This is my first post, sorry for the length. Tales of the Unexplained: The setup: Marshall DSL 50 (head) 8 ohm Speaker Out , plugged into Amp In of PS-100. PS-100 Speaker Out plugged into a 1x12, 8 ohm speaker cab. All switches set to 8 ohms. Tried different cables. All things on same electrical circuit. With No input cables to Marshall: Ps-100 Powered up and Marshall powered up out of Standby. I get a horrible,grinding,low buzz/hum, (almost the pitch of Bb on a guitar). Not a ground loop issue. If I disconnect the DSL and plug a guitar into the Line In of the PS-100 it’s fine. I swapped out the Marshall with a Mesa Boogie Mark V, same cables , same settings and everything is fine. No noise/attenuates great /works as it should. Tried the Marshall by itself, into the same cab and it works great. I’ve been running the Marshall/Ps-100 rig for 2 years and this is the first time this ever happened. All of a sudden they don’t like each other. Anyone had issues as such?
Welcome to the forum!
First thing I would do is check is to see if you accidentally pressed the rear panel Ground Lift switch into the Lift position on the PS 100.
Dave
I don’t think it’s a ground issue. I totally re-diagnosed the problem. Hooked up a Mesa Boogie Mark IV. Everything works as expected. Did the same with a Mark V. No problems. Then again, Hooked up the DSL-50. Terrible noise still there. The kind that tells you to shut it down NOW. And this is with or with nothing plugged into the DSL inputs; and also, with the volume knobs turned all the way down (or anywhere) on the PS-100, in standby mode or operating mode. I hooked up the DSL-50 by itself to a speaker cab, and it sounds great, no problem with the amp. Swapped audio and electrical cables; double checked that all switches are in the correct position. Checked ground lift. As I posted, I never had this problem with the Marshall and PS-100 until now. Strangest thing, but something weird electrically has to be happening. So disappointing since I got the Power Station to tame the DSL-50 running a 2-12 cab with Greenbacks, so I don’t blow them up. Thanks to anyone who can share a similar experience. I may call the factory direct…
Man. That sounds frustrating. Especially since it worked before and doesn’t now.
A few questions:
- If you hookup the Marshall to the PS-100 Amp In and then PS-100 Speaker Out goes to your cab and you leave the PS-100 totally off (not standby but totally off), do you get the same issue? If not, presumably, as soon as you turn on power, you get the issue, right?
- What is the position of the PS-100 relative to the Marshall? If you move the PS-100 away from the Marshall (or vice versa), does the problem go away?
In reply: With the Marshall hooked up and PS-100 totally powered off there is no sound. With the Marshall in Standby mode and PS-100 powered up there is no sound (which is normal). As soon as I power up the Marshall out of Standby( PS-100 powered up/ either Standby or operate), the horrible noise occurs and I shut it down. I also moved the PS-100 4 feet away- made no difference. Hook the Marshall up to different cabs- works great , no issues. Hook up a Mesa Mark IV or Mark V to the PS-100, and everything is fine, no issues. This is bizarre! Has to be an answer but I’m lost-even being an Electronics Tech Engineering Major. Thanks for the reply.
From a normal troubleshooting POV, if two different amps work fine with the PS-100 and a third amp doesn’t, I would suspect the problematic amp.
The fact that the amp works normally direct to a cab still leaves the possibility that there could be some kind of ground or power supply fault in the amp.
Dave
Thanks. I guess I will have to delve into a Marshall issue. It’s baffling since everything was fine for 2 years, then this happens. How can the amp work normally but cause this with the PS-100? Totally bizzarre.
You just have a different interaction with the Marshall plus speaker cab versus the Marshall plus the PS-100. And the PS-100 is likely revealing an issue with the Marshall that you wouldn’t otherwise know of. But I agree with Dave that the Marshall is highly likely where the issue resides.
Appreciate the feedback. Hope this is the last post for me with this issue. Well…last night gave it a last try, Went over the Marshall, looking for anything. Swapped out all 3- prong electrical cables with heavy duty cables from copy machines.. Plugged Marshall and PS-100 into the same heavy -duty power strip. One thing I failed to mention was that I had a Source Audio Collider pedal plugged into the PS-100 FX loop; send/return. I powered things up and Bam! Everything is working normally! Was getting a little low hum, reached around back and pressed the FX level button in. Uh Oh- here comes the crazy loud buzz again. Powered down; took the Collider out of the loop. Powered back up and all is fine again. I fiddled with the FX level knob and the button again(nothing in loop) and started getting a low level buzz, intermittent. I started thinking there’s a pc board or cold solder joint issue in the area of the FX send/return. I then put the Collider back in the FX loop.Powered up- no issues.(I even pressed the FX level button in and out with no resulting probs, or the noise coming back) I played thru the Marshall for an hour and everything worked great. Came back later and hooked up My Mesa Boogie Mark IV; played for an hour and No issues. All I can do now is keep an eye/ear on things. Everything seems OK now. I have no explanation. Maybe there is a board issue with the PS-100. I bought it in September 2023. I forget if the warranty is over. Hoping the problem goes away but not holding my breath. Thanks again guys. One thing to mention: I had a monitor speaker buzzing once- swapped out the 3-prong power cable and the noise went away - proving that those cables can go nutty too. If I ever come up with an answer I’ll post again.
Got it. Thanks for adding that - that’s significant information right there. Sounds like a classic ground loop issue introduced by the pedal in the loop. If you are unfamiliar with the term, take some time to look it up and understand what you should be looking out for and what you can do about it. If you were to search for ground loop on this forum, you will find a lot of examples.
You likely “solved” the issue during your troubleshooting, but, if you don’t know what you did that solved the ground loop issue, the problem could come back. Keep in mind, it’s very unlikely that there is a problem with your PS-100 based on what you’ve described. You’re doing all the right stuff right now focusing on removing and adding devices and trial and erroring your way through finding where the problem is.
Thanks for thre update.
For more information on this subject, see:
Dave
Thanks again. Watched the video. Exact same hookup with my Mark IV or Marshall. Only thing again that confuses me is the noise I was getting was super loud,like the amp was dimed, at the literal pitch of a low Bb on a guitar- but nothing plugged into the Marshall input and volumes turned all the way down on all units. Even did it with NO cables or FX plugged into the FX loop. Reminds me of a Roland JC-120 amp I had that the PCB went out in- turned it on (nothing plugged into it), and a similar loud hum so bad you could see the speakers/ dust caps bouncing back and forth. Not a normal ground loop sound. Another note: When all is working , I definitely think using the Power Station’s FX loop is better sounding than using the amp’s FX loop.