MOTU M2 Very Quiet Response to Synthesizer

[walks]

Hello,

I'm having trouble with my Motu M2. I bought it to record my modular synthesizer into my computer. Like most modular synths, mine has a very hot output and I usually have no problem plugging it directly into a mixer if I'm playing live or with other people. However, when I plug it into either input on my M2, with either balanced or unbalanced cables, and then into my computer via USB-C, the absolute maximum volume that I can record in Ableton is -4dB, and that's with the output cranked and a really terrible noise floor. It's making it difficult to record anything at all. I'm happy to provide any other information and any help is appreciated.

Thanks!

[mikehalloran]

Let’s take a look. From the manual:

1. These two XLR/TRS combo jacks accept a mic cable or a quarter-inch cable, balanced or unbalanced, from a guitar or line level source.

2. Use GAIN knob to add up to 60 dB of boost to the input signal. Watch the input level meter in the LCD while adjusting gain. Try to adjust gain as high as possible without clipping, which is indicated by the red rectangle at the top of the meter.

60 dB is a lot of gain.

You don’t say what you are plugging in. My Yamaha has a much lower output if I use balanced cables, for example. We have no idea if this applies to your synth.

You say “either output”. Ok… let’s look at that. There’s no mixer in an M2. Plugging into 1 outputs Left only and 2 outputs R only. In Ableton or any DAW, you need to create a Mono track and select the correct Input that you have your synth. Selecting 2 if plugged into 1 will result in a very low level or none at all.

See if this helps.

[walks]

Thanks, Mike! I appreciate your thoughtful response.

I should have mentioned that I tried this with both balanced and unbalanced cables and did not see a meaningful different in output between the two.

When I try to add gain with the M2's gain knob, it brings up the noise floor before getting the volume to a reasonably recordable level. I have not been able to correctly balance the gain on the M2 and the output on the synth to get a reasonably loud recording volume without getting an uncomfortable amount of noise. I don't have this problem when I'm listening to headphones through the output module's headphones output, or when I plug the line outputs on the output module directly into powered speakers.

Let me know if any other information would be helpful; I'm pretty new to recording so I'm not always sure what's important.

[mikehalloran]

…
When I try to add gain with the M2's gain knob, it brings up the noise floor before getting the volume to a reasonably recordable level. I have not been able to correctly balance the gain on the M2 and the output on the synth to get a reasonably loud recording volume without getting an uncomfortable amount of noise. I don't have this problem when I'm listening to headphones through the output module's headphones output, or when I plug the line outputs on the output module directly into powered speakers.

Let me know if any other information would be helpful; I'm pretty new to recording so I'm not always sure what's important.

That’s not the problem you described in your original post (OP). I was going to ask what synth & mixer but none of that is important because I know the problem and there is likely no amount of level tweaking that will fix it.

“Line Out/In” are terms often used incorrectly as they cover so many different levels and impedances. Instrument Level (guitar/bass but includes most keyboards and drum machines, believe it or not) and the old +4 Line Level used in broadcast and pro studios are way different and there are many “Line Levels” in between.

I will spare you the next four paragraphs where I explain everything and cut to the solution. You need a direct box to boost your signal so that the impedance and output level matches the M2’s required Input.

A simple step up transformer will probably work—the better the transformer, the better the low end. The M2’s Mic Pres are flat enough so no worries there.

I recommend Amazon for their no-hassle 30 day returns and am limiting recommendations to items I have actually used. Although there are a zillion different boxes at all price points, the transformer sounds really good in this.
https://smile.amazon.com/Whirlwind-1-c ... ef=sr_1_44

This one’s my favorite. Note that it’s a pair of transformers. The XLR jacks mirror the TRS so you can use either one. Also, balanced/unbalanced is not a problem. Again, the bottom end sounds great.
https://smile.amazon.com/Morley-MLLS-2 ... ref=sr_1_1

There’s an older, discontinued version of the above with TRS jacks only called the Ebtech LLS-2 (Morley owns Ebtech). The transformer is the same and these can sometimes be found used.

I use the LLS-2 for most things as do my students and other users but my iPad doesn’t have quite the output I like. When that happens, the only real solution is an Active DI. Again, there are many choices but this is the one I use. Note it has an input volume trim pot and -10 dB RCA and TS jacks for some of the old junk (synths, drum machines, cassette decks etc.) that I hook up in addition to the 1/8” TRS for my iOS devices. Absolute overkill for your immediate need but still, you get the idea.

https://smile.amazon.com/Radial-2-chan ... ef=sr_1_52.

[walks]

Incredible, thanks again Mike!

Does this mean I'm dealing with a ground loop issue?

My synthesizer is a Eurorack modular system, so I also always have the option to change the output module to better accommodate recording. Do you think that using either of these devices as the main output for my system would have a similar effect to adding a direct box to the signal flow? No worries if Eurorack is outside your area of expertise; you've really helped me figure this out.

https://happynerding.com/category/isolator/

https://joranalogue.com/products/transmit-2

[mikehalloran]

A ground loop issue will present itself as a strong 50/60 Hz noise when a ground is unexpectedly amplified in the signal chain. You’ll hear it if you have one. The IMP and Radial have ground lift switches in case you hear one; the LLS-2 isolates the transformer to prevent them.

The two links you provided are overkill. Also, they are stereo. If you have stereo out, get the Morley LLS-2 as it’s a dead simple, passive solution. If mono, try the IMP. If buying from Amazon, try a cheap one, too, and if it sounds as good (and fixes the problem, of course) return the other and declare victory.