www.megadrum.info

Hello,
Like I already said I am an electronician that collect old edrum brains(Simmons,Ddrum,Pearl,Tama,Dynacord....)
I am much more competent on electronic than on playing drums....
I am always trying to make new drum voice generators.....
Here are two pictures of my two channels drum generator based on 8 bits samples on Eproms.....no software,just standart components......
I have made a PDF with schematics,comments,PCBs but it seems that I can not upload it??????
I hope this will interest someone!
See you soon
Thierry EPPHERRE from FRANCE

You can post your PDF in a ZIP file.

Hello,
Here 4 RAR files:
comments on my project
3 schematics

Hope you'll be interested........
See you soon
Thierry EPPHERRE

Hello,
Here sch2.rar I couldn't upload yesterday!!!!!!
Thierry EPPHERRE

Looks interesting, but enough to install a rar extractor ? No !

Cant you zip them up ?

I couldnt wait and installed winrar.

I must say that your project is very interesting and its nice that it doesn't need a firmware too. Have you tought about adding some kind of filtering envelope ?

The only thing I dont really understand is this: "to simplify the board layout, the adress and data of the sound Eprom are swapped".

This all seems a bit retro! Things were done this way back in the 80's as there was no other choice. Nowadays we have much easier and better solutions. Whilst there is no 'firmware' you still need to be able to program the samples into eprom - its much easier to program an AVR!

Where's the other eprom for the amplitude control? 8bits of data alone doesn't give you much dynamic range - especially since we're talking of percussion instruments here where dynamic range is required! An extra 8 bits of amplitude control gives an effective 16bit sample.

Frequently, you need to re-arrange the sequence of the address and/or data lines to make a simple pcb layout. Instead of A0,1,2,3 you might do A2,3,1,0 since it makes the pcb layout easier. You then need to re-arrange the sequence of data put into the eprom to compensate.

Hello,
Here are some comments about my project:
+Yes I have idea to implement a dynamic filtering with a LM13700 based VCF
+Like say Kartman,I have simplified the PCB with swapped adress and datas line of the Eprom: I made a short Quick Basic program to rearrange datas on the sound file before burning the Eprom.I use my own DIY Eprom programer to burn these 27C4001
+The 8 bits samples sound better than you can think (it was made like that on SIMMONS,DYNACORD,but also on DDRUM PLUS!,DDRUM2 and DDRUM AT.....and these are very very good....)
There is no "Eprom for amplitude control",the loudness and the shape of the sound is controled by an analog Env generator with a decay control.
The 8 bits sample is compressed to maintain a better S/N ratio and it's real shape is reconstructed with the Env....
You can edit sounds on your audio editor in 16 bits,compress it ..... before converting in 8 bits unsigned raw data .....
I could send you a MP3 to demonstrate my project but it's too big to post here (4.6 Mo)
Happy that somebody is interested by my project.....
See you soon
Thierry EPPHERRE