seppoman Posted March 31, 2008 Author Report Share Posted March 31, 2008 no news :) I've been quite busy with other things in the last weeks and will continue to be so, so this project isn´t really top priority for me right now. But as the results are very satisfying anyway, all that needs to be done is maybe another evening of testing a few things like CV tracking etc. and laying out the PCB with changed supply connector and a bit more space around the filter caps. This shouldn't be too much work, so thanks for reminding me, I'll get going soon again :DS Quote Link to comment Share on other sites More sharing options...
gpmacklin Posted April 2, 2008 Report Share Posted April 2, 2008 Good to hear. :) Quote Link to comment Share on other sites More sharing options...
Peake Posted April 15, 2008 Report Share Posted April 15, 2008 Hallo, I have a Foniktronic SSM2044 board and he's used three 5mm MKS2-type Wima metallized poly caps and one 820pf dipped Silver Mica for the poles: http://www.modular.fonik.de/Page29.htmlYour choice of caps likely is better-sounding, but I thought I'd chime in regarding the size issue, if that's helpful at all. Great idea, I'd certainly buy a PCB as well!(Edit: Pardon my presumption; I want to help but am simply not very good at doing so!) Quote Link to comment Share on other sites More sharing options...
seppoman Posted April 16, 2008 Author Report Share Posted April 16, 2008 (Edit: Pardon my presumption; I want to help but am simply not very good at doing so!)Hey, no need to apologize :)I know that the fonik board uses different cap types - actually my first proto even had only ceramic caps on it (oh my god, outrageous sin ;)) and I still liked the sound a lot. I had the impression that with ceramics, the sound was slightly rougher and the resonance started in with a much larger resistor value at one place but I don't really know what other effects to look for (tuning stability, tracking, range of oscillation...?). So maybe I should get myself a few different cap types and compare them more in-depth.But for the PCB design, I think I should just provide enough space to also use Styroflex caps, as some people might want to use them. When doing the layout, my goal was to match the 8 cm width of the AOUT_NG pcb and make it as small as possible. To really keep these dimensions, I'd need to use not only the MKS2 type, but even MKS02 (similar but with half pin spacing). And these are very hard to find, especially in the high precision variant, so it's probably not a good idea to spec them for a public pcb. 820pF are not available at all from the MKS series - I don't really know what kind of difference it makes whether all four caps are from the same series/type or not?Anyway, another cm of width probably just doesn't hurt too much, so I might just make it a bit more spacious :)Thanks for your input :)S Quote Link to comment Share on other sites More sharing options...
stryd_one Posted April 16, 2008 Report Share Posted April 16, 2008 My 2c:DEFINITELY leave room for styroflex. Mismatched caps means mismatched frequency tracking and a few other nasties.... In fact to be honest, if you didn't test this, then you may want to do so before you spend lots of $$$ on PCBs. I'm collecting reading material for you now... I have a lotta links about this so it might take a while to filter (heh) out the crap ;) Quote Link to comment Share on other sites More sharing options...
seppoman Posted April 16, 2008 Author Report Share Posted April 16, 2008 DEFINITELY leave room for styroflex. Mismatched caps means mismatched frequency tracking and a few other nasties.... In fact to be honest, if you didn't test this, then you may want to do so before you spend lots of $$$ on PCBs.Well, I will surely leave enough room, and I did confirm that with the Styroflex caps the self-oscillation roughly stays in tune over some octaves - I will conduct a few more tests with wider range and also using the MBCV application to test usability as a VCO (so far I tried only with MBSID). I think at least I tested enough so far that there can't be something completely wrong, but to be honest my usage of a VCF doesn't really include the thought of using it as a wide range VCO, so I was already content with what I found out so far :) What I can say for now is that tracking is certainly good enough for using it in it's intended function. If it wasn't, I doubt there was much that could be done about it - the SSM is quite monolithic in it's central functions, so probably just giving it the best caps will need to suffice :)I'm collecting reading material for you now... I have a lotta links about this so it might take a while to filter (heh) out the crap ;)That would be nice :)S Quote Link to comment Share on other sites More sharing options...
Peake Posted April 16, 2008 Report Share Posted April 16, 2008 actually my first proto even had only ceramic caps on it (oh my god, outrageous sin ;)) and I still liked the sound a lot. I had the impression that with ceramics, the sound was slightly rougher and the resonance started in with a much larger resistor value at one place but I don't really know what other effects to look for (tuning stability, tracking, range of oscillation...?). So maybe I should get myself a few different cap types and compare them more in-depth.I almost used ceramics until I saw his rev3 notes (having bought a rev1 board)! Interesting point about them sounding harsher. That could be useful ;DI also wonder why one cap is of a different value. The 2044 datasheet IIRC mentions nothing, and does not display any variance in the depiction of the individual cells the caps connect to. But there it is of course, right there in the datasheet. I don't know if the Mono/Poly, CATSRM and other synths using it followed that advice or not. But for the PCB design, I think I should just provide enough space to also use Styroflex caps, as some people might want to use them. When doing the layout, my goal was to match the 8 cm width of the AOUT_NG pcb and make it as small as possible. To really keep these dimensions, I'd need to use not only the MKS2 type, but even MKS02 (similar but with half pin spacing). And these are very hard to find, especially in the high precision variant, so it's probably not a good idea to spec them for a public pcb. 820pF are not available at all from the MKS series - I don't really know what kind of difference it makes whether all four caps are from the same series/type or not?Anyway, another cm of width probably just doesn't hurt too much, so I might just make it a bit more spacious :)Thanks for your input :)SI sort of figure that you know what you're doing, so keep up the excellent work! It is extremely exciting stuff. Regards,-Mike Quote Link to comment Share on other sites More sharing options...
snebenan Posted May 7, 2008 Report Share Posted May 7, 2008 Very Cool.But how hard is it to find some SSM2044 chips? And what do they cost?//Peter Quote Link to comment Share on other sites More sharing options...
seppoman Posted May 7, 2008 Author Report Share Posted May 7, 2008 But how hard is it to find some SSM2044 chips? And what do they cost?That's one of the main advantage of the 2044 - in contrast to many other SSM/CEM ICs, the 2044 is still widely available. I guess that's because it was a late model that was still in production when the digital era killed all good synth companies, so maybe SSM still had a large stock when they went bancrupt as well. Anyway, they're sold by many vintage synth repair guys, but the cheapest source I found so far is eBay - there, a variety of users which are probably synonyms of "Hongkongsuperseller" offers packs of 2, 10 and 50 pieces for very reasonable prices. E.g. 2 pieces incl. worldwide shipping are 20 USD, ten pieces are 71 USD etc.S Quote Link to comment Share on other sites More sharing options...
Echopraxia Posted May 7, 2008 Report Share Posted May 7, 2008 The 2044s are the real deal from aka "hongkongsuperseller" right? I was just reading another thread about bogus parts from this seller. Quote Link to comment Share on other sites More sharing options...
seppoman Posted May 7, 2008 Author Report Share Posted May 7, 2008 this thread? http://www.midibox.org/forum/index.php/topic,10697.msg81965.html#msg81965HKSS has more than 20000 feedback - I can't imagine ebay wouldn't have closed down his account years ago if a significant number of counterfeit claims had been filed. I guess these rumours are spread by his competition...I got my SSMs from him, too, and they do look like excellent VCFs, smell like excellent VCFs and sound like excellent VCFs. :DS Quote Link to comment Share on other sites More sharing options...
stryd_one Posted May 7, 2008 Report Share Posted May 7, 2008 The 2044s are the real deal from aka "hongkongsuperseller" right? I was just reading another thread about bogus parts from this seller.No, you read another thread about RUMOURS of bogus parts, which are not yet proven, and if anything have been proven FALSE.Please feel free to direct me to any real hard evidence, otherwise let's not start this conversation again ;) Quote Link to comment Share on other sites More sharing options...
Echopraxia Posted May 8, 2008 Report Share Posted May 8, 2008 That thread you linked seppo was way more indepth from the one I was referring too and it does take home styrd's point and now I will forever hold my piece.echopraxia orders 50 2044s from hongkongsuperseller ;) Quote Link to comment Share on other sites More sharing options...
Pascal Posted May 13, 2008 Report Share Posted May 13, 2008 Seppo, this is exactly this, what i have searched . . . . :-)Give my more Infos abut that ;-) When you have a Shematic-Layout for me from the Filter i was very happy!? Quote Link to comment Share on other sites More sharing options...
Peake Posted May 14, 2008 Report Share Posted May 14, 2008 I've just started playing with a concept- making that fourth pole have the same cap value as the other three. It did significantly change the overall range of the circuit (shifted it way down) and the resonance, with the trimpot at maximum, only self-oscillates for a tiny region in the top octaves. I haven't checked much yet to confirm/deny that this is a step in the right direction or not as I've got multiple projects going at once. This -may- provide for a slightly darker, smoother sound, if the last pole is actually offset on purpose, ala' the stories I read about the TB303 filter (IF IT IS SET UP LIKE A 303 FILTER, WHY CHANGE IT YOU BASTARD, I can hear the shouts now). If the last cell is indeed offset upward from the other three, then it would produce a slightly brighter, airier response. It would make the filter darker and audibly deeper-cutting, harder filtering, to then match all four poles, ala' the Moog 904a, etc. Might anyone know more than this? I don't want to derail the very exciting thread, I'm just poking around hoping for possible improvement/variation. Quote Link to comment Share on other sites More sharing options...
seppoman Posted May 14, 2008 Author Report Share Posted May 14, 2008 Hi Peake,the effects you're describing with that different cap value don't seem very desirable to me ;) I think the SSM already sounds quite warm and maybe slightly on the dark side as long as resonance isn't cranked up, so going even further in that direction and thereby losing resonance performance doesn't seem good to me."why change it" doesn't sound bad ;D - the 820pF value for the fourth cap is suggested in the datasheet and used in every implementation schematic I found out on the net. I don't know the technical background why this is so, but it does work well for me. And the resonance problems suggest that changing that value too much somehow brings the filter "out of balance". Somewhere on the net I read a comment about someone having changed the cap values, but he changed all four caps while keeping the ratio between the two values constant. so if you want to tune the ssm slightly darker, maybe you could try using something like e.g. 1nF and 3x 12nF.S Quote Link to comment Share on other sites More sharing options...
Peake Posted May 14, 2008 Report Share Posted May 14, 2008 Cool..."the 820pF value for the fourth cap is suggested in the datasheet and used in every implementation schematic I found out on the net."Thanks, I hadn't checked the Mono/Poly etc. Back to the 820, and my desire for a Moog 904a or three ;DI really look forward to the dual board! Quote Link to comment Share on other sites More sharing options...
stryd_one Posted May 15, 2008 Report Share Posted May 15, 2008 You would probably also change the rolloff of the filter, meaning it will not have the desired musical effect... Poles having multiples of 3db/oct is deliberate. Quote Link to comment Share on other sites More sharing options...
jimh54 Posted August 7, 2008 Report Share Posted August 7, 2008 Seppoman,Is there a schematic for this? I can't seem to find it on the dokuwiki page.Thanks Quote Link to comment Share on other sites More sharing options...
/tilted/ Posted August 7, 2008 Report Share Posted August 7, 2008 Is there a schematic for this? I can't seem to find it on the dokuwiki page.nope, but there's a [url=http://www.midibox.org/forum/index.php/topic,11790.0.html]bulk order for the PCB/url]. Quote Link to comment Share on other sites More sharing options...
seppoman Posted August 14, 2008 Author Report Share Posted August 14, 2008 Is there a schematic for this? I can't seem to find it on the dokuwiki page.I will provide a schematic soon, but at the moment I've got a lot of work to do and am away from home every second week, so I thought I'd better concentrate on getting the bulk order going instead of drawing schematics :)S Quote Link to comment Share on other sites More sharing options...
pdman Posted February 3, 2009 Report Share Posted February 3, 2009 I bought a couple of PCBs and want to use one of them as a modular filter in my synth.However without the schematic it will be more difficult to kludge the pcb for use in a modular filter.Is the schematic available yet or posted anywhere?Thanks Quote Link to comment Share on other sites More sharing options...
seppoman Posted February 3, 2009 Author Report Share Posted February 3, 2009 no not yet. A few days ago in another thread, I promised (again) to publish it in the next few weeks :) Quote Link to comment Share on other sites More sharing options...
boops Posted February 19, 2009 Report Share Posted February 19, 2009 hi seppoman ,like pdman.and after a complete reading of the threads,i will be happy to have the "famous"shematic for trying a modular synth style module...thanks for your work and your answer,hope soon;-) Best regards.. Quote Link to comment Share on other sites More sharing options...
nebula Posted February 19, 2009 Report Share Posted February 19, 2009 Guys, the layout's pretty clear, and armed with that it should really not be rocket science to create a schematic for yourself. Why burden Seppo?Here are some schematics (and other resources) for SSM2044-based filters. Seppoman's design doesn't deviate really far from much of this:http://electro-music.com/forum/topic-15933.html&highlight=http://pdf1.alldatasheet.com/datasheet-pdf/view/96412/ETC/SSM2044.htmlhttp://www.analog-synth.de/synths/mod2/ssmlowpass/ssmlowpass.htmhttp://embeddedcookbook.com/parts/SSM2044/docs/http://www.electricdruid.net/index.php?page=info.ssm2044 <--really interesting stuff!http://www.next.gr/inside-circuits/voltage-controlled-filter-ssm2044p-l5878.htmlThese are from the first two pages I got from googling "SSM2044 SCHEMATIC". Quote Link to comment Share on other sites More sharing options...
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