Hum and noise problems

[andefeldt]

Ok, I'd better get a new one then.
I've been looking for a replacement, but can't seem to find one in Europe.

How much do you charge for a new power supply?

[JohnClark]

Please feel free to give us a call or write to info@voodoolab.com for current pricing and availability. You can also contact any of our distributors in Europe for getting a replacement somewhat locally.

http://www.voodoolab.com/intern_dealers.htm

I hope that helps!

[andefeldt]

Thanks!

I've send an e-mail to the Danish distributor. Hope they can help me out. I'll update when I'm further in the process.

[andefeldt]

Ok, got a new power supply and the hum is much lower than before - it's still present however. When using a drive pedal it's amplified quite a bit (but still less than with the old power supply). I suspect it to be a issue with ground. When the power supply is in my rack the hum isn't increased (except if I'm placing it on top of a rack drawer made of metal - then it hums like a mad man!).

However, I have no idea how to fix this as the power supply for the GCX is without the 3rd ground pin as are all the other power supplies and cables (standard on all music equipment here in Denmark). So what to do?

I'm currently in between amps, so I'm playing through my soundcard for my computer (Lexicon Alpha). My computer is connected to another wall outlet (but it's the same power group in my fuse box /same curcuit), so this shouldn't be the issue (or could it be?).

Any ideas?

[JohnClark]

These type of power supplies rarely have an Earth Ground connection at the Mains AC side. This is not likely to be the problem here. Power supplies that do have the Earth Ground connection at the Mains AC side don't usually carry this connection through to the device being powered anyway.

To eliminate the possibility of a difference between the outlets used, it would be worth a test to power these from the same outlet panel. Also, if for some reason you are still using a CRT monitor... turn it off!

Also, can you check that this GCX has its Chassis Ground still connected? To do this you will need to remove the four small Phillips head screws on the sides of the GCX (two on each side) to remove the top panel. The Chassis Ground wire should be directly behind the front panel jacks. It should be a wire from the circuit board to a ground lug that is mounted with a screw that holds the PRE/PWR circuit board in place.

[andefeldt]

No CRT moniters around And using the same power outlet didn't do anything.

I've opened the GCX and it looks fine:



My connections are not made in the front. My guitar (and my floor board) is connected through guitar output in the back and loop 1 is connected via feedthrough - (I have the Digital Music Corp version of the GCX, which is labelled Feed Through 1 (from guitar) and 2 (to loop 1). I've tried connecting through the front inputs (1 and 2), but that didn't help.

I've minimized the hum to only the BOYC Large Beaver (ver. 1) pretty much (there's always a bit present in the signal). I switched the tube in the Tube Driver and it stopped being so noisy. There's still noise, but that's the normal noise. I've tried using the Large Beaver alone (just guitar to beaver to sound card) and that almost didn't make any noise! I'm suspecting the BYOC pedal has a faulty part somewhere and when using it together with a lot of effects (and buffers) it's acting up. I've tried other power cables and separate power supply for it without any luck. I've tried replacing the large beaver with another BYOC pedal (Ultimate Fuzz) and that behaved exactly the same way (also when running on battery)! Tried replacing it with a tremolo pedal (Boss) and no more hum (except the always present low level hum). I have no idea where to look though inside the BYOC pedal! I'm very close to ordering another muff clone (Vick Audio 73 Ram's Head) but I'd lick to figure out whether it'll help or not.

I've tried moving the BYOC pedal to other loops, used other cables etc, but it's acting the same no matter what.

The GCX is still sending an audiable "pop" sound when switching on a "new" loop.

So any more ideas?

[andefeldt]

Ok, I decided to give my patch cables a checkup with the multimeter (used the same cables for my old setup without problems). Apparently some of them had quite a bit resistans! So I made small jumpers for the GCX with some old George L's I had laying around and replaced the bad patch cables with cables not failing my test. Now I have very little hum and only when using the BYOC Large Beaver (still thinking about buying a replacement). So as far as noise, everything is fine now.

Now my only problem is the "pop" sound when activating a loop. That still haven't been sorted out... Ideas?

[JohnClark]

Right on! Glad you found the main troublemaker.

You have a quite old GCX. I'd guess it to be from the mid '90s. I'm not too sure how you are using the Feedthrus here. They should only allow signal to pass from the front of the GCX to the rear.

For the pop, I'd try running thru a buffer after the last GCX Loop. If this unit isn't modified, you would take the Out of the last loop in the signal path and connect it to a Feedthru on the front panel. Then you will connect the rear panel Feedthru to the input of your amp (or sound card).

I hope that helps!

[andefeldt]

Ok thanks.

The unit is from 1994 (printed on the PCB and on one of the components), so it's almost as old as they can be.

The two back "output" Jacks (feed through and guitar out) are apparently connected in my unit, just as the new ones. So that's great.

I'll give it a go with the buffer, which I think will help. My current loop 8 is the Boss CE-5 pedal which has a buffer. With that loop active, I hear no popping noises. I'll try the GCX buffer or maybe just try adding an unused boss pedal at first.

I'll update when I've tested it.

[andefeldt]

That didn't help

I tried removing all cables from the loops and just leave a clean signal running through the GCX. The popping still occours when activating a loop! That can't be good? What can it be? Relay failure?