Moog Music Forum

My MF-101 gets very noisy when a USB cable is plugged into the MP-201. Any thoughts on the cause or a solution?

Bryan

My thought is that the USB cable isn't properly shielded. If you're certain that the USB cable is of a good quality, then my next guess is that it has something to do with the power being transferred, causing a rise in voltage going to the MP-201 and affecting the VCF, which is what the MF-101 is. Just my thought on it.

We tried a few different USB cables at the recording studio. I'm wondering if this could be a power issue. The computer was plugged into one outlet and the MP-201 was plugged into another outlet on a different wall.

I don't have any issues at home, but that is using a laptop on batter power.

Any thoughts?

Bryan

Is the computer a laptop, by chance? Grounding issues can cause system noise when USB is connected, especially to laptop computers. If you are using a laptop, try unplugging the laptop's power cable (run on battery, if it's an option) and see if the noise goes away or changes at all. One thing you might also do is experiment with plugging the laptop and the multipedal into different power circuits, or into the same circuit if they are plugged into different circuits now. Also, places like Radio Shack (or your non-USA equivalent) often sell clip-on ferrite noise filters for USB cables. Some USB cables have these already (you may see them on USb cabled designed for cameras or digital video) -- in this case you'll see a heavy cylindrical lump on one end of the USB cable. You might try one of these to see if it helps.

Cheers,

Amos

aha, you posted while I was typing, answering some of my questions. Yes you might try adjusting where the computer, MF-101, and MP-201 are plugged in... This sort of thing is almost always a power/ground-loop issue.

Thanks for the input. Sounds like we're on the same page in our thinking.

Bryan

make sure everything connected to the recording / audio chain in one way or any other , is all sourcing power from the same outlet. this prevents ground loops.

willi wrote:make sure everything connected to the recording / audio chain in one way or any other , is all sourcing power from the same outlet. this prevents ground loops.

I didn't initially expect this issue, as the MP-201's power adapter is ungrounded.

Bryan

Although there is no ground on the power adapter, the unit's circuit has a 'ground', which in this case is not connected to an _earth_ ground, but is probably connected to the chassis/case in some manner. Similarly, the computer and all the other devices have chassis grounds, etc. Since the units are connected the possibilty exists for electrical interplay... I am not an EE, so someone more versed in this subject can please feel free to correct me, but I did have some very dirty power where I lived in Hawaii and had to do some research to arrive at this understanding -- and, although it was years ago now, I recall being amazed that this issue can be caused even when using a ground lift for anything plugged into a different wall socket (and that the issue was fixed once everything was chained off the same wall socket).

Make sure your cables and the building wiring are in good repair; as long as you don't pull too much power from the wall it should be ok. Poor quality or improper wiring can cause things to get hot enough to catch fire when pulling an excessively large load through a single socket. That said, most wall sockets are something like 15 Amps if I recall correctly; this is a fair bit of electrical power, and I run all sorts of gear simultaneously off a single socket just fine (Hammond, CP70, CS50, Wurlitzer, digital romplers, moogerfoogers, 2 15" JBL Eons, computer, hard disks, monitors, cable modem, recording interface, etc.).

Bryan T wrote:My MF-101 gets very noisy when a USB cable is plugged into the MP-201. Any thoughts on the cause or a solution?

Bryan

Have you found a solution for this problem? If so, please give us the details.

My 'solution' has been to use MIDI cables instead of USB. However, I'm not sure I've had the LPF wired up while I was running MIDI recently. I haven't encountered noise with my other pedals or Little Phatty.

Bryan

Bryan T wrote:My 'solution' has been to use MIDI cables instead of USB. However, I'm not sure I've had the LPF wired up while I was running MIDI recently. I haven't encountered noise with my other pedals or Little Phatty.

Bryan

And what do you suggest when the MIDI cable are causing the same noise issue? This is happening to me when I'm running my Electro Harmonix 16 sec looping pedal (this is where MIDI signal starts because it only can send MIDI out) into my M-Audio 8X8 MIDI Sport patch bay to my Frostwave sequencer, then to my Analog Solution Red Square Modular synth out to my Moogerfoogers? They all have 2 prong wall warts and the Red Square is ground lifted. I have tried different plugs on different circuits too. Everything is removed from the racks to see if the rack rails were causing the ground loop, All the cable are good (audio and MIDI)