TS-9 & Multi Effect Processor Ground Loop

the_dude

Squier-Nut
Feb 17, 2021
658
Japan
Has anybody here dealt with ground loop issues with a simple 2 pedal & amp setup?

I usually play through a TS-9 (tubescreamer) into a small Vox practice amp and never had any issues with ground loops. But recently I wanted to add my Zoom G3n to the chain (for reverbs and such). I am using a daisy chain from the Zoom's 9 volt adapter (9v 500 mA) to power the TS-9 and the G3n. When using some effects on the G3n I can hear what I think it is a ground loop hum - but it is mostly noticeable when using certain effects on the G3n (guitar amp simulators).

One way to test if it is a ground loop is to 'lift' the ground somewhere in the chain, but I was thinking, could it be that the Zoom's adapter is unable to power the whole chain (and that some effects pull more power than others) or is it a ground loop?

Have you guys every dealt with ground loops in such a simple setup?
 

kdm1218

Squier-Meister
Jun 18, 2021
239
TX
It may be that the adapter is being overloaded by both. However if you are running a different amp sim from the zoom into the front of your amp then you are probably just introducing noise by the nature of running an amp sim into an amp. An amp sim is designed to run into a cab or other speaker system (PA, etc). What you have set up is basically like if you could run two amps in series with one into the other.
 

the_dude

Squier-Nut
Feb 17, 2021
658
Japan
I wasn't planning on using any of the amp sims when running into an amp. I was just pointing out that it is those effects that I can hear the noise. If was thinking of running the amp sims when recording (directly into my audio interface) and at that point the noise would be an issue.

I mainly use the G3n for reverbs, chrous, delays etc. The amp sims are more power hungry than these effects.
 

kdm1218

Squier-Meister
Jun 18, 2021
239
TX
An amp with a guitar plugged in but not being played also has a hum. Without hearing it, it sounds like normal behavior. I have a Line 6 Helix and if you don’t turndown your guitar volume or the volume pedal the amp sim has noise at “rest” too. Have you tried it with the interface yet to see if the same issue persists, or you are just guessing that it will?

What you are describing and it only affecting that category of models is not a ground loop. And various effect types don’t have an effect on if a unit is getting enough power when you are using the factory power supply.
 

the_dude

Squier-Nut
Feb 17, 2021
658
Japan
If I have only the G3n in the chain (G3n->amp, no guitar) and enable the guitar amp sim, even with the amp at full volume (input gain and master volume) I can only hear the noise floor of the G3n (the unit itself or it's model).

But as soon as add the TS-9 to the chain (TS-9->G3n->amp, no guitar) I get a high pitch sound that is extremely noticeable. Maybe even too high of a frequency to be a ground loop, I will test it later to see what frequency the noise is at.

I thought it could be a faulty patch cable, so I picked up a new one the other day, but same thing.
 

the_dude

Squier-Nut
Feb 17, 2021
658
Japan
Using an FFT the noise is a sine wave starting at 2600hz with even harmonics. And is only there when the TS-9 is in the chain and both powered by the daisy chain.

Did some more testing. I am certain it has something to do with the power, maybe the daisy chain, not sure. For a test I took the adapter from my son's Zoom B3n (which is the same adapter as the G3n) and plugged the G3n and TS-9 on their own adapters and there is no noise with that setup.

Another odd thing I noticed by accident, is if the ring of any of the none used terminals on the daisy chain touch the sleeve of the cable coming out of the TS-9 the G3n looses power and reboots itself.
 

Hal Nico

Squier-Nut
Dec 21, 2020
868
UK
I wouldn't put a pedal into an amp stomp box. The input impedance may be an issue. Why not forget the TS9 and use one of the G3n FX to get the overdrive you want ?
 

kdm1218

Squier-Meister
Jun 18, 2021
239
TX
Using an FFT the noise is a sine wave starting at 2600hz with even harmonics. And is only there when the TS-9 is in the chain and both powered by the daisy chain.

Did some more testing. I am certain it has something to do with the power, maybe the daisy chain, not sure. For a test I took the adapter from my son's Zoom B3n (which is the same adapter as the G3n) and plugged the G3n and TS-9 on their own adapters and there is no noise with that setup.

Another odd thing I noticed by accident, is if the ring of any of the none used terminals on the daisy chain touch the sleeve of the cable coming out of the TS-9 the G3n looses power and reboots itself.
Yep you just need it to not be daisy chained and give the TS9 its own power. If you don’t have another adapter you could always use a battery and just unplug the pedal when done so it doesn’t draw on the battery.

In the pedal world, it’s a well documented thing that a digital pedal paired with an analog overdrive, distortion, or even compressor tends to be noisy. A few analog pedals daisy chained together are usually fine, but throw a digital in the mic and exactly what you are describing starts to happen. It even happens with the high quality power bricks if you try to chain a digital and analog together on the same output.
 

the_dude

Squier-Nut
Feb 17, 2021
658
Japan
I wouldn't put a pedal into an amp stomp box. The input impedance may be an issue. Why not forget the TS9 and use one of the G3n FX to get the overdrive you want ?
The analog TS-9 sounds far better than the digital one :cool:

I mainly want to use the G3n for reverbs, delays, and modulation effects.
 


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