JCA22H mod recommendations?

[ledvedder]

I have a JCA22H head sitting around collecting dust. I'd like to do some mods to it, so I'm looking for some ideas.

I'm thinking something clean to slight breakup on the crunch channel. Then, either SLO or some type of BE on the overdrive channel.

What's your recommendations?

 

[RaceU4her]

whatever pyschodave did to his i would do

 

[ledvedder]

whatever pyschodave did to his i would do

His is the single channel Jca20h.

 

[MrDowntown]

The SLO won the most overated amp thread (unsubstantiated of course). That’s exactly what I’d do

 

[ledvedder]

I can't seem to find a schematic for the SLO mod on a 22h.

 

[glpg80]

His is the single channel Jca20h.

Shouldn’t matter.

 

[ledvedder]

Shouldn’t matter.

So, would I do the mod to the crunch or the overdrive channel? I wish I could find a schematic for the mod on the 22H.

 

[glpg80]

So, would I do the mod to the crunch or the overdrive channel? I wish I could find a schematic for the mod on the 22H.

Overdrive

@psychodave where you at Holmes

 

[sahlomonic]

I can't seem to find a schematic for the SLO mod on a 22h.

Should be doing the same as you would on the 50H. It's just the first couple stages and gain pots you're swapping values of. I'll send you a 22H schematic over FB if you don't have one.

You can also do a gain cut switch that acts sort of like a 'clean' mod on the Normal channel. Standard on the Soldano SLO front panel.

 

[ledvedder]

Should be doing the same as you would on the 50H. It's just the first couple stages and gain pots you're swapping values of. I'll send you a 22H schematic over FB if you don't have one.

You can also do a gain cut switch that acts sort of like a 'clean' mod on the Normal channel. Standard on the Soldano SLO front panel.


View attachment 139861

So it needs to be done to the crunch channel? I'd prefer it on the OD channel. I'm trying to go for a clean to mild drive thing on the crunch channel.

I have the JCA22H schematic, but it's a pain to reference. It just has the locations, not values (R12, C11, etc). Then I have to reference a different chart for the component values.

 

[ledvedder]

How different is the SLO from the BE?

 

[sahlomonic]

How different is the SLO from the BE?

You can apply the gain cut on the OD channel as well. Short, short answer: BE has higher plate loads on the first stage, different cold clipper, and the gain pot is in another gain stage further down than SLO. I mean, it's very different, but also not that different.

The Custom22 and 50H schematics I have show the values, and should be the same as the 22H (C22 is just slightly different in a couple areas)

 

[JackBootedThug]

I think there's a good thread about this on the Guitar amp board.....

 

[sahlomonic]

I think there's a good thread about this on the Guitar amp board.....

There is, but that thread is pretty dead. I try to give it a little life every now and then, but not a lot of dudes posting in there anymore

 

[ledvedder]

I mean, I'd like to do the SLO on the OD channel.

 

[Speeddemon]

Add a Depth Mod/Resonance to it.

Did that to mine when I had it....along with some other toggles that I already forgot what they did.

 

[paulyc]

Crazynutz drew out the schematic as psychodave described it, it’s here on the forum somewhere (for the single channel), but he (psychodav)described cutting traces and using unobtanium parts for some of it…

 

[ledvedder]

Crazynutz drew out the schematic as psychodave described it, it’s here on the forum somewhere (for the single channel), but he (psychodav)described cutting traces and using unobtanium parts for some of it…

Yeah, I've downloaded that schematic. I'm just not sure how it would be done on my 2 channel one.

 

[ledvedder]

Add a Depth Mod/Resonance to it.

Did that to mine when I had it....along with some other toggles that I already forgot what they did.

Yep, I already have a depth and NFB control.