Hissing from effects loop?

[thesockmonster]

Going crazy trying to diagnose this hum/hiss I'm getting from my effects loop (5150 III 50w, solid state loop). Any suggestions are welcome.

- Hiss is present when guitar isn't plugged in to amp.

- Hiss is on all 3 channels.

- Hiss is present when plugging guitar into FX loop

- Hiss is present when nothing is in loop.

- Hiss is SIGNIFICANTLY reduced with an NS2 in loop.

- Hiss is present when plugged into multiple outlets.

Ideas?

 

[Oblivion DC]

Does it matter which channel you're on?
If you plug the effect Send of a different head into the Return of the 5150III do you still get the same hiss? How about the Send of the 5150III into the Return of the other amp?

 

[gtrplr71]

That's not the loop I had the same issue. It seemed like the loop to me but it was actually a preamp tube. You description is exactly my problem to a tee. take a pencil with an eraser, on each channel barely tap each tube that drives the preamp channel with the eraser and listen and see if any feedback is present low or high. hope that helps.

 

[thesockmonster]

That's not the loop I had the same issue. It seemed like the loop to me but it was actually a preamp tube. You description is exactly my problem to a tee. take a pencil with an eraser, on each channel barely tap each tube that drives the preamp channel with the eraser and listen and see if any feedback is present low or high. hope that helps.

Hm, hadn't thought of that...it's a pink noise kind of hiss. Will swap in some preamp tubes when I get home.

 

[Racerxrated]

Hate to say it but everyone should stock up on some NOS pre and power tubes at some point. These newer tubes just don't cut it. Old school tubes, even used are more reliable and in most cases will last longer than any new production. The really don't make tubes like they used to.

 

[Oblivion DC]

Hate to say it but everyone should stock up on some NOS pre and power tubes at some point. These newer tubes just don't cut it. Old school tubes, even used are more reliable and in most cases will last longer than any new production. The really don't make tubes like they used to.

And they sound better too.

 

[thesockmonster]

Hate to say it but everyone should stock up on some NOS pre and power tubes at some point. These newer tubes just don't cut it. Old school tubes, even used are more reliable and in most cases will last longer than any new production. The really don't make tubes like they used to.

And they sound better too.

I've owned a few RFTs, some Baldwins, and even some Mullards. They do make a difference, just getting harder and WAY more expensive to obtain.

Horror story - had a Single Rec loaded with NOS RFT and Mullards, sounded tits. Was in a rush to sell off gear...ended up shipping the Single Rec to a buyer FULLY loaded with NOS tubes.

 

[thesockmonster]

Yup, preamp tube. V1, simple issue. Back up to 100% again. Simple enough!

 

[Oblivion DC]

Oh god that sucks. Nice surprise for the buyer but you have to wonder if he even knew what a great stroke of luck had befallen him.

Hate to say it but everyone should stock up on some NOS pre and power tubes at some point. These newer tubes just don't cut it. Old school tubes, even used are more reliable and in most cases will last longer than any new production. The really don't make tubes like they used to.

And they sound better too.

I've owned a few RFTs, some Baldwins, and even some Mullards. They do make a difference, just getting harder and WAY more expensive to obtain.

Horror story - had a Single Rec loaded with NOS RFT and Mullards, sounded tits. Was in a rush to sell off gear...ended up shipping the Single Rec to a buyer FULLY loaded with NOS tubes.

 

[Oblivion DC]

Yup, preamp tube. V1, simple issue. Back up to 100% again. Simple enough!

Tits!

 

[thesockmonster]

Yup, preamp tube. V1, simple issue. Back up to 100% again. Simple enough!

Tits!

No kidding. Plus, found out two of my cables are microphonic...which sucks, because they're in a Pedal Python sheath...will have to re-do that.

 

[Oblivion DC]

Yup, preamp tube. V1, simple issue. Back up to 100% again. Simple enough!

Tits!

No kidding. Plus, found out two of my cables are microphonic...which sucks, because they're in a Pedal Python sheath...will have to re-do that.

Jeeze - is that something that just happens to cables over time, or did yours start out sounding funny and now you've figured out why?

On the plus side at least it's gonna sound great when you're done!

 

[gtrplr71]

Yup, preamp tube. V1, simple issue. Back up to 100% again. Simple enough!

That's awesome I am glad you got it back up and ripping.

 

[thesockmonster]

Yup, preamp tube. V1, simple issue. Back up to 100% again. Simple enough!

Tits!

No kidding. Plus, found out two of my cables are microphonic...which sucks, because they're in a Pedal Python sheath...will have to re-do that.

Jeeze - is that something that just happens to cables over time, or did yours start out sounding funny and now you've figured out why?

On the plus side at least it's gonna sound great when you're done!

Not sure, it's a first for me. One of my 15' leads had the same behavior as a microphonic tube...tap on it, and it rings out through the amp. Funny thing is, you could tap anywhere on the amp and get the ringing with this cable plugged in.

Quick Google search suggested the cable was microphonic - sure enough. Weird.