Lack of “headroom”

I’m using my Mod Duo mostly with my basses. The signal can have quite extreme variations. This is usually not an issue for my sound interface and my bass preamp, but seems to pose an issue to the Mod Duo. When cranking up the bass pot and playing the low B string, the Mod Duo distorts – even at the “Low” setting with the Fine Adjust all the way down to -12 db. Interestingly enough, when I use the hardware bypass, there is almost no distortion.

For me, this means I have to turn the Mod Duo way down to avoid any digital clipping reaching the PA when I play live. And that results in a rather low signal, which is often an issue.

Any advice on how to deal with this? Is there any way to make the Mod Duo sensitivity behave more like it does in hardware bypass mode?


Hardware bypass is basically just sending the signal through a wire so it cannot clip.

There are 2 places when the MOD is active that you could be clipping: the input ADC, or the output DAC, (well, or if you have a distortion plugin in your pedalboard…). The LEDs should indicate hardware clipping on the input or output, though sometimes with very low notes a meter can be deceiving, so you typically want to leave a lot of headroom for bass (which is why bass amps often have 2-10x more power than a guitar rig). If its clipping on the output that’s easy you can add a compressor and/or just a simple gain plugin to turn it down. With active bass pickups its quite possible that you are able to simply produce a larger signal than the mod can handle. If you’ve already adjusted the input gain to be as low as possible then you could next get a signal attenuator or just leave your volume knob a little lower, or use a HW compressor pedal in front of the DUO.

Hope that helps a little.


What color LED are you seeing on the Input?

I think I’ve found the balance, eventually - it’s not easy, but having a preamp with a volume control between your bass and the MOD helps a lot (I’ve got 14 pedals, a KP mini and a Jule Monique before my signal reaches the MOD :slight_smile: ) - thinking about it, the step-down in volume between the in and out of the Kaoss Pad probably helps me the most…

I just saw I forgot to reply to this – thanks for all your comments. My issue is that I’m seeing red LEDs even on the input. I’ve solved the issue by placing an EBS MultiComp in front of the Mod Duo. That also happens to give a nice beefy signal for the Mod plugins.

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that’ll do it! Might be good to experiment with something that gives clean gain too, and see how that works - there are some amazing compressors in the MOD - at the moment, I’m LOVING putting the Calf Multiband Limiter at the end of everything to prevent clipping. It works beautifully, and means I can drive everything just a touch harder without the risk of digital flatulence :wink: (it’s in the unstable section at the moment, with no proper skin on it, but if you drop the pedal onto a board, you can click the gearwheel and see all the parameters, though I just leave it in its default position and it works beautifully…)

Did you try to lower the input gain and fine adjust on the DUO? If not, do you know how to do so?

Jarno, I’ve tried bringing both input gain and fine adjust down to the minimum. It’s still not enough.

Sorry to revive an old thread, but I’ve just got my mod duo and both my guitar and bass have active pickups, I’m seeing red LEDs on the input when playing, obviously turning the volume down on the instrument fixes that. However is the recommended solution to play with the input gain?

Hello @pjd

Did you look in the wiki? You can adjust the overall volume with the help of the Wiki: Adjusting volumes part of the wiki.

Greetings and God bless

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Hi @mj_prod,

Yeah, it’s what I’ll try next time I have some time free to sit down with the mod again, but I’m very much an audio newb (but open source software old hand) and just wanted to check that this really is the best solution.

I’ve just tried playing with the input gain, even with the stage set to low and the fine adjust set to -12db my guitar with active pickups will make the input LED glow yellow.

I really hope this doesn’t mean I need an extra device between the guitar and the mod :’(

Hello @pjd,

I think if it lits yellow your gain into the mod will be fine. It should not light red all the time so everything should be fine. @ssj71 had a better answer in this thread already.

Keep having fun with your mod duo!

Greetings and God bless