MPC One +: Imbalanced Audio Input

Hi,

I have connected a single mono jack from my Behringer RD9 though one of the inputs on the MPC One then though stereo outs from the MPC One out to my my audio Interface(ESI Amber i2) for output to speakers and/or DAW

I am having an issue with the above setup in that there is an imbalance in Left and Right audio levels when the input volume knob on the MPC One is set at certain points along its travel (though this does not happen at max volume) when monitoring the mono input that the RD9 is connected to.

Here is a video of how this looks on my interface: : https://photos.app.goo.gl/J8VAxzmUmMgoisTu8

The metering on the MPC One itself shows no imbalance, though the meters on the MPC One are very diffrent in design and frame rate etc compared to my Interface.

It would seem from testing via recording the MPC One outputs into a DAW and checking the levels that the left channel is 0.5db out from the right.

I have tested the input with another instrument in this case a Roland S1 connected in mono only to the MPC inputs and this issue is not as obvious as it is with the RD9.

I have put in a ticket to Akai support on this, but have not heard back from them yet.

Would anyone here have any thoughts/feedback on this ?

It's quite common to have some left-right level differences, since it's hard to match the gain knobs perfectly, especially on compact 2-in/2-out interfaces.

There is only one gain/volume knob on the MPC One + for both L and R channels. and I have the Gain on the Interface set on both channels to the lowest value so they match.

Also I am able to load a 909 kit on the MPC itself and not have any issues with levels, so this seems like a input issue on the MPC rather then an output issue

Are you connecting the RD-9’s mono output to the MPC’s L/R inputs using a Y-cable?

If you connect the RD-9’s mono out to only the MPC’s L channel using a straight cable, and set the input source to Input 1 (not Input 1,2), the volume difference between left and right should be resolved.

I am connecting via a mono cable from the RD9 to the Left channel on the MPC and setting the monitoring/input to that channel only(so mono).

When you record the RD9 into the DAW via the Akai and through the interface, is the waveform lower on the right?

Yes I have been told in the audio recorded there is a corresponding 0.5db drop in channels to what is being shown on the meters on the interface and in the DAW.

The issue you are tracking—an imbalance between Left and Right audio channels that fluctuates based on the Input Volume knob position—is a known design flaw rooted in the analog input circuitry of several modern Akai MPC hardware models.

This issue has been widely reported to affect the MPC One, MPC One Plus, MPC Live 2, and MPC Live 3.

Nature and Cause of the Flaw

The imbalance (typically registering between $\mathbf{0.5 \ \text{dB}}$ and $\mathbf{1.0 \ \text{dB}}$) is a consequence of inherent analog component tolerance and is not a software bug.

Cause: The flaw is directly attributed to the use of low-tolerance, cheap quality ganged potentiometers (tapers) for the Input Gain knob. These components, which must simultaneously control both Left and Right channels, fail to provide perfectly matched resistance across their physical travel. This results in the differential gain between channels.

Behavior: The imbalance is most pronounced at mid-range settings on the input knob.

The Manufacturer's Shifting Position (InMusic/Akai)

The official support narrative regarding this hardware behavior has been inconsistent:

Initial Status: The problem was reportedly acknowledged by InMusic (Akai's parent company) in earlier support discussions, recognizing it as a hardware tolerance issue.

Current Status: The official position has since shifted to classifying this degree of imbalance as "normal behavior" for the hardware. By classifying it as acceptable tolerance, the issue is deemed not eligible for a warranty repair or replacement.

Impact on Mixing and Performance Workflow

This hardware behavior compromises precision when mixing, sampling, and performing live:

Compromised Stereo Field: The fluctuating imbalance means that a perfectly mono source will appear slightly skewed in the stereo field, negatively impacting critical mixing decisions.

Defeats Audio Interface Functionality: The need for perfectly matched volume control in live performance (e.g., fading samples in or out) is essential. If the user must rely on an external audio interface or mixer simply to accurately control the fading in and out of the MPC's input, the inherent utility of the MPC as an all-in-one standalone production and performance hub is significantly defeated.

Low-Level Mixing Difficulty: If a user attempts to set the input gain to a preferred low level (e.g., to hit a $\mathbf{-18 \ dBFS}$ sweet spot on a virtual instrument), the analog imbalance is likely to be present, making accurate gain staging and mixing difficult or impossible without external compensation.