Noise spike in new analog synth.

[memac]

Hi All.

I am a new live user, and I was happy to get a new analog synth patched in. I noticed that there was a faint hum through my headphones (shure IEMs, so quite sensitive) and showing up on the spectrum tool.

It is pretty quiet, taking the noise floor from -130 to -116 in the 40 to 60hz band. This goes away when I touch the chassis of the unit, so there seems to be a grounding issue. Multiple cables and power points make no change.

My question to experienced producers.. is this going to have a noticeable effect on my productions? Or is this a fairly normal type of thing that can be ignored? I need to decide whether to return the unit, and want to make the right decision within the return window.

Thanks so much for any advice!

[Shift Gorden]

Hey oh!

What's the synth and what kind of interface do you have?

You'll likely always have some sort of noise with analog gear, although it shouldn't really be noticeable. I think your issue is that it definitely appears to be a grounding issue, which is frustrating.

I hate to say it, sounds like you might have a faulty unit, mate.

[Tone Deft]

that's a reasonable noise floor. what synth is it? the manual should say what the audio performance should be.

[memac]

Thanks both!

It is a Moog Sirin. Lovely sound despite this.

I couldn't see anything in the manual to indicate noise expectations, but not 100% sure what to look for. Yeah, I think it is grounding issue, but I just don't know enough about how that works, there is no ground pin on the 12v adapter.

[Tone Deft]

all you have to do with ground loops is make sure all your stuff is plugged into the same circuit breaker in your house. IOW on the same circuit. this problem arises when two pieces of gear reference grounds from different circuits in your home.

I don't think you have an issue. that noise floor will not appear in your mixes, or is it? at -116dB to -130dB? that's really quiet.

if you don't want the synth I'll take the noisey little bugger off your hands. sounds like you have a faulty unit and you should just donate it to a good cause, like me.

[Tone Deft]

another thought...

hums can be conducted (through wires) or radiated (through the air.) conducted ground loops are what I've mentioned. to check for RADIATED hums move your synth around and see if those spikes change in amplitude. also try turning off EVERYTHING around it to see if something nearby is being noisy.

send it over to me, I'll take a look at it. I'll even pay for shipping.

[memac]

Thanks TD

Appreciate your advice. I don't think it is a "ground loop" as it was happening in isolation from other equipment. I have limited understanding of that but I think only happens with multiple devices on multiple circuits?

Interesting thought about radiated hum. I did try to isolate from other devices. I'll try to go even more extreme. Hard to get away from all potential sources of interference. The strange thing is that grounding the unit by touching it worked.

Cheers for the offer.I don't think I'm quite ready to send it back across to your side of the pond from Sydney Oz

[TLW]

A little noise from analogue synths or analogue gear in general isn’t unusual - they mostly contain amplifiers after all, and amplifiers make some self-noise. For what it’s worth I have a Minitaur which is very quiet but not silent, it has around 8-12dB of self noise depending on where the filter frequency is set, which indicates the noise source is probably either the oscillators or the filter itself.

Assuming you’re recording in 24 bit 14dB of noise isn’t going to show up much, if at all. My MS-20mini is far noisier than that but the noise gets lost in the mix or drowned out by the synth itself while it’s playing. If it shows up between notes it’s easy to gate the noise out.

As for earthing issues, again, lots of analogue - and some digital - things gain or lose noise when touched because they then earth via you. Changing the USB or audio cables might help as might using a DI box to “float” the earth between interface and synth.