sc20h jcm 800 fx loop

fer1991

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Hi, I've got a jcm 800 sc20h. Bought it new, and put some mesa 12ax7 that really gave life to the amplifier.

Has anyone fixed the fx loop problem in this amp? I'm a home-volume user, and when I turn on the fx loop I get:
- pops every time I get on or off the 5watt mode.
- pops when I hit pedals on and off.
- volume drops and dynamic range changes (it's not only volume, I cant get the same tone just by adding some volume).

The only reason I use the fx loop it's to get a tinny bit of delay, and drives me mad the tone sacrifice.. guess this amp can only take "in front" pedals?

I know.. I know there is an official sc20h thread but I wanna know if anyone has fixed or found a simple solution to this.
thanks to everyone!
 

Michael Roe

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Hi, I've got a jcm 800 sc20h. Bought it new, and put some mesa 12ax7 that really gave life to the amplifier.

Has anyone fixed the fx loop problem in this amp? I'm a home-volume user, and when I turn on the fx loop I get:
- pops every time I get on or off the 5watt mode.
- pops when I hit pedals on and off.
- volume drops and dynamic range changes (it's not only volume, I cant get the same tone just by adding some volume).

The only reason I use the fx loop it's to get a tinny bit of delay, and drives me mad the tone sacrifice.. guess this amp can only take "in front" pedals?

I know.. I know there is an official sc20h thread but I wanna know if anyone has fixed or found a simple solution to this.
thanks to everyone!
Yes, that is a known issue or really not an issue but just how it is designed. The solution is to use a buffer in the loop or a pedal with a buffer.
Other guys will chime in here with better answers that actually use the loop with pedals. I have one but the only thing I use in the loop is a rack FX unit which does not have that problem.
BTW, Welcome to the forum!
 

ampmadscientist

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Hi, I've got a jcm 800 sc20h. Bought it new, and put some mesa 12ax7 that really gave life to the amplifier.

Has anyone fixed the fx loop problem in this amp? I'm a home-volume user, and when I turn on the fx loop I get:
- pops every time I get on or off the 5watt mode.
- pops when I hit pedals on and off.
- volume drops and dynamic range changes (it's not only volume, I cant get the same tone just by adding some volume).

The only reason I use the fx loop it's to get a tinny bit of delay, and drives me mad the tone sacrifice.. guess this amp can only take "in front" pedals?

I know.. I know there is an official sc20h thread but I wanna know if anyone has fixed or found a simple solution to this.
thanks to everyone!

What happens when you plug a guitar cable between send and return?
Still getting the same volume change?
 

South Park

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Some pedals have to much impeadance for that preamp stage and don’t work right
 

fer1991

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when I patch it the "problems" are still there. I guess it's something with the fx loop getting in the circuit when it's on. But it's a desing thing, btw.. with the loop off the sound it's just awesome. Thanks for the answers, I hope someone comes out with a simple solution like "cut this leg on this cap".. for now I'll put my delays very low in the font, not a big deal really love the amp.




Yes, that is a known issue or really not an issue but just how it is designed. The solution is to use a buffer in the loop or a pedal with a buffer.
Other guys will chime in here with better answers that actually use the loop with pedals. I have one but the only thing I use in the loop is a rack FX unit which does not have that problem.
BTW, Welcome to the forum!
What happens when you plug a guitar cable between send and return?
Still getting the same volume change?
 

pedecamp

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when I patch it the "problems" are still there. I guess it's something with the fx loop getting in the circuit when it's on. But it's a desing thing, btw.. with the loop off the sound it's just awesome. Thanks for the answers, I hope someone comes out with a simple solution like "cut this leg on this cap".. for now I'll put my delays very low in the font, not a big deal really love the amp.
This is normal for this amp unfortunately, they should have engineered the loop better, i didn't like this about the loop either so I sent it back and got an SV20H which doesn't have this problem. So as of now there is no work around. I'm hoping by next year this time they fix it and I'll consider getting another.
 

fer1991

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I hope they fix it, and when they'll do, they keep the sound of the amp with the loop off.


This is normal for this amp unfortunately, they should have engineered the loop better, i didn't like this about the loop either so I sent it back and got an SV20H which doesn't have this problem. So as of now there is no work around. I'm hoping by next year this time they fix it and I'll consider getting another.
 

South Park

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Not all loops are the same stay away from switchable loops the slo 100 has one of the best out thar
 

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