Here are the mods I did to my JCA20

Very cool. Is this a Jose inspired Mod?

I plan on modding my JCA100HDM one day. I am first gonna fix that crap of a loop. Not sure about actual tone mods. I thought I might go small to start, like reducing some coupling caps to tighten up the low end, and a snubber cap to reduce the fizz. Go from there. I keep putting it off because I am not looking forward to pulling the PCB out, lol.
 
nico22":1ufxzb0x said:
:thumbsup:
Thanks Dave.
What is plate voltage please? and maybe also the V1 pin 1 voltage?
Nico
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I have no idea what the voltages are.... I don’t remember from biasing. I honestly never measured V1 (or any other) I guess I could at some point. You could probably get an idea based on what the metro loop uses and the dropping resistor I needed. It should get you in the area.
 
ok thanks Dave.
I noticed the 4,7k screens grids resistances. Pretty unusual value. how does it affect the sound?
 
I have the 22h and did the depth mod to it, bought a sat mod off ebay didnt install yet but these are some killer little amps, cheap as hell too, sounds great
 
nico22":143gg44y said:
ok thanks Dave.
I noticed the 4,7k screens grids resistances. Pretty unusual value. how does it affect the sound?
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It darkens it up a bit, but I made up for it by changing R48 and R6.
 
Those amps can be made to sound so good, yours sounds incredible. I cut the trace feeding the slope and put the master pre ts, it was easier just to replace the volume pot and run the wires the traditional way
 
nakoshoko":37x7v6ep said:
Thanks a lot for sharing!
Much appreciated !
The model of the base amp is Jet City 20 or 20h?
Kind regards!
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Not sure I know the difference. It’s just a regular old Jet City 20 watt head.
 
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