Problems Using A "Stereo" Wireless Transmitter System - RG?

[Paul Marossy]

Trying to help someone with this problem. They have a Parker which has a "stereo" output and are trying to have a dual wireless system.

"I am having troubles with signal bleed between the peizo and humbuckers. Has anyone successfully gone wireless in stereo?

I am using 2 wireless transmitters & receivers using a stereo cable out to the transmiters-the cable is definately not the problem. As far as I can tell, the bleed is occurring within the guitar itself.

My theory is that since both lines share the same ground, signal bleed occurs. Everything works fine when I use my stero cable(eliminating the wireless system)."

I at first thought that a shared ground couldn't be the problem and then I thought about how stuff gets kinda weird in RF design, so I wasn't so sure after that. Later he wrote this:

"I spoke to some more people and the thought is that the shared ground is the problem. These wireless transmitters were not designed to share a ground. I am essentially grounding the 2 wireless units together by using one cable which seems to be raising a little havoc with frequencies in the Parker. "

So my question is can a shared input ground cause this problem, and what is the fix? Is it as simple as lifting one of the grounds on a TRS cable? I personally think it might be the guitar's electronics as some people have this problem and aren't using wireless systems. These same people claim that replacing the pickup selector switch made the problem go away. It could be a case of how the thing is wired & designed. I was thinking it might be some kind of "design flaw", if you will, where at audio frequencies it might have some crosstalk but it's at such a low level that you can't really hear it (as in you have it plugged straight into signal chain via hardwired cables). But at radio frequencies (wireless) it gets picked up, amplified and then reproduced at the other end. I'm really not sure what the deal is.  

Anyone want to take a stab on this one?!?!

[SISKO]

If the problem is the common ground, i think the problem maybe solved with inductors. Inductors have very low dc resistance (ground would still be ground for all DC and audio signals) but their impedance raise with freq so at the freq of the transceiver it would work as a very high resistance.
Its value would be freq depedant., so you need this data.

This would only work if the bleed is generated by the transsmitter and the bleedtrough is done at the IF or HF amplfier.

[Paul Marossy]

That's an idea. Wondering if poor shielding might be a contributor?

[R.G.]

There's electronics inside the guitar?

I wonder if it's picking up one of the wireless transmitters inside the guitar. Kind of DIY radio interference.

[Paul Marossy]

There's electronics inside the guitar?

I wonder if it's picking up one of the wireless transmitters inside the guitar. Kind of DIY radio interference.

Yes, there's electronics inside the guitar. There's conventional high impedance magnetic pickups and piezo saddles on the bridge. Everything goes through the Fishman "PowerChip" circuit. That could well be the problem!

[therecordingart]

Trying to help someone with this problem. They have a Parker which has a "stereo" output and are trying to have a dual wireless system.

"I am having troubles with signal bleed between the peizo and humbuckers. Has anyone successfully gone wireless in stereo?

I am using 2 wireless transmitters & receivers using a stereo cable out to the transmiters-the cable is definately not the problem. As far as I can tell, the bleed is occurring within the guitar itself.

My theory is that since both lines share the same ground, signal bleed occurs. Everything works fine when I use my stero cable(eliminating the wireless system)."

I at first thought that a shared ground couldn't be the problem and then I thought about how stuff gets kinda weird in RF design, so I wasn't so sure after that. Later he wrote this:

"I spoke to some more people and the thought is that the shared ground is the problem. These wireless transmitters were not designed to share a ground. I am essentially grounding the 2 wireless units together by using one cable which seems to be raising a little havoc with frequencies in the Parker. "

So my question is can a shared input ground cause this problem, and what is the fix? Is it as simple as lifting one of the grounds on a TRS cable? I personally think it might be the guitar's electronics as some people have this problem and aren't using wireless systems. These same people claim that replacing the pickup selector switch made the problem go away. It could be a case of how the thing is wired & designed. I was thinking it might be some kind of "design flaw", if you will, where at audio frequencies it might have some crosstalk but it's at such a low level that you can't really hear it (as in you have it plugged straight into signal chain via hardwired cables). But at radio frequencies (wireless) it gets picked up, amplified and then reproduced at the other end. I'm really not sure what the deal is.  

Anyone want to take a stab on this one?!?!

You could try using a stereo wireless in-ear monitoring system to see if the problem is present there. If so, the problem is in the guitar and if not it's in sharing a ground between two bodypack transmitters. I'll check with some of the Applications Engineers here to see what I can come up with.

[therecordingart]

http://forums.parkerguitars.com/topic.asp?TOPIC_ID=12694

[Paul Marossy]

http://forums.parkerguitars.com/topic.asp?TOPIC_ID=12694

That's a completely different problem than the one I am talking about here. I brought that up and it was not the problem in this case.

http://forums.parkerguitars.com/topic.asp?TOPIC_ID=13238