MOTM

A lot of early analog drum circuits used cheapie filters with high
resonance. The effect you're describing is a damped oscillation caused by
the filter 'ringing,' and by tweaking the filter component values, you can
get all sorts of drum sounds.

I think PAIA had/has a board that lets you play with this kind of thing.

-----Original Message-----

 For drums, the TR-808 uses a "bridged T-network" in order to create a
waveform similar to an oscillator decaying in amplitude.  Rather than using
the trigger to trigger EG's controlling separate VCO's and VCA's as in the
606 and 909, it seems the trigger itself is transformed into the sound.  In
my limited understanding, it's like a VCO that runs out of steam.  Like the
skin of a drum, it oscillates after being hit, then tapers off into
silence.  For the 808 toms, this circuit is modified with diodes such that
the frequency decays as well.  Perhaps this technology could be rolled into
a  MOTM module with increased flexibility such that it could produce more
than just drum sounds.

At 11:35 AM -0400 10/19/01, Tkacs, Ken wrote:
>
>A lot of early analog drum circuits used cheapie filters with high
>resonance. The effect you're describing is a damped oscillation caused by
>the filter 'ringing,' and by tweaking the filter component values, you can
>get all sorts of drum sounds.
>
>I think PAIA had/has a board that lets you play with this kind of thing.

Exactly :)  Roland calls it a "periodic damping oscillation".  The circuit
looks like a filter (in the more general sense of the word -- it's not a
VCF) as it has an RC network in the feedback path of an op-amp.  It has two
parallel elements in the feedback path: a resistor; and a T-network
composed of two caps (parallel to the afformentioned resistor, and in
series to each other) with a second resistor between the two caps going to
ground.

I wouldn't want MOTM to make anything "cheapie"!!  However, I'm thinking
this damped oscillation idea could be incorporated into a more
sophisticated  "trigger to audio converter".  Perhaps 1U, with trigger in,
audio out, and a couple of VC inputs.

I'm no EE, I'm just throwing around half-baked ideas :)

> For drums, the TR-808 uses a "bridged T-network" in order to create a
>waveform similar to an oscillator decaying in amplitude.  Rather than using
>the trigger to trigger EG's controlling separate VCO's and VCA's as in the
>606 and 909, it seems the trigger itself is transformed into the sound.  In
>my limited understanding, it's like a VCO that runs out of steam.  Like the
>skin of a drum, it oscillates after being hit, then tapers off into
>silence.  For the 808 toms, this circuit is modified with diodes such that
>the frequency decays as well.  Perhaps this technology could be rolled into
>a  MOTM module with increased flexibility such that it could produce more
>than just drum sounds.

MAM is making drum modules.
What you expect from an analogue/digital drum machine, but
in a big rackmount enclosure with many parameters for
each voice.

JH.


-----Urspr\ufffdngliche Nachricht-----
Von: <mark@...>
An: Tkacs, Ken <ken.tkacs@...>
Cc: <motm@yahoogroups.com>
Gesendet: Freitag, 19. Oktober 2001 18:11
Betreff: Re: FW: [motm] Re: Drum modules..


> At 11:35 AM -0400 10/19/01, Tkacs, Ken wrote:
> >
> >A lot of early analog drum circuits used cheapie filters with high
> >resonance. The effect you're describing is a damped oscillation caused by
> >the filter 'ringing,' and by tweaking the filter component values, you
can
> >get all sorts of drum sounds.
> >
> >I think PAIA had/has a board that lets you play with this kind of thing.
>
> Exactly :)  Roland calls it a "periodic damping oscillation".  The circuit
> looks like a filter (in the more general sense of the word -- it's not a
> VCF) as it has an RC network in the feedback path of an op-amp.  It has
two
> parallel elements in the feedback path: a resistor; and a T-network
> composed of two caps (parallel to the afformentioned resistor, and in
> series to each other) with a second resistor between the two caps going to
> ground.
>
> I wouldn't want MOTM to make anything "cheapie"!!  However, I'm thinking
> this damped oscillation idea could be incorporated into a more
> sophisticated  "trigger to audio converter".  Perhaps 1U, with trigger in,
> audio out, and a couple of VC inputs.
>
> I'm no EE, I'm just throwing around half-baked ideas :)
>
> > For drums, the TR-808 uses a "bridged T-network" in order to create a
> >waveform similar to an oscillator decaying in amplitude.  Rather than
using
> >the trigger to trigger EG's controlling separate VCO's and VCA's as in
the
> >606 and 909, it seems the trigger itself is transformed into the sound.
In
> >my limited understanding, it's like a VCO that runs out of steam.  Like
the
> >skin of a drum, it oscillates after being hit, then tapers off into
> >silence.  For the 808 toms, this circuit is modified with diodes such
that
> >the frequency decays as well.  Perhaps this technology could be rolled
into

> >a  MOTM module with increased flexibility such that it could produce more
> >than just drum sounds.
>
>
>
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>

In a message dated 10/20/01 8:34:43 AM, jhaible@... writes:

<< MAM is making drum modules. >>

So does Touched-By-Sound, which used to be associated with MAM:

http://www.novamusik.com/mi_tbs.htm

You can get the big single unit or smaller individual units.

Ivan