Here are the mods I did to my JCA20

[psychodave]

Edit

 

[Inearthed]

Thanks for sharing, Dave

 

[Shask]

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]

Thanks Dave.
What is plate voltage please? and maybe also the V1 pin 1 voltage?
Nico

 

[LP Freak]

Sounds great

 

[Markedman]

Fuck yeah when you turned the master up!

 

[psychodave]

Thanks Dave.
What is plate voltage please? and maybe also the V1 pin 1 voltage?
Nico

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.

 

[FourT6and2]

Cool

I don't know much about these amps. There are a few different versions?

 

[nico22]

ok thanks Dave.
I noticed the 4,7k screens grids resistances. Pretty unusual value. how does it affect the sound?

 

[155]

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

 

[psychodave]

ok thanks Dave.
I noticed the 4,7k screens grids resistances. Pretty unusual value. how does it affect the sound?

It darkens it up a bit, but I made up for it by changing R48 and R6.

 

[SpiderWars]

Did you just use an exacto knife to cut and then the cut segment of trace just lifts up and away?

 

[psychodave]

Did you just use an exacto knife to cut and then the cut segment of trace just lifts up and away?

Dremel. Exacto knife could work though.

 

[paulyc]

THANK YOU !!!!

 

[nakoshoko]

Thanks a lot for sharing!
Much appreciated !
The model of the base amp is Jet City 20 or 20h?
Kind regards!

 

[Monomyth]

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

 

[seanseanhd]

Sounds great.

 

[errrrrl]

Wow.

 

[Beyond Black]

Very cool of you. That amp sounds amazing.

 

[psychodave]

Thanks a lot for sharing!
Much appreciated !
The model of the base amp is Jet City 20 or 20h?
Kind regards!

Not sure I know the difference. It’s just a regular old Jet City 20 watt head.