[sdiy] drum accent circuit

[Dave Magnuson]

Hi Theo, thanks for the reply,

At 07:18 AM 7/29/04, Theo wrote:
<snip>
>Even less components, if you ditch the whole transistor trigger/envelope
>part like in the above.
>Then opamp 5a can be the output buffer, the BF245 (your VCA) can sit right
>after R8.


I was trying to leave the 2 trigger inputs, so it can be mapped to a 
keyboard on 2 keys.


>The HiHat is pretty high frequency no problems with "bass loss" cause of a
>cap to block DC here.
>So there is no real need to change everything to symmetrical power.

My intention was simply to convert the final stage to bipolar power source 
to let it interface better with the remainder of my synths.  The rest of 
the circuit could remain on a single rail... that's fine.



>If you don't like the accent circuit that is there, then a FET, bipolar or
>4066 switch to change the amplification factor of a opamp (the output
>buffer/mixer?) driven by the accent gate signal would do.

I would be leaning towards something like this...  I'd rather have the 
accent independent of the stock EGs.  I intended to chop off the circuit 
after R88 so the sound and operation of the hi hats is still similar to a 
DR-110.


>BTW you may want to add a switch to select between the "CY source" (IC1,2)
>and the "noise source" (IC3,4) or both.
>Instant timbre variation :)

That's a good idea.   I was already planning on adding a transistor white 
noise source and a mixer so I could use both noise sourses.  Adding a third 
control for the CY source would be nice.

I was also considering varying the clock frequency that feeds the shift 
register.  It's an 80kHz signal, and I may make it variable from 40kHz to 
100KHz or so for some timbre sweeps.   I'll also be adding OH decay (by 
varying value of R20)   and making some adjustments to the filter.


>Just some thoughts,
>Theo


Thanks Theo!





>----- Original Message -----
>From: Dave Magnuson <resfreq at hoohahrecords.com>
>To: <synth-diy at dropmix.xs4all.nl>
>Sent: Thursday, July 29, 2004 5:13 AM
>Subject: [sdiy] drum accent circuit
>
>
> > Hi everyone,
> >
> > I'm cloning the DR-110 hi hat circuit, and I'd like to come up with a
> > better way to generate accent.  The original thumps pretty loudly, and it
> > has a single-supply output section.  I'd like something with better sound
> > (no feedthrough), and a bipolar supply (to get rid of DC offset).
> >
> > I've used photoshop to cut down the schematics to only the hats, accent
> > circuit and output section.  You can find them here (250K pdf file):
> >
> > http://www.hoohahrecords.com/resfreq/mods/dr110/dr110hh.pdf
> >
> > Now, what I'm thinking is this:
> > Use a simple AD envelope generator (or fixed attack, variable decay) and a
> > CA3080 based VCA.  I would bias the VCA so that it's always allowing
>signal
> > to pass at approx 50% volume, then the env generator could add accent up
>to
> > full volume.  Finally I'd use a TL071 or similar for driving the output.
> >
> > Is this a typical way of approaching this, or is there some easier method
> > that I'm overlooking?
> >
> > thanks in advance,
> > Dave
> >
> > Resonant Frequency:
> > resfreq at hoohahrecords.com
> > http://www.hoohahrecords.com/resfreq/index.html
> >
>
>
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Resonant Frequency:
resfreq at hoohahrecords.com
http://www.hoohahrecords.com/resfreq/index.html