CB55 Mods *Updated*

[Barcode]

This is my first post on the forums. Thanks for having me.

Here is a list of mods that I found for the CB55. The how-to's for the Bass Drum Pitch and Decay mods can easily be found on the web but the others are listed but how-to's are no where to be found. Here is what I've come up with so far. I do not have the CB55 PCB yet so none of these have been tested yet and pot values have yet to be determined...

Individual Voice Level - Rather than jumpers use pots between J3, J4, J5, and J6. Also, I personally plan on using switching jacks for the individual voice outs. When nothing is plugged into the individual out the drum voice will be part of the main mix out. Use a 10KA pot for each.

Bass Drum Decay - Replace R33 with a 1KB Pot and 500R trimmer

Bass Drum Pitch - Replace R31 with a 1MB Pot and 2M trimmer

Snare Drum Pitch - Replace R50 with a 1MB Pot and 2M trimmer

Snare Drum Noise Level - Replace R57 with a 10KB Pot (This mod will only slightly change the noise level going to the snare drum. I will continue to experiment and report back)

Rimshot Pitch - Replace R43 with a 1MB Pot and 2M trimmer

I will keep this list updated as I find changes or if other folks make posts.

[Circuitbenders]

Check out the outputs thread, as the snare and hats outputs aren't as easy as just wiring outputs to where J3 and J4 should be. You have to account for the annoying snare and hat submix that goes straight to the main mix out via R61, R72 and J7 etc. Otherwise the sounds aren't removed from the main mix when you plug in a jack, and they bleed onto each others individual outputs.

http://www.circuitbenders.co.uk/forum/index.php/topic,2419.0.html

[Barcode]

I'm finally getting around to posting the mods. After doing some testing I limited the amount down to mods I found to be really useful. The first post has been updated.

[aerror]

thanks a lot @barcode

[gert]

hey @all, i am the new one here.

i just finished my dr-55 clone board and had lots of fun with it, so now i would also be interested in adding some mods. i found some informations on the interwebs which seem to be missing here, could we possibly merge this all into one huge information source for the mods? i will try them out the following days to confirm what really works. anyone possibly have an idea which resistor defines hihat pitch? thats the only one i miss for now, i did not look into the circuit too much yet. thanks for helping!

[gert]

finally came around to finalize and integrate my mods.

lots of wires... luckily they do not affect eachother noticeably, midi to trig is done with a cheap "deek robot" board and some simple code (had someone help me with that, maybe i can post the code if someone is interested):


closed case, i went with a polycarbonate hammond but coated the inside with copper tape for better shielding, it fits the board, trigger converter, pots and connectors quite well, not much space left though:


and the mod point and pot value details, i used only little information for the usual points and tried to find some of my own. when two wires are attached the pot replaces the resistor, for snappy decay you need two wires, other values just put the pot against ground, so you can run one ground wire to the pots and minimize wiring effort:







i also came up with a closed/open hihat circuit idea which sounds quite good to me, i may post a sound demo soon.

one problem i noticed, and i think it is not because of my mods - the snare sounds a little different sometimes, the "snappy" is varied a bit and sometimes the body pitch changes slightly. it is more than the usual "analog variation" you have in drums, anybody experienced this behaviour yet?

[Circuitbenders]

Somebody give that man some kind of prize! 

Any chance of a some audio?

[gert]

thank you. i tried the kit in my larger setup yesterday and it sounds really great, i hope to record it maybe today. also the snare problem is not noticeable in the mix, its maybe a phenomenon you hear when you listen to two hours of plain snare hits while trying to modify the board

[gert]

so, i finally found time to record things: https://soundcloud.com/zerozillion/circuitbenderscouk-boss-dr-55-clone-modified


it was quite hard to find the right recording volume to get all the louder sounds, watch the volume knob!

[rempesm]

Hi Gert,

Thanks for sharing all these goodies.  That's some awesome flexibility you've managed to pull out of the board.

I'm just finishing up the standard build but I think I'll definitely need to add in those mods.

A few points of curiosity:

Did you happen to find any other mods for Rimshot outside of Volume in your travels?

I was originally planning on using a modded TR505 with trig outs for this but I would be curious to see the code you used to do midi to trig as I'm not certain if I'm going to be able to get the closed hi-hat mod working otherwise.  As far as I can tell the TR505 has trigger durations all over the place which necessitates using the trigger conditioning circuitry.  Unfortunately I'd have no idea how to setup a similar conditioning circuit that's already on the board which would spit out 5ms trig instead of 10ms trig.

Lastly, I can't really tell from the photo but do you have anything hooked up to those momentary buttons or do you have any plans for them?

[gert]

you're welcome!

i found the rimshot so nice on it's own, as it cuts the mix perfectly in my usage, that i did not want to mod it in any way. but it is basically easy, just poke around on the resistors, put a smaller resistor in parallel and listen to what happens. if you found a "good spot", desolder the resistor and put a pot there (it's good to have several values to try). if you find a better spot later, solder back the resistor and put the pot to the other place. sometimes a pot in parallel to a cap can change timing or timbre aswell, i only understood a few core principles when i did the mods and basically just poked around until i got it right for my needs, and this was over a course of two weeks in my free time. so no instant results, it takes a while to get it done properly.

i just emailed the guy that helped me with the code, if i may post it here. for my needs i set it up on midi channel 10, and it responds to typical general midi note numbers, 12 triggers all in all.

yes right, the closed hi-hat would need a proper short impulse but there is no conditioning circuitry left, for me it was easy to do with the trigger board. i also heard that the TR505 triggers are really not much "normed".

possibly you can use a 555 and a fairly small capacitor to condition the trigger? http://www.learnabout-electronics.org/Oscillators/osc45.php  i saw some simple solutions once in a Facebook discussion, but cannot find any now on google.

the 4 momentary buttons were meant to trigger the sounds in standalone mode, but until now i was too lazy to integrate diodes in the arduino trigger lines to run these together to the cb-55 trigger inputs. mostly when you use it you will hook it up to midi anyways, so you hear instant results.

[gert]

An update: Possibly for the BD and SD reso potentiometers a logarithmic (A) one would work better, as the tweaking range until 3 o'clock is doing only subtle changes and after 3 the reso hits in quite fast, the distance to set it properly is just a few millimeters. Iirc i would have taken log right from the start, but in my stock are only chinese log pots with a 24 step raster...

For the trigger board, as mentioned in the CF thread: I did only test this with a dedicated Note on/off sequencer, i will once fire midi clock, MMC/MTC at it to see how it performs in these situations.

[01012k7]

I am atb the moment building another 4 boards so will add the mods when they are working  

[Leonard Charles]

I had a go at dropping the kick down in pitch, I found replacing c10 with a higher value Cap made a good drop in pitch, more sub for your buck. I replaced the 68nf for a 100nf. 

I also added a switch and code (104) cap to C23 on the snare circuit. This means that when you flick the switch the snare note drops an octave(ish), sounds awesome. If you have done the other snare mods then they wont work on the lower octave but will still work on the higher octave.

[01012k7]

I had a go at dropping the kick down in pitch, I found replacing c10 with a higher value Cap made a good drop in pitch, more sub for your buck. I replaced the 68nf for a 100nf. 

I also added a switch and code (104) cap to C23 on the snare circuit. This means that when you flick the switch the snare note drops an octave(ish), sounds awesome. If you have done the other snare mods then they wont work on the lower octave but will still work on the higher octave.

sounds cool