Guitar Gear Forum

I finally got around to making a video of my modded JCA22H. I did the Cap'n Crunch, Silver Hammer, NFB, High cut, and depth mods. I'm playing it on my Peavey Wolfgang through my EVH 112 and Laney 112 with Vintage 30. I'll admit, I'm no cinematographer

[youtube]https://www.youtube.com/watch?v=HLsnxivNLc4[/youtube]

ibzguy wrote:OT of usual JCA tweakery but do you have any of your bands stuff on youtube? I avoid Facebook like the plague.

Nothing on YouTube yet.

Well if your bands songs are as crunchy as that tone was just call yourselves Peter Pan & The Extra Crunchies!

ibzguy wrote:Well if your bands songs are as crunchy as that tone was just call yourselves Peter Pan & The Extra Crunchies!

What were you expecting from a JCA22H?

Back to upgrades: I may have cheated some. Rather than source out all the parts for what I want to do I just went with the Epic Amplification SLO OD MkII. It seemed to cover most of what I was wanting to do all in one kit. Even addressed that god forsaken loop!

Anyone have any dealings with them?

ibzguy wrote:Back to upgrades: I may have cheated some. Rather than source out all the parts for what I want to do I just went with the Epic Amplification SLO OD MkII. It seemed to cover most of what I was wanting to do all in one kit. Even addressed that god forsaken loop!

Anyone have any dealings with them?

Yep, all of the mods I did are from Epic. Bryce has been awesome!

ibzguy wrote:Back to upgrades: I may have cheated some. Rather than source out all the parts for what I want to do I just went with the Epic Amplification SLO OD MkII. It seemed to cover most of what I was wanting to do all in one kit. Even addressed that god forsaken loop!

Anyone have any dealings with them?

I see this mod is new, and looks interesting. I know the loop is the main thing I would like to change on mine. I think many other issues could be fixed easier if you could actually run a proper EQ in the loop, lol.

I wonder how this varies from the original SLO mod, as far as just the main tone part.

I don't have any issues with the loop on my 22H.

ledvedder wrote:I don't have any issues with the loop on my 22H.

The 22H is the only one that has a proper loop, after the tone stack, before the master section. All of the other amps have the loop before the Tone Stack like the SLO, which sucks, and makes it about useless.

I ordered the Phil X and Epic OD mods from Epic Amplification. It should give me a good plexi/hot-rodded plexi vibe.

Finally got a chance to check out my SLO MkII Epic Amp order. Wow!!! Nice to have everything right there in one order. Plus, the great directions. An idiot like myself can follow them. Unfortunately that project is about #4 in the current project list.

Shask wrote:

ledvedder wrote:I don't have any issues with the loop on my 22H.

The 22H is the only one that has a proper loop, after the tone stack, before the master section. All of the other amps have the loop before the Tone Stack like the SLO, which sucks, and makes it about useless.

I used to think the same way. This is not wrong but it is not right as well. In fact it's more what you want to work with rather than the loop itself and the design.

What I like about the soldano loop is that it is in the circuit all the time. Some people prefer the sound by bypassing it in the pcb (which means taking a tube out of the circuit path actually) but there are two ways to do it and depending on way the sound changes slightly. Miced up, most people can't even tell the difference. So Mike Soldano did good there and he actually did because he didn't comprimise to save a tube. Well he doesn't mass produce at least then...so he could not comprimise.

He did so in the avenger and SL 60 and other preamps or whatever but he never used solid state op amps. There are now good enough solid state stuff to carefully utilise in a loop.



In my avenger he took the ouptut of the plate, then dropped the signal considerably to the ground to create a voltage divider so as to drop the output impedance down to 2K vs the almost 40K which is normally. This may be good enough to drive pedals etc and NOT overdrive them but he has to recover and he does that in the loop return with a big cathode cap...So why?


I mean I don't want to use pedals in the loop (personally). I want to use line level stuff.


So in this case his original design is the correct one. Because it has a strong signal level to drive the g major correctly (and THEN IS WHEN IT DOES NOT ALTER THE FUCKING SIGNAL DAMN IT!!!) and the impedance comes down to 600 ohms taken from the cathode of the original design (4th stage and cathode follower tube).

That makes it great for sex with the 14K unbalanced input of the g major without adding anything to the circuit and that means there is no need for recovery in the loop return unless you desire the linearity.


So I ordered a tube built into the avenger to recreate the original buffer and have a three way switch in the loop return with no cap, 1u cap, 22u cap to select what I like best...


If I used boss pedals or guitar level multieffects or an hx stomp which is overdriven more easily (nothing wrong with those because they were designed to be like this and used with other types of signals) then I would maintain the original design...



Now the loop return doesn't clip easily if at all.


Along with the phase inverter staying clean by design (in logical levels) in the soldano amps you still have, even not ideally, time effects after distortion. So it's ok.



In the new loop design, what is the output impedance of the circuit out? It does use a tube buffer after the master volume obviously but also uses (pretty much the ultimate tone kevin o'connor loop design) ways to regulate the signal...

To me one of the drawbacks is, you now put the whole preamp sound through your effects. The master volume will change that sound depending on setting and you have to recover treble inside the multi effect. That will eat some of its headroom in some cases AND if said effect is not happy with the signal the preamp is putting out as far as level goes, then you will have to keep master volume of the new SLO lower and then compensate in the effects unit. Not always good depending on the processor. So it may be a problem IF you play very loud. There maybe the fixed level old design was better and the tonestack afterwards allowed for easy tone regulatrion after the effects as well. Kind of having post eq in your fingertips to use live. Wait isn't this how normal amps work? Yes it is.


If you overdrive the PI you still get time effects before distortion by the way no matter the design when you have a loop before. And some amps love the overdriven PI and have it as a part of their sound.

I have some killer upgrades in progress on my 2nd JCA22H! Brown Iris Px, Epic OD, cap upgrade, eCap upgrade, TW master volume, and octal power tube mod. As always, Bryce at Epic Amplification has been super helpful and responsive to all of my idiotic questions I can't wait to finish this up and see how she sounds!

I ordered some mods for my Amelia from Epic. Does anyone know what his usual turnaround time is?

facefirst wrote:I ordered some mods for my Amelia from Epic. Does anyone know what his usual turnaround time is?

It took about a week to get mine.

I think it only took about 1 wk for me to get my kit also. Now if I was as on top of things as Bryce I'd be finished already. Also have a nice metal grill coming to replace the front baffle. Looked all over to find one locally and a 5 min search later had one already painted black and almost the right size from ebay. I think it was only about $15 shipped!

Glad to hear Brice is open to questions as I'm sure I'll have a few.

BTW: How cool is the Grunt? Kind of getting a case of GAS for that one.

Yeah, the Grunt does look cool.

This is the most fun amp I've ever had, when it comes to learning about amp circuits. I've been enjoying modding both of my 22H's, and learning how changes in each area affect the tone. And I can't say it enough... Bryce has been super cool and responsive to all of my questions/concerns.

What did you change exactly? The 22h has the slo lead circuit on channel 2 if I remember?

Did you change the first coupling cap, anything on the gain control and anything in the fourth to cathode follower stages?

Here's a couple demo videos of my 2nd JCA22H. The first is the Brown Iris Px mod on the crunch channel from Bryce at Epic Amplification. The second is the Epic OD mod on the overdrive channel. Bryce worked with me to make a few tweaks to this one for my liking. I also did his octal tube socket mod to run 6v6 or 6l6. I wish I had a better setup for making videos, but it is what it is.

[youtube]https://www.youtube.com/watch?v=Vy1fWwzcjTs[/youtube]
[youtube]https://www.youtube.com/watch?v=nQpBZIV715Y[/youtube]

Does anyone know what the effect of R15 is on the JCA22H? One of mine was missing the resistor there. The service manual says it's 1.8k, but I only had 1.5k on hand. I'm just wondering if that makes much difference?

R15 in the manual seems to be the second stage cathode resistor...1.8k bypassed by 1u.

How was it missing and it still worked?

theghostnow wrote:R15 in the manual seems to be the second stage cathode resistor...1.8k bypassed by 1u.

How was it missing and it still worked?

The amp was previously modded, so I ripped all of the mods out, to start from scratch.

Time to bump this!

I finally did something I have been meaning to do for a few years now. I modded my JCA100HDM. I did 3 different things, which took me all day. I modded it to SLO Specs, I moved the Loop to after the tone stack, and I rewired the loop to be pedal level.

The SLO mod is pretty easy and well documented. I did this with a few changes in the poweramp to try to get more bass. I also replaced the ceramic caps with Wima film caps while I was at it. Why not. lol.

Second I moved the loop to right before the Phase inverter. This was a pain in the ass. I had to cut 3 traces, including drilling through the PCB. I drilled a hole in the back and added a new post-loop Master volume. I used shielded cables back and forth. It was a pain, but very glad I did it. It really helps balance the volume.

Last I re-wired the whole loop to be pedal friendly. I basically just copied the loop from the JCA22H, which is a much better design from what I have read. This got a little janky as I had to stand up resistors in little triangle formations and such on the board, but it doesn't look too bad for all the changes. It sounded pretty good like this, but right before I boxed it all back up I remembered I had a leftover Tantalum capacitor left over from when I modded the loop on my Triple Recto. I threw it on the return stage like the Mesa, and it doubled the volume, but I swear it also made the whole amp punchier. I have tried several pedals, and they have all sounded pretty good except for a few Chinese pedals like Donner and Joyo. They darkened the tone, but all my Boss, Digitech, etc.. are very transparent.

It is funny because the amp actually ended up way different than I expected. I thought it would be like a tamed 5150, because I have never played a real SLO. However, it is more like a killer modded JCM800. Stock it was kind of mushy and overly smooth. It didn't sound bad, but it was just OK. Now it is very open, crunchy, and punchy. I find myself playing Van Halen and Motley Crue riffs over and over, lol, which is funny because I am very much a metal guy. It has a nice bouncy feel that is very dynamic, but quick and punchy. It is so much fun to play. With a boost in front it gets pretty mean. Throwing something in the loop to crank the bass gets it closer to my Triple Recto or 5153 50W, but much tighter. It has only been a few days, but so far I am loving it. It has way less gain than stock, but it is more usable now. I still wish it had more bass, but then again, one of my goals was to not make it something its not. I think the SLO mods cleaned up the mushy low end and lowered the gain which made it more dynamic. All the loop mods basically made the loop usable. The new Master Volume makes the volume less jumpy and easier to dial in.

I see this amp sticking around for a long time now.

Shask wrote: I drilled a hole in the back and added a new post-loop Master volume. I used shielded cables back and forth. It was a pain, but very glad I did it. It really helps balance the volume.

I've been wanting to do this myself. I'd love to see pics or instructions for this if you have time.
Sounds like you made some nice improvements!

mrfret wrote:

Shask wrote: I drilled a hole in the back and added a new post-loop Master volume. I used shielded cables back and forth. It was a pain, but very glad I did it. It really helps balance the volume.

I've been wanting to do this myself. I'd love to see pics or instructions for this if you have time.
Sounds like you made some nice improvements!

Hey, if you just want a master volume right before the power amp and none of the other stuff, you basically just need to cut the trace in between the LDR and C13. It is kind of at the front around where the bass knob is. You would run a wire from the leg of the LDR connected to the trace you cut to the left lug on the pot, and then run a wire from the middle leg of the pot to the leg of C13 that is closer to the front, which was connected to the trace you cut. Then the right leg of the pot would be connected to ground. I grounded mine to the Effects Loop board because I put the knob next to it.

I changed C13 to 47nF for more bass, so I just attached the wire to the leg before I put in the new cap.

Actually, you would probably need to attach a cap in between the LDR and the pot so that it doesn't get static when you move the pot. I would put a 47nF cap on the pot probably, on that left lug, and then attach the wire to it.

i have pictures, but the limits on size of attachments for this board would make it the size of a postage stamp, and it would take a magnifying glass to see anything, lol.