Maxim MDS-500

[Peter Snow]

Hi Michael,

Thanks for the info. I have a Simmons SDS8 that has a "Filter" pot that affects the tone
of the noise. It seems the noise filter is automatically swept (no depth control) on all 
vocies except the snare which is fixed. Don't know if it's supposed to be like that or if 
it needs attention.

The Maxim has a noise filter control (marked just "Noise"). It is so vicious I 
thought at first it was a level control, because for the first 3/4 of a turn there 
is no sound at all - then the noise comes in quickly with very little room to control it. 
However with careful listening I can tell it is actually a filter control.
But there are no filter sweeps, so I am none the wiser as to whether the 2044 is acting 
as a filter or an oscillator.  

When I get time I'll just have to rip out one of the voice boards and check it out.

The reason I thought about subbing the 2044's for something simpler was to get some 
spare 2044's to use in synth filter modules! :)

Thanks again,
Peter

WeAreAs1 at aol.com wrote:
> 
> Hello Peter,
> 
> Those SSM2044's are most likely being used as normal filters, not as sine
> wave oscillators.  Most of the similarly-designed Simmons drum modules also
> have filter chips (some with SSM2044, some with various CEM chips).  The
> filters are there to put a filter envelope on the noise component of the
> sound, and also to act as a general tone control.  They may, however, not
> give the user access to the filter cutoff in every design.
> 
> Most of the Simmons modules create their basic drum tone waveform with a
> typical two-opamp triangle wave oscillator (such as the ones typically used
> to make simple LFO's).  The Simmons SDS5 used exactly this combination
> (SSM2044 filter with opamp triangle linear-response VCO).  I imagine that
> your Maxim unit uses the same technique, since they were probably trying to
> copy Simmons in the first place.  I suppose you could remove the 2044's and
> replace them with some other kind of filter, if you're up to the effort.
> 
> Michael Bacich