Studio Diary #36: Why Does My Fryette Power Station Squeal?

For the last couple of months, I’ve been dealing with a problem with my Fryette PS-100 Power Station: it emits an awful squeal.

I’ve figured out why: it was caused by a ground loop. Read on if you want to know the whole story.

What Is The Problem?

I’m trying to use my Fryette PS-100 Power Station as a passive loadbox, so that I can get the glorious sound of my Tweed Deluxe amp into my Axe-FX 3.

• The Power Station is unpowered. It’s not just switched off, it’s not even plugged into the mains.
• My Tweed Deluxe is plugged into the PS-100 as normal.
• I’m using the XLR Line Out to take the signal into my Axe-FX 3.

When I do, I get the most awful squeal or howling sound. The sound doesn’t just come out of my speakers; the noise can be heard coming out of the PS-100 itself.

How Did You Fix It?

By luck.

I was packing it up to send back for repair, and I thought I’d try it again. It’d been a couple of months since I last used it. I didn’t want to risk my Tweed Deluxe amp so I plugged in my Marshall DSL 20HR instead. Damn thing worked absolutely fine. Arrggghhhh!

Wondering if it was a faulty speaker cable, I took the cable out the back of the Marshall, and used that with the Tweed Deluxe instead. No joy; the PS-100 was back to its old squealing self.

There’s a Ground Lift button on the back of the PS-100, which I’d totally forgotten about. I accidentally knocked this button while changing cables yet again … problem solved.

Months of frustration, caused by something as simple as:

1. a ground loop, and
2. me never once engaging the Ground Lift to see if that was the problem 🤦‍♂️

Why Do You Have A Ground Loop?

This bit does baffle me a bit.

• Both the Marshall and the Tweed Deluxe are plugged into the same power extension.
• That power extension is plugged into the same wall socket as the Axe-FX 3.

In theory, they should all share the same route to ground? I don’t understand this very well. Kinda feels like I should, doesn’t it?

I think it’s unlikely that there’s a fault with the Tweed Deluxe itself. I’ve had similar problems in the past in this room, when cabling up the Kemper, and when running microphones into video cameras.

Final Thoughts

I’m glad to have solved this one.

I’ve been putting off sending the Fryette back. I wasn’t looking forward to that hassle. And now I don’t need to 🙂