MT15 noise gate 4 cable method issues

[Goran Lorencin]

Anyone tried a Sentry or similar in the signal chain using 4 cable method?

I`ve used Sentry in the normal(two cable method) way and all is ok, but wanted to also tame the amp lead signal as it is quite noisy when cranked up. Thing is I am getting hum and lower signal strenght out when using 4 cable method. Any idea why?

I have a new isolated power supply with more than enough juice to run most of todays pedals, self made (and tested) Mogami cables and Mogami patch cables, new power leads and use a Furman power conditioner for the amp and the pedalboard power supply.

Is it possible to damage tubes if using the Sentry in a certain way?

 

[andy474x]

Anyone tried a Sentry or similar in the signal chain using 4 cable method?

I`ve used Sentry in the normal(two cable method) way and all is ok, but wanted to also tame the amp lead signal as it is quite noisy when cranked up. Thing is I am getting hum and lower signal strenght out when using 4 cable method. Any idea why?

I have a new isolated power supply with more than enough juice to run most of todays pedals, self made (and tested) Mogami cables and Mogami patch cables, new power leads and use a Furman power conditioner for the amp and the pedalboard power supply.

Is it possible to damage tubes if using the Sentry in a certain way?

Unfortunately many PRS amps (Customs, MT15’s, earlier Archons) have a grounding problem in the effects loops. I’ve had the same problem with my MT15 and Custom 50. Basically introduces just as much noise as it is removing when using the noise gate. My solution was to add an Ebtech Hum Eliminator (the smaller 2 channel version) and run your signal through one side of the Ebtech before going into the amp and through the other side in your effects loop. You may have to play with where exactly the unit is in your signal chain within that. Bummer to have to do, but the Ebtech unit is pretty affordable.

 

[Goran Lorencin]

Follow up, everything resolved ... well almost. I put the 4 cable method to the test again in two variants, It appears that the last time I made a mistake connecting patch cables or something, do not know exactly what happened. So it looks like my MT15 may not have the grounding problem.

1st was: guitar to input-Sentry to input-Danelectro EQ to input-Supermoon reverb to return-FX loop AND send-FX loop to return-Sentry AND send-Sentry to input Tone City Comp Engine to input PlexRanger to input-amp.

2nd had one difference, the reverb put behind distorsion instead of behind EQ.

And the 2nd variant was much better in regard to noise from the reverb (Mr.Black Supermoon), because it was much quieter than having the reverb in 1st variant (behind EQ or to say in the chain that goes to amp return FX loop), BUT in this configuration the Sentry started gating the reverb like it was "unwanted noise" and it was useless to have that configuration. Weird thing is that it was making hum even when I put the amp volume to 0, as soon as I enabled the reveb, the hum came back, so it must be a wiring thing from the reverb that introduces the hum regardless of the volume knob setting. I tried it with different audio cables and power cables and it does not change the introduction of hum.

So in the end the reverb went back to behind EQ (that goes to amp return-FX loop), as it works the correct way in regard to the Sentry, but to say again, not even noise gating gets rid of the hum, if the reverb is ON the hum is simply introduced in the signal chain until I put the amp to standby.

Any ideas why this is happening, how to remedy this issue, or an explanation for why exactly is hum almost non-existent if reverb is put behind distorsion (the chain from send-Sentry to input-amp)? I also changed some power supply cables and outputs, but all outputs have enough juice to power any of my pedals, 10 available outputs 250-500mV (Harley Benton ISO AC10-pro), all gear is relatively new.

Cheers

 

[Goran Lorencin]

Unfortunately many PRS amps (Customs, MT15’s, earlier Archons) have a grounding problem in the effects loops. I’ve had the same problem with my MT15 and Custom 50. Basically introduces just as much noise as it is removing when using the noise gate. My solution was to add an Ebtech Hum Eliminator (the smaller 2 channel version) and run your signal through one side of the Ebtech before going into the amp and through the other side in your effects loop. You may have to play with where exactly the unit is in your signal chain within that. Bummer to have to do, but the Ebtech unit is pretty affordable.

Andy, please accept my apologies ... yesterday I had some time to start looking for the hum/hiss culprit, and went systematically trough all the gear, and you were right, IT IS THE FX LOOP that is to be blamed for an enormous amount of noise. An amount that is TOTALLY NOT ACCEPTABLE and I was not aware of this until I started to use a noise gate with 4 cable method a few weeks ago.

I don˙t know why or how PRS has the balls to put out a unit with this kind of fault - I am very disappointed. I could hardy believe what I was hearing, and having issues with pedals for which I thought everything else was the reason for not functioning properly, just not the amp. For me this is a warranty return case, I am blown away that all of us just accepted the HUGE fault and just went on using it as if all is ok, and even buying stuff to get over the HUGE flop PRS made in designing this unit ... this is very disappointing as this is a very simple amp that should not have this kind of flaws. Would have rather seen the MT15 without FX loop, than having a faulty one that I can not use, totally absurd.

So now everything must go in from the front input and there is no way to use 4CM to kill the lead channel noise or for connecting anything to the FX loop for that matter ... man am I disappointed.

Has anyone tried to fix this internally and permanently? Does anyone know what is to blame on the board? This really shines another light on the situation.

 

[andy474x]

Andy, please accept my apologies ... yesterday I had some time to start looking for the hum/hiss culprit, and went systematically trough all the gear, and you were right, IT IS THE FX LOOP that is to be blamed for an enormous amount of noise. An amount that is TOTALLY NOT ACCEPTABLE and I was not aware of this until I started to use a noise gate with 4 cable method a few weeks ago.

I don˙t know why or how PRS has the balls to put out a unit with this kind of fault - I am very disappointed. I could hardy believe what I was hearing, and having issues with pedals for which I thought everything else was the reason for not functioning properly, just not the amp. For me this is a warranty return case, I am blown away that all of us just accepted the HUGE fault and just went on using it as if all is ok, and even buying stuff to get over the HUGE flop PRS made in designing this unit ... this is very disappointing as this is a very simple amp that should not have this kind of flaws. Would have rather seen the MT15 without FX loop, than having a faulty one that I can not use, totally absurd.

So now everything must go in from the front input and there is no way to use 4CM to kill the lead channel noise or for connecting anything to the FX loop for that matter ... man am I disappointed.

Has anyone tried to fix this internally and permanently? Does anyone know what is to blame on the board? This really shines another light on the situation.

I know they had a fix for the archon, and it was fairly easy to have done, just disconnecting a couple of components and maybe changing one or two others, can’t remember what exactly but it was easy enough. Whether they have a mod for the MT15 loop or not, I haven’t heard.

I agree that it’s very unfortunate. Although it shouldn’t have happened, I like the amp enough to accept it, and use the Ebtech unit to fix the issue, since it’s fairly cheap ($80).

If you choose to talk to PRS about it and get a schematic for a fix, please let me know!

 

[Goran Lorencin]

I know they had a fix for the archon, and it was fairly easy to have done, just disconnecting a couple of components and maybe changing one or two others, can’t remember what exactly but it was easy enough. Whether they have a mod for the MT15 loop or not, I haven’t heard.

I agree that it’s very unfortunate. Although it shouldn’t have happened, I like the amp enough to accept it, and use the Ebtech unit to fix the issue, since it’s fairly cheap ($80).

If you choose to talk to PRS about it and get a schematic for a fix, please let me know!

I did already write to them and I`m now waiting for an answer. Will let you know if I get any useful info.