MC-2oh2 drums into filter / VCA

[darenager]

BTW I experimented with running the drum output into the filter, sounds ace, I might add a switch to route it - I wonder if it is possible for a firmware update to elect to send the drums through the noise output @tubbutec so they go into filter ?

[tubbutec]

BTW I experimented with running the drum output into the filter, sounds ace, I might add a switch to route it - I wonder if it is possible for a firmware update to elect to send the drums through the noise output @tubbutec so they go into filter ?

I tried this. It does sound amazing! Unfortunately using the noise output for drums results in a volume that is too low for my taste. I think I will put it in anyway. Unfortunately this could only be corrected by changing the value of a resistor on the 2oh2 board. Would result in higher volume for noise (and for "sample through filter"

[darenager]

Great! Maybe a little external circuit to boost the level from the noise pin would do the trick.

I also tried drums through VCA, quite handy too, I am also thinking of a mod to route it to the mix, looks like C69 on 202 PCB is the input to the headphone/line out, but probably need a little amp first.

[tubbutec]

Taking this from an email I sent someone else. But still untested. This is how I would go about putting something into the VCA Headphone / line out jack

First picture shows how to take the signal from the TAPE-out socket in a "normalized" fashion. When nothing is connected the signal goes to the headphone or line out. If something is plugged in it is taken out of the mix

Second picture shows two possible injection methods. The resistor values still need to be found. A lower value will result in a higher signal

[darenager]

Thanks for that! The normalised switching jack is a great idea best of both worlds, separate drums out when recording, headphone mix when using portable.

For now I just used a 100k resistor from the tape jack tip signal into junction of R147/148 (see pic) just as a temporary solution, it works ok, but for sure will experiment with other solutions, I guess injecting the drums into various different sections might need a few different resistor values due to different input levels of VCF, VCA, mix.

[darenager]

To clarify on the switching jack idea do I take the signal from the tape out tip terminal after first severing the pcb trace joining tip and ring, then send that to headphone/line out, such that when the jack is inserted into tape out the connection is broken and the drums come from the tape out (I think this is right but just checking) In this scenario I think a TRS to TS cable (with ring unconnected) would be needed to prevent the ring and sleeve being connected as a TS to TS cable would short them?

Also the v1 cyan and v2 blue areas on your diagram, I assume that if v2 blue is chosen the drums will appear at line out but not headphone out?

[tubbutec]

In this scenario I think a TRS to TS cable (with ring unconnected) would be needed to prevent the ring and sleeve being connected as a TS to TS cable would short them?

We are pretty sure these are normal switched mono jack sockets, no adapter of any kind needed.

Also the v1 cyan and v2 blue areas on your diagram, I assume that if v2 blue is chosen the drums will appear at line out but not headphone out?

No,with both versions the signal will appear on all outputs

[darenager]

Great, thanks for clarifying, I’ll try some stuff over the next few days and post here.

[darenager]

Ok, I did the mod using variant 1, the resistors I chose were 27k which seem to give a good balance between accented drums and non accented, I think anywhere from 10k to 47k should be fine depending on how loud you want the drum mix relative to the synth.

I cut the trace on the tape out between the tip and middle connectors of the jack socket, I used a Dremel as it is quite a wide area to get through, I then twisted one end of 2 27k resistors together so they form a Y shape, the joined end goes to the tape out tip connector, then a wire from each resistor to the two points shown in the pic below. It works very well, inserting a cable into tape out removes it from the main out as Tobias predicted. The only minor issue is a bit of digital noise on the output when nothing is playing, could be because I did not use shielded cable or could just be how the drum output sounds, either way no big deal as it is silent when a jack is inserted to tape out, and when playing it cannot be heard. Also turning volume down does not turn drums down, but this is handy as it allows setting a mix between drums and synth, but I thought I’d mention it.

Edit: The mixed drum out has a different sound, not quite as crisp, but a bit punchier and more bass. Both sound usable but different, maybe different value resistors might yield different results.

Definitely recommend this mod for portable usage, it is great.

[adhmzaiusz]

BTW I experimented with running the drum output into the filter, sounds ace, I might add a switch to route it - I wonder if it is possible for a firmware update to elect to send the drums through the noise output @tubbutec so they go into filter ?

I tried this. It does sound amazing! Unfortunately using the noise output for drums results in a volume that is too low for my taste. I think I will put it in anyway. Unfortunately this could only be corrected by changing the value of a resistor on the 2oh2 board. Would result in higher volume for noise (and for "sample through filter"

Which resistor? I am totally willing to experiment with this… these resistors seem giant compared to behringer stuff I’ve modded

[adhmzaiusz]

Ok, I did the mod using variant 1, the resistors I chose were 27k which seem to give a good balance between accented drums and non accented, I think anywhere from 10k to 47k should be fine depending on how loud you want the drum mix relative to the synth.

I cut the trace on the tape out between the tip and middle connectors of the jack socket, I used a Dremel as it is quite a wide area to get through, I then twisted one end of 2 27k resistors together so they form a Y shape, the joined end goes to the tape out tip connector, then a wire from each resistor to the two points shown in the pic below. It works very well, inserting a cable into tape out removes it from the main out as Tobias predicted. The only minor issue is a bit of digital noise on the output when nothing is playing, could be because I did not use shielded cable or could just be how the drum output sounds, either way no big deal as it is silent when a jack is inserted to tape out, and when playing it cannot be heard. Also turning volume down does not turn drums down, but this is handy as it allows setting a mix between drums and synth, but I thought I’d mention it.

Edit: The mixed drum out has a different sound, not quite as crisp, but a bit punchier and more bass. Both sound usable but different, maybe different value resistors might yield different results.

Definitely recommend this mod for portable usage, it is great.


IMG_3667.jpeg

Hey Darenager, I just finished this mod but I’m curious—did you install the 10uf BP cap from the jack tip to resistors?

[darenager]

Yes I did, I might try changing the resistors I used to a slightly higher value maybe 33k or 39k, although I quite like the sound of it now. I think I might install a switch to route to mix/filter as well, but not until I try the next update with the drums in the noise pin as that might be sufficient.

[tubbutec]

BTW I experimented with running the drum output into the filter, sounds ace, I might add a switch to route it - I wonder if it is possible for a firmware update to elect to send the drums through the noise output @tubbutec so they go into filter ?

I tried this. It does sound amazing! Unfortunately using the noise output for drums results in a volume that is too low for my taste. I think I will put it in anyway. Unfortunately this could only be corrected by changing the value of a resistor on the 2oh2 board. Would result in higher volume for noise (and for "sample through filter"

Which resistor? I am totally willing to experiment with this… these resistors seem giant compared to behringer stuff I’ve modded

Well, a 0603 resistor on the 2oh2 board. However there is no point in replacing it now - without a firmware update you would only get louder noise - fine of course if that is what you want. But I am still not sure if that is a good idea to pursue - you might have noticed some digital noise on the drum output. This is the noise of the 5V supply, pretty bad because the 5V is not regulated well (just a zener diode and a transistor).
lowering the "white noise" resistor might (untested) also increase the digital noise going into the audio path - not great.

[darenager]

So do you think sending drums via noise pin isn’t worthwhile in conclusion?

I wonder if a small (100nf or so) ceramic capacitor across the 5v rail would clean it up a bit?