GCX And Amp Hum Issue

[ttosh]

When I plug directly into my amp it is pretty dead silent on high gain settings, at least very quiet for a high gain amp.

When I plug into the front of the GCX and come out of the GCX into my amp using the GCX buffer I get a hum noise, like a 60cycle hum?

I tried a few different cables, all unbalanced. The GCX nor the amp has any kind of ground lift.

Would and ISP Decimator be a good candidate for a fix for this, since there are very few variables in the chain?

Any input is appreciated.

 

[steve_k]

When I plug directly into my amp it is pretty dead silent on high gain settings, at least very quiet for a high gain amp.

When I plug into the front of the GCX and come out of the GCX into my amp using the GCX buffer I get a hum noise, like a 60cycle hum?

I tried a few different cables, all unbalanced. The GCX nor the amp has any kind of ground lift.

Would and ISP Decimator be a good candidate for a fix for this, since there are very few variables in the chain?

Any input is appreciated.

1. Don't use the buffered input. Does that help? Buffers aren't all they are made out to be and unless you got 100' of lead, certainly not needed.

2. You must use the same power source for the amp and GXC and pedals. I know you got a Furman or something in the rack.

3. Ground the GCX to your rack and see if that helps.

I would use a Decimator just for the sake of using the GCX. Its one of those impedance mismatches that is hard to fix between instrument level and line level. If you aren't married to the GCX, try an RJM RG16 or Effects Gizmo. Ron has done the best job I think with production equipment and isolation. I always had the same crap with my GCX. I have also a Bradshaw 4x4 and this is dead quiet.

The RG16 does have a ground lift inside, as does the Bradshaw 4x4. If you pop the chassis on the GCX, it may have a dip switch inside for ground lift. Not sure...

Ebtech and ART make a $50 box that help out with ground issues.

Steve

 

[ttosh]

When I plug directly into my amp it is pretty dead silent on high gain settings, at least very quiet for a high gain amp.

When I plug into the front of the GCX and come out of the GCX into my amp using the GCX buffer I get a hum noise, like a 60cycle hum?

I tried a few different cables, all unbalanced. The GCX nor the amp has any kind of ground lift.

Would and ISP Decimator be a good candidate for a fix for this, since there are very few variables in the chain?

Any input is appreciated.

1. Don't use the buffered input. Does that help? Buffers aren't all they are made out to be and unless you got 100' of lead, certainly not needed.

2. You must use the same power source for the amp and GXC and pedals. I know you got a Furman or something in the rack.

3. Ground the GCX to your rack and see if that helps.

I would use a Decimator just for the sake of using the GCX. Its one of those impedance mismatches that is hard to fix between instrument level and line level. If you aren't married to the GCX, try an RJM RG16 or Effects Gizmo. Ron has done the best job I think with production equipment and isolation. I always had the same crap with my GCX. I have also a Bradshaw 4x4 and this is dead quiet.

The RG16 does have a ground lift inside, as does the Bradshaw 4x4. If you pop the chassis on the GCX, it may have a dip switch inside for ground lift. Not sure...

Ebtech and ART make a $50 box that help out with ground issues.

Steve

Great advice and I will give it all a try. I think I have to use the buffer since I want both outs on the back to be accessible to feed to a dual amp setup I have planned. I do not think the feed through and guitar out are both available unless the buffer is used. I guess a simple Y cable would be okay to use in this instance and bypass the buffer to see if that helps the noise issue.

The RG16 I know is a top notch unit and RJM makes some great stuff. I want to make what I already have work if possible and not have to purchase anything else unless I have exhausted all my possibilities. I will check on the dipswitch for the lift on the GCX on the inside, that was a great tip also...

Thanks!

 

[steve_k]

When I plug directly into my amp it is pretty dead silent on high gain settings, at least very quiet for a high gain amp.

When I plug into the front of the GCX and come out of the GCX into my amp using the GCX buffer I get a hum noise, like a 60cycle hum?

I tried a few different cables, all unbalanced. The GCX nor the amp has any kind of ground lift.

Would and ISP Decimator be a good candidate for a fix for this, since there are very few variables in the chain?

Any input is appreciated.

1. Don't use the buffered input. Does that help? Buffers aren't all they are made out to be and unless you got 100' of lead, certainly not needed.

2. You must use the same power source for the amp and GXC and pedals. I know you got a Furman or something in the rack.

3. Ground the GCX to your rack and see if that helps.

I would use a Decimator just for the sake of using the GCX. Its one of those impedance mismatches that is hard to fix between instrument level and line level. If you aren't married to the GCX, try an RJM RG16 or Effects Gizmo. Ron has done the best job I think with production equipment and isolation. I always had the same crap with my GCX. I have also a Bradshaw 4x4 and this is dead quiet.

The RG16 does have a ground lift inside, as does the Bradshaw 4x4. If you pop the chassis on the GCX, it may have a dip switch inside for ground lift. Not sure...

Ebtech and ART make a $50 box that help out with ground issues.

Steve

Great advice and I will give it all a try. I think I have to use the buffer since I want both outs on the back to be accessible to feed to a dual amp setup I have planned. I do not think the feed through and guitar out are both available unless the buffer is used. I guess a simple Y cable would be okay to use in this instance and bypass the buffer to see if that helps the noise issue.

The RG16 I know is a top notch unit and RJM makes some great stuff. I want to make what I already have work if possible and not have to purchase anything else unless I have exhausted all my possibilities. I will check on the dipswitch for the lift on the GCX on the inside, that was a great tip also...

Thanks!

Be aware....the GCX I think is not a piece of equipment that lends itself to multiple amp arrangements. Each head will need its own cab or load. All the 8 loops on a GCX are NC (normal close) and are serial. You cannot have an input at loop 1 and an output at loop 8 without jumping all the loops in between. You have to use a Y-cable for two amps and this just throws you right back into the Jimi Hendrix era dark ages to combine two amps. Or, the first amp is on all the time for the second amp to get signal. This is one reason I didn't care for it. Other than the grounding issues, wait until you try to live with the phase reversal of the amp/speakers. It will sound like shit. RJM has way outdone Voodoo on this one.

Steve

 

[ttosh]

When I plug directly into my amp it is pretty dead silent on high gain settings, at least very quiet for a high gain amp.

When I plug into the front of the GCX and come out of the GCX into my amp using the GCX buffer I get a hum noise, like a 60cycle hum?

I tried a few different cables, all unbalanced. The GCX nor the amp has any kind of ground lift.

Would and ISP Decimator be a good candidate for a fix for this, since there are very few variables in the chain?

Any input is appreciated.

1. Don't use the buffered input. Does that help? Buffers aren't all they are made out to be and unless you got 100' of lead, certainly not needed.

2. You must use the same power source for the amp and GXC and pedals. I know you got a Furman or something in the rack.

3. Ground the GCX to your rack and see if that helps.

I would use a Decimator just for the sake of using the GCX. Its one of those impedance mismatches that is hard to fix between instrument level and line level. If you aren't married to the GCX, try an RJM RG16 or Effects Gizmo. Ron has done the best job I think with production equipment and isolation. I always had the same crap with my GCX. I have also a Bradshaw 4x4 and this is dead quiet.

The RG16 does have a ground lift inside, as does the Bradshaw 4x4. If you pop the chassis on the GCX, it may have a dip switch inside for ground lift. Not sure...

Ebtech and ART make a $50 box that help out with ground issues.

Steve

Great advice and I will give it all a try. I think I have to use the buffer since I want both outs on the back to be accessible to feed to a dual amp setup I have planned. I do not think the feed through and guitar out are both available unless the buffer is used. I guess a simple Y cable would be okay to use in this instance and bypass the buffer to see if that helps the noise issue.

The RG16 I know is a top notch unit and RJM makes some great stuff. I want to make what I already have work if possible and not have to purchase anything else unless I have exhausted all my possibilities. I will check on the dipswitch for the lift on the GCX on the inside, that was a great tip also...

Thanks!

Be aware....the GCX I think is not a piece of equipment that lends itself to multiple amp arrangements. Each head will need its own cab or load. All the 8 loops on a GCX are NC (normal close) and are serial. You cannot have an input at loop 1 and an output at loop 8 without jumping all the loops in between. You have to use a Y-cable for two amps and this just throws you right back into the Jimi Hendrix era dark ages to combine two amps. Or, the first amp is on all the time for the second amp to get signal. This is one reason I didn't care for it. Other than the grounding issues, wait until you try to live with the phase reversal of the amp/speakers. It will sound like shit. RJM has way outdone Voodoo on this one.

Steve

good info, PM sent to discuss my signal further and to explain the configuration since you have been very helpful already.

 

[petejt]

But if you plug into the 'Guitar Input', doesn't the Feed Thru output tap off from it, before sending the signal through the buffer circuitry and Guitar Output socket? Otherwise how does it "feed through"?

 

[ibanez4life SZ!]

I too run a dual amp rig with a GCX...I had lot of noise issues, but eventually got them trouble shooted. The unit seems to be VERY prone to ground loops.

Basically, I plug the guitar into the input of loop 1, chain through the loops I need for pedals out front, run the out of the last loop to the 'guitar in' out front, which then splits my signal to both amps. Simple, and I have both amps on all the time.

I did need to get a Ebtech Hum X on the power chord of one of the amps to eliminate the ground loop completely though.

I'm considering an RJM...but for now, the GCX works the way I have it, and it sounds great

PM me if you'd like anymore help on wiring it up!

Eric

 

[zuel69]

I actually opened up my GCX and disconnected it's internal ground wire.

When I plug directly into my amp it is pretty dead silent on high gain settings, at least very quiet for a high gain amp.

When I plug into the front of the GCX and come out of the GCX into my amp using the GCX buffer I get a hum noise, like a 60cycle hum?

I tried a few different cables, all unbalanced. The GCX nor the amp has any kind of ground lift.

Would and ISP Decimator be a good candidate for a fix for this, since there are very few variables in the chain?

Any input is appreciated.

 

[ttosh]

I too run a dual amp rig with a GCX...I had lot of noise issues, but eventually got them trouble shooted. The unit seems to be VERY prone to ground loops.

Basically, I plug the guitar into the input of loop 1, chain through the loops I need for pedals out front, run the out of the last loop to the 'guitar in' out front, which then splits my signal to both amps. Simple, and I have both amps on all the time.

I did need to get a Ebtech Hum X on the power chord of one of the amps to eliminate the ground loop completely though.

I'm considering an RJM...but for now, the GCX works the way I have it, and it sounds great

PM me if you'd like anymore help on wiring it up!

Eric

I am going to try a few things today, I will add this approach to them and see where I land. Thanks for the feedback sounds very helpful!!

 

[ttosh]

I actually opened up my GCX and disconnected it's internal ground wire.

When I plug directly into my amp it is pretty dead silent on high gain settings, at least very quiet for a high gain amp.

When I plug into the front of the GCX and come out of the GCX into my amp using the GCX buffer I get a hum noise, like a 60cycle hum?

I tried a few different cables, all unbalanced. The GCX nor the amp has any kind of ground lift.

Would and ISP Decimator be a good candidate for a fix for this, since there are very few variables in the chain?

Any input is appreciated.

I may give this a try if all else fails as well.

 

[zuel69]

Yea, it's attached with a lug and nut so no cutting or anything. It solved my rack noise issues.

I actually opened up my GCX and disconnected it's internal ground wire.

When I plug directly into my amp it is pretty dead silent on high gain settings, at least very quiet for a high gain amp.

When I plug into the front of the GCX and come out of the GCX into my amp using the GCX buffer I get a hum noise, like a 60cycle hum?

I tried a few different cables, all unbalanced. The GCX nor the amp has any kind of ground lift.

Would and ISP Decimator be a good candidate for a fix for this, since there are very few variables in the chain?

Any input is appreciated.

I may give this a try if all else fails as well.

 

[boardwlk17]

When I plug directly into my amp it is pretty dead silent on high gain settings, at least very quiet for a high gain amp.

When I plug into the front of the GCX and come out of the GCX into my amp using the GCX buffer I get a hum noise, like a 60cycle hum?

I tried a few different cables, all unbalanced. The GCX nor the amp has any kind of ground lift.

Would and ISP Decimator be a good candidate for a fix for this, since there are very few variables in the chain?

Any input is appreciated.

i had the same issue got some isolation transformers from bob bradshaw also needed one from my wireless

 

[again with this]

hey... If I may jump in here, doesn't the GCX do A/B/Y like this:

I am asking, because I am planning on doing this eventually. It may change my path to goals if this hasnt' worked for you.

Thanks

 

[amiller]

hey... If I may jump in here, doesn't the GCX do A/B/Y like this:

I am asking, because I am planning on doing this eventually. It may change my path to goals if this hasnt' worked for you.

Thanks

I have a question about that diagram. Where it's labled "Audio in" ... that looks like some kind of "Y" connection. How is that accompolished?

 

[again with this]

hey... If I may jump in here, doesn't the GCX do A/B/Y like this:

I am asking, because I am planning on doing this eventually. It may change my path to goals if this hasnt' worked for you.

Thanks

I have a question about that diagram. Where it's labled "Audio in" ... that looks like some kind of "Y" connection. How is that accompolished?

like this:

Oh, and I just got mine plugged in and I am not getting hum coming from the GCX. Although now, I have to chase the hum through my Mesa rack... ugh... no fun.

 

[amiller]

hey... If I may jump in here, doesn't the GCX do A/B/Y like this:

I am asking, because I am planning on doing this eventually. It may change my path to goals if this hasnt' worked for you.

Thanks

I have a question about that diagram. Where it's labled "Audio in" ... that looks like some kind of "Y" connection. How is that accompolished?

like this:

Oh, and I just got mine plugged in and I am not getting hum coming from the GCX. Although now, I have to chase the hum through my Mesa rack... ugh... no fun.

Oh, I get the second diagram, however, it does not let you choose between switching from one amp to the other. You get both amps all the time.

 

[again with this]

hey... If I may jump in here, doesn't the GCX do A/B/Y like this:

I am asking, because I am planning on doing this eventually. It may change my path to goals if this hasnt' worked for you.

Thanks

I have a question about that diagram. Where it's labled "Audio in" ... that looks like some kind of "Y" connection. How is that accompolished?

like this:

Oh, and I just got mine plugged in and I am not getting hum coming from the GCX. Although now, I have to chase the hum through my Mesa rack... ugh... no fun.

Oh, I get the second diagram, however, it does not let you choose between switching from one amp to the other. You get both amps all the time.

Hey dude. Yes. "Example 2" is Y only. Feed Example 2 into "Combining Multiple Amps" for A/B/Y.

 

[amiller]

Hey dude. Yes. "Example 2" is Y only. Feed Example 2 into "Combining Multiple Amps" for A/B/Y.

OK, I think I get it. Is this correct?:

1) Guitar into "Feed Thru In 1"
2) "Feed Thru Out 1 and 2" goes into "Loop 1 In" and Loop 2 In"
3) Finally, "Loop 1 Send" and "Loop 2 Send" go to the amps.

 

[ttosh]

Hey dude. Yes. "Example 2" is Y only. Feed Example 2 into "Combining Multiple Amps" for A/B/Y.

OK, I think I get it. Is this correct?:

1) Guitar into "Feed Thru In 1"
2) "Feed Thru Out 1 and 2" goes into "Loop 1 In" and Loop 2 In"
3) Finally, "Loop 1 Send" and "Loop 2 Send" go to the amps.

yes and this is where my ground loop problem lies......

 

[again with this]

Hey dude. Yes. "Example 2" is Y only. Feed Example 2 into "Combining Multiple Amps" for A/B/Y.

OK, I think I get it. Is this correct?:

1) Guitar into "Feed Thru In 1"
2) "Feed Thru Out 1 and 2" goes into "Loop 1 In" and Loop 2 In"
3) Finally, "Loop 1 Send" and "Loop 2 Send" go to the amps.

yes and this is where my ground loop problem lies......

Bummer you don't have lift switches. I fixed my noise problem with couple switch flips. Did you try the lug thing?