Those are the things you do not have to worry about if you do not want to. the board works as it is delivered. but if you like to improve and customize and understand, here is a lot more info:

D4 string Bass volume

by default, the Polybass effect on the D4 string is similar to the E6 and A5 string. but some musicians like to have no effect on the D4 string and others prefer it to be lower so there is a transition between the strings with effect and the ones without.
try out your setting on the single little trimmer on top of the board!

weak (dead) notes

every guitar has some resonances in the neck that “eat” the energy of certain notes, so they fade away quicker than the others. usually the worst is around G…A. those irregularities are better audible with the Polybass, but not related to it. so sorry, we cannot fix this, nor your luthier, but you can improve a lot by holding the neck firmly when you play that note.


the original RMC system has a treble enhancement on the input and a compensating treble cut on the output. since we only replace the board with the input stage, this treble enhancement is compensated on the new board. this compensation filter is switchable with a jumper which is set by default, so when you plug the board as you receive it, the sound should be similar.

warmer sound

try to take off the jumper to experience a warmer sound, see if you like it.

more treble options

if you prefer the more trebly sound, you have options:

flat with compensation
put the jumper back and go on with the two opposite filters as RMC created them (probably to improve the noise of the ancient chip).

really flat
make to system really flat and leave the phase response of the pickup as the string really vibrates. again, there are two options to achieve this:

really flat by cutting resistor
unplug the new board again and unscrew the lower board as well and cut resistor as in picture:

really flat by cutting track
unplug the new board again and cut track as on picture. needs some skill.

the advantage is that you do not need to unscrew the lower board and that you can add a jumper

and with it switch the filter in case you want the more mellow sound or return to the original RMC board

Here some possible improvements and extensions that you do not need to worry about if you are all happy now:

Roland GuitarSynth and compatible

in case you are using the Roland Synth volume as it was intended originally, you will notice that it still works like before, but probably you feel bothered because it also controls the Polybass. the easiest fix ist that you change the setting in the Roland box to not control the Synth Vol by the GK and instead use the Vol knob on it or add a Vol Pedal.

another easy solution is to remove the jumper Control which leaves the Polybass effect at a constant mid volume.

here in the picture, the jumper is in the position for full Polybass volume.

you can also replace the jumper by a little switch. if its a On-Off-On kind, you get the options NoEffect-Half-Full.
we can provide the connector and recommend a switch.

you can also set the jumper to full volume and add another potentiometer that controls the Polybass effect, wired as in picture…

or the Polybass effect can be sent out through a separate channel where volume is regulated. see below.

Split Polybass effect out

this needs more skill. either you add another connector or split the bridge between the DIN13pin7 and the 1/4” output

and add another wire, either for guitar only or for Polybass only. as you see on the picture there is only one resistor which does that bridge. remove it and add a wire to the 1/4”tip, connect it to X16pin2 and remove R84. or:
to make it nicer, you can also add another two pins to X2 and replace the flat cable by a 16pin (this is what we do in the Paradis guitars)

solder battery wires

we used a solder free wire connector to make it as simple as possible for most of the users. but if you travel around the world and need top reliability we recommend to solder those wires.


we have a circuit on board that flashes when the battery becomes low. you can connect a led to X11 pin5(+) and pin6(-). since such a LED is not lit during ordinary operation, in the Paradis guitars we use a common Anode two color LED and connect the red part as mentioned and the green wire goes through a 4k7Ohm to ground, so its constantly lit (very dim, so we do not spend the battery)


in the classic Polysubbass unit, there is a switch to turn priority off, so all played bass strings are octavated. few people have used this, but if you like the octave on all 3 bass strings at once, you can install a switch to Prio1 (A-string) and Prio2 (D-String). unsolder the two zero-ohm resistors on the component side.

using the Polybass board without the RMC base

you can use the Polybass with any polyphonic piezo pickup and some additional mono pickup of your choice by creating the correct cabling. we can also provide a output board and the flat cable to connect it. then you have many options to connect volume controls and send out signals… we can provide you with the necessary information  SWITZERLAND