Effects Loop Bleed Issue

[batflash]

Hello all,

I play through a Fender Super Sonic 112 Combo that has an issue with the effects loop bleeding the dry signal from preamp to power amp. Example; if you plug a volume pedal in the Send/Return, or a tuner w/ mute, or even just open the circuit by plugging in a patch cable on the return side, you get a fair amount of preamp bleeding through to the power amp.

I was hoping someone has come across this issue before and figured out where to modify the circuit. I know some other Fenders along with a couple of Marshalls have this same issue. They say, "yeahhh it's a serial effects loop" yet it has this problem.

Any help would be great. Thanks!

-Bats

[Enzo]

Sounds like crosstalk.

But does the loop return level control affect the level of this bleedthrough?

[batflash]

Hey Enzo,

yeah, it's affected by the Return Level. Would it help if I linked a copy of the schem?

Schem Link from Fender

Thanks,

Bats

[Enzo]

Thanks, I am a Fender warranty station, I have all the docs.

I assume turning off the FX loop helps?

I don;t know what you are going to do about it, it still looks like just crosstalk.

How does it impact actual play of the amp?

[batflash]

The amp sounds fine. I've had plenty of troubles with the amp since I bought it 2 years ago. Broken wires from tube sockets. Reverb cut in and out. Hissing/noisy Effects loop & Reverb sections. The Power tube plates glow red and in my opinion, run too hot. Other than that, the amp sounds great. I actually love the sound of the amp. But between reliability and functionality it's getting on my last nerves.

I recently took it to a Fender authorized tech here in Miami and had him look at my issue with the bleed. Well, he didn't quite understand what I was talking about so I showed him. Long story short, he wanted to see if another amp of the same model had the same problem. Well, it does. It's built into the design. I called fender and told them about it and after the rep talked it over with their tech, he said it was due to a capacitor that they added to keep the noise down on the send/return section. He says it was a design choice they had to make.

I don't get it all. It's not how a 1200 dollar amp should function. I think if I could fix the fx loop issue, then I could deal with the other problems.

I'm not the only one on the 'net who has this issue either. Think of all the guys that run multi-fx units with tuner mutes and volume pedals. What if you're running a completely wet delay or reverb?

I can't see what so hard about a simle patchpoint between a preamp and power amp. Imagine if patchbays in studios were this bad! We'd have every discerning sound guy and studio owner crying out to patchbay manufacturers!

What do I do?

-Bats

[batflash]

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