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What does bass response mean in this schematic?

Hello !
i'm making the MXR plus clone.In the schematic bellow R7=4k7,C7=0.047u ,but in other mod thay said change C7 with 0.1u for more bass response.I dont understand what "bass response" mean ??? just the signal will be clipped take effect  or all the signal run through the pedal ?
Thanks for advance!

Picture of What does bass response mean in this schematic?
gmoon5 years ago
I've got a MXR D+, and it's a fun pedal in some applications. It's not a super heavy type of distortion, though. It's more old-school.

The RC network on the feedback loop (R7, R13, C7) is actually the gain control. But the Distortion+ has a weird frequency "side-effect"--when you turn the gain above 3/4, it boosts highs and cuts the low freqs (bass).

That's not a bad thing, live. The D+ acts a little like a treble booster as well as a distortion (makes harmonics jump out), and helps the guitar rise above the "mush" on stage.

This page on MXR D+ mods explains it perfectly:

(R13)...is labeled as a gain control, however you’ll notice that it changes the tonality depending on its setting. This is because it is changing the frequency response of the opamp at the same time. With the gain control all the way up it only clips frequencies 723hz and higher, though it is at max gain. In its minimum gain setting it is boosting and clipping almost all frequencies (3.4hz and higher) though it has much less gain. This is why it sounds muddy and undefined when the the gain is lower and why it thins out when you turn the gain up...

That link above has some other nice mods for the circuit, including a mod for boosting the low-end response, if that's what you want...
rickharris5 years ago
One can assume it means that more of the lower frequencies will pass through

C7 / R13 and R7 form a filter network. The signal that passes through them to ground will have less effect on the feedback your going to get -

your best bet is to build it and see what sound suites your purpose. Only you can tell that