Alternative to Rolan's TD20

[Lakedaemon]

Hello...

I recently built 6 DIY pads (cost is aroud 30-40€ for each pad) that work and look just as good as 250€+ overpriced Roland pads (except that they are to my specifications),
I'll probably build some E-cymbals next (tape switch being the challenge but I have an idea that might just work). Those won(t be expensive too.

And I'm considering building Megadrum too.
I own a TD20 and if Megadrum could work just as fine than the TD20 (in conjonction with drum monitor and BFD),
I was thinking that I could sell my TD20 unit too (to drastically reduce my costs).

Now, I'm concerned about 2 things :
a) Are three zones pads supported by megadrum (for example like a chokable Ridewith edge/bow/bell sounds (1piezo and 3 tape switch that feeds 2 stereo jacks))
b) what about the number of inputs...
AS I'm considering building the following drum set :
1 Snare, 1 or 2 kick drums, 6 Toms, 1 Hihat, lots of cymbals (1Ride, 2+ Crash, 1 splash, 1 china)
and maybee some other pads to remotelly control my comp (say stop, play and rewind in guitar pro ^_^)

I would like to have at least the same number of inputs than my TD20 : 16 stereo jacks
and ideally, I would like to be able to have as many stereo inputs as I want.

Now, I read that megadrum's design is modular...is it possible to have more than 16 stereo inputs with megadrum ?
Is the atmega32's pin counts/DAC chanels enough for this ?
Or would it need a new design with say an atmega128 with 80+ pins and 16 DAC channels ?

I'm a bit new to electronics (but very willing to learn...) as my only experience till now has been soldering stereo jacks and piezo transducer (yet, I'm quite good at programming and solving complex stuff : I'm a mathematician)...

On a side note, could you counsel me a good book about electronic circuit with micro controller designing

Best regards,
Lakedaemon

[dmitri]

Hello...

Hi

I recently built 6 DIY pads (cost is aroud 30-40€ for each pad) that work and look just as good as 250€+ overpriced Roland pads (except that they are to my specifications),
I'll probably build some E-cymbals next (tape switch being the challenge but I have an idea that might just work). Those won(t be expensive too.

And I'm considering building Megadrum too.
I own a TD20 and if Megadrum could work just as fine than the TD20 (in conjonction with drum monitor and BFD),
I was thinking that I could sell my TD20 unit too (to drastically reduce my costs).

Now, I'm concerned about 2 things :
a) Are three zones pads supported by megadrum (for example like a chokable Ridewith edge/bow/bell sounds (1piezo and 3 tape switch that feeds 2 stereo jacks))

Not at the moment. The only thing that prevents me from adding support for such pads/cymbals is that I don't have one of them to do testing with.

b) what about the number of inputs...
AS I'm considering building the following drum set :
1 Snare, 1 or 2 kick drums, 6 Toms, 1 Hihat, lots of cymbals (1Ride, 2+ Crash, 1 splash, 1 china)
and maybee some other pads to remotelly control my comp (say stop, play and rewind in guitar pro ^_^)

I would like to have at least the same number of inputs than my TD20 : 16 stereo jacks
and ideally, I would like to be able to have as many stereo inputs as I want.

At the moment MegaDrum32 supports 22 inputs, giving 10 stereo inputs plus HiHat controller and Kick input. I have 32 inputs version in development and it is progressing well. The Digital board for this version will be the same and there will be a slightly different Analogue board(s), see News on the website. Now, if you want more inputs right now there is nothing to prevent you from building two MegaDrums - the cost of even two(3,4...) MegaDrums won't hurt in comparison with TD20. I will even add support for chaining MegaDrums so that they would use a single USB or MIDI connection.

Now, I read that megadrum's design is modular...is it possible to have more than 16 stereo inputs with megadrum ?
Is the atmega32's pin counts/DAC chanels enough for this ?
Or would it need a new design with say an atmega128 with 80+ pins and 16 DAC channels ?

The number ADCs is not so important. Multiplexing is used for increasing the number of inputs. The limit on number of inputs per module comes from a speed limit of a Microcontroller. Again, if you want more inputs - build more modules.

I'm a bit new to electronics (but very willing to learn...) as my only experience till now has been soldering stereo jacks and piezo transducer (yet, I'm quite good at programming and solving complex stuff : I'm a mathematician)...

I myself had not been soldering more than some jacks before starting this project:)

On a side note, could you counsel me a good book about electronic circuit with micro controller designing

I find everything I need on Internet using Google. May be someone else can recommend something like this?

Best regards,
Lakedaemon

And good luck to you! Ultimately, it's up to you to decide "to build or not to build". You're gambling here since I don't provide any warranty:) It may turn out that MegaDrum will be inferior to any other Edum MIDI trigger on the planet, or it can beat TD20 beyond your wildest dreams!:)

[Lakedaemon]

>Now, I'm concerned about 2 things :
>a) Are three zones pads supported by megadrum (for example like a chokable Ridewith edge/bow/bell sounds (1piezo and 3 tape switch that feeds 2 >stereo jacks))

Not at the moment. The only thing that prevents me from adding support for such pads/cymbals is that I don't have one of them to do testing with.

I see ^_^. Fair enough.
I took one of those apart once to see what electronic there was inside.
If you are interested, I should be able to provide you with a schematics of the (very simple) conections.
(yet, I'm sure this can already be found on the internet ^_^).

I have 32 inputs version in development and it is progressing well. The Digital board for this version will be the same and there will be a slightly different Analogue board(s), see News on the website.

This is nice ! I'll definitely watch this (thus, the megadrum module would have 1 more stereo input than the TD20).

Now, if you want more inputs right now there is nothing to prevent you from building two MegaDrums - the cost of even two(3,4...) MegaDrums won't hurt in comparison with TD20. I will even add support for chaining MegaDrums so that they would use a single USB or MIDI connection.

I thought about that and I might do it (yet I would rather have a more elegant and less bulky solution).
But let's build one module first ^_^

The number ADCs is not so important. Multiplexing is used for increasing the number of inputs. The limit on number of inputs per module comes from a speed limit of a Microcontroller.

I see. Is multiplexing like :
you plug the first 8 inputs in the DAC and take a sample,
then you deconnect the first 8 inputs and plug in the next 8 in the DAC and take a sample
rinse and repeat ?

And good luck to you! Ultimately, it's up to you to decide "to build or not to build". You're gambling here since I don't provide any warranty:) It may turn out that MegaDrum will be inferior to any other Edum MIDI trigger on the planet, or it can beat TD20 beyond your wildest dreams!:)

I'll build it (the digital card first...)
I have wanted to dabble into electronics for a long time and this seems like a good reason)...
Thanks for the great designs and your quick answer ! (If I manage to build it, I'll help compare it with a TD 20 ^_^)

[dmitri]

The number ADCs is not so important. Multiplexing is used for increasing the number of inputs. The limit on number of inputs per module comes from a speed limit of a Microcontroller.

I see. Is multiplexing like :
you plug the first 8 inputs in the DAC and take a sample,
then you deconnect the first 8 inputs and plug in the next 8 in the DAC and take a sample
rinse and repeat ?

Very close to what happens in reality