Blah Blah Cafe, the Jean-Michel Jarre forum

[synthx]

Hey,

Some time ago we spoke about drummachine or rhythm box modification with midi and stuff like that. Id like to share a project I did for a friend of mine, maybe this will generate some nice ideas for those wanting to control their rhythm boxes externaly.

The rhythm unit i modified was an Electro harmonix DRM16. Since these come in neat little stompbox like chasis I wanted to make it rackmounted, my friend wanted both control and separate audio ouputs for each sound. A guitar amp was an helpfull tool to locate each sound, and a midi>CV converter set to 5Volts was helpfull in triggering the sounds.



The old EH machines all look awfull on the inside, coldsloder joints and unwashed resin is standard in these products.



Half way through, much wires and more to be added.



Close up of the mess.



Installed in the 19" Rack. Looks even worse than I had imagened it.



The frontpanel was made in 3mm thick aluminium designed in frontpanel designer, two whole evenings later it was finished (It is a lot of work calculating both front and back measures). A friend of mine owns a CNC machine so he got the design and 24 Hours later I had my frontpanel.

Instead of installing MIDI into the box I went for external signal inputs of max +5V this way I can build another device that is just patched into this rhythm machine and if he wants to use the triggers for other machines he just can unplugg them and plug them into another rhythm unit or whatever. This makes it cheaper in the long run as then I just have to make one rackmounted control unit instead of one for each machine he wants to modify. The cost for this modification was about 150 Euro in total.

Hope it gives some nice ideas for modifications

Best regards,
/Syn

[Nico_Noyau]

Wow, looks amazing now, I love that !
It's quite expensive, but on the other hand, it's really worth it.
It doesn't change anything for the sound, right ?

[synthx]

Wow, looks amazing now, I love that !
It's quite expensive, but on the other hand, it's really worth it.
It doesn't change anything for the sound, right ?

Nope it doesn´t change the sound, however it is nice to be able to take out each sound by them selves and EQ them without everything else. I tried to add breaking connections so that if you patched the bassdrum out separatley the bass drum would not go to the master outputs, however this proved to be a little hard to do as breaking one path after OPamps would result in hearing the whole drumrythm without the sound I wanted to have on the connection. Some sounds seemed to be made up of several others so breaking them apart would make them sound very different from wha you hear in the mixed outs.

Glad you liked it, I am thinking of taking upp the production of the Electro harmonix Talking pedal and make a few of them in rack enclosures. Only problem is that the pedal controls two resistors at once one is 7K and the other 11K one of the has a fourth so called center tap, so it remains to test and see if I can work arround this somehow.

[Nico_Noyau]

I'm currently working with 3 friends on a Talking Pedal in rack format since April, for the moment, I have found schematics (damn hard to get !!) and one of them is trying to make a PCB

[synthx]

I'm currently working with 3 friends on a Talking Pedal in rack format since April, for the moment, I have found schematics (damn hard to get !!) and one of them is trying to make a PCB

Ok, nice. I found a TP in a store so I bought it. The OPamps are 4558 I know the schemos fail to mention this.

[jarrekid]

You might want to take a look at this for MIDI to trigger decoding. Obviously you wouldn't use the pot outputs (unless perhaps you want MIDI controlled tempo and stuff, that would be cool!), but the 8 digital trigger outputs would be useful for that external box.

[Nico_Noyau]

I'm currently working with 3 friends on a Talking Pedal in rack format since April, for the moment, I have found schematics (damn hard to get !!) and one of them is trying to make a PCB

Ok, nice. I found a TP in a store so I bought it. The OPamps are 4558 I know the schemos fail to mention this.

Lucky bastard, I'm looking for one since 3 years
How much did you pay for it ?
I'm really really jealous here


But thanks a lot for the name of the OP amps !!

[synthx]

You might want to take a look at this for MIDI to trigger decoding. Obviously you wouldn't use the pot outputs (unless perhaps you want MIDI controlled tempo and stuff, that would be cool!), but the 8 digital trigger outputs would be useful for that external box.

Thanks for the tip, but I think I will go for Doepfers Midi>trigger converter and buy enough of the 5V TTL outputs to make it an 64 trigger unit. The funny thing is, if this machine got used with drumpads that can send variable voltage from 1 to 5V and everything inbetween it would be velosity sensetive. I tried setting the MIDI>CV convert to 3V and the volume was lower than at 5V. Just a funny feature it got without even knowing it

[synthx]

Lucky bastard, I'm looking for one since 3 years
How much did you pay for it ?
I'm really really jealous here
But thanks a lot for the name of the OP amps !!

I paid 2995 SEK about 300 Euro. I´ve talked to guitarists that have had this pedal but they would not let go of theirs for under 350 Euro.

If you want pictures of the interior or any other info on the TP let me know. I´ve already opened it to see what is lurking inside it

[Nico_Noyau]

Oh, right, 300€ is quite expensive
But yes, I'd be really interested in photos of the 2 sides of the PCB aswell as these 2 pots used.
And can you confirm me aswell how are these 2 pots working ? Can we just move one of them at the same time ?

[jarrekid]

You might want to take a look at this for MIDI to trigger decoding. Obviously you wouldn't use the pot outputs (unless perhaps you want MIDI controlled tempo and stuff, that would be cool!), but the 8 digital trigger outputs would be useful for that external box.

Thanks for the tip, but I think I will go for Doepfers Midi>trigger converter and buy enough of the 5V TTL outputs to make it an 64 trigger unit. The funny thing is, if this machine got used with drumpads that can send variable voltage from 1 to 5V and everything inbetween it would be velosity sensetive. I tried setting the MIDI>CV convert to 3V and the volume was lower than at 5V. Just a funny feature it got without even knowing it

Haha nice one!

[synthx]

Oh, right, 300€ is quite expensive
But yes, I'd be really interested in photos of the 2 sides of the PCB aswell as these 2 pots used.
And can you confirm me aswell how are these 2 pots working ? Can we just move one of them at the same time ?

Yepp, they are expensive. A friend of mine knows of an guitarist who owns another one. If you want I can try and ask what he would let it go for. Otherwise there is a guitar store in NYC that has an online shop, they get them in to the store from time to time. I know I have the URL somewhere.

I will take some images for you and post them in the thread. The two pots are controlled simultainiously by the pedal, one is 7K and the other is 11K. The 11K one is the one with the center tap which is soldered to GND (In the case of this pedal GND and minus is the same if I remember correctly). I am working on a way to do the same thing but with one pot instead of two and use a standard expression pedal instead. I can share the info once i get there on how to do it.

[olivier_0001]

Very good working !

I'm surprised with the good front panel, good job !
You speak about a CNC machine ?

I'm busy with two projects :
A single rack with 2 EH small stone and EHelectric mistress
Just input and output to the back panel, and pot and button to the front panel.
but I'm very interesteed with your designer

Second I am going to receive a minipops 7 and my project is approximately the same of you. But some difference. Only one sound output with midi contrable trimpot for some of sound quija, quiro,... midi kit and midi trigger for each sound.

If someone have informations about minipops 7, welcome !
About trigger location on the board, and direct audio

Do you have informations about delay caused by the midiconverter ?
I think it's max 0,5 sec.

Olivier

[synthx]

Very good working !

I'm surprised with the good front panel, good job !
You speak about a CNC machine ?

Yepp, the panel is made with CNC and drawn in frontpanel designer (Freeware). A friend of mine who does all sort of work within the synth/audio field bought one and now he makes a lot of panels for people who need it. And he has better prices than Schafer.

I'm busy with two projects :
A single rack with 2 EH small stone and EHelectric mistress
Just input and output to the back panel, and pot and button to the front panel.
but I'm very interesteed with your designer

Nice, search for "frontpanel designer" and I am sure you will find it. This program is very easy to make frontpanels in. Why not put the outs and ins on the frontpanel as well ? It would save you some money to do so and it would be easier to patch.

Second I am going to receive a minipops 7 and my project is approximately the same of you. But some difference. Only one sound output with midi contrable trimpot for some of sound quija, quiro,... midi kit and midi trigger for each sound.

If someone have informations about minipops 7, welcome !
About trigger location on the board, and direct audio

I think the information you are looking for is available on the net. I might have
the image somewhere on my HD.

Do you have informations about delay caused by the midiconverter ?
I think it's max 0,5 sec. Olivier

Sorry, no information or experience in this field ...yet ...

[jarrekid]

Very good working !

I'm surprised with the good front panel, good job !
You speak about a CNC machine ?

Yepp, the panel is made with CNC and drawn in frontpanel designer (Freeware). A friend of mine who does all sort of work within the synth/audio field bought one and now he makes a lot of panels for people who need it. And he has better prices than Schafer.

Yes, Schaeffer's prices are very very high in my opinion...