SV20 Effects Loop Hum

[halloweenman]

Just got one of these and tried a volume pedal (JHS little black amp box) in effects loop for bedroom playing and noticed I get slight but noticeable hum when activated.

I know it's not the pedal as when I connect only patch cable (no pedals just a cable) between loop send and return the hum is still there. The hum is not affected by volume, it remains constant. It's only there when effect loop button is activated and something connected, even if it's just a cable.

Is this normal or a faulty unit? Can others try this and let me know if they get the same result? Thanks.

 

[Dirty Harry]

Congrats on the new amp, they’re awesome
I’ve never noticed any hum from the loop on mine under normal use, which 90% of time is in a band situation.
I tried it to answer your question though, and with just a cable in loop I can’t detect any hum. With 2 cables & a pedal a very slight hum, that I would never have picked up if not in a quiet room specifically listening for it.

 

[Dogs of Doom]

could it be the cable?

 

[marshallmellowed]

could it be the cable?

This is true, even a short patch cable, if it's not well shielded, can pick up extraneous noise. The proximity of other devices in the room can also contribute.

 

[Dogs of Doom]

This is true, even a short patch cable, if it's not well shielded, can pick up extraneous noise. The proximity of other devices in the room can also contribute.

I started a thread here once, a long time back. I had just got my EL 50/50 & hooked up my JMP-1, Quadroverb II, etc. & had a nasty hum/buzz. I can't remember who suggested that it was probably a cable, & not a ground loop. I had all new cables...

Sure enough though, one was noisy. Replaced it & everything was quiet...

I bought those isolation washers, for the rack, etc. & it still didn't help - because it was a bad cable...

 

[speyfly]

A hum can be be caused by a lot of things, bad ground, ungrounded outlet, florescent lights etc.

That said, is the hum there when nothing is plugged into the loop? The reason I ask is that the SV20H (at least mine) always has a gain hum, totally natural for a hi-gain amp in my experience.

Finally found my LBB (took some searching) and no difference between nothing in the loop and a LBB in the loop.

 

[halloweenman]

Congrats on the new amp, they’re awesome
I’ve never noticed any hum from the loop on mine under normal use, which 90% of time is in a band situation.
I tried it to answer your question though, and with just a cable in loop I can’t detect any hum. With 2 cables & a pedal a very slight hum, that I would never have picked up if not in a quiet room specifically listening for it.

Thanks. I noticed immediately, it's quite noticeable on mine with just a cable. Seems like a faulty amp unfortunately.

 

[halloweenman]

T

could it be the cable?

Thanks, unlikely, I've tried different cables, same result.

 

[halloweenman]

A hum can be be caused by a lot of things, bad ground, ungrounded outlet, florescent lights etc.

That said, is the hum there when nothing is plugged into the loop? The reason I ask is that the SV20H (at least mine) always has a gain hum, totally natural for a hi-gain amp in my experience.

Finally found my LBB (took some searching) and no difference between nothing in the loop and a LBB in the loop.

Thanks. No hum with nothing plugged in. It's defo an issue with the FX loop.

 

[purpleplexi]

I use the LBB and there's definitely no difference with it in or out on mine.