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FDP Forum / Miscellaneous and Non-Fender Topics / Amp and pedals weirdness

Rick Knight
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St Peters, MO USA

Busy doing something close to nothing
Apr 13th, 2019 11:05 AM   Edit   Profile  

I bought a used Wampler Plexi Drive Deluxe that worked fine on the boost side, but howled like a Banshee when the Plexi side was engaged. I assumed that it must be defective and returned it. Then my tech put a Clapton mid boost in a pedal for me. It made a loud oscillating sound when engaged. I took it and the head to his shop, but the noise didn’t happen there. The only amp problem he found was that V1 was loose. It did the same thing when I got home. Then I picked up a used 2nd generation Marshall Guv’nor. It also made an oscillating sound, but not as loud as the mid boost. When these things happened, I put one or more of my old pedals in its place, using the same cables, without any issues. Whatever is going on is out of my depth. Suggestions appreciated.

Mike DeTorrice
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USA

Apr 13th, 2019 02:28 PM   Edit   Profile  

Strange ! Were they all running on plug-in power supplies or on batteries ?

Peegoo
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Just beyond Mars

there's a world of fools
Apr 13th, 2019 05:29 PM   Edit   Profile  

Is it a squeal tone? Please give us some details about the oscillation sound.

Leftee
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VA

Knuckleheading
Apr 13th, 2019 05:41 PM   Edit   Profile  

What amp?

Cal-Woody

USA/California

Why do I keep fixing things that work?
Apr 13th, 2019 06:36 PM   Edit   Profile  

Could be a bad cord grounding out and causing the problem.

Rick Knight
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St Peters, MO USA

Busy doing something close to nothing
Apr 13th, 2019 06:42 PM   Edit   Profile  

Mike deTorrice: All on the same Gator plug in power supply.

Peegoo: It's a regular variation. That's probably not a good description but I don't know what else to say.

Leftee: Dr Z Z28.


Rick Knight
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St Peters, MO USA

Busy doing something close to nothing
Apr 13th, 2019 06:44 PM   Edit   Profile  

Cal-Woody, do you mean a bad power cord or an input cable?

Leftee
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VA

Knuckleheading
Apr 13th, 2019 06:59 PM   Edit   Profile  

I wonder if V1 is going microphonic. Is that a EF86?

Rick Knight
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St Peters, MO USA

Busy doing something close to nothing
Apr 13th, 2019 07:05 PM   Edit   Profile  

Leftee, yes it is.

Edited to add: I read that "Some preamp tubes seem inherently microphonic(like the EF86 always seems on the brink.)" this morning. Maybe just someone's opinion, but maybe not?

(This message was last edited by Rick Knight at 10:50 AM, Apr 14th, 2019)

Rick Knight
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St Peters, MO USA

Busy doing something close to nothing
Apr 14th, 2019 10:21 AM   Edit   Profile  

Another update, he said he checked for microphonic tubes when it was in the shop.

ejm

usa

Apr 14th, 2019 10:34 AM   Edit   Profile  

"All on the same Gator plug in power supply."

So you have more than one pedal connected together with a daisy chain cable?
If not, and you're using a separate jack on the Gator supply for each pedal, that brings up another question: Are the outputs of the Gator truly isolated, or are they merely daisy chained to each other inside of the supply?

Some pedals do not want to play well with others when using the same power source.
It's usually thought of as a problem when mixing digital pedals with analogs.
However, I have had it happen to me, using all analog type pedals, at least twice.
Some pedals, for whatever reason that I'll leave to others to speculate why, just want their own supply. (I fixed one problem by increasing the supply filtering inside of the offending pedal.)

If this sounds like it could be your problem, like someone suggested try using batteries on one or maybe all of the pedals to see if the problem goes away.

(This message was last edited by ejm at 12:35 PM, Apr 14th, 2019)

Rick Knight
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St Peters, MO USA

Busy doing something close to nothing
Apr 14th, 2019 11:57 AM   Edit   Profile  

"So you have more than one pedal connected together with a daisy chain cable?"

I've tried it with more than one and only one connected.

"Are the outputs of the Gator truly isolated, or are they merely daisy chained to each other inside of the supply?"

That, I don't know. The Gator is the power supply from my small board for bass pedals. It has given me no problem in that application, and was at hand when I started messing with guitar pedals. I will try other power supplies and batteries to see what effect that has.

I appreciate everyone's help in trying to sort through this.

ejm

usa

Apr 14th, 2019 12:16 PM   Edit   Profile  

It sounds like you may have two problems going on here.
Taking them one at a time......

If it's the G-BUS-8-US power supply, there is nothing in the literature that I looked at that would indicate that the outputs are isolated.

That basically means that the outputs are daisy chained inside of the supply.

As another note, this also means that you cannot use it to power up both negative and positive ground pedals at the same time. Negative ground pedals are not the norm, however.

Have you powered up the offending pedal (the Wampler) with the Gator by itself?
Did it have the problem then?
If so, did the Wampler come with its own wall wart supply? (I see you bought it used, so you may need to check with Wampler. He has answered e-mails from me in the past after a day or two.)

I have a Hermida Nu Valve OD that came new with its own wall wart.
It does not like to share a daisy chain with other pedals, and for some reason wants its own supply.

Switching subjects to your other problem with the Clapton boost..........

I trust that your tech that made the boost pedal has checked it out?

I have a Clapton Strat. One day I took it apart and shielded the cavities. I also put some shielding tape near the preamp board.
It howled when the boost was turned up.
I ended up removing the shielding tape in the circuit board area, but left the tape around the pickups and controls.
For some reason it did not like any shielding around the circuit board area.


reverendrob
FDP Data Goon
Moderator

She hath it all,

& hath no need of thee.
Apr 16th, 2019 09:58 AM   Edit   Profile  

Step one will be simple: test the same exact rig you're having issues with, in the same location, with ANOTHER amp.

If no problem, you've narrowed it down to the amp itself.

What you're describing sounds like a tube that goes microphonic if hit hard - not necessarily 'overall', but in a particular frequency or six.

I have an ancient Telefunken ECC82 I keep around *because* it does that with some pedals or if the amp gain is on insane levels (old HRD before they tamed it). Absolutely no issues "clean" or even with more gain than most of you are ever likely to see - but if you approach gain *and* massive dirt, it squeals and crackles and oscillates in a glorious way.


Rick Knight
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St Peters, MO USA

Busy doing something close to nothing
Apr 16th, 2019 04:03 PM   Edit   Profile  

Here's what I learned from the latest round of messing with this:

Changing guitars and pickup types had no effect.

The only other readily available guitar amp is a Frontman 25. Using the Gator power supply, the mid boost pedal made a quieter but still noticeable oscillating sound with it. Then I tried a 9V wall wart. It hummed. So I got the more substantial power supply from an SKB board and had no noise in the Frontman. So, using that power supply, I plugged the pedal into the Z again, resulting in a big hum.

There is no shielding inside the mid boost pedal.

I now wish I hadn't returned the Wampler pedal so quickly, but it's too late to worry about that now.

insanecooker
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Houston, TX

Apr 17th, 2019 07:37 AM   Edit   Profile  

Can you film/record what you’re getting?

ejm

usa

Apr 17th, 2019 08:33 AM   Edit   Profile  

"There is no shielding inside the mid boost pedal."

Is the mid boost pedal in a metal box?
If so, there's the shielding.


Rick Knight
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St Peters, MO USA

Busy doing something close to nothing
Apr 17th, 2019 08:45 AM   Edit   Profile  

"Is the mid boost pedal in a metal box?
If so, there's the shielding."

Point taken. I was thinking in terms of the shielding used in guitars.

FDP Forum / Miscellaneous and Non-Fender Topics / Amp and pedals weirdness




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