PRS MT15 few hours old, issues issues issues

[filip989]

Hi everyone,

So you've helped me with the cab, but I have a problem already, maybe someone can shed some light.

Anyway, I tried out the amp in the store before buying it. Worked ok so I asked for a oedal to connect to the fx loop. Worked fine. One detail that I realized afterwards, they gave me a boss dd-8, which is a buffer if I'm not mistaken.

I get home, power it up, works fine. A bit later I connect my pedalboard (nothing fancy, prophet delay and afterglow chorus in fx loop - both true bypass, polytune 3 and crybaby mini in front of the amp). Hissing noise from the prophet. Quiet "heaertbeat" thumps from the afterglow. Connecting them in reverse, one by one, dc brick, adapter, battery, same problem. In front of the amp works fine.
Wah in the fx loop, same problem.
Hissing and thump are both quiet and not a big issue on their own. But, switching the pedals on and off produces a loud pop. No matter how many times, no matter how long it's on.

So I realized that the dd8 is probably buffer. I put my polytune in the fx loop and yep, no pop. Or a very quit pop that is. So obviously true bypass are a bigger issue.

And on top of that, I turn master volume and clean volume down, guutar volume down, stanby on. The amp sounds like a dial up modem. Little cracks and beeps. This also happened a few times during playing, but I thought I might have just poped the strings at first.

I've sent an email with a video to the shop, wanring to make a claim. Their workshop is open during my own working hours and doesn't work on weekends.

I asked for a tech to be available on Saturday when I bring it in along with my pedalboard. Also asked rhey consider giving me a new one since I live 120 km away and really don't wanna leave it there, wait for it to maybe get fixed and then drive to pick it up again. 480 km for an amp that's faulty from day one... nope.

Anyway, I know the hissing and the fx loop are obviously still an issue. But what could the dial up sound be? It surely cannot be interference as everything around the amp was turned off and amp was dialed all the way down and on standby. This one really puzzles me and would like an idea what it might be.

I have slim hope the shop will be very keen on solving this as a faulty unit. It's just the way it is over here unfortunately so I'd love to understand more how this might happen so I might negotiate a bit better.

Thanks

 

[andy474x]

The “dial up” noises you’re hearing may be from your cell phone, or interference from another wireless device, I would be surprised if that kind of noise were coming from the amp. Cell phones can do exactly that from several feet away from an amp.

Regarding other noises from the effects loop, a couple possibilities. One is your pedals may just not like the signal from effects loop, some amps have line level loops and certain pedals aren’t made for that. Chorus pedals are especially prone to that (although any pedal can be) because chorus pedals sum together multiples of the input signal as part of their function to create the effect - they’re designed to do that with an instrument level signal, when a much “louder” line level signal is used, and then multiplied by the effect, it greatly exceeds what the pedal is designed to handle, throws off the ratio of signal level the unit expects to see along the way through the circuit. Another possibility, the the beating sound from your pedals could be due to the digital “clocks” in them talking back through the power supply, I’ve experienced this many times when daisy chaining power supplies on digital pedals. Digital pedals often need to be on isolated power to get rid of that, I see you’re using a DC Brick, I would recommend upgrading to the Iso Brick or another isolated supply.

I would try using a buffered pedal at the end of your effects loop chain, last pedal before going into the effects loop return - something about some of the PRS amps effects loops, the loop return is picky. It’s some kind of open-circuit or grounding issue that quite honestly is above my pay grade, but I suspect your true bypass pedals are creating that issue momentarily when you switch them on and off.

I’m sure someone with an electronics background could rip those descriptions to shreds scientifically, but they’re true where the rubber meets the road.

 

[filip989]

Thanks for the reply!

So I could try putting the polytune 3 just at the end after delay and chorus?

The delay is digital, chorus is analog. Pedals coul be an issue, yeah, I feel that too

However, the dial up noises happening when both volumes are at 0, guitar volume at 0 and amp on standby... I hava a problem understanding how interference could get through like that?
Also while playing, I've had amps that picked up radio signal before. But never when playing and never when everything is turned down.

 

[filip989]

Here you can download the "dial up" sound if you want, uploaded it so I can send it to service in an email.

https://jumboiskon.tportal.hr/download/fa7a7f02-e702-4c06-a8a9-2a3b421d5e0f

So again, al volumes dialed down to zero and stand-by is on.

 

[filip989]

Update: the problem is not here anymore. Went away on it's own. Poping pedals, thump from the chorus, dial up modem sound on standby. Only the quiet delay hiss is present, but it is very quiet.

Maybe I had some power issue in the electric installations in the house? Beeps on standby puzzle me still (the workshop replied it was strange for them too, but they have contacted PRS about it). Manual says that the amp doesn't need to use standby at all... could that be a part of why there is sound (possivly interference then) when standby is on?