Friedman Butterslax with popping noises in effects loop

[pompeiisneaks]

Basically it's a known problem. If you let the amp warm up for ten to fifteen minutes, the popping stops. He sent me a replacement but I can't get the owner in to swap it out now.

Phil

Sent from my LG-H932 using Tapatalk

[Gaz]

That's strange. 15 seconds seems more reasonable. There is DC until C2 charges up, which shouldn't be that long since C2/R1 are not too large.

[pompeiisneaks]

I think there's a pretty significant impedance mismatch and somehow letting thing's balance out for a while seems to resolve it. That's what I'd read/heard, but I also don't get it.

~Phil

[pompeiisneaks]

So I finally got the board from friedman to replace in this amp, and had it for a LONG time before the owner finally contacted me.

I went out yesterday and swapped out the old loop for the new one, and still had popping. So I figured at that point maybe it was something in the loop.

We started one pedal at a time until popping showed up, and guess what, it was the t.c. electronic's pedals doing it.

He had two strymon's and some other pedal I don't recall that did the popping, the T.C. didn't, but once they were out of the loop, the popping stopped.

Would a buffer pedal settle this kind of thing down? What's really the cause of something like that? Does the TC being in the loop create the impedance mismatch and a buffer will sort it?

~Phil

[Deric]

I think most Strymon and most TC pedals have selectable buffered or true bypass.

My experience with the Metro type loops is that they all pop with true bypass pedals. No pop with buffered bypass.

[norburybrook]

I think most Strymon and most TC pedals have selectable buffered or true bypass.

My experience with the Metro type loops is that they all pop with true bypass pedals. No pop with buffered bypass.

yep, there's internal dip switches with TC pedals to set various things including the buffer.



M

[pompeiisneaks]

Oh ok so maybe we just need to set that for the TC effects and solve the popping, cool!

~Phil

[John_G]

Phil,
Have you made sure that there are pull down resistors fitted at the input and output of the Friedman loop.
A couple of un terminated jack plugs inserted into the respective sockets then measure resistance across each jack just to make sure they are fitted,
If they are (220k send and 2M2 return ??? ) then fitting resistor(s) to the TC pedal(s) is the next step or as you have suggested use the TC buffers ( do they have separate input/output buffers on switches ), if so then only one may be needed.
John

[pompeiisneaks]

John, if you look at page one, I reverse engineered the loop and have the schematic:


, it looks like a 220k on the send and 3.3M on the return.

The new one might be different, he's asking me to swap the old one back in, as I'd tuned it to have a near unity gain on the output from the input, the new effects loop was tuned by Dave Friedman or someone at his side and Dave told me to not touch the pots. The new one makes his amp so loud he can't even use the attenuator to mellow it out hehe.

I'm going back this weekend to swap the old one back in and I'll get the dip switches fixed in the TC Electronics ones.

~Phil

[John_G]

Phil,
I hope Mr Frey won't mind me posting his schemo.
For comparison purposes only.
Yours is missing a source resistor in the send FET.
All the best with solving this problem
John

Metroloop_Rev4_v1_4.png

[pompeiisneaks]

Phil,
I hope Mr Frey won't mind me posting his schemo.
For comparison purposes only.
Yours is missing a source resistor in the send FET.
All the best with solving this problem
John

Metroloop_Rev4_v1_4.png

john, thanks, mine, though is the Freidman Loop, and I reverse engineered it from the actual part. I accounted for all components on the board. I'm guessing it's one of a few changes from the metro board. I did hear it was based on the metro board, though so that seems to confirm somewhat.

~Phil