MOTUnation.com

Hello,

I just tried two 2nd hand Motu 24i/o interfaces and in both cases, when I got my ear close to the enclosure, I could hear hum. Is this normal?
Thanks,

C.

I can't say since I've never owned one, but probably not.

Did you try them both plugged into the same exact location? Perhaps try another line that might be cleaner with less on the circuit just for the hell of it.

Ok, thanks. But still, this doesn't sound normal to me.

It's transformer hum. Usually it's not very loud. Not what the solution is. Maybe someone can chime in.

I would like to add a mod to use an external modern and silent transformer.

I've had a 24i/o from new, and I can tell you they do suffer a bit of transformer buzz. The transformers can get pretty damn hot in the summer too.

The 24i/o actually has two transformers side-by-side in it, as opposed to the one found in the 2408 Mk3. I think this accounts for the extra buzz. There's possibly some interaction between the flux of each transformer. I guess they run them in parallel to supply the extra current required for all those I/Os.

Yeah, it seems one transformer is for the analog circuitry and the other of for the digital one. Any one ever tried modifying the 24i/o to use a single, external transformer?

If sound is really an issue to you, maybe think about building a clear case for it with a silent fan and opening for the wires with rubber covering the cut. Maybe you can even find a fan and switch that can be powered by battery instead of tapping into MOTU power. Now that I think about it, you could probably use a regular computer fan with like 4 C batteries attached to the +5v line. All you would need is the battery housing for that. Or even 4 AA batteries instead.

Seems simpler to make something like that than to mod the unit for external power.

Or even put the MOTU in another room, depending on your needs, cables you have etc...

Just some ideas.

Thank you for the tips. The unit is at the shop right now and the guy said he would make a quote to mod it so that there is no more internal transformer.