Guitar Gear Forum

Anyone who has done the SLO mod for the JCA 22 could please help me with the component changes? I seem to be getting mixed up with the values and components as there looks like there are a few different opinions in the SLO thread. Thanks...

The 22H preamp circuit is a bit different in some spots from the 50H and 100H, but you could get reasonably close to the SLO. There is another mod that I am working on for the 22H at the moment if you would like to try it out after I get it squared away. Definitely more in the vein of a Hotrod Marshall thing.

I knew Jay would make it by, eventually

GRIMESPACE wrote:I knew Jay would make it by, eventually

Never too far from home. I'm still hammering out the tunes on my JCA20H/Greenback rig. That little amp loves the pedals!

If you saw the video of Mine and Pablo's mini amp fest, the first 3 minutes were of a JCA100H that I modded for a friend of mine. Dude loves the crap out of it. Says it's very "'80s So-Cal"

Digitech Rp1000 tested with 4CM in the JCA100HDM and work like a charm. I didn't try all effects of course only the ones I use that are stored in mt patches mainly chorus, phaser, delays, reverb. Hope this can be usefull to someone.

Finally I tested a Guitar with 2x Humbuckers and it's really not easy to get clean sound, you really need to have a low preamp (1) to get there with a JB full volume on the guitar. I have a spare 12AT7 to try on V1 slot and that way maybe I can have some more clean headroom. By the way where's the V1 position on this amp?

Jay wrote:The 22H preamp circuit is a bit different in some spots from the 50H and 100H, but you could get reasonably close to the SLO. There is another mod that I am working on for the 22H at the moment if you would like to try it out after I get it squared away. Definitely more in the vein of a Hotrod Marshall thing.

Thanks Jay, Hot Rodded Marshall is good. Will await...
I tried to match up the components and for instance- "change C28 (250p) to 470p" Put on toggle for Bright mode" C28 is an electrolytic on the 22. So I'll just hold off for now.

NU-X Time Force delay works well in the loop f you want to add to the approved delays list. Only time will tell whether it will hold up to gigging, it's not the sturdiest build quality. But the delays are top notch for the money. It was $60 on amazon prime so I figured it was worth the risk.

If the Nova Delay was on your radar but you don't have the scratch for it, the NU-X is a nice alternative.

Is the V1 slot (JCA100HDM) the first one on the left? with metal cover?

HavPT wrote:Is the V1 slot (JCA100HDM) the first one on the left? with metal cover?

V1 is nearest the guitar input. Not sure if left or right, it's easier to look at it from inside and outside chassis by checking location that way.

Ok understood, thanks!

Hi all,

For my birthday this year, I booked time in a studio and invited some friends. Literally wrote, learned, and recorded this in 4 hours. Turned out to be a perfectly respectable rock song.

https://soundcloud.com/gainzilla/feels-like-a-crime


Guitar is an '83 Tokai LoveRock gold top. Amp is the Jet City JCA20HV I've been modding for a while. I'm playing guitar and singing.

Amp Mods:
- Anti-harshness mods to prevent el84s from peeling pain off the walls (small cap across the NFB resistor, zobel after PT/Conjunctive filter before PT)
- Changed PI values to be more el84 friendly
- A few general circuit value changes - Bit closer to a JCM800
- Mojo Dijon caps

Pretty rad first post. Sounds great! Welcome to the club

Holy crap! That sounds stellar, Gainzilla! You need to post a thread about this in the regular forum so it get's the recognition it's due. Too good to sit in just this thread alone

to the club! I'd love to see some documentation shots of what you actually did, if you don't mind showing. Very interested in whatever makes the head from a regular H to an HV, too.

Thanks! The whole party was 50% cheaper than my kids last birthday party. Lol

The hv schem is nearly identical, with only a handful of values changes and be additional resistor.

- C29: 47mf input cap in 20H (omitted in 20HV)
- R28: 220k v1 plate in 20H (100k in 20HV)
- C24: .02mf stage2 coupling cap in 20H (.2mf in 20HV)
- C23: 470p bright treble peaker in 20H (270p in 20HV)
- C15: 1mf 3rd stage cathode bypass cap in 20H (25mf in 20H)
- Additional resistor: 150k to ground from the junction of R53 and the gain pot
- Depth switch in 20HV
- FX loop in 20HV (reportedly mojotone lossless)

I thinks that's about it. Literally as described... Less gain and warmer than the 20H l. Lol

Also, I just remembered, the first mod I did to the amp was to swap out the rectifier diodes with Fast recovery diodes.

Cheers!

Where should I post my sound clip? I'm pretty u finalist with this board. Perhaps I should poke around a bit! Thanks for the warm welcome!

Cheers!

Forgot to ask - what speaker(s) / cab?

Thanks for posting the info!

As for posting the clip, I'd make a new thread about it in the Amps & Guitars main forum. The soundcloud clip you posted above is perfect!

Gainzilla wrote:Hi all,

For my birthday this year, I booked time in a studio and invited some friends. Literally wrote, learned, and recorded this in 4 hours. Turned out to be a perfectly respectable rock song.

https://soundcloud.com/gainzilla/feels-like-a-crime


Guitar is an '83 Tokai LoveRock gold top. Amp is the Jet City JCA20HV I've been modding for a while. I'm playing guitar and singing.

4 hours? Damn, nice work!

GRIMESPACE wrote:Forgot to ask - what speaker(s) / cab?

Can't believe I forgot to post that. The cab was the Jet City JCA12S+ loaded with a WGS Reaper 30. Pretty cool, portable rig.

The amp is capable of more gain than on the recording, but I ran the gain around noon and hit the front end with a Joyo Ultimate Drive set up like a clean boost and a bit of tone shaping. Really digging this setup right now.

Cheers!

Slobber Rod wrote:4 hours? Damn, nice work!

Thanks, man! Yeah, I booked the studio for 6 hours, then showed up 45 minutes late. Factor in set up, tear down, and a bit of celebrating, Im pretty happy with it.

Cheers!

question for you FX loop users, particularly the 22H and 2212C; What are you using for a lead boost? Currently I'm using a boss GE-7, which works at moderate volumes but not so much when you push the amp to higher gigging levels.

Should I be using an actual clean boost? Will this actually overcome the fact that I'm pushing the power section when I get to higher volume levels? Or will it react the same as the GE-7 and just add more gain? Boosting my leads is the only issue I'm having now. I'm on the lookout for a good deal on a 50 or 100 in the near future, which should solve the headroom issue and ultimately give me more volume to work with, but for now I really am digging the little 2212C.

Never had a loop like this before so any help is appreciated, thanks!

The loop on my 50 is pretty picky, but I've had luck with the TC BLD and MXR Micro Amp (as clean boost), and limited luck with the MXR 108 eq to do a solo boost. When I do, volume can jump up significantly.

It's really up to what you're trying to do. If it's just jumping the volume, that boost in the loop trick is fine. If it's adding gain, then you need to hit it up front with an OD or clean boost (to ram the front-end) If it's boosting particular frequencies, then an EQ serves both front and loop fine.

Thanks Grimespace. I'm actually only after a boost in volume. Been using EQs for this function for years, but those were different loop designs. Don't really need to change the EQ-ing, so am going to try an actual clean boost. After a little reading it looks like the BLD is top of the list for me to check out.

Thanks again brother, I knew you'd be able to help!

Lots of other clean boost options out there, too. Good luck - make sure you report back what you find!

Hello everyone I am Jordan. I am brand new to the forum and am a brand new owner of a JCA22H. I purchased the amp after selling my AC30HW for the simple facts that it has an effects loop and it has a lot of MOD support. I want both the clean/crunch and scoop mods on my 22H and want them to be switchable. I have spent hours looking over the schematics for the JCA50,100 and 22H as well as searched the main places in the forums and see that there are some inconsistencies. and differences to how people are installing the mods across the models. Also some of the more advanced people take some liberties when explaining the mods making it hard for a newb like myself to understand. I have performed many simple mods on past amps and feel I can conquer these and a few more with some help. Yes I am aware how to discharge the caps. Yes I am aware of the SLO mods, the pot mods, the slope resistor mod and bright switch mods etc.

Is anyone out there able and willing to answer a few questions I have about installing the clean/crunch and scoop mods on my JCA22H?

'Able' depends on the question... what questions do you have? Fwiw, I've made those mods to my 50H. Pretty sure I documented those pretty heavily in this thread, but happy to help ya out.

And, you answered my first question about discharging caps

Second question is what are you looking to get out of the clean/crunch mod? I can tell you that my first reaction was 'this sucks' - the gain does drop considerably, but so does the volume. The other thing is that the clean mod (for me) doesn't do well with gain pedals, so trying to set it up as a clean pedal platform isn't (again, IMO) really practical. As long as you go in with that expectation, I think you'll be fine. In fact, I made peace with it, and even wound up liking it quite a bit.

Good luck, and to the board, brother!