SSM2044 VCF schematic and PCB layout

mono-poly · Posted: Tue Mar 06, 2007 7:13 am Post subject:

Ok i bought some ua726's from the guy.
I got them gave him feedback etc...
But a month a go a friend needed one and none of them did work.
A friend of my bought some ca3080's same story.
Same goes with his mn3xxx ic's.
They are all relabeld crap.
And no bad word about cy (chipforbrains) here!
He really is the best and honnest chip/part suplier from the east!
I think most people should check their stuff before putting up feedback.
Because i am kinda sure most MN3xxx ic's i bought from hkss are relabeled crap to.

kryptic · Joined: Feb 16, 2007 Posts: 40 Location: somewhere

Oh, that definitely sheds some new light on it then. I did not realize that cy was actually chipforbrains. I must say that I have actually dealt with chipforbrains myself and the transactions went flawlessly and he is a very good and recomended seller. My friends who dealt with hkss did not purchase many chips but rather jacks and pots which were the same quality as futurlec only cheaper pricewise. Thanks for informing me of your experience mono-poly, I think I will have to reevaluate my opinion on hkss being that I was not basing my opinion on chips but rather other parts such as jacks and pots. If the chips are relabeled, that is just horrible business practice, so I will not be making any chip purchases from him.

(although I still think the HK mafia story was a bit of a stretch. I doubt the mafia is interested in making profits by selling $.02 switches and relabeled chips, the profit would not justify the time/trouble)

funkyfarm · Posted: Tue Mar 06, 2007 12:36 pm Post subject:

fonik · Posted: Tue Mar 06, 2007 2:32 pm Post subject:

as you might already know these filter ICs where used inside Korg Polysix, Korg Mono/Poly, Fairlight II, PPG Wave 2.2 und 2.3, Emu SP-1200, Siel DK600 and Siel Opera 6...

mono-poly · Posted: Wed Mar 07, 2007 4:40 am Post subject:

Feedback is nice to blackmail each other Very Happy

I am pretty sure you can buy knobs etc from hkss but i would avoid ic's etc for sure.

amos_joseph · Joined: May 09, 2005 Posts: 50 Location: Lincoln, NE

I've purchased knobs and switches from him several times without any problems, but I've never picked up any ICs from him. It's a good thing I saw this post, I was looking for some CA3080 ICs. I guess I'll order them from Small Bear Electronics instead.

sneakthief · Joined: Jul 24, 2006 Posts: 569 Location: Berlin

I would love to hear some sound samples of this filter! Anybody?

I searched and only found a couple of tiny mp3's...

fonik · Posted: Mon Mar 12, 2007 4:18 am Post subject:

maybe tonight i could do a sample...

fonik · Posted: Mon Mar 12, 2007 5:00 pm Post subject:

here are two samples.

first the ssm2044 as filter. a 5th saw wave sound is filtered without resonance first. the cutoff lowers and the modulation appears. then the resonance comes in (you can hear the volume drop):
ssm2044_VCF (1.7MB)

then the ssm2044 in selfoscillation, no filtering:
ssm2044_OSC (1MB)

the samples are recorded direct from the output of the filter into my terratec EWT88 I/O.

hope that helps.

Funky40 · Posted: Mon Mar 12, 2007 8:15 pm Post subject:

hi fonik,

while you are thinking about a PCB run:
I like and will do the SSM together with the Wasp into 1 Frontpanel,+ also an input and output mixer.
( + also inverting switch for the CV inputs)

I had this Idea in the first weeks having my doepfer SSM and Wasp.
I used them always as a Team patched up in parallel.
( i like in general to patch up synthvoices with LP, BP, and Hp in parallel, and mix them up as neeeded .
And no, i nearly never use my Dotcom state variable filter Q107 )
And i serously thought about to take the dopefers out of their Faceplates.
so l'm happy for the fonik PCB layouts....................

what do you guys think about such a module ?

__________________________________________________________________

And as i have now another Polivoks filter with input mixer (3inputs) and an outputmixer for Lp + BP ( +single outs),
i can say:
i definitly make other music with this, then with the "normal" polivoks).
will say: An SSM and an Wasp filter togehter with two mixers as single modules will be used different, not only by me, i think.
Buildin this modules togehter into one must be really very handy.

ok, maybe it's just my route, but maybe not. Wink

softfin · Posted: Tue Mar 13, 2007 8:43 am Post subject:

Thank for the samples Fonik!
Sounds so good that now I have no other option than to build one Smile

If you end up ordering a run of PCBs for these, I'm definately in for a couple.

Best,
Lassi

fonik · Posted: Tue Mar 13, 2007 9:03 am Post subject:

fonik · Posted: Thu Apr 19, 2007 11:19 am Post subject:

vtl5c3 · Posted: Thu Apr 19, 2007 12:06 pm Post subject:

Hi Matthias,

Those boards look really nice. How do you cut them to get such straight edges? I'm still using tin snips, which doesn't look good at all.

Romeo

fonik · Posted: Thu Apr 19, 2007 10:57 pm Post subject:

etaoin · Joined: Jun 30, 2005 Posts: 761 Location: Utrecht, NL

krisp14u · Joined: Nov 11, 2006 Posts: 206 Location: uk

as some one who got there hands on some of these PCB's early

they are top quality

cheers Matthias

paul D

etaoin · Joined: Jun 30, 2005 Posts: 761 Location: Utrecht, NL

Fonik,
How does this new design differ from the one on your website?

fonik · Posted: Fri Apr 20, 2007 12:43 am Post subject:

fonik · Posted: Fri Apr 20, 2007 12:50 am Post subject:

ambi-J · Joined: Apr 12, 2007 Posts: 20 Location: belgium

I did the same job last year!

here is my ssm2044 filter: it's a simple implementation of the schematic on the datasheet and it works good. values are adaptet to make overdrive on the input possible and Q goos a little further in selfoscillatin.
there are near 10 of these build right now.

ssmfiltertje.pdf

Description:

this is the pdf: unfortunatly it's in duth

Download (listen)

Filename:

ssmfiltertje.pdf

Filesize:

179.72 KB

Downloaded:

457 Time(s)

fonik · Posted: Fri Apr 20, 2007 7:18 am Post subject:

very nice layout, indeed and
welcome

as you can see from the schematics i added a unity gain to mix the CVs for the Q control. the 2nd section of this unity gain has a trim pot in its feedback path to adjust the point of self oscillation. i furthermore added a resistor to the q control potentiometer to get a reversed audio response.

i wonder about the input section. i actually added a attenuator to lower the gain on the input, since i have some hot signals in my modular Smile

i decided to put the PTC in physical contact to the IC. i have had no time yet to measure the stability of the tune. what are your experiences?

krisp14u · Joined: Nov 11, 2006 Posts: 206 Location: uk

softfin · Posted: Fri Apr 20, 2007 10:33 am Post subject:

I built it on stripboard recently, sounds fine, and to me it resembles considerably my moog filter with 22n (they're changeable to 68n with a 4pdt toggle) caps in the filter core.

Anyway I think Fonik's SSM2044 is a good and useable filter. Only the resonance control needs to be adjusted slightly to get it easier into selfoscillation.
I'm not yet sure how to do it, but probably it would be possible simply by reducing/increasing some resistors in the resonance control path.

Hey Fonik btw, could you sell me a couple of those SSM2044 boards without the SSM chips ? I have a handful of those chips already so I think I don't need more at the moment...

ambi-J · Joined: Apr 12, 2007 Posts: 20 Location: belgium

you can lower the point of self-oscillation by decreasing the value of the 13k resistor on pin 2 in the schematic on the data-sheet (the one i use in my pdf)
I use a 10 k value and it gives selfoscillation on the last 10à20 pc of the pot.
if you go too low i think you may damage the chip?

I don't use ptc on my boards. I think you do not need them: the chip heat almost nothing and even if I put my finger on the chip (to warm it up) the frequention did not rise notably.
it might be neccesary on older batches of the chip (the one i use is one of the last. it comes from cfb) especially in extreme conditions like in a ppolyphonicsynth in live conditions, but even then i never have seen a tempco on a filterchip.

a bigger problem is the tracking: I can't get it better than 3 octaves (self-osc without input). with a little input from a osc ( even not audible) it's better.