Schweezly wrote:I also recently joined...picked up a 50H last week and just had a chance to put it through a full test yesterday at practice. A few thoughts:
-it seems to have more punch than my JVM. It also seems to have a little more low-mid presence and a brighter top end. Through my Orange 412, I had the treble at maybe 11am and the presence barely on. I loved the crunch at about 8 on the gain, and OD at about 2.5
-I'm torn between the 2 "channels". Speaking of which, I'm very confused by how they work. The "crunch" volume doesn't seem to do anything. It doesn't matter if I use the crunch or the overdrive gain...only the OD volume does anything. Is this an issue with the amp, or am I just lost? I also plugged in a generic channel switch and it didn't switch. Maybe I should read a manual
-I liked it overall, but it seemed like it might have been a little lost at times. I've got 2 gigs this weekend so I might run each amp at one and see what I think. I loved the punch and some of the dynamics, but I feel some things were lost in the middle.
My JVM is currently stuck in clean red mode, which is dark and not my favorite mode. That one of the reasons I grabbed this (I've got 6 gigs in July). We'll see if I end up sticking with both.
Well, to start things off, the two channels bleed into each other a bit, so you get a little crunch on the OD. And redorkulously enough, there is NO switch on the front panel as a hard bypass. So, unless you have the footswitch, you can't switch between Crunch and OD. I put up a little mod in the DIY section to install a toggle for the channels if you would like to have the ability to switch channels without the foot controller.
Couldn't he plug a known working cable into the footswitch jack and test changing channels from OD to crunch by shorting the tip to chassis ground (touch tip to metal nut on any jack)? Just a thought, although I do recommend installing a channel switch as discussed earlier in this thread, provided his amp is working correctly, as this test would bear out.
Hmmm, I'd be interested in both the test and a switch. I'm more confused/concerned about why I can't find any use for the "crunch" volume. It doesn't matter which gain knob I use, only the OD volume controls volume (and I don't remember that being the case when I tested it)
I tested at gc on a Wednesday night, had to run and came back an bought it Friday. I was in a hurry and didn't test again, but I've got a few weeks if there turns out to be an issue
Well, the amp defaults to OD when no switch is plugged in. That's why I made the suggestion for the little switch mod. The Crunch channel can only be activated with the footswitch, otherwise. I don't know why JCA did it that way.
mjtripper wrote:Here is an after / in progress shot. The normal channel is a clean channel now with no bleed from the overdrive channel. The bleed really isn't too bad stock until you start to want a clean channel and as you clean it up the bleed gets annoying, at least for me. The OD voicing changes are just to give it a little of a british flavor and to tighten the low end a little. Some changes are just to reduce noise. I swapped out some components just to a different brand but kept the value just because I had them. I bought this used and had to fix a trace as well as replace the foot switch jack so while I was in there anyway I removed it from the pcb in case it fails again and wired in a front panel normal/od switch.
R2 = 10k Add 620pF between V1-7 and V1-8 C2 = 10nF R6 = 100k-3w Add 47K to ground between R5 and normal gain R4 = 1.5k Add 4.7uF as R4 bypass C7 = 120pF R10 = replace with 2 1M split with 1000pF to ground Remove R20 R9 = 470k C5 = 2.2nF C6 = 620pF C9 = 10nF R18 = 470k R16 = 15k Add 270k in series/after C11 R26 = 39k Add 10nF snubbers to D1-D4 Move relay connection from grid of 3rd od stage to 2nd od stage
Schweezly wrote:I also recently joined...picked up a 50H last week and just had a chance to put it through a full test yesterday at practice. A few thoughts:
-it seems to have more punch than my JVM. It also seems to have a little more low-mid presence and a brighter top end. Through my Orange 412, I had the treble at maybe 11am and the presence barely on. I loved the crunch at about 8 on the gain, and OD at about 2.5
-I'm torn between the 2 "channels". Speaking of which, I'm very confused by how they work. The "crunch" volume doesn't seem to do anything. It doesn't matter if I use the crunch or the overdrive gain...only the OD volume does anything. Is this an issue with the amp, or am I just lost? I also plugged in a generic channel switch and it didn't switch. Maybe I should read a manual
-I liked it overall, but it seemed like it might have been a little lost at times. I've got 2 gigs this weekend so I might run each amp at one and see what I think. I loved the punch and some of the dynamics, but I feel some things were lost in the middle.
My JVM is currently stuck in clean red mode, which is dark and not my favorite mode. That one of the reasons I grabbed this (I've got 6 gigs in July). We'll see if I end up sticking with both.
Well, to start things off, the two channels bleed into each other a bit, so you get a little crunch on the OD. And redorkulously enough, there is NO switch on the front panel as a hard bypass. So, unless you have the footswitch, you can't switch between Crunch and OD. I put up a little mod in the DIY section to install a toggle for the channels if you would like to have the ability to switch channels without the foot controller.
Couldn't he plug a known working cable into the footswitch jack and test changing channels from OD to crunch by shorting the tip to chassis ground (touch tip to metal nut on any jack)? Just a thought, although I do recommend installing a channel switch as discussed earlier in this thread, provided his amp is working correctly, as this test would bear out.
Hmmm, I'd be interested in both the test and a switch. I'm more confused/concerned about why I can't find any use for the "crunch" volume. It doesn't matter which gain knob I use, only the OD volume controls volume (and I don't remember that being the case when I tested it)
I tested at gc on a Wednesday night, had to run and came back an bought it Friday. I was in a hurry and didn't test again, but I've got a few weeks if there turns out to be an issue
Well, the amp defaults to OD when no switch is plugged in. That's why I made the suggestion for the little switch mod. The Crunch channel can only be activated with the footswitch, otherwise. I don't know why JCA did it that way.
Well that's good to know, at least I know it works
By itself, what will removing R20 do? I have been playing/modding a Epiphone Valve Jr I got a few weeks ago in preparation for modding the JCA22H I have. I already purchased the bits needed for the depth mod which seems fairly mandatory at this point...But what will happen if I just cut R20 out of the circuit all together - or put it on a switch? Just curious.
Guitars: Early 90's Ibanez EX Series, Late 80's B.C. Rich Mockingbird, Fairly new Epiphone LP Custom Amp: JCA22H with 4x12 Ibanez Cab No pedals or any real skills...
Meelocheck wrote:By itself, what will removing R20 do? I have been playing/modding a Epiphone Valve Jr I got a few weeks ago in preparation for modding the JCA22H I have. I already purchased the bits needed for the depth mod which seems fairly mandatory at this point...But what will happen if I just cut R20 out of the circuit all together - or put it on a switch? Just curious.
By itself very little , it would change the load on the second stage of the crunch, from ~287k to 330k, so a tiny bit more gain in that channel .
Meelocheck wrote:By itself, what will removing R20 do? I have been playing/modding a Epiphone Valve Jr I got a few weeks ago in preparation for modding the JCA22H I have. I already purchased the bits needed for the depth mod which seems fairly mandatory at this point...But what will happen if I just cut R20 out of the circuit all together - or put it on a switch? Just curious.
C7, R10, and R20 help control the gain and voicing of that channel. Just removing r20 will increase the gain going into the next stage but in combination with the change in c7 and r10 does more to change the voicing then the gain. The standard soldano setup there is a 120pf in parallel with 2.2M without the next (r20) one to ground. To do the srv or scoop mod you replace the 2.2M in parallel with the 120pf with two 1M and put a 1000pf to ground between them in addition to bypassing the normal channel 2nd gain stage cathode with 22uf. The 1000pf to ground scoops out the mids and the 22uf increases the gain. I prefer 1.5k/4.7uf on the cathode just to keep the low end flub in check. With this setup and the resistor to ground right before the normal gain of 47-68k or so when you max the gain it's a nice bluesy breakup and up to about 5-6 is nice and clean. It really depends on what you want out of it and I wanted a very clean sound that stays tight in the low end because I use my neck pickup clean a lot.
Ok, thanks. I was just curious. I do plan on modding my 22 but not until the warranty expires (me being a pussy I guess). I am looking into the mods that will give me a better clean sound on the crunch channel and less low end flub/muddiness in general. Getting low, down and dirty, the amp starts to sound a bit muddy depending on which guitar I am using. The Epi LP flubs bad while the Ibanez seems tighter up top with a little less flub down low.
Also, is there any way to really isolate the pre-amp volume controls? The overdrive side definitely bleeds into the crunch side when I switch over. With the OD side set to zero I get better clean tones out of the crunch side (pre-amp crunch set to 1 with master crunch set to 6). I know the amp technically doesn't have a clean channel but it does ok with those settings IMO. I just don't like hitting the footswitch and then still having to tweak on that OD pre-amp knob. Thanks again, gents.
Guitars: Early 90's Ibanez EX Series, Late 80's B.C. Rich Mockingbird, Fairly new Epiphone LP Custom Amp: JCA22H with 4x12 Ibanez Cab No pedals or any real skills...
Meelocheck wrote:Ok, thanks. I was just curious. I do plan on modding my 22 but not until the warranty expires (me being a pussy I guess). I am looking into the mods that will give me a better clean sound on the crunch channel and less low end flub/muddiness in general. Getting low, down and dirty, the amp starts to sound a bit muddy depending on which guitar I am using. The Epi LP flubs bad while the Ibanez seems tighter up top with a little less flub down low.
Also, is there any way to really isolate the pre-amp volume controls? The overdrive side definitely bleeds into the crunch side when I switch over. With the OD side set to zero I get better clean tones out of the crunch side (pre-amp crunch set to 1 with master crunch set to 6). I know the amp technically doesn't have a clean channel but it does ok with those settings IMO. I just don't like hitting the footswitch and then still having to tweak on that OD pre-amp knob. Thanks again, gents.
The only way I have found to kill the od bleed into the normal channel is move that relay connection. I tried a couple other things that lowered it, mainly by lowering the od gain, but nothing really eliminated it until I moved the relay connection. The mods I listed will give you a sort-of-fendery clean channel. Reducing c2 and c9 to 10nf from 22nf will tighten up the low end some but you could try 4.7 or even 2.2 there as well is you want it even tighter. Just remember c2 and anything else with the first gain stage also impacts the normal channel. Another method would be to reduce the 1uf bypass caps on the first 2 od gain stages.
I forgot to take a picture of the bottom of the board before I put it back together but I just mocked this up. I used a little grinding attachment on a dremel to cut the trace. In hindsight you could just put the drill hole right through the trace. You can also run the wire under the board, I just prefer as many of the connections to be on top as possible.
Okay, so I did the SLO mod, FX loop level mod and change the slope resistor from 47k to 39k on the 50H a few days ago, and just got time to get it kinda loud. This thing is a monster. I should have recorded it. Even with the amount of finger rust I have, it still sounded phenomenal. The gain knob on the OD channel is usable for the whole sweep. I didn't change the gain pot, but it's still a noticeable difference. The string separation is improved, the gain has a bit more of an open grind to it and more 3d quality. The change from 6L6s to 6550s is a lot more noticable with the mods. The slope resistor change may have also helped, but with the added grind in the mids/upper-mids that the 6550s added, the JCA took on a little bit of Marshall flavor. The presence knob does a LOT for the tone/feel of the amp. Keep in mind I was using my LP with the Seth Lovers, so they may be letting the amp do more of the work, and letting the knobs actually have influence over more of the tone rather than slamming the input of the amp with a high-output bucker.
Also, I have heard from a lot of JCA50/100 owners that they did NOT like the way the FX loop level drop mod changed the tone. Most replies were that the tone of the amp because boxy and stiff. In my last SLO clone, I did not notice a severe change in playability when I did the mod, and after tonight, I'm almost certain that the mod just takes to the SLO circuit values better than the JCA/Soldano Hotrod values.
Regardless, if any JCA50/100 owners 'like' their amps, I encourage them to try the SLO mod and slope resistor mod.
Ah, good thread. I will have to read through it all when I get the time. I have a JCA20 that I've done the opposite of most....modded to have less gain.
Still got some tweaking to do on it, but it sounds pretty good for what it is.
Jay - sure sounds like the SLO is a winner mod. I can definitely vouch for the slope resistor mod - as you know, I've got mine on a switch so that I can switch between stock & mod values, and I really like both. Stock is tighter, more aggressive, and the lower value kicks in a looser, sweeter tone that I really love when playing leads and more rock-oriented stuff.
käsebrot wrote:Nice to see this thread is alive again!
So here is my favorite mod on the 22H:
C2: 2,2nF - coupling cap between 1. and 2. gainstage, decreases gain and buzz, makes the overall sound clearer C9: 10nF - coupling cap between 2. and 3. gainstage, reduce the flubbiness in OD channel R3: 1,5k - makes the overall sound little darker, adds a little bit gain R16: 22k - Soldano uses 39k, Marshall often 10k - 22k sits in between and reduces the Soldano smoothness, adds a little bit Marshall grit R18: 470k - votage divider should be reduced with the 22k at R16 to avoid blocking distortion R26: 39k - slope resistor in tone stack - sits between Soldano (47k) and modern Marshalls (33k) - just like Orange and Diezel R42: 56k - a little bit higher NFB pushes the amp in a more modern (Mesa Rectifier) direction
These are only a few changes but quite effective. I like the results very much. The focus is on the overdrive channel, sounds best to my ears with this configuration.
If you like it more brutal and raw, then put in 1,5k for R15 and R23, change the R16 to 15k (or even 10k) and swap out C13.
käsebrot, how would you compare this to the SLO mod, and would this work just as well with the 50/100 series?
No offense, kaesbrot, but honestly, changing the stock JCA to SLO spec made chords CLEARER. and leads are just that much better. Like I said, the string separation is just that much better. I don't think it added gain, really. Before, the gain knob really fizzed and fuzzed out at anything past 5 on the knob. I could crank it to 10 after the mod and everything was still nice and clear.
What kind of speakers are you using? Perhaps that would be the difference?
All those mods you listed are actually pretty close to a mod I had done on an SLO clone a while back. It really does tighten up the amp.
First stage was 1k5//.68uf 4n7 couplers on 1-2 and 2-3 stages. 10k for 3rd stage cathode 470k divider after 3rd gain stage 39k slope resistor
If you want more Marshall flavor, change the 4th cathode resistor to 820R and remove the bypass cap.
käsebrot wrote:I don't know, which part of the SLO mod would marke the amp sounding clearer. With the 220k at R19 you add a lot of gain. And yes, Leads are better because its easier to play solos with the extra gain - but in my opionion, chords loose definition.
If you like the amp with SLO mod better, why not. That's a matter of personal taste and all we do here is to show different possibilities to mod really good amps.
I also like a 0,68uF at V2 (but not at V1). Makes the OD channel a little bit tighter, but then I wouldn't go under 10nF at the coupling cap there.
With the stock 1k8 cathode resistors on the 1st, 2nd and 4th stages, 10k third stage, 470k divider and 4n7 couplers in addition to the SLO spec preamp, the .68 cap on the first stage gave the amp a more raw feel than anything. Almost like a not-so-fuzzy 5150.
Another mod I was doing, but didn't get a whole lot of time to experiment with in place of stock SLO values:
2k7//.68 first stage 1k2//1u5 second stage 10k third stage 1k5//1uf fourth stage 4n7 first Co 470p bypass on 3rd stage anode 220k/330k divider after 2nd stage 180k/180k divider after 3rd stage 33k slope
Wish I had some time to try different anode resistors, but it started becoming like a "vintage" high gain sort of tone.
