www.megadrum.info

This is a positional sensing addon board for MegaDrum for those who cannot, for any reason, make it on their own.

The board is 25GBP (British pounds) plus shipping. Shipping to the UK - £3, to EU - £6, to the US and almost to any other country - £8. Read on the information below and PM me if you're interested.

The addon board uses precision rectifiers to condition input signals from positional sensing capable pads. See history of development of positional sensing in MegaDrum in http://www.megadrum.info/forums/viewtop ... f=3&t=1215

This addon board allows to use positional sensing capable pads on 5 inputs - inputs 4, 6, 8, 10 and 12
For those who wonder what those positional sensing capable pads are - these are mesh head pads with centrally located piezos. Examples are: Roland PD-125, Pintech mesh head pads, Drumtec mesh head pads or even properly built DIY mesh head pads. Your software synthesizer must also support positional sensing - it must recognise MIDI CC16 and modify sound based on it's value.

I tested it with a Drumtec 14" pad and Pintech 10" pad. The best PositionalLv setting for both pads is 2. With Drumtec I got best results with PositionalLow set to 10 and PositionalHi set to 20. With Pintech I got best results with PositionalLow set to 11 and PositionalHi set to 16. See http://www.megadrum.info/content/miscellaneous-settings for details about PositionalIn, PositionalLv, PositionalLow and PositionalHi settings. Note, the bigger size of the pad the more reliable hit position detection is. It seems like 10" is the minimal size required for positional sensing. The position detection reliability also depends on the quality of a pad and mesh head's tension.

The main board in MegaDrum must be compatible with this addon board. You can check if your MegaDrum is compatible or not by comparing your main MegaDrum board with this image:

If your MegaDrum has a placeholder for an optional wire jump (two solder holes marked 'PINTST' and circled in the picture) then your MegaDrum is compatible. All MegaDrum modules/kits built by me in at least last 12 months are compatible. You still need to solder a wire jump between these two 'PINTST' solder holes. Once the wire jump is soldered, you must not use MegaDrum without this addon board otherwise you risk causing a short circuit on the HiHat controller jack which may damage your USB port or power supply.

This picture shows how to connect the addon board to your MegaDrum main board:

A few questions...

Does the price include the 40 conductor jumper?

What does the PINTST actually do?

I am also assuming that this will work with the 56 channel module using just the 40 conductor ribbon.

And why an odd number of channels? MD has an option for eight channels of PS and most rectifiers are available in dual or quad configurations. Not that I need that many... just curious..

Guitardude wrote:A few questions...

Does the price include the 40 conductor jumper?

The cable between the main board and the addon board? Yes, it's included.

What does the PINTST actually do?

When shorted it provides +5 to the addon board.

I am also assuming that this will work with the 56 channel module using just the 40 conductor ribbon.

It will work with any 56/32 inputs module or kit provided the main board has these PINTST solder holes.

And why an odd number of channels? MD has an option for eight channels of PS and most rectifiers are available in dual or quad configurations. Not that I need that many... just curious..

One of op amps is used for HiHat controller input to allow to use high/low impedance controllers without needing a high/low impedance switch.

Hi there

I'm planning to build a new MegaDrum Kit with the positional sensing add on.

Dmitri, you wrote that with the add on board the high/low impedance switch for the hihat pedal is not needed anymore, which is great .
I was just wondering what the connection between input jack and pad connector will now look like.

Is it for the Hihat pedal stereo input jack:
Tip -> Pin 40 (Hihat Pedal Power)
Ring -> Pin 38 AND 39 (High/Low Impedance pedal)
or
Ring -> Pin 38 OR 39

or something completly different

Thanks a lot
Kain

With the addon board Pin 40 (HiHat power) and Pin 39 (Low impedance pedal input) remained unchanged. Pin 38 now goes via an opamp buffer so it should be suitable for both low and high impedance pedals.

Hi Dmitri,

Does the Positional Sensing add-on board work with the Megadrum Lite board also? There is no signal on pins 4, 6, 8, 10 & 12 for the Lite. But then again, pins 4, 6, 8, 10 & 12 for the 56-input board are for Aux-E inputs which doesn't make sense either. Surely, pins and inputs don't mean the same thing. For my better understanding, would you care to explain the relation between pins and inputs, please?

Also, is the 40-pin connector pinout of the Postional Sensing board different from the one on the mainboard?

Thank you,

petrob

It works with the Lite kit just the same. Unused pins on the Lite kit (pins 1-12) will be unused with or without the Positional sensing addon board.
The relation between pins and inputs is described in "MegaDrum Lite kit - instruction manual.pdf" from the first post in viewtopic.php?f=3&t=2667 or in "MegaDrum kit - instruction manual.pdf" from the first post in viewtopic.php?f=3&t=1420

Yes, I saw the pins vs inputs tables in the PDF instruction files. But that doesn't say what the aforementioned inputs 4, 6, 8, 10 & 12 correspond to. I assume they're for the heads of the snare and 4 toms (can you use positional sensing on a cymbal?) but I would like to have a clear confirmation of which of the 5 pins is controlled by the positional sensing board. I'm trying to design an input jack PCB and I'd like to regroup the input jacks with PS seperately.

Thanks again!

petrob

With default inputs names:

input 4 is SnareH on pin 33.
input 6 is RideB on pin 31.
input 8 is Crash on pin 29.
input 10 is Tom1H on pin 27.
input 12 is Tom2H on pin 25.

I don't think positional sensing will work with cymbals so if you want to use inputs 6 and 8 for positional sensing then you can connect mesh pads which support positional sensing to these inputs and rename as needed.

Thanks Dmitri!

Just for info, I checked the manuals for Roland's TD-8, TD-10 and TD-12 modules. There's positional sensing for the Snare head on all three modules and for the Ride cymbal's bow on the last two. I didn't check higher-end modules (TD-20 and up) since I can't afford them but the 5 PS inputs of the megadrum look very generous compared to only 2 on the Rolands. Well done Dmitri!