If I get the “squeal” while using the zmacs with PS2, where in the chain would I put my ISO transformer?
Between guitar and input of Zmacs?
Between zmacs and front of amp?
Maybe move amp head away from PS2?
Switches between two amps and one had the squeal.
Thanks. Elroy Rules!
Hi Sumrog01 and welcome to the community!
This is hard to say. I don’t think there is a wrong or a right place. Well, the right place is where the ground loop is,
which is what we don’t know.
Probably not this one unless you are a giant capacitor.
Physical distance can help when magnetic fields are the cause.
I don’t have experience with the ZMACS yet, and I have never had a multiamp rig. Maybe there is a location that normally gives people success; unfortunately, I don’t know what it is! I would just try different locations.
Before I had Zmacs if I had the squeal using the PS2, I could put the ISO transformer between last pedal and amp and it would take care of it. I had 3 amps plugged in Zmacs using loop for he PS2. Only one amp squealed so I will put ISO in between Zmacs and that particular amp and should be good.
Well I found out that whenever I plug more than 1 amp into Zmacs I get squeal. One at a time through Zmacs and I’m good. Amps are not set at super high gain. Revv D40, Fuchs ODS2, SC50 and Todd Sharp JOAT45. I’ve moved all amps away from PS2. And this is ok. I dont need multiple heads plugged in so Now that I know I will just use one amp at a time for recording. I can still switch between different cans which is more useful anyway
Try pushing in the Ground Lift switch on the back of the PS-2.
Also make sure all amps and PS-2 are plugged into the same AC circuit (outlet, power strip, etc).
All amp inputs and outputs are ground isolated when not operational. Only the operational one connects to audio ground.
If you have pedals connected to the ZMACS input and the PS-2 loop but grounded together on the pedalboard, you need to isolate the ones in the PS loop.
Would help to see a chart of your signal flow from guitar to pedals in front and in the loop.
Dave.
Hello.
So I have a very simple signal path.
Guitar into Zmac. Four 8 Ohm heads through Zmac. One 8 ohm cab to test everything.
No pedals.
When I use just the Zmac with no PS2 It’s perfect switching between amps.
When I have the PS2 in loop of zmac. I. An o LY have one amp plugged in at a time. As soon as I even plug another head into Zmac with PS2 running I get squeal.i live in a townhouse so I have to use PS2.
Months a big deal as I don’t mind using one amp through the Zmac and PS2 at a time as I can still switch cabs.
Also ground lift helped with the squeal mostly but the ground gun was very loud.
All is plugged in my furman
Hope this helps.
John
Where did you purchase it? What are the last 4 digits of the serial number and where are you located?
Thanks,
Dave
Zmac from Chuck Levins. I’ve had the PS2 for so long maybe Zzounds?
I’m in Charlottesville VA. Steve knows me. John Gormus.
The PS2 would get squeal when I used high gain amp and pedals but ISO took care of it.
It seems to be more of a PS issue than a Zmac issue?
Now that I know the work around (one amp at a time) I’m ok with it as changing cabs still works for me.
Thank you
John Gormus
240 988 4947
Good Morning David,
I was speaking with Pete at Chuck Levins and he was concerned that the Zmacs works fine until the PS2 is looped in.
He asked me to ask if upgrading to a newer PS unit might help. Since I have an old PS2 unit maybe thats the issue? They have PS100 in stock if I need that. He is not just trying to sell me another unit, it is just a suggestion.
Also I can do a quick video if that helps:
Again no pedals. All plugged into the Furman.
When I use 4 amps with the Zmac. It works but still too loud for my townhouse.
If I only plug in 1 Aamp and use Zmac with PS2 looped, again no issues.
As soon as I plug additional amps (whether its just 1 ro 3 more) I get the squeal.
Thanks again for your help and let me know your next suggestion
JG
Nevermind. I tore it all down. Plugged all back in and now it works.
Fuckin Guitar Players!
JG
Don’t feel bad. That happens a lot.
I still want to know the serial number.
Dave
Works great. Only thing to mention and I don’t care is whether loop button is engaged or not on Z, the PS2 is still working. If I hit bypass on PS of course it’s full volume. Works great
That may need a factory update. Where are you located?
I sold the PS2. Am picking up a PS2A today.
I am friends with the person I sold it to. He is only using with one head at a time. If you think it still needs an update I will let him know. He is in Roanoke VA.
John
Dave just an FYI. I have a 1973 Marshall JMP100. So I got my new PS2a. Marshall using just PS2a perfect. Using Marshall with zmac I get the squeal. Non of the other amps were on.
No pedals of course. Tomorrow I’m going to test Marshall alone thru zmacs and then thru zmacs with everything plugged in.
This is all just for information. I can work around all of this but I’m your test dummy. LMK know if you want me to try any specific scenarios you want me to try.
John
Hi John
This could be a few things, but probably a ground loop.
This can be quite complicated to understand, but the solutions Joe demonstrates here are simple to implement:
Unplug everything and start again. Make sure you only have one wall connection powering your entire rig.
It could also be a magnetic issue depending on how close the PS-2A is to your amp and guitar:
Post a picture of your setup will help.
Will do but I’m familiar with the squeal and have checked all of those boxes. It really just comes down to this.
When I run amp with gain and volume up directly through the PS2A. No issues.
When I run it though the zmacs and use the attenuator loop. Squeal.
PS2 and zmacs are both minimum 3 feet away and all plugged into my Furman.
I need to verify this again. When connecting just the Marshall thru zmacs with PS2. Fine. When other amps are connected then the squeal comes into play.
I’ll keep trying different things
John
