FM3 Noise from Output cables

F

FatBoy99

New Member
I've recently bought a Fm3 and set it up with a couple analog pedals. I've been using output 2 with a ts-ts cable into the Amp return in a couple band live sessions and experienced no noticeable noise issues. I altered the configuration of my board recently:

1. Output 1 is now used as the main output. A 20cm xlr-ts cable to my Reverb pedal, then a 6m ts-ts to the Amp return.

2. The fm3 and truetone cs6 use the same power cables. Instead of using 2 separate powercables from 2 power sockets, I'm now using a y-split power cable that powers both my fm3 and cs6 from 1 power socket.

And this has presented a significant level of noise. So I've experimenting a bit to find the culprit, and here's what I have discovered:

1. Using output 2, ts-ts to Reverb then 50cm ts-ts patch cable to amp: almost NO noise at all

2. Using output 2, ts-ts to Reverb then 6m instrument cable to amp: SMALL level of noise, not enough to disturb live sessions, but is present.

3. Using output 1, xlr-ts to Reverb then 6m instrument cable to amp: OBNOXIOUS noise, the overall level of the pure output of the fm3 decreases significantly.

The noise is definitely coming from the cables after the output. Changing the output levels of the Fm3 does NOT affect the noise level at all. I've tried scenario 2 without the reverb directly to the amp, same deal; so the Reverb pedal is fine.

The xlr-ts cable is custom made by a guy I know. He's a quite well-known professional but I recall him saying he's never made a xlr-ts patch cable before.

The thing is, I really do need the output1 to work to complete my setup. I'm currently thinking about getting rid of the Reverb pedal altogether and using a much longer xlr-ts cable directly to the Amp return.

Is this even worth a shot?

Could the y-split power cable be the culprit?
 
FatBoy99 said:
I've recently bought a Fm3 and set it up with a couple analog pedals. I've been using output 2 with a ts-ts cable into the Amp return in a couple band live sessions and experienced no noticeable noise issues. I altered the configuration of my board recently:

1. Output 1 is now used as the main output. A 20cm xlr-ts cable to my Reverb pedal, then a 6m ts-ts to the Amp return.

2. The fm3 and truetone cs6 use the same power cables. Instead of using 2 separate powercables from 2 power sockets, I'm now using a y-split power cable that powers both my fm3 and cs6 from 1 power socket.

And this has presented a significant level of noise. So I've experimenting a bit to find the culprit, and here's what I have discovered:

1. Using output 2, ts-ts to Reverb then 50cm ts-ts patch cable to amp: almost NO noise at all

2. Using output 2, ts-ts to Reverb then 6m instrument cable to amp: SMALL level of noise, not enough to disturb live sessions, but is present.

3. Using output 1, xlr-ts to Reverb then 6m instrument cable to amp: OBNOXIOUS noise, the overall level of the pure output of the fm3 decreases significantly.

The noise is definitely coming from the cables after the output. Changing the output levels of the Fm3 does NOT affect the noise level at all. I've tried scenario 2 without the reverb directly to the amp, same deal; so the Reverb pedal is fine.

The xlr-ts cable is custom made by a guy I know. He's a quite well-known professional but I recall him saying he's never made a xlr-ts patch cable before.

The thing is, I really do need the output1 to work to complete my setup. I'm currently thinking about getting rid of the Reverb pedal altogether and using a much longer xlr-ts cable directly to the Amp return.

Is this even worth a shot?

Could the y-split power cable be the culprit?
Click to expand...
Might not be the issue, but Output 1 connection should optimally be either xlr>>xlr, or the Humbuster cable config specified in the FM-3 manual. Xlr>>ts done incorrectly (non-Humbuster config) often results in reduced s/n ratio. Carefully check yr xlr>>ts wiring, and correct it if it's miswired. Seems to be the most likely issue.
 
Bobbyoso said:
Might not be the issue, but Output 1 connection should optimally be either xlr>>xlr, or the Humbuster cable config specified in the FM-3 manual. Xlr>>ts done incorrectly (non-Humbuster config) often results in reduced s/n ratio. Carefully check yr xlr>>ts wiring, and correct it if it's miswired. Seems to be the most likely issue.
Click to expand...
Did not know that xlr-ts needed humbuster configurations as well. I believe they are currently wired traditionally. I'll go try shorting the TS side and come back with the results. Thanks.
 
FatBoy99 said:
Did not know that xlr-ts needed humbuster configurations as well. I believe they are currently wired traditionally. I'll go try shorting the TS side and come back with the results. Thanks.
Click to expand...
👍. Check the diagram in the manual to ensure it's wired correctly; more than a few people have miswired them, usually with similar issues.
 
I've looked up a few diagrams and it seems that I would need a balanced wire shorted on the TS side, whereas my current cable seems to be unbalanced.

Just for precaution, are you sure humbuster-ing an XLR is a thing? Because the process seems to require the effort, and I'm not too familiar with wires.
 
FatBoy99 said:
Did not know that xlr-ts needed humbuster configurations as well. I believe they are currently wired traditionally. I'll go try shorting the TS side and come back with the results.
Click to expand...
XLR (balanced) -> TS is not the same as a Humbuster, because the internal circuitry for the XLR doesn't provide the Humbuster noise-reduction, it's only balanced. Only the 1/4" outputs have the Humbuster circuitry. Balanced ≠ Humbuster.

See p. 23 in the manual, particularly the tip on #17 and #20. Also p. 8, the Humbuster definition, specifies how Out 1 and Out 2 cables differ.

FatBoy99 said:
[…] are you sure humbuster-ing an XLR is a thing?
Click to expand...

It's not.
 
FatBoy99 said:
I've looked up a few diagrams and it seems that I would need a balanced wire shorted on the TS side, whereas my current cable seems to be unbalanced.

Just for precaution, are you sure humbuster-ing an XLR is a thing? Because the process seems to require the effort, and I'm not too familiar with wires.
Click to expand...
Sorry, I misspoke; you're right, the humbuster isn't used on xlrs on Output 1. It is used on TRS output 2, going from TRS to the specific TS connection shown on p. 8. The xlr Output 1 connectors shouldn't be terminated in TS in any event, according to the manual. Sorry I added to the confusion. (thanks also to Greg Ferguson, who also responded with the correction to my misguided advice re: xlr and humbuster config).
 
Thanks for letting me know. Hmmm. So I guess I'll have to use unbalanced XLR-Ts and live with the noise if I want to use both outputs. Could there be any other way to exterminate the ground loop?

I read someone saying that they used an isolated transformer box instead of humbusters and got rid of the noise completely. Could that work?
 
I read someone saying that they used an isolated transformer box instead of humbusters and got rid of the noise completely. Could that work?
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a DI box will help for sure - it converts unbalanced TS to balanced XLR and also offers high impedance input and low impedance output
 
First of all - what type of noise are you getting? Hum, hiss, buzz, etc are all different and point to different causes.

Second - is the noise the same or different if you remove the reverb pedal (ie, go straight from out1 to amp)?

When you say ‘amp return’, do you mean FX return? What is the specific amp model?

Do you happen to have a reamper handy? It may not necessarily solve the issue, but if you could try it between the balanced XLR out and the unbalanced (I assume) input to the reverb pedal or amp it could help troubleshoot the issue, including trying the ground lift (which may help with ground loops) and including seeing whether there is an impedance mismatch that’s causing or contributing to the noise.
 
SteveD61 said:
a DI box will help for sure - it converts unbalanced TS to balanced XLR and also offers high impedance input and low impedance output
Click to expand...

But - IIUC - OP is going from a balanced out into an unbalanced input - not from unbalanced output to balanced input. A passive DI run backwards might work, but a re-amper (which is intended to feed a balanced line level signal into an unbalanced instrument input on pedals or amps) would be more appropriate, no?
 
Rumbletone said:
First of all - what type of noise are you getting? Hum, hiss, buzz, etc are all different and point to different causes.

Second - is the noise the same or different if you remove the reverb pedal (ie, go straight from out1 to amp)?

When you say ‘amp return’, do you mean FX return? What is the specific amp model?
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1. The noise hums and hisses at the same time I guess.

2. The reverb pedal is fine, I tried multiple methods to single the issue down to the output/following cable. I've also now found that using a normal ts-ts from output2 produces the same noise, just reduced quite a bit from the input noise gate. So I'm now pretty sure it is an issue with the balanced out/unbalanced input.

3. Yes I mean the fx loop, and the Amp is definitely not the problem. Tried with multiple amps and at home, I connect via audio interface with the same cable configuration as the amp return. Same issues all around.

I think your idea of using a reamper is an excellent idea. I'm ordering a Walrus Canvas right now - I'll update you on the outcome. Thanks.

Or I'm being a big dumbdumb and it's just by using the same power source for the fm3 as the cs6, but I can't find that being an issue.
 
FatBoy99 said:
1. The noise hums and hisses at the same time I guess.

2. The reverb pedal is fine, I tried multiple methods to single the issue down to the output/following cable. I've also now found that using a normal ts-ts from output2 produces the same noise, just reduced quite a bit from the input noise gate. So I'm now pretty sure it is an issue with the balanced out/unbalanced input.

3. Yes I mean the fx loop, and the Amp is definitely not the problem. Tried with multiple amps and at home, I connect via audio interface with the same cable configuration as the amp return. Same issues all around.

I think your idea of using a reamper is an excellent idea. I'm ordering a Walrus Canvas right now - I'll update you on the outcome. Thanks.

Or I'm being a big dumbdumb and it's just by using the same power source for the fm3 as the cs6, but I can't find that being an issue.
Click to expand...

I think you need to start by eliminating the cs6, reverb pedal, etc from the signal chain for troubleshooting purposes. Start with just the FM3 and the amp. If no issue, then add one device and see whether the problem arises again. If not, remove that device and add another. If the issue doesn’t arise with any one of the devices added back in, then start with combinations. Once you find the combination that reproduces the issue, then you can narrow the potential sources.

For example, eliminate ‘the same power source for the fm3 and the cs6’ as the potential issue by removing the cs6 entirely - both from the signal chain and the power supply. If the noise doesn’t change, then you know that’s not the issue. Same for the reverb pedal - even if the gear is all working as intended, an impedance mismatch - for example, because you are changing to the balanced XLR output from the unbalanced output 2 - could be causing the issue with the input to the reverb pedal, but you won’t be able to identify it unless you methodically add the devices back one by one.
 
Greg Ferguson said:
XLR -> TS can be done, but it won't be a Humbuster. From p. 29 in the FM3 manual…

View attachment 139885
Click to expand...

And of course it also won’t be balanced. And IIUC it will also be 6dB quieter, all other things being equal.

And although there isn’t room for it on the FM3 back panel, I’d love if it had redundant sets of outputs - ie, Output1 has balanced XLR outputs as well as balanced TS, and ideally the same for output2. I find that it’s about 50/50 that I’m plugging my main outputs into balanced vs unbalanced, so either I use output2 as the redundant output when I need unbalanced (which works fine, but means they can’t be used for something else), OR I need to haul around a device to convert from balanced to unbalanced (ideally placed at the input end, especially if the cabling run is long), OR I need to bring an extra set of XLR-F to TS cables (though in most cases I think XLR-F to TRS would work fine too - maybe it’s an issue only when plugging it into a battery-powered pedal with input jack switching?).
 
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