PX-8 Plus: FX Loop Problems

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StringSinger
Posts: 3
Joined: Tue Apr 30, 2019 11:32 am

PX-8 Plus: FX Loop Problems

Post by StringSinger » Sun Oct 27, 2019 5:56 pm

Hi,

I have a Dingbat with integrated PX-8 Plus powered by a Pedal Power Plus 2. I really want to use the second channel of my Mesa Filmore on the high setting for some parts and have some delay as well. So I want to do a four cable method with the PX-8+ using the insert loop between loops 6 & 7. However, I've gotten the following results trying it 2 different ways:

Scenario 1: Standard PX-8+ Setup
Loss of low-end frequencies and other tone changes when the FX Loop is used.

Scenario 2: PX-8+ with the internal jumper set to Bypass(vs. Quiet Switching)
Tone is fine but a very loud hum is present when the FX loop cables are plugged in.

Any ideas, input etc. on how to make this work would be great because everything would be great if I could make this work without it having an effect on the tone.

StringSinger
Posts: 3
Joined: Tue Apr 30, 2019 11:32 am

Re: PX-8 Plus: FX Loop Problems

Post by StringSinger » Mon Oct 28, 2019 6:31 pm

Forgot to mention. There is no hum when I just hook my DD-500(bypassing the PX-8+) into the FX Loop.

JohnClark
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Location: The Lab

Re: PX-8 Plus: FX Loop Problems

Post by JohnClark » Thu Oct 31, 2019 12:41 pm

So there was no hum when you had the jumpers set to Quiet Switching, just the tonal change? did the hum happen even with all loops bypassed?

Just to be sure we have things connected properly, here is a quick rundown of the necessary connections. All connections should be made directly with a single cable, bypassing any interface boxes or patch-bays for the purposes of testing.

1. Guitar to PX-8+ Input.
2. PX-8+ Insert Send to the Instrument Input on your amp.
3. Amp FX Send to PX-8+ Insert Return.
4. PX-8+ Output to your amp's FX Return.

With all loops bypassed, or even without any pedals connected would be the first test to try to narrow down the source of the hum.

Let us know how it goes!
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StringSinger
Posts: 3
Joined: Tue Apr 30, 2019 11:32 am

Re: PX-8 Plus: FX Loop Problems

Post by StringSinger » Thu Mar 05, 2020 9:02 am

Hi, so obviously I'm way late with my reply but I didn't want to start a new thread for the same problem. I got a bit side tracked but I'm back on it now. From what I can tell there is an antenna ground loop happening. I do have all the connections as you have described above and still no joy. I did get it to stop with an Ebtech Hum Eliminator isolation transformer but that really killed the tone, dropped the volume etc, maybe it's just that particular iso transformer but I weary to spend money on another one. I'd really love to make this work because I like all the gear involved I just need it to play nice together.

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