hum problems

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jswevers

jswevers

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Dear all,

I have some serious hum problems with my Einstein (especially channel 2 and mode 3 of channel 1). I am sure it is not caused by the Einstein. I just switched from a passive A/B switching box (to switch two series of effect-pedals on my pedal board) with passive 3PDT switches to a
remotely controlled relay based A/B switching box (the remote loopy 2 : www.thegigrig.com): this
humming even when both loops are in bypass. All pedals on my pedal board have separate 9 VDC (Pedal Power 2) and the remote loopy has a separate boss PSA.

When I installed the passive switching box again it was all back to normal levels ...

What can I do/test to find the cause of this and how can I fix this humming problem.

Any feedback is welcome.

Kind regards,

Jan
 
The effects are in the amp's loop or in front of the amp?
You most likely have a ground loop. What goes in front of the amp and what goes in the FX loop shoud not have common ground, this will surely generate hum.

Post a schematic or a detailed picture of your setup, so I can see where could the problem be, and also what can be done to separate the two circuits.
 
The switch box that causes problems is between guitar and amp:

guitar -> Switch box -> amp input
switchbox switches 2 series of effects (there are 2 send and 2 returns) in/out this path between
guitar and amp input.

Jan
 
Do you also have something in your amp's fx loop? Is the hum there when you bypass the two pedals? How about if you only use the switcher without the pedals in the loops?
 
Do you also have something in your amp's fx loop? in both cases (something in the amps fx loop AND
nothing in the amps fx loop): the hum is the same.

Is the hum there when you bypass the two pedals? yes

How about if you only use the switcher without the pedals in the loops? I have not checked this (will do this soon)
but I do not expect any difference because the hum is gone if I replace the switch box (remote loopy 2) by
my old passive one with passive 3PDT switches.

thanks for the help!
 
I had problems with hum when I had pedals in front of my amp and found out, that they weren't true bypass.

For my wha I found a good working but not very cheap solution: the G-Lab True Bypass Wha Pad.
Cool toy and made the hum go away. Since then I prefer nothing exept my wha with this pad in front of my amp ;-)
 
you can get hum, when you connect two active devices.

so if you have your guitar, an a/b-box (passive), an fx-unit and an amp that you connect, then the problem is most likely not the passive switcher but the active fx-unit, connected to the a/b-box which is connected to the amp --> ground loop

you can most likely break that loop by adding a hum eliminator somewhere in between (e.g. between a/b-box and amp). examples are ebtech hum eliminator oder lehle p-split
 
I think I solved the problem: humming noise is now the same as when I directly plug my guitar
cable into the amplifier (Einstein): there must have been some bad cables/contacts on my pedal board.

I must say that by having these problems and after fixing them
I notice that the humming noise of my Einstein is rather high for channel 2 and channel1/mode3(even when my guitar (with humbucker pickups goes directly in the amp)) : is there something I can do to reduce this humming noise? I use a Planet Waves guitar cable.

Kind regards,

Jan
 
There is a simple way to check if the hum is from the amp or from the guitar. Turn off the volume of the guitar: the hum that you hear is the amp's self noise, and probably some interference in your cable. You should check with shorter and loger cables to see how much noise the cable ads.
Then, with the guitar volume open, you will hear the hum of the pickups. I also use humbuckers and still get hum, and I also felt that with the Einstein it was more noticeable than with my previous setup, even if the amp is dead quiet with the guitar volume closed :confused:
 
That is what I also notice: Einstein has a lot of hum.

thanks for letting me know such that I do not have to search for ghosts that are not there.
I have read in de Einstein manual that if there is a lot of hum this can be caused by the pre-amp tubes, especially
the first one (at least this is my interpretation of what the manual says) ... I will check this
 
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