[sdiy] learning from early drum machines?

[Dan Snazelle]

thanks for this amazing info! 
i will spend a little time tomorrow studying it.
you said "earliest drum machines" used this method..can you be a little more specific
on which machines? i would like to look at a few schematics for reference.

thanks







--------------------------------------------
check out various dan music at:

http://www.myspace.com/lossnyc


http://www.soundclick.com/lossnyc.htm


http://www.indie911.com/dan-snazelle
(or for techno) http://www.myspace.com/snazelle






________________________________
> Date: Sat, 10 Jan 2009 21:14:05 -0800
> From: dayoldbread at ghettosynth.com
> To: subjectivity at hotmail.com
> Subject: Re: [sdiy] learning from early drum machines?
> CC: synth-diy at dropmix.xs4all.nl
>
> Hi Dan,
>
> It's really quite easy to make beats without microprocessors. The earliest electronic drum machines used diode matrices as read only memory. You can replicate this approach or use a more modern variant like an eprom.
>
>
> In essence, a counter cycles through memory and every place you want a beat you store a one which becomes a gate output.
>
> Think of a simple sequencer using a 4017 with reset after the 8th output. Each ouput then represents an eight note. Now think of the kick drum playing a 4/4 beat and you want an output on each quarter note. So you connect every other output to the anode of a small signal diode and tie all the cathodes toegether. You've just created a four input or gate. Now use the common cathode to trigger the gate input of your kick drum sound.
>
>
> Repeat for each sound. What you end up with is a matrix of diodes where the anodes are connected to some gates and the cathods are tied together for each sound.
>
> If instead of diodes you use a four bit counter and an epprom then you use the data lines of the eprom to trigger your sounds. Of course you have to program the eprom with the correct patterns.
>
>
> With little work you can use a static ram chip and make the memory programmable much like the earliest programmable drum machines. None of this requires a micro, however, all of this could be done much more easily with a single PIC.
>
>
> I hope this helps.
>
> BTW: I listened to your music, nice stuff,
>
> Later,
> Daryl
>
>
>
>
>
>
>
> On Sat, Jan 10, 2009 at 5:04 PM, Dan Snazelle> wrote:
>
>
>
>
>
> OK
>
>
>
> i have a goal and it might be crazy.
>
> to make something that generates a beat (with multiple sounds) a primitive drum machine.
>
>
>
> now my plan was to check out the early (roland, korg,etc) drum machines from the 70's (maybe before they started using CPU's to make the beat) so i could figure out if the pattern making circuitry is even possible without microprocessers or pics.
>
>
>
>
> i am scared of code so this might be an exercise in stupidity.
>
>
>
> i KNOW i can make the circuitry for the drum SOUNDS.
>
> i know that they can be controlled by a trig/gate.
>
>
>
> what i dont know how to do is program gates with buttons, that trigger 4 or 5 different sounds at different times (without using 4 or 5 giant 16 step seqs)
>
>
>
> ideally an 808 style seq would be great but i KNOW that is way way too advanced. memory would be nice but i have never used memory before
>
>
>
> anyway..
>
>
>
> any tips on where to find old drum machine schematics?
>
> or even, which models to look into?
>
>
>
> thanks guys
>
>
>
>
>
> right the sky is the limit till i figure out it's too hard) ]]
>
>
>
>
>
>
>
> --------------------------------------------
>
> check out various dan music at:
>
>
>
> http://www.myspace.com/lossnyc
>
>
>
>
>
> http://www.soundclick.com/lossnyc.htm
>
>
>
>
>
> http://www.indie911.com/dan-snazelle
>
> (or for techno) http://www.myspace.com/snazelle
>
>
>
>
>
>
>
> _______________________________________________
>
> Synth-diy mailing list
>
> Synth-diy at dropmix.xs4all.nl
>
> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
>
>