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FX Loop Capacitors

Posted: Tue Sep 08, 2020 4:24 pm
by Marshmallow
hey guys,

I need help with the fx loop capacitors I highlighted.

1. Are those capacitors really necessary?

2.) If i need them, can the 1kv be changed to 500v?

1. In some diagrams, they aren't included, in some layouts they have the 250pf with 220k resistor connected to the send return jacks but then was told its not really needed.

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here's the 1984 diagram before dumble updated it.

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here is modified one in 1988. It also says that it's not really necessary. 🤔

It's a little hard for me to find those parts so I wonder if I can run the wires without them capacitors. What's the effects of those capacitors?

Re: FX Loop Capacitors

Posted: Tue Sep 08, 2020 4:57 pm
by NippleWrestler
Looks like it would serve to roll off some high end.

Re: FX Loop Capacitors

Posted: Tue Sep 08, 2020 5:05 pm
by Marshmallow
NippleWrestler wrote:
Tue Sep 08, 2020 4:57 pm
Looks like it would serve to roll off some high end.
Fair enough, thanks for that. I'll just install it without it and install it later on.

Cheers

Re: FX Loop Capacitors

Posted: Tue Sep 08, 2020 5:41 pm
by Optical
NippleWrestler wrote:
Tue Sep 08, 2020 4:57 pm
Looks like it would serve to roll off some high end.
Other way around, it is bright cap essentially, to increase high end toward low volumes
Used in a circuit like this, it was probably added to compensate for a loss of treble due to load mis-match in the fx loop. There's no dedicated fx loop driver, so high end is the first thing to go if the driving stage impedance goes too high which it probably would in many circumstances.