Using a stereo effect pedal as a signal splitter?

lukedlb

I've long had an eye out for a Gigrig humdinger or the like to split my guitar signal and run them to two amps when it dawned on me that I have a stereo output option on my neo ventilator Leslie effect that I have never employed. I'll test this option later in the week to see if the buffered bypass permits this without the Leslie effect. 
Should I worry for other issues? Ground, phase, etc?

steamabacus

You won't do any damage. There may be an issue with hum from a ground loop (but there may not, it will vary with circumstances) but these can easily be overcome with a transformer isolator - Orchid Electronics do a very good quality one for £20. This is 'full galvanic isolation' which is actually better than just a 'ground lift' switch (I'm not sure if the Humdinger is fully transformer isolated or not).

Phase issues are a possibility but will vary with equipment and where exactly they are placed in the room, etc. If you are using the same two amps in the same location, an easy fix to swap the phase of one amp is to flip the two connections over on the speaker.

I've run a stereo setup occasionally using a stereo delay pedal (and an Orchid isolator if needed) without any problems.

markymoo

steamabacus said:

You won't do any damage. There may be an issue with hum from a ground loop (but there may not, it will vary with circumstances) but these can easily be overcome with a transformer isolator - Orchid Electronics do a very good quality one for £20. This is 'full galvanic isolation' which is actually better than just a 'ground lift' switch (I'm not sure if the Humdinger is fully transformer isolated or not).

Phase issues are a possibility but will vary with equipment and where exactly they are placed in the room, etc. If you are using the same two amps in the same location, an easy fix to swap the phase of one amp is to flip the two connections over on the speaker.

I've run a stereo setup occasionally using a stereo delay pedal (and an Orchid isolator if needed) without any problems.

Hi there.  I am having an issue with this currently.  I have a fairly complex pedal board which 2 stereo pedals at the end of the chain of which I have recently been splitting out the L and R outputs into 2 different amps.  It sounds great when I'm playing but there is a very distinct hum when I'm not playing.  I understand the phasing issue can be resolved with and ABY switch if I had a mono signal but obviously this isn't possible with a split L and R signal.  Is there a switch than can sort this?  I'm not sure/confident I know enough to 'flip the connections' on the speaker.       FYI, one amp is a Laney VC30 2x12 valve amp, the other is a Fender mustang solid state amp.  I am looking for another identical Laney eventually (is the phasing not likely to be an issue if its the same amp??)   Cheers

crunchman

@markymoo if there is a hum is more likely to be a ground loop issue not a phasing issue.  The Orchid Isolator (or similar) will be the solution.

steamabacus

markymoo said:

steamabacus said:

You won't do any damage. There may be an issue with hum from a ground loop (but there may not, it will vary with circumstances) but these can easily be overcome with a transformer isolator - Orchid Electronics do a very good quality one for £20. This is 'full galvanic isolation' which is actually better than just a 'ground lift' switch (I'm not sure if the Humdinger is fully transformer isolated or not).

Phase issues are a possibility but will vary with equipment and where exactly they are placed in the room, etc. If you are using the same two amps in the same location, an easy fix to swap the phase of one amp is to flip the two connections over on the speaker.

I've run a stereo setup occasionally using a stereo delay pedal (and an Orchid isolator if needed) without any problems.

Hi there.  I am having an issue with this currently.  I have a fairly complex pedal board which 2 stereo pedals at the end of the chain of which I have recently been splitting out the L and R outputs into 2 different amps.  It sounds great when I'm playing but there is a very distinct hum when I'm not playing.  I understand the phasing issue can be resolved with and ABY switch if I had a mono signal but obviously this isn't possible with a split L and R signal.  Is there a switch than can sort this?  I'm not sure/confident I know enough to 'flip the connections' on the speaker.       FYI, one amp is a Laney VC30 2x12 valve amp, the other is a Fender mustang solid state amp.  I am looking for another identical Laney eventually (is the phasing not likely to be an issue if its the same amp??)   Cheers

As crunchman said, noise issues are likely to be a ground loop where there are two (slightly unequal) routes to ground leading to noise that should be shunted away to ground looping back around the signal chain. The solution is to break one of the routes to ground (keeping one connected) - there are various ways to achieve this but the Orchid isolator is a cheap and high quality solution.

Better featured ABY pedals will have the option to isolate (or lift the ground) and flip the phase of one output. I'm not sure what stand alone phase changing boxes are available - I think Radial do one but they are pricey, Maybe Bright Onion could custom build something? Or a DI box?

...

I've done a quick search and found this Palmer box which would do it.

Alternatively, anything which has balanced outputs could be used to flip the phase. A balanced cable is basically two signal lines (in- and out-of-phase) and an outer screen - the two signals are normally combined at the input (and thus removing any rf noise picked up by the cable in the same manner as a humbucker works) but you could tap the positive or negative phase signal only with the correct cable.

In my experience, though, phase issues are less of a problem than ground loop issues when using two amps.

[edit] This article may help.

hotpickups

Blimey that palmer is pricey. I got Bright Onion to make me a stereo sum to mon splitter box with ground lift and phase switches on it. I think it was about £70. No problems at all and he's a great guy to deal with

steamabacus

hotpickups said:

Blimey that palmer is pricey.

The Radial Phazer is even more! (though it does do a lot more in terms of phase adjustment)

By far the cheapest method is to flip the speaker connections (since you have no 'screen' you need to maintain like on a signal cable)

lukedlb

Ok, it works. The signal is equally split through the bypassed neo ventilator without any phasing issues. The pedalboard has picked up some hum so I'll need to fix that before I make the change permanent. 
The only drawback is i can't use it inside a loop as that would effectively prohibit the stereo outputs. Although it could be used to turn off the second amp (no signal goes to it). 

Whitecat

steamabacus said:

You won't do any damage. There may be an issue with hum from a ground loop (but there may not, it will vary with circumstances) but these can easily be overcome with a transformer isolator - Orchid Electronics do a very good quality one for £20. This is 'full galvanic isolation' which is actually better than just a 'ground lift' switch (I'm not sure if the Humdinger is fully transformer isolated or not).

Phase issues are a possibility but will vary with equipment and where exactly they are placed in the room, etc. If you are using the same two amps in the same location, an easy fix to swap the phase of one amp is to flip the two connections over on the speaker.

I've run a stereo setup occasionally using a stereo delay pedal (and an Orchid isolator if needed) without any problems.

Silly question - where do you place the isolator in your signal chain?

steamabacus

Whitecat said:

steamabacus said:

You won't do any damage. There may be an issue with hum from a ground loop (but there may not, it will vary with circumstances) but these can easily be overcome with a transformer isolator - Orchid Electronics do a very good quality one for £20. This is 'full galvanic isolation' which is actually better than just a 'ground lift' switch (I'm not sure if the Humdinger is fully transformer isolated or not).

Phase issues are a possibility but will vary with equipment and where exactly they are placed in the room, etc. If you are using the same two amps in the same location, an easy fix to swap the phase of one amp is to flip the two connections over on the speaker.

I've run a stereo setup occasionally using a stereo delay pedal (and an Orchid isolator if needed) without any problems.

Silly question - where do you place the isolator in your signal chain?

Immediately after one of the two stereo outputs. Here's a photo I took a while back ...

Whitecat

Ta v much! Running into this issue with just a specific pedal config at the moment and I'm 100% this thing will solve it.

lukedlb

I fixed the pedalboard hum only to find one generated by having both amps on. This wasn't present with the G2 so I think the isolator is on my Xmas list.