Guitar Gear Forum

gorkyporky wrote:

Big John wrote:

gorkyporky wrote:...the list says that the effects loop tolerates MXR Micro Amp and the TC Booster Line Driver. Would putting that in the loop boost my overdrive channel a bit louder as well? Because when i put an overdrive in front of the amp, it just gets more gain and changes the tone, but not the volume...

You can use a clean boost in the loop for raising the amp's overall volume and it won't change the tone of the amp if the pedal is neutral sounding. Awesome way to bring up solos if the soundman is asleep. Myself, I prefer to go the other way and use a rhythm cut pedal, then kick it off (bypassing the pot) for solos.

So this clean boost would work even with heavily distorted channels and at high volumes? I have my volume for the overdrive channel set at about 6 during practice. Would it still work? I mean this two specific pedals, the micro amp and the line driver?

Hiya - Just rolled back a few posts and realized I missed some...

I'm the one that tried those two pedals, but it's been a while and not at high-volume. Unfortunately, my BLD died on me, so I'm not able to test that (they're a bit hard to find these days, anyway). I did try out my Micro Amp in the loop a while back, and it worked pretty well for boosting volume without adding gain - as long as I didn't crank it to the point of clipping. I've also tried out my MXR EQ in the loop, which can boost clean and/or do so on select frequencies.

I'll try to do a bit of testing at higher volume in my studio this weekend & let you know what I find.

sleewell wrote:Can I join?

Hey sleewell! Sorry I missed you, too

Hell yeah you can join in. Is that thing heavily modified from the stock JCA? Gut shots are mandatory

Btw - congrats on the kiddo!

GRIMESPACE wrote:

gorkyporky wrote:

Big John wrote:

gorkyporky wrote:...the list says that the effects loop tolerates MXR Micro Amp and the TC Booster Line Driver. Would putting that in the loop boost my overdrive channel a bit louder as well? Because when i put an overdrive in front of the amp, it just gets more gain and changes the tone, but not the volume...

You can use a clean boost in the loop for raising the amp's overall volume and it won't change the tone of the amp if the pedal is neutral sounding. Awesome way to bring up solos if the soundman is asleep. Myself, I prefer to go the other way and use a rhythm cut pedal, then kick it off (bypassing the pot) for solos.

So this clean boost would work even with heavily distorted channels and at high volumes? I have my volume for the overdrive channel set at about 6 during practice. Would it still work? I mean this two specific pedals, the micro amp and the line driver?

Hiya - Just rolled back a few posts and realized I missed some...

I'm the one that tried those two pedals, but it's been a while and not at high-volume. Unfortunately, my BLD died on me, so I'm not able to test that (they're a bit hard to find these days, anyway). I did try out my Micro Amp in the loop a while back, and it worked pretty well for boosting volume without adding gain - as long as I didn't crank it to the point of clipping. I've also tried out my MXR EQ in the loop, which can boost clean and/or do so on select frequencies.

I'll try to do a bit of testing at higher volume in my studio this weekend & let you know what I find.

Spent some time boosting the loop with my Micro Amp & MXR EQ pedals this morning. Ran both channels fairly loud on the masters and I feel that both those pedals would make great solo boosts. The Micro Amp didn't seem to color the sound at all - just gave me MORE when I kicked it in. Only thing that might be a problem is that it seemed to make a much bigger difference on the Crunch channel than the OD channel. I'll have to experiment some more to make sure, but all-in-all, I think it's a very workable solution.

On a side note, John's suggestion has equal merit. In fact, I recall several guys (including FastRedPonyCar) stating that they were using volume pedals in the loop as a sort of attenuator, to provide "boosted" / non-boosted volume levels.

Ok, so I bought another Zoom G3 to see if it worked in the loopof a 5012c...verdict...It does and doesn't the crunch seems to be ok but overdrive has the same issue as other pedals. If you press the active switch helps but still has issues with gain

GRIMESPACE wrote:Hiya - welcome to the group!

Hopefully Jay, MidnightLaundry, BigJohn, or one of the other regulars will pipe in on this. Caps are definitely something I'm interested in going through at some point. First on my list, however, is to install new heater wiring and probably an external bias & probes.

Please tell us more about the Verellen. This was one of the early modded versions that JCA sold, right? Very interested in any gut shots & details as to what the changes actually comprise.

There were a limited amount of Verellen clean heads offered through JCA. Mine was not one of those originally released, but sent it to him personally to work his mojo.

As much as I want to share with the world, I have a great deal of appreciation and respect for Ben and I am going to keep his mod a secret, unless he personally tells me he doesn't give a sh!t haha. Although I am sure he doesn't want a flood of people sending these 20watters to him and would like to focus on the amps of his own design, (which are AWESOME, and $$$) if he didn't care, he probably would have just sent me instructions

Regardless, It is a very simple modification. Remove this, jumper that, add a duplicate of one of these dohickeys and tap them in here and here. It is certainly not the same as the clean mod that has already been described on this forum.

Along with his mod, I added the choke mod and replaced the small ceramic caps with silver micas. I don't plan on doing an orange drop recap any time soon, but these small mods definitely helped the amp even more. Personally, I can just loop at these caps and I think to myself "Yeah...this is better"


I did go ahead and pull the trigger on duplicating the mod on my second head before making a video to compare, but I am actually looking at picking up a third head locally for a handshake and a song. I couldn't wait to have two of the same amp setup in stereo, so the comparison had to wait. I actually haven't been able to make noise this week at all, but next week....it's on! Video soon, but here is a sneak peak of both amps in my garage after I finished recovering them and adding my Verellen plaquards

Hmm, I forgot about Silver Micas...I bet the amp is less harsh.

Been a long time since I have been on here. Switched to bass guitar and am really digging the transition. Had some medical issues that lead me down that road and took over use of my hand. All is well though.

Here is my contribution to the JCA20H Brown Eye Mod. It is basically a write up of what needs to happen. I try to see things in a logical fashion so I put each task into an individual bullet point.








Link to my photobucket album. http://s150.photobucket.com/user/TnPaul ... -%20JCA20H

I really should record a clip of it and post it on here. It sounds fantastic. Especially with a Greenback. I do not like them with V30s at all.

But Jay, I got a question for you: I would like to reduce the gain relatively dramatically via toggle switch. I want to keep the voicing the same because I love the voicing, but the gain is over the top for what I am required to play. I need a tiny bit of breathing room. As it stands, to get any clean out of it, I need to turn the preamp to 0.25 and the master up to taste. I would like to reduce the gain on tap. Any suggestions?

Well a brand new owner of a JCA50H and I can add one thing - Joyo Delay, phaser and chorus do NOT work in the loop - so i shall be buying a GT 10 or 100 real soon. Having only had a hour long blast on my new amp I am a very happy owner of a JCA - Using my 89 Washburn KC90V with a JBJ in the bridge I get an almost quintessential 80's vibe!

Whelp, happy to say I'm staying in the club. Snagged a deal on a 6505+ head this week and after playing it extensively head-to-head against the JCA22, the JCA's staying. I like the gain structure more, the lead channel is much more useable and my GT100 sounds great in the loop.

Great stuff, Marshallnoise! Interested to see how it all works out. Clips are mandatory!

DocRawk - welcome to the board and to the JCA club. Have you swapped tubes & set up the bias yet? Lots of mods available for that platform. Love my JCA, too!

Axe - glad to hear you're gonna hang around. Pretty interesting that you're wanting it over the Peavey - you've got quite the collection happening!

Surprised me too. But I just dig the tone of the JCA more.

GRIMESPACE wrote:
DocRawk - welcome to the board and to the JCA club. Have you swapped tubes & set up the bias yet? Lots of mods available for that platform. Love my JCA, too!

New valves and a bias are next on the list ;-) Not going to mod just yet, not while I have a warranty = very cautious after I bought a second hand Ashdown valve head that dies 2 weeks after buying to find the parts are nearly impossible to get!! ;-)

Axe wrote:Surprised me too. But I just dig the tone of the JCA more.

It feels more dirty and raw to me...I find myself wanting to dig in harder. Love ma JC22H

Meelocheck wrote:

Axe wrote:Surprised me too. But I just dig the tone of the JCA more.

It feels more dirty and raw to me...I find myself wanting to dig in harder. Love ma JC22H

That's *exactly* what I find too. I replaced the stock tubes with EHXs in the preamp section and JJs for the power section and the tone is so raunchy without getting muddy or blurry. It's definitely an amazing amp, especially for the price.

How quiet (at idle) is your 22H compared to the Marshall & Fender, Axe?

Noise (hum & buzz) control is next on my list for mods.

GRIMESPACE wrote:How quiet (at idle) is your 22H compared to the Marshall & Fender, Axe?

Noise (hum & buzz) control is next on my list for mods.

Dead quiet. Quieter than the JMP and as quiet as the Super-Sonic.

I don't suppose you could put up a few detailed gut shots? Big John posted about JCA putting in a twisted pair heater, and I'm just curious if it's been adopted in the newest units. Yours is near-new, right?

Mine's just a few months old but I have no idea how long the store had it in stock.

Hi - I've lurked on this thread on and off and picked up some good tips. Installed depth mods on both my JCA100H and 20H. However my 100H has developed a fault and I wondered if anyone here could help?

The Normal channel has gone kaput. Happened while playing at home, it went pop and just left a loud hum instead of a signal. Odd thing is the OD channel is working perfectly. Its not a preamp valve (swapped them all) so I'm a bit stumped about what it could be. Any ideas?

EDIT: measuring a few of the resistors and R48 by the input jack is reading 0 ohms. Could that be it? (disclaimer - i'm not an electronics expert!)

Hi guys

Just bought on eBay a Bias test Probe and will be ordered new valves soon - where is the bias trim pot on the jca50h please?

hi DocRawk - looks like that's a 50h in the pic above my previous post. The bias 'wheel' is over on the left side of the pic to the immediate right of two purple wires. Not sure that's a stock 50h, as on my 100H the bias pot is smack in the middle of the board. Maybe someone else can clarify? In any case the bias 'pot' is a black metal wheel that has knurls on the outside (don't use your fingers to move it! Use a wooden or plastic tool, for safety)

massless wrote:Hi - I've lurked on this thread on and off and picked up some good tips. Installed depth mods on both my JCA100H and 20H. However my 100H has developed a fault and I wondered if anyone here could help?

The Normal channel has gone kaput. Happened while playing at home, it went pop and just left a loud hum instead of a signal. Odd thing is the OD channel is working perfectly. Its not a preamp valve (swapped them all) so I'm a bit stumped about what it could be. Any ideas?

EDIT: measuring a few of the resistors and R48 by the input jack is reading 0 ohms. Could that be it? (disclaimer - i'm not an electronics expert!)

Gonna start with my usual disclaimer - if you haven't discharged your filter caps (or even know what I'm talking about), you need to put that thing back together and take it to a tech. Probing around inside your amp could be lethal if you hit the wrong thing. I'm not kidding. We don't wanna have to tell your next of kin that you're having to get your feedings intravenously (if you're lucky) because you were trying to save a few bucks.

I'm going off my 50H schematic, but I'm pretty sure values & identifiers are same with the 100H - at least for the preamp section

If the OD channel doesn't sound any different, I wouldn't think it'd be R48 (1Meg - Brn/Blk/Blk/Yel) as that appears to be tied to the main input and would affect both channels. It may be reading zero resistance now because it's in-circuit. If you pull the V1 tube, does it still read zero?

I'd start with the easy stuff - did you carefully check your wiring for the depth mod? Is there any chance it's shorting something out? Did you do any other mods, like the T-Filter or clean / scoop switch?

You might check out:

• R42 (also 1Meg) or C28 (270pf)
• C29 (0.022uf), C23 (120pf), or R34 (2.2Meg)
• The normal channel gain pot (VR9)
• The normal channel volume pot (VR4)
• The relays used for switching channels: VT4A and VT1A.

I could be wrong, but that appears to be the only components unique to the normal channel

Axe wrote:Mine's just a few months old but I have no idea how long the store had it in stock.

Very interesting - instead of routing the heaters straight from one preamp tube to the next, there's black traces leading the voltage away from the signal components. Perhaps that's why your amp is so quiet - probably more so than my 50H, until I get in there and do the heater mod.

Thanks Axe - that helps a lot

massless wrote:hi DocRawk - looks like that's a 50h in the pic above my previous post. The bias 'wheel' is over on the left side of the pic to the immediate right of two purple wires. Not sure that's a stock 50h, as on my 100H the bias pot is smack in the middle of the board. Maybe someone else can clarify? In any case the bias 'pot' is a black metal wheel that has knurls on the outside (don't use your fingers to move it! Use a wooden or plastic tool, for safety)

Thanks ;-)

DocRawk wrote:

massless wrote:hi DocRawk - looks like that's a 50h in the pic above my previous post. The bias 'wheel' is over on the left side of the pic to the immediate right of two purple wires. Not sure that's a stock 50h, as on my 100H the bias pot is smack in the middle of the board. Maybe someone else can clarify? In any case the bias 'pot' is a black metal wheel that has knurls on the outside (don't use your fingers to move it! Use a wooden or plastic tool, for safety)

Thanks ;-)

Be careful in there, dude - the warnings I stated in the post above apply to all. Touch the wrong thing in there, and you could wind up a puddle of goo. 400+ volts is kick-yer-ass-into-next-week kinda fun...