PRS Archon FX Loop Noise Solutions

[METAL123]

Hey everyone. So after spending quite a long time trying to find solutions for the noisy Archon loop, I thought I'd made this thread for anyone else experiencing the same issue. I've done a lot of research online, been in contact with PRS several times, and have been to an authorized PRS dealer, and an amp tech.. I'll go in order from the most obvious solutions to the less obvious ones.

1) Power supply, cables, and pedals
Before you blame the FX loop for noise, make sure that it's actually the problem and not your pedalboard. Try just one pedal at a time running on a 9 volt battery. Also try using different cables. Poor shielded and poor quality cables can cause noise. Generally speaking, it's a good idea to get higher quality cables and an isolated power supply.

2) Cable placement
Where you place your FX loop cables and where they come into contact with other cables and parts of the amp can introduce unwanted noise. Make sure that your FX loop patch cables aren't touching any power cables or speaker cables. In fact, try to have them as far away from these cables as practically possible. Also, make sure your FX loop cables are away from the left side of your amp (the side closest to the power on/off switch). Tying you FX loop cables together can help cancel out noise.

3) FX Loop Mod
In late 2014 models, PRS began modding the loop to prevent noise. Models of the Archon built prior to this will not have the mod done. You can often tell which year that your amp was built by the first 2 numbers in the serial number (located on the back of the amp). It's best to email PRS customer service with your serial number and they can tell you if the mod has been done or not. They can also provide you a PDF of the loop mod which you can take to a local tech to see if it needs to be done or not. If your amp doesn't have the mod, getting it done should help.

4) Tube Driver
The stock tube in the Archon that drives the FX loop has 100% gain. I had that tube replaced with a Mullard 12au7 Blackburn (which is around 20% gain), and noticed a significant drop in noise. It may be worth taking your amp to a tech to try out different tubes that drive the loop.

5) Volume Pedal
I've heard others say that the Archon's FX loop is before the pre-master volume and that the noise of your effects are amplified at 100%. To combat this, I've heard of people cranking the master volume and putting a volume pedal at the end of the loop to act as the master volume. I can't speak for the efficacy of this or if it's a good idea or not, as I've never tried it. But thought I'd mention it nonetheless.


I hope that this helps anyone experiencing this issue. The solution for me personally was the cable placement and tube driver swap. Now, on the lead channel, the loop for me is quite quiet. The clean channel still does have a bit of noise, but way quieter than before. I'm happy with it nonetheless. It's worth noting that FX loops will introduce some noise to a degree. The problem with the Archon's loop is more of an issue at lower volumes. When cranked, the natural tube noise will hide any loop coming from the loop often times.

 

[Black Plaid]

#5 -> That's my solution so far.

About the FX driver tube, is it only on in the FX loop?

 

[METAL123]

#5 -> That's my solution so far.

About the FX driver tube, is it only on in the FX loop?

Yes, there is a single tube that only drives the FX loop. Doesn’t affect the sound of the amp, only what goes through the loop.

 

[andy474x]

Just to add one to that list, I’ve had that problem with a couple other PRS amps as well (MT15, Custom 50) and the Ebtech 2 channel hum eliminator works very well. The problems I’ve had seem like some kind of grounding (or ground loop) issue, and the Ebtech unit really cut that down, and I don’t feel it effecting the tone.

I’m referring to the HE-2, which has 1/4” jacks, not the popular “Hum X” wall wart, if anyone goes looking.

 

[CarlGuitarist]

Thanks for this. I’ve been battling that loop for a while, especially regarding the cable orientation affecting hum. I guess the best thing is just to use straight jacks and make sure the cable is laid away from the input transformer.

 

[ReturnToCoda]

I have a new Archon (built 2019) so I am sure it is built post fx loop update, that being said the noise from the fx loop is still an issue. 100% this is a design flaw, even though I have seen people on this forum suggest otherwise. I have tried all the suggestions above and while they mitigate some of the issue they never completely get rid of it. I have a nice collection of amps and a professional set up with power isolation, regulation and conditioning and this is the only one that gives me an issue so I know it is the fault of the amp (also tried more than one Archon as I returned one initially thinking the first amp was faulty) . Furthermore, I found the one and only consumer solution without modifying the amp, but many might not like the answer. The answer is running this through the Boss Waza Tube Amp expander, which allows you to run the effects after the power section of the expander and bypass the fx loop of the Archon completely. I had an expander in my collection so this was not an extra purchase but I can confirm that when you run it this way you get all the great sounds of the Archon without the noise and it sounds fantastic. I don't like the idea of dedicating my tube amp expander to the Archon but I love the amp too much to let it go. I really wanted the beautiful clean channel noise free and I am glad I finally solved it. Unfortunately it's an expensive fix if you don't own an expander already.

 

[GuitarJammin]

I have a new Archon (built 2019) so I am sure it is built post fx loop update, that being said the noise from the fx loop is still an issue. 100% this is a design flaw, even though I have seen people on this forum suggest otherwise. I have tried all the suggestions above and while they mitigate some of the issue they never completely get rid of it. I have a nice collection of amps and a professional set up with power isolation, regulation and conditioning and this is the only one that gives me an issue so I know it is the fault of the amp (also tried more than one Archon as I returned one initially thinking the first amp was faulty) . Furthermore, I found the one and only consumer solution without modifying the amp, but many might not like the answer. The answer is running this through the Boss Waza Tube Amp expander, which allows you to run the effects after the power section of the expander and bypass the fx loop of the Archon completely. I had an expander in my collection so this was not an extra purchase but I can confirm that when you run it this way you get all the great sounds of the Archon without the noise and it sounds fantastic. I don't like the idea of dedicating my tube amp expander to the Archon but I love the amp too much to let it go. I really wanted the beautiful clean channel noise free and I am glad I finally solved it. Unfortunately it's an expensive fix if you don't own an expander already.

That's a pretty awesome find! Good to know. I own an archon 25 and avoid the effects loop because it would seem to dilute the great tone when using the hi gain channel for metal.

 

[ReturnToCoda]

That's a pretty awesome find! Good to know. I own an archon 25 and avoid the effects loop because it would seem to dilute the great tone when using the hi gain channel for metal.

Agreed, as I pointed out in my post I exchanged the first amp (100 watt head) I received because I actually thought it was faulty. The second amp came and had the same issues so I took to google and saw I was not alone. Aside from the noise issues I noticed that dip in tone as well. It's a real shame because it is a fantastic amp otherwise.

 

[Toolmaster Of Brainerd]

I'm planning on picking up a lower gain tube for the effects loop. Any recommendations? Will different brands of tubes in the effects loop slot make the amp sound different? If not, then is it only gain factor that matters? Is there any reason to not put a 20% gain factor 12AU7 in there? Are there tubes with lower gain factors?

 

[Deleted member 5962]

I'm planning on picking up a lower gain tube for the effects loop. Any recommendations? Will different brands of tubes in the effects loop slot make the amp sound different? If not, then is it only gain factor that matters? Is there any reason to not put a 20% gain factor 12AU7 in there? Are there tubes with lower gain factors?

What would be the objective for putting a low gain tube in the loop spot?

 

[Toolmaster Of Brainerd]

What would be the objective for putting a low gain tube in the loop spot?

To try to reduce hiss from the effects loop

 

[Deleted member 5962]

To try to reduce hiss from the effects loop

That's not the way to fix it though, and affects the whole gain structure of the amp.

 

[Toolmaster Of Brainerd]

That's not the way to fix it though, and affects the whole gain structure of the amp.

I've seen a few people saying that a lower gain tube in the effects loop slot will reduce the noise, but otherwise doesn't alter the tone. Is this not true? The 4th item in the OP's list above suggests a tube swap to reduce noise.

My knowledge of tubes is nonexistent lol. I appreciate the help.

 

[Deleted member 5962]

I've seen a few people saying that a lower gain tube in the effects loop slot will reduce the noise, but otherwise doesn't alter the tone. Is this not true? The 4th item in the OP's list above suggests a tube swap to reduce noise.

My knowledge of tubes is nonexistent lol. I appreciate the help.

I would not use a lower gain tube, I'd use a lower NOISE tube. One that was rated to be lower noise. That said, this has been discussed a lot here, and the general feeling is, only some pedals cause this issue. I kept saying I didn't have it at all, but then I put an MXR 10 band in the loop and it was noisy. Thing is, that same pedal added noise in the loop of.... PRS Custom 50, Bogner ATMA, Mesa Mark V, Mesa Mark V25, Mesa TA15, Budda SD18.... so in my setup, it's THAT pedal, or it's 18v power supply being plugged into my pedal board supply, that is causing the noise. Interesting thing about the noise with that pedal is, if I flip the way it's plugged in, it gets 3 times as noisy. One way is WAY better than the other, but still noisy. But I've had TC delays, TC verbs, TC flanger, and several other pedals in the loop and didn't have any noise issues. Only the MXR 10band. Sucks, because you could do some cool things with the EQ, but I don't have to have it so it's out of the loop. Noise gone.

 

[3rdstone]

I would not use a lower gain tube, I'd use a lower NOISE tube. One that was rated to be lower noise. That said, this has been discussed a lot here, and the general feeling is, only some pedals cause this issue. I kept saying I didn't have it at all, but then I put an MXR 10 band in the loop and it was noisy. Thing is, that same pedal added noise in the loop of.... PRS Custom 50, Bogner ATMA, Mesa Mark V, Mesa Mark V25, Mesa TA15, Budda SD18.... so in my setup, it's THAT pedal, or it's 18v power supply being plugged into my pedal board supply, that is causing the noise. Interesting thing about the noise with that pedal is, if I flip the way it's plugged in, it gets 3 times as noisy. One way is WAY better than the other, but still noisy. But I've had TC delays, TC verbs, TC flanger, and several other pedals in the loop and didn't have any noise issues. Only the MXR 10band. Sucks, because you could do some cool things with the EQ, but I don't have to have it so it's out of the loop. Noise gone.

I have a MXR 10 band on 2 different pedal boards. Neither one is noisy in the effects loop of a Custom 50 or Carol Ann Triptik. You must have gotten a bad one.

 

[Goran Lorencin]

I would not use a lower gain tube, I'd use a lower NOISE tube. One that was rated to be lower noise. That said, this has been discussed a lot here, and the general feeling is, only some pedals cause this issue. I kept saying I didn't have it at all, but then I put an MXR 10 band in the loop and it was noisy. Thing is, that same pedal added noise in the loop of.... PRS Custom 50, Bogner ATMA, Mesa Mark V, Mesa Mark V25, Mesa TA15, Budda SD18.... so in my setup, it's THAT pedal, or it's 18v power supply being plugged into my pedal board supply, that is causing the noise. Interesting thing about the noise with that pedal is, if I flip the way it's plugged in, it gets 3 times as noisy. One way is WAY better than the other, but still noisy. But I've had TC delays, TC verbs, TC flanger, and several other pedals in the loop and didn't have any noise issues. Only the MXR 10band. Sucks, because you could do some cool things with the EQ, but I don't have to have it so it's out of the loop. Noise gone.

So you are saying in your case it is the pedal and not the FX loop?

Cause I think I tried many configs and always came to the conclusion that whenever I connected a cable to FX loop, be it with only one pedal in thje chain or more, it was always putting out an enormous amount of noise - for shame! It must be a grounding issue which, by the look of it, is not present in all MT15s. I also got a loud pop when enabling some pedals, especially compressor and reverb ... but weirdly not on PlexiRanger OD or Sentry noise gate.

 

[Goran Lorencin]

Thanks for this. I’ve been battling that loop for a while, especially regarding the cable orientation affecting hum. I guess the best thing is just to use straight jacks and make sure the cable is laid away from the input transformer.

It didn`t make any difference in my case, noise was always there.

 

[Toolmaster Of Brainerd]

It didn`t make any difference in my case, noise was always there.

What year is your archon from? It sounds like you need to do the loop mod.

Once I did the loop mod on mine, everything got much better.

A couple pedals still make noise. If I set my tc flashback into looper mode, that adds a lot of noise. If my behringer eq is off it's silent but if I turn it on its extremely noisy. It's nowhere near as bad if I put it in front of the amp instead. I also tried putting my tc hall of fame and flashback into buffered bypass instead of true bypass and that was extremely noisy.

My theory is that the impedances of the pedals and the effects loop return need to match and that when I put the pedal in buffered mode it changes the impedance. No idea if this is how it actually works.

 

[Goran Lorencin]

What year is your archon from? It sounds like you need to do the loop mod.

Once I did the loop mod on mine, everything got much better.

A couple pedals still make noise. If I set my tc flashback into looper mode, that adds a lot of noise. If my behringer eq is off it's silent but if I turn it on its extremely noisy. It's nowhere near as bad if I put it in front of the amp instead. I also tried putting my tc hall of fame and flashback into buffered bypass instead of true bypass and that was extremely noisy.

My theory is that the impedances of the pedals and the effects loop return need to match and that when I put the pedal in buffered mode it changes the impedance. No idea if this is how it actually works.

I deviated a bit on the forum while searching for the solution for my MT15 ... do not own the Archon. Just thought that maybe there is a universal solution to the FX loop problem.

 

[Deleted member 5962]

So you are saying in your case it is the pedal and not the FX loop?

Cause I think I tried many configs and always came to the conclusion that whenever I connected a cable to FX loop, be it with only one pedal in thje chain or more, it was always putting out an enormous amount of noise - for shame! It must be a grounding issue which, by the look of it, is not present in all MT15s. I also got a loud pop when enabling some pedals, especially compressor and reverb ... but weirdly not on PlexiRanger OD or Sentry noise gate.

Yes, it was definitely the pedal, which SUCKS because a 10 band EQ in the loop of an Archon would make it do almost everything you could ever want.

That said, there is a reason some people avoid loops altogether. There is NO standard of impedance of pedals. If you hang out at TGP much in the amp forum, after a while, it seems like there is more than one complaint with the loop of almost every amp made, followed by many other people saying they never had an issue with it. It's because all these pedals vary wildly in impedances. Plus, chaining 3-4-22 of them together that all put out a different impedance can further cloud the issue.

Yes, sometimes a group will identify a particular pedal, or brand, that doesn't work with a particular amp loop. It can almost always be traced to the impedance. I read so much about this stuff a couple years ago, when I had 6-7 tube amps in the house and every single one had different things it "liked" or "didn't like" in the loop, that I resigned myself to treating each amp like it's own thing and putting only pedals that "worked" in the loop of that amp. But the 10 band EQ was noisy in all of them and again a huge disappointment because of the tone shaping it allowed. It was GREAT, but too noisy to live with.

All that said, my two relatively meager TC pedals (Flashback and Arena Verb) both have done great in every loop.