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A True Rompler


Sasha
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While looking at fairly simple cymbal circuit of tr 909 clone I got an idea of building few rompler modules with various percussion samples. It could be a cool extension to MB808 project. I started to search for some info about 27C256 EPROM and how to convert audio to hex so it can be burned into chip. So, I stumbled upon very interesting project by Sebastian Tomczak. He already did some diy rompler. In his A True Rompler 1 he was playing an loop, and in version 2 he burned 8 note loop and he can play the individual parts of the that loop which is much better than I thought it could be done. What I was expecting is 1 EPROM 1 sample. Here are his page and videos:

A True Rompler 1: http://little-scale.blogspot.com/2008/11/true-rompler-1-raw-digital-audio.html

A True Rompler 2: http://little-scale.blogspot.com/2008/11/true-rompler-2-drum-machine.html

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I've done work on this type of percussion myself. The attached PDF is a good start point, but needs some work for a more modern device:

1) Bigger, more modern EPROM or Flash ROM and a higher sample rate. Bigger ROM would allow switched samples for more sounds too

2) At least an R-2R ladder rather than that terrible resistor based D->A converter, my thought would be to do uLaw compression, (which I think may be used in the 909), to give better use of the 8 bits.

Building it 'as-is' will work, but 2732's are very hard to get nowadays, and old flash BIOS chips are free from older motherboards, (and are usually socketed).

Marc Bareille's Quantix 8 will do this type of work, and is a cool and very flexible module, thought the base cost of 52 Euro, plus the rest of the  parts, might put some people off, (I think mine must have run to about 100 Eoro, though I had some parts in stock). The quality of the control software is very good.

If there is enough interest, I'll tidy up my prototype, and perhaps some person with right skills could rustle up a PCB. I'd probably put the D->A stage on a plug in, then people could choose what type of data format they wanted.

Hope it's of interest.

Alphadrum.pdf

Alphadrum.pdf

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