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I say the main difference is a the pots are 1m instead of 500k making the jca sounding a bit darker and a 100k plate resistor for one of the loops stages. I'm going to work on the warren haynes mod, the depth mod, the scoop mod and the clean/ crunch mod an a couple of others. I'm also going to fix the layout of the thread soon. and some cosmetic mods too, I want to retolex in white snakeskin and I want to do a metal grill.
The thread is a work in progress so check back often and don't be afraid to discuss and join in! What mods do you want to see?
High Voltage Warning
WARNING! - Please Read this Information Carefully:
The projects described in these pages utilize POTENTIALLY FATAL HIGH VOLTAGES. If you are in any way unfamiliar with high voltage circuits or are uncomfortable working around high voltages, PLEASE DO NOT RISK YOUR LIFE BY BUILDING THEM. Seek help from a competent technician before building any unfamiliar electronics circuit. While efforts are made to ensure accuracy of these circuits, no guarantee is provided, of any kind!
USE AT YOUR OWN RISK: THE WEBMASTER, PROJECT COORDINATOR, PROJECT CONTRIBUTORS AND WEB SPACE PROVIDER EXPRESSLY DISCLAIM ALL LIABILITY FOR INJURY OR PROPERTY DAMAGE RESULTING FROM THIS INFORMATION! ALL INFORMATION IS PROVIDED ‘AS-IS’ AND WITHOUT WARRANTY OF ANY KIND.
BASIC REQUIREMENTS Before handling
* UNPLUG IT FIRST Pretty self explanatory. Do not, ever, ever, leave the equipment plugged in and start work on it. Leaving it plugged in guarantees that you will have hazardous voltages inside the chassis where you are about to work. This is like setting a trap for yourself.
* LET IT DRAIN If the amp has been turned on recently, the caps will still have some high voltage left in them after the switch is turned off. Let it sit for five minutes or more (I recommend an hour) after you turn it off.
* SUCK IT DRY When you open up an amp, you need to find a way to drain off any residual high voltage. A handy way to do this is to connect a shorting jumper between the plate of a preamp tube and ground. This jumper will drain any high voltage to ground through the 50k to 100K plate resistor on the tube. To do this successfully, you will need to know which pins are the plate pins. Look it up for the amp you're going to be working on. You'll need to know this for the work anyway. Leave the jumper in place while you do your work ( high voltage electrolytics caps can "regrow" voltage like a battery sometimes. Really. ) Remember to remove it when you finish your work.
* TEST IT Take your multimeter and ground the (-) lead. Probe the high voltage caps and be sure the voltage across them is down, preferably to less than 10V.
* BUTTON IT BACK UP FIRST Take the shorting jumper out. Put the chassis back in the cabinet, making sure all of your tools, stray bits of solder, wire, etc. are out of it. You don't have to actually put all the screws and so forth back in if you believe more work might be needed, but make sure that the chassis is sitting stably in the cabinet and won't fall out. At the end of a listening test, either continue buttoning up if you're done, or go back to UNPLUG IT FIRST.
Stock schematic jca 50h
Took me a while to fix the schematic as the one that was provided to me was really messed up.
Stock schematic jca 22h
Stock schematic jca 100h
The thread is a work in progress so check back often and don't be afraid to discuss and join in! What mods do you want to see?
High Voltage Warning
WARNING! - Please Read this Information Carefully:
The projects described in these pages utilize POTENTIALLY FATAL HIGH VOLTAGES. If you are in any way unfamiliar with high voltage circuits or are uncomfortable working around high voltages, PLEASE DO NOT RISK YOUR LIFE BY BUILDING THEM. Seek help from a competent technician before building any unfamiliar electronics circuit. While efforts are made to ensure accuracy of these circuits, no guarantee is provided, of any kind!
USE AT YOUR OWN RISK: THE WEBMASTER, PROJECT COORDINATOR, PROJECT CONTRIBUTORS AND WEB SPACE PROVIDER EXPRESSLY DISCLAIM ALL LIABILITY FOR INJURY OR PROPERTY DAMAGE RESULTING FROM THIS INFORMATION! ALL INFORMATION IS PROVIDED ‘AS-IS’ AND WITHOUT WARRANTY OF ANY KIND.
BASIC REQUIREMENTS Before handling
* UNPLUG IT FIRST Pretty self explanatory. Do not, ever, ever, leave the equipment plugged in and start work on it. Leaving it plugged in guarantees that you will have hazardous voltages inside the chassis where you are about to work. This is like setting a trap for yourself.
* LET IT DRAIN If the amp has been turned on recently, the caps will still have some high voltage left in them after the switch is turned off. Let it sit for five minutes or more (I recommend an hour) after you turn it off.
* SUCK IT DRY When you open up an amp, you need to find a way to drain off any residual high voltage. A handy way to do this is to connect a shorting jumper between the plate of a preamp tube and ground. This jumper will drain any high voltage to ground through the 50k to 100K plate resistor on the tube. To do this successfully, you will need to know which pins are the plate pins. Look it up for the amp you're going to be working on. You'll need to know this for the work anyway. Leave the jumper in place while you do your work ( high voltage electrolytics caps can "regrow" voltage like a battery sometimes. Really. ) Remember to remove it when you finish your work.
* TEST IT Take your multimeter and ground the (-) lead. Probe the high voltage caps and be sure the voltage across them is down, preferably to less than 10V.
* BUTTON IT BACK UP FIRST Take the shorting jumper out. Put the chassis back in the cabinet, making sure all of your tools, stray bits of solder, wire, etc. are out of it. You don't have to actually put all the screws and so forth back in if you believe more work might be needed, but make sure that the chassis is sitting stably in the cabinet and won't fall out. At the end of a listening test, either continue buttoning up if you're done, or go back to UNPLUG IT FIRST.
Stock schematic jca 50h
Took me a while to fix the schematic as the one that was provided to me was really messed up.
Stock schematic jca 22h
Stock schematic jca 100h
Mods
Basic SLO Mod
I'll add the crunch/clean switch, the bright switches and the scoop mod individually that way it doesn't overwhelm some one who just wants the basic aggressive stock s.l.o sound.
Numbering is for the 50H
The Predator mod
A high gain metal mod for both channels. changes up the lead channel a bit and adds the sucker punch to the crunch channel. The change in r36 is optional.
Numbering is for the 50h
The sucker punch mod:
r34= 680k
c23=250pf
This mod only affects the "crunch channel" not the lead channel
The resistor numbers for this are for the 50h
Simple clean channel:
This is the less involved simple way to do it, for the beginner. You can make it switchable. basically you add a 39k resistor to ground after r42 an before the gain pot. I think dues has 68k in his and say it sounds "punchier".
The resistor numbering is for the 50h
Simple crunch channel:
So you want more gain huh? replace r42 with a 470k resistor (Or solder another 1m resistor in parallel with the stock r42) and replace c28 with a 470pf cap ( i recommend a silver mica cap). There you go gainiac.
The resistor numbering is for the 50H
S.l.o. clean/crunch switch:
Use a dpdt switch to put 470k resistor in series with another one making the total resistance close to 1m (aka the stock value) and adding a 39k resistor to ground. When the switch is activated the first 470k resistor is out of the circuit along with the 39k resistor to ground and you have a resistance of 470k aka the crunch mode. Same concept as the "simple" versions of this.
The resistor numbering is for the 50h
Decadence Mod
Similar to the clean/crunch mod except this gives you a crunch AND a better clean channel.
The resistor numbering is for the 50H
Simple scoop mod
The simple scoop mod is a basically a t-filter. You replace r34 with 2 1m resistors in series with a .001uf cap soldered from the middle of the resistors to ground.My version has a standard 22uf fenderish cathode bypass cap on r 45 and is switchable.
Depth
So basically Your looking at the pot exactly like this. the above just illustrates the resistor number for the nfb resistor and to what output jack you connect it to.
also in case you have a 20h and want to join the fun here's the 20h mod thread.
http://acapella.harmony-central.com/...nd-owners-c
Basic SLO Mod
I'll add the crunch/clean switch, the bright switches and the scoop mod individually that way it doesn't overwhelm some one who just wants the basic aggressive stock s.l.o sound.
Numbering is for the 50H
The Predator mod
A high gain metal mod for both channels. changes up the lead channel a bit and adds the sucker punch to the crunch channel. The change in r36 is optional.
Numbering is for the 50h
The sucker punch mod:
r34= 680k
c23=250pf
This mod only affects the "crunch channel" not the lead channel
The resistor numbers for this are for the 50h
Simple clean channel:
This is the less involved simple way to do it, for the beginner. You can make it switchable. basically you add a 39k resistor to ground after r42 an before the gain pot. I think dues has 68k in his and say it sounds "punchier".
The resistor numbering is for the 50h
Simple crunch channel:
So you want more gain huh? replace r42 with a 470k resistor (Or solder another 1m resistor in parallel with the stock r42) and replace c28 with a 470pf cap ( i recommend a silver mica cap). There you go gainiac.
The resistor numbering is for the 50H
S.l.o. clean/crunch switch:
Use a dpdt switch to put 470k resistor in series with another one making the total resistance close to 1m (aka the stock value) and adding a 39k resistor to ground. When the switch is activated the first 470k resistor is out of the circuit along with the 39k resistor to ground and you have a resistance of 470k aka the crunch mode. Same concept as the "simple" versions of this.
The resistor numbering is for the 50h
Decadence Mod
Similar to the clean/crunch mod except this gives you a crunch AND a better clean channel.
The resistor numbering is for the 50H
Simple scoop mod
The simple scoop mod is a basically a t-filter. You replace r34 with 2 1m resistors in series with a .001uf cap soldered from the middle of the resistors to ground.My version has a standard 22uf fenderish cathode bypass cap on r 45 and is switchable.
Depth
So basically Your looking at the pot exactly like this. the above just illustrates the resistor number for the nfb resistor and to what output jack you connect it to.
also in case you have a 20h and want to join the fun here's the 20h mod thread.
http://acapella.harmony-central.com/...nd-owners-c
I hadn't played my JCA50H in about a week, but when I went to the basement (My guitar room) I noticed that I had left my amp on
Everything seems fine, but was wondering if it had any effect on my tubes since they had been on for a week straight. I also want to soon replace all of the tubes to warm the tone up a bit, what are the best tubes (that you guys have found) to warm this head up?
Everything seems fine, but was wondering if it had any effect on my tubes since they had been on for a week straight. I also want to soon replace all of the tubes to warm the tone up a bit, what are the best tubes (that you guys have found) to warm this head up?
Originally Posted by Blakkwater
Originally Posted by cscbo1
I hadn't played my JCA50H in about a week, but when I went to the basement (My guitar room) I noticed that I had left my amp on
Everything seems fine, but was wondering if it had any effect on my tubes since they had been on for a week straight. I also want to soon replace all of the tubes to warm the tone up a bit, what are the best tubes (that you guys have found) to warm this head up?
Everything seems fine, but was wondering if it had any effect on my tubes since they had been on for a week straight. I also want to soon replace all of the tubes to warm the tone up a bit, what are the best tubes (that you guys have found) to warm this head up?
I haven't had a chance to play around with tubes too much, just the stock chinese. I hear that a 12au7 in v1 make it sounds marshallish on the lead and super clean on the crunch channel.
Originally Posted by FastRedPonyCar
Originally Posted by OceansBetweenUs
The only one I can confirm is the JCA22H. I'm not sure if the 100H/100HDM/50H does or not. Seems there's a thread around here where someone from Jet City says the loop was done differently for the 22H due to complaints...which I don't know if that includes all previous models or not. Seems most Soldano and Soldano-designed amps have the same issue with loops that don't work quite right with pedals.
Originally Posted by jenksdrummer
I already have the EHX Nano Holy Grail that works great in the loop.
I have the G Major, but I hate fiddling with the patches and have decided I prefer the plug and playability of single pedals more.
Originally Posted by OceansBetweenUs
Oh I know. I just went back and checked Billy's JCA pedal thread - the Hardwire Delay and Reverb work, but not the chorus
I already have the EHX Nano Holy Grail that works great in the loop.
I have the G Major, but I hate fiddling with the patches and have decided I prefer the plug and playability of single pedals more.
I already have the EHX Nano Holy Grail that works great in the loop.
I have the G Major, but I hate fiddling with the patches and have decided I prefer the plug and playability of single pedals more.
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