Custom 20/50 effects loop noise reduction strategies

Beach Radio

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Jul 4, 2015
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Soliciting the group for ideas!
I got my repaired Custom 20 back from PRS Tech a few months ago and they fixed the distortion roar I was getting from my effects loop - it was great to have the amp back.
But I still am getting more noise in the effects loop than I want - and maybe that's just the way it is with this tube driven effects loop.
But I was able to reduce the noise a bit by doing the following:
1. Running the amp and pedal board power through a Furman AC215A
2. Using an isolated power supply for the pedals (yeah, I know... should have done that way before...)
3. Tweaking the Send/Return jacks
4. Better cables

I haven't tried tube subsitutions or a noise gate in the loop - the loop is equally noisy just with a patch cable alone compared to the whole pedal board.
Anyone have any thoughts?
The pedal board in front of the amp sounds dead quiet but I really want my Tremolo and Delay after the pre-amp gain.
Thanks!
 
Interesting.
I have the H as well as a Custom 50 combo. When I first got the Custom 50 (used) it was noisy. Then I remembered the effects loop dials. Popped them both up to about 2 o'clock or so and BAM, gone! I wish I knew something more to tell you but now it's as squeaky clean the H always was.
Makes me wonder if you have a tube issue.
Have you spoken to PTC about it?
 
Yeah - 2:00 on the send seems to be the sweet spot... I do wonder about the tube, I replaced it once with another JJ with no change. Does someone other than JJ make a 12DW7? Also, I wonder if there is too much RF in my area that that tube can't help but pick up...
Thanks for your feedback
 
The loop in my Custom 50 has some noise when I run pedals in the loop. When I put a patch cable in the loop I don't notice any added noise. I recently isolated my pedals, instead of using a daisy chain, and that helped.

I run my loop send and return at 100%, it affects the breakup of the amp and I just like it most at that spot. The good news is that the noise from the loop doesn't amplify as the MV is turned up. A noise clamp in the loop doesn't cut any hiss, though.
 
Yeah, the hum/noise doesn't increase with a volume increase. The noise level/hum is pretty much identical at 1 as it is on 10.
 
wasn't there a post here about reversing the tank making the verb quieter?
 
My Custom 20 Reverb has no noise issues... are you saying flipping the tank will reduce noise in the loop?
 
Update
When I put a loop in my send cable right near the input jack like this:
IMG_0633.jpg

The noise in my effects loop is practically eliminated.
I don't understand why - it really bizarre...but it's been an awesome discovery...
 
Hi guys,

I have also become the owner of the Custom 50 recently. Bought it second hand, in great condition, from a very well known guitar store in UK. The amp was shipped to me in Germany.

First to say - I really love the sound of the amp, couldn't be happier with it. The other reasons why I like the amp and why I purchased it is because of all the nice features and primarily because it is a real 2 channel amp, with separate EQs and what not.

I wanted and amp that can help me reduce the number of distortion pedals and use the amp distortion primarily. This is really the first amp I've come across that have both channels great sounding.

BUT - unfortunately I have been so frustrated with the noise of the amp, which actually comes when using the effects loop. It's not unplayable but really frustrating. I guess it is the same problem that you are all facing.

Now I'm very much thorn apart what to do - I still have the right to return the amp or to keep it (since I love the sound) but it's just not fully usable and enjoyable with this hum/hiss that is producing.

I've read that lot of people are complaining about this and that PRS hasn't recognize this as a problem. I myself, cannot do anything, since I've bought it second hand and don't have the right to complain to PRS.

Nevertheless this problems is reported by everyone. There is small thread on one German forum (musiker-board) that mentions this exactly and the guy said that he had to repair the amp on his own (he sent it to a certain amp repair shop, they fixed it and said it was a design flaw) after sending it to PRS and not getting any results. This is just something that I've read there and I'm sharing it here.

The last response was from a guy that had the same issue and he said that he managed to fix the hum by inverting the phase on either send or return jacks, by using the Lehle P-Split (since it has the button to invert the phase or lift the ground).

Update
When I put a loop in my send cable right near the input jack like this:
The noise in my effects loop is practically eliminated.
I don't understand why - it really bizarre...but it's been an awesome discovery...

I have also noticed, depending of how the send/return cables are positioned on the back that the noise level varies. I notice that when the cables are crossing each other that the noise is reduced instead of when the are separated, if you know what I mean.

Could this have to do something with the phase?
 
Hi guys,

I have also become the owner of the Custom 50 recently. Bought it second hand, in great condition, from a very well known guitar store in UK. The amp was shipped to me in Germany.

First to say - I really love the sound of the amp, couldn't be happier with it. The other reasons why I like the amp and why I purchased it is because of all the nice features and primarily because it is a real 2 channel amp, with separate EQs and what not.

I wanted and amp that can help me reduce the number of distortion pedals and use the amp distortion primarily. This is really the first amp I've come across that have both channels great sounding.

BUT - unfortunately I have been so frustrated with the noise of the amp, which actually comes when using the effects loop. It's not unplayable but really frustrating. I guess it is the same problem that you are all facing.

Now I'm very much thorn apart what to do - I still have the right to return the amp or to keep it (since I love the sound) but it's just not fully usable and enjoyable with this hum/hiss that is producing.

I've read that lot of people are complaining about this and that PRS hasn't recognize this as a problem. I myself, cannot do anything, since I've bought it second hand and don't have the right to complain to PRS.

Nevertheless this problems is reported by everyone. There is small thread on one German forum (musiker-board) that mentions this exactly and the guy said that he had to repair the amp on his own (he sent it to a certain amp repair shop, they fixed it and said it was a design flaw) after sending it to PRS and not getting any results. This is just something that I've read there and I'm sharing it here.

The last response was from a guy that had the same issue and he said that he managed to fix the hum by inverting the phase on either send or return jacks, by using the Lehle P-Split (since it has the button to invert the phase or lift the ground).



I have also noticed, depending of how the send/return cables are positioned on the back that the noise level varies. I notice that when the cables are crossing each other that the noise is reduced instead of when the are separated, if you know what I mean.

Could this have to do something with the phase?

I think when cables cross each other frequently that creates shielding from radio frequency interference (RFI) - see https://en.m.wikipedia.org/wiki/Twisted_pair
Phase inversion is more complicated and involved (I think) - hopefully someone more knowledgeable will comment.
 
Update
When I put a loop in my send cable right near the input jack like this:
IMG_0633.jpg

The noise in my effects loop is practically eliminated.
I don't understand why - it really bizarre...but it's been an awesome discovery...

DUDE! SERIOUSLY??? I am going to do that tomorrow morning with my Custom 50 and see what happens.
 
I sent it back, I could not stand it having this issue and I didn't want to spend additional money and time to repair it. I'm disappointed in the PRS quality here.
 
I was getting noise in the effects loop in the Custom 20 that I bought at the experience last year. I wondered if it was in my pedalboard, so I took a single 3 foot cable and ran it from the send to the return. (No pedalboard involved.) It created noise. When I unplugged it, the noise was gone. I called PRS, and the rep said it's the proximity of the cable to the H transformer. He had me plug the cable in again and hold at an angle away from the transformer, and the noise reduced. But my wife refused to stand behind the amp and hold the cable for the entire worship set (of course!). So I've just been using it as a single channel amp and plugging the whole pedalboard straight into the clean channel, using my OCD pedal for dirt. It sounds fantastic. I mean, really fantastic. But I still feel like I've only got half the amp I paid for. There are some real quiet moments during the worship in which I would hate to risk the noise getting picked up by the mic in front of the amp, if I plugged in the loop. I really wish they could come up with a solid fix. I love the sound of this amp so much, I don't want to change it for another. But I can't help wonder what it would be like if I could have my lead channel for dirt, with the effects running through the loop.
 
I have a custom 50 and a 100, both have same noisy loop, so does my blistertone, and archon....I think they need to go back to the drawing board on the loops, my boogies are quiet, not these amps...
 
I've used the loop on my Custom 50 many times without excess noise being a problem. Don't get me wrong, there is a little bit of noise, but it's minimal. But, like I said above, I run the loop send and returns at 100%. Have you guys tried that? I would recommend trying it and seeing if the amp behaves to your satisfaction. With nothing in the loop the send/return knobs have no effect on my amp, with the loop in use it sounds the same way at 100%.

Just to see what you guys are dealing with, tonight I played with the loop levels with just one cable hooked directly to the send and return. With the return side set below 2:00 I do get a hum more like a 60 cycle/single coil hum, but not the way I normally set it. Normally it's more of a low pitch purr, discernible but quiet enough that it wouldn't be a problem in a live situation. It does help to use straight jacks that will point the cable further from the back of the amp.
 
I've used the loop on my Custom 50 many times without excess noise being a problem. Don't get me wrong, there is a little bit of noise, but it's minimal. But, like I said above, I run the loop send and returns at 100%. Have you guys tried that? I would recommend trying it and seeing if the amp behaves to your satisfaction. With nothing in the loop the send/return knobs have no effect on my amp, with the loop in use it sounds the same way at 100%.

Just to see what you guys are dealing with, tonight I played with the loop levels with just one cable hooked directly to the send and return. With the return side set below 2:00 I do get a hum more like a 60 cycle/single coil hum, but not the way I normally set it. Normally it's more of a low pitch purr, discernible but quiet enough that it wouldn't be a problem in a live situation. It does help to use straight jacks that will point the cable further from the back of the amp.
Yes - I now run my my loop levels at 100% and that simply seems like the quietest and most dynamic level with limited noise. But again, unless I put a loop in my send cable near the jack I have to deal with excess noise. Cable positioning seems to be the critical issue.
 
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