much even better copies. And, they like the functional simplicity of the old synths, which is making these synths managenable without a need to be a computer software guru. and so easy and quick to start playing with as stand-alone units.

Just a few other thoughts:

The old chips should not be too difficult to manufacture. Dave Smith knows this because his chips are new!

All patent and other rights should have got old in 20+ years, am I not right!? But, where to get the data needed and what does it cost?

One other problem is that the longer we wait, the less there will be vintage synths around. So the market is shrinking, which is not interesting for the manufaturers.

On the other hand, if the missing chips were there as new, the market could even start growing. However, current musical instrument manufacturers probably don't want to get new rivals, and may therefore avoid helping anybody to start manufacturing even their own old chips.

Original manufacturers should therefore got to be involved. For example, Noritake Itron IS willing to start manufacturing old VFD displays, which are probably one of the most difficult parts to get for the Oberheim Xpander and Matrix-12 lovers. The minimum new patch size is 1000 and engineering cost starts at 20k, so the question is if there are still enough users left.

I assume that there are more than 200 owners of these Oberheims, because even in the Xpantastic forum there are 121 members of which only a few tens of percents appear to be still active, however. In any case, 1000 displays may not be all too much asked for although only 200 chips may be needed right-away. But, who would like to invest to the 800+ extra spare components, which he may need to stock for 20 more years?

Are then all musicians/vintage lovers and people around so poor that no-one can invest the minimum of $ 20.000 per each new patch of 1000 components? Looks like this is true. ...

Please, take a look at our efforts to get the Noritake Itron Vacuum Fluorescent Displays to be re-manufactured at
http://launch.groups.yahoo.com/group/xp ... essage/317

AND, ii you are a user, owner or just an Oberheim lover, please take part in the poll bekow:
http://launch.groups.yahoo.com/group/xp ... essage/466

Best Wishes,
Tiitu. [-o<

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Re: Where can i get Curtis filters from?

Post by Altitude » Thu Aug 14, 2008 12:18 pm

Tiitu wrote: The old chips should not be too difficult to manufacture. Dave Smith knows this because his chips are new!
Yes, they are. You are talking about hundreds of thousands of dollars for a modern fab to do something like that. We just had a very basic ASIC (mixed signal) quoted and it was $300,000 for tooling with a expected production run in the millions of parts, and that was a reasonable bid, anything less than that, you are talking WAY more money. No one in their right mind would do this without having at least enough sold to make a profit before even making a single wafer. The chips used in the Evolvers are not new, they are the NOS Marion parts made for an Oberheim synth that never materialized.

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