JCA OWNERS!!! (RE)JOIN THE JET CITY LOUNGE!!!

[käsebrot]

- 500k pot for depth is fairly enough and much more usable than 1M

- SLO Mod doesn't make the amp sound cleaner and also don't reduce fizzyness, increasing the plate resistor to 220k adds even more gain and compression - maybe good for soloing but worse for riffing

- but changing the gain pots to 500k (and also the caps and resistors there) is a good one - I recommend it for more usable gain control

- CD silver micas are not bad , but in this amp, I would use high voltage ceramics (f.e. 2kV Vishay or Murata) - the higher the voltage the darker the sound. The CD SMs sound very smooth with glassy highs, good Ceramics (especially as bright and treble cap) will at a decent "smear" to the sound, which is well known from Marshall amps. Also take in mind, that SMs can produce issues with dc leakage, so if your amp will make some strange sounds, first check the micas!

- the loop in 50H/100H/100HDM works with line level (4db) and changes a little at higher volumes. TC Flashback does not work properly on this one, it will sound very mushy and will be louder in the crunch channel. No effect will work like you are comfortable to with other amps with post master loops (which the 22H has), every effect will be going through the EQ section which is really a matter of taste, if you like this. I do not.

- if you want to tighten up the sound a little bit, reduce the coupling caps between 1st&2nd and 2nd&3rd Gainstage to 10nF (you can also try even lower values, but this will make the amp quite thin sounding).

- if you wand to improve sound overall, then a) use good tubes, b) bias the power tubes correctly - you won't find much JCAs, where the bias setting is ok, when purchase them new (this is a really big thumbs down in my opinion!), c) swap the caps for better ones - I recommend MKT1813 (better than Mallory 150 imho) in front of the signal path, Sozo Standard in the end (especially in the PI) - all Sozos will sound too wooly, all MKT1813 too brittle.

- if you really want to use Orange Drops (for whatever), then avoid the polypropylene ones (715P, 716P, sound really bad in this amp, like a glassy and snarling Mesa with much biting treble) and go for polyester (225 Series, sound smooth with good colouration in the mids). Try CD DME polyester caps (the winered cheap ones) in the tone stack, you will not regret it!

- there is no need to change the OT, they are quite good and better tubes and caps will improve the sound much more than an other OT

- ALWAYS TAKE CARE OF THE HIGH VOLTAGE IN GUITAR AMPS!


just my .02


note: all these suggestions are only my personal preferences. I've modded and recapped nearly 30 JCAs and this is my own experience.

edit: Loop Level

[Tortuga]

käsebrot - could you be a bit more specific on the caps and resistors you're referring to, with regard to the gain pots? I'm all for getting more usable gain control, but which components and what values should they be changed to in a JCA50H?

Thanks, as always, for your insight!

[käsebrot]

If you use 500k gain pots, you have to change the two 1M resistors (R41,R42) at the pots to 470k, the 1n (C27) to 2n2, the 470p (C21) to 1n. That's all - as described as a part of the "SLO mod".

[midnightlaundry]

I lied. This amp isn't done.

This amp has a ton of gain. Has anyone changed the 220k plate resistors to 100k? It would sound less compressed and more open I'm sure.

[Meelocheck]

Issue I had with mine looks to be a faulty bias pot. I didn't pull the board to check the solder joints yet, but I tried to wiggle it to see if it was loose in any way and the thing started working immediately afterward. I am hoping/guessing I found the culprit.

Now I am going to do the depth mod which is easy enough...but a couple days ago someone posted a vid of a guy plying a JCA22 (I think, may have been a 50 or 100)...Anyway, it was fucking ripping. It is what I want my 22 to sound like. I have no idea which mods I need to do but I am looking to get rid of the fizz and tighten up the bottom end. I have no issue getting components and am going to replace some of the caps with the 715p's because it is what I can get. Will the SLO mod do what I want? The predator mod?

I so wish that I had bookmarked that video because his amp was emitting forth the glorious tone of freedom, beer and titties, all at the same time. I actually wept. I need that sound coming out of me...

[thesockmonster]

- 500k pot for depth is fairly enough and much more usable than 1M

- SLO Mod doesn't make the amp sound cleaner and also don't reduce fizzyness, increasing the plate resistor to 220k adds even more gain and compression - maybe good for soloing but worse for riffing

- but changing the gain pots to 500k (and also the caps and resistors there) is a good one - I recommend it for more usable gain control

- CD silver micas are not bad , but in this amp, I would use high voltage ceramics (f.e. 2kV Vishay or Murata) - the higher the voltage the darker the sound. The CD SMs sound very smooth with glassy highs, good Ceramics (especially as bright and treble cap) will at a decent "smear" to the sound, which is well known from Marshall amps. Also take in mind, that SMs can produce issues with dc leakage, so if your amp will make some strange sounds, first check the micas!

- the loop in 50H/100H/100HDM works with line level (0db) and changes a little at higher volumes. TC Flashback does not work properly on this one, it will sound very mushy and will be louder in the crunch channel. No effect will work like you are comfortable to with other amps with post master loops (which the 22H has), every effect will be going through the EQ section which is really a matter of taste, if you like this. I do not.

- if you want to tighten up the sound a little bit, reduce the coupling caps between 1st&2nd and 2nd&3rd Gainstage to 10nF (you can also try even lower values, but this will make the amp quite thin sounding).

- if you wand to improve sound overall, then a) use good tubes, b) bias the power tubes correctly - you won't find much JCAs, where the bias setting is ok, when purchase them new (this is a really big thumbs down in my opinion!), c) swap the caps for better ones - I recommend MKT1813 (better than Mallory 150 imho) in front of the signal path, Sozo Standard in the end (especially in the PI) - all Sozos will sound too wooly, all MKT1813 too brittle.

- if you really want to use Orange Drops (for whatever), then avoid the polypropylene ones (715P, 716P, sound really bad in this amp, like a glassy and snarling Mesa with much biting treble) and go for polyester (225 Series, sound smooth with good colouration in the mids). Try CD DME polyester caps (the winered cheap ones) in the tone stack, you will not regret it!

- there is no need to change the OT, they are quite good and better tubes and caps will improve the sound much more than an other OT

- ALWAYS TAKE CARE OF THE HIGH VOLTAGE IN GUITAR AMPS!


just my .02


note: all these suggestions are only my personal preferences. I've modded and recapped nearly 30 JCAs and this is my own experience.

Damn. Was afraid of that...the Flashback says it's line level, but...are there any mods out there for the effects loop?

[käsebrot]

- lowering the 1st 220k plate resistor to 150k or even 100k will reduce overall gain and makes the amp more dynamic and vintage sounding (1st plate on 20HV is 100k). It's a matter of taste. You could also go 180k and use a 1,5k cathode instead of the 1,8k, which increases gain slightly and makes the overall sound a tad darker and give you more "roarrr", fe. Splawn does so.

- the new black bias pots (not those formerly "vintage" style ones) of the JCA amps are pure crap. Sometimes just not useable. I would replace them with Piher 50k, so you could expect the bias stays in the right setting when carrying the amp around. I would trust the new ones there.

Meelocheck:

If you want to get rid of the fizz, don't use Orange Drop 715P, it will make the fizz and harsh treble even worse than it is. To tame the fizz, use good tubes and bias the amp properly. If that's not enough, increase the fizz cap a little (300p on 22H, maybe something between 56k and 100k on the 50H/100H/100HDM), also lowering the first coupling caps will help. You can also try a 56k/250pf (slope/treble cap) in the tonestack, it's darker and more vintage sounding. But not my first choice for metal styles.

The only good thing of SLO Mod is changing the gain pots (as I've written already). Skip the rest.
Predator Mod is nothing you will do to your amp. That's a collecion of single conversions which don't fit to each other. I know an amp tech who has done this several times for customers who were willing to pay for - even although he advised them against this. Every single customer then hated the way the amp sounds after Predator mod.

I can tell you, Mike Soldano knows what he does. Those amps are really good. If you want to make them even better, spent your money in quality tubes and caps! A few things could be adjusted for personal likings - but I won't to too much of modding with different values. If you are into this, then better buy another amp which fits your suits as it is stock.


Thesockmonster:

I have tried Flashback, Flashback X4 and Alter Ego. They don't sound good to my ears on the bigger JCAs with this classic Soldano loop (which works with 4dB - that was my mistake in the post before). And this is really a good reason why I prefer the 22H, which has a PMV Loop (which works with 0dB).

[thesockmonster]

- lowering the 1st 220k plate resistor to 150k or even 100k will reduce overall gain and makes the amp more dynamic and vintage sounding (1st plate on 20HV is 100k). It's a matter of taste. You could also go 180k and use a 1,5k cathode instead of the 1,8k, which increases gain slightly and makes the overall sound a tad darker and give you more "roarrr", fe. Splawn does so.

- the new black bias pots (not those formerly "vintage" style ones) of the JCA amps are pure crap. Sometimes just not useable. I would replace them with Piher 50k, so you could expect the bias stays in the right setting when carrying the amp around. I would trust the new ones there.

Meelocheck:

If you want to get rid of the fizz, don't use Orange Drop 715P, it will make the fizz and harsh treble even worse than it is. To tame the fizz, use good tubes and bias the amp properly. If that's not enough, increase the fizz cap a little (300p on 22H, maybe something between 56k and 100k on the 50H/100H/100HDM), also lowering the first coupling caps will help. You can also try a 56k/250pf (slope/treble cap) in the tonestack, it's darker and more vintage sounding. But not my first choice for metal styles.

The only good thing of SLO Mod is changing the gain pots (as I've written already). Skip the rest.
Predator Mod is nothing you will do to your amp. That's a collecion of single conversions which don't fit to each other. I know an amp tech who has done this several times for customers who were willing to pay for - even although he advised them against this. Every single customer then hated the way the amp sounds after Predator mod.

I can tell you, Mike Soldano knows what he does. Those amps are really good. If you want to make them even better, spent your money in quality tubes and caps! A few things could be adjusted for personal likings - but I won't to too much of modding with different values. If you are into this, then better buy another amp which fits your suits as it is stock.


Thesockmonster:

I have tried Flashback, Flashback X4 and Alter Ego. They don't sound good to my ears on the bigger JCAs with this classic Soldano loop (which works with 4dB - that was my mistake in the post before). And this is really a good reason why I prefer the 22H, which has a PMV Loop (which works with 0dB).

Really not wanting go rack...thinking a multieffects may be best in this situation, like a Zoom G3 or Line 6 M9. Frustrating.

However, the Nova series...is that a better option over the Flashback X4?

[midnightlaundry]

I run this amp at 4-5 on the gain. It's more than enough, but it's so compressed that it comes across as too smooth, like the EVH Soldano years. I think I prefer a more toothy attack.

I'll try throwing in some 100k/1.5k resistors tommorow.

[midnightlaundry]

Does anyone have the full schematic for the 5012 with the phase inverter and power tubes?

[justinjag77]

- lowering the 1st 220k plate resistor to 150k or even 100k will reduce overall gain and makes the amp more dynamic and vintage sounding (1st plate on 20HV is 100k). It's a matter of taste. You could also go 180k and use a 1,5k cathode instead of the 1,8k, which increases gain slightly and makes the overall sound a tad darker and give you more "roarrr", fe. Splawn does so.

- the new black bias pots (not those formerly "vintage" style ones) of the JCA amps are pure crap. Sometimes just not useable. I would replace them with Piher 50k, so you could expect the bias stays in the right setting when carrying the amp around. I would trust the new ones there.

Meelocheck:

If you want to get rid of the fizz, don't use Orange Drop 715P, it will make the fizz and harsh treble even worse than it is. To tame the fizz, use good tubes and bias the amp properly. If that's not enough, increase the fizz cap a little (300p on 22H, maybe something between 56k and 100k on the 50H/100H/100HDM), also lowering the first coupling caps will help. You can also try a 56k/250pf (slope/treble cap) in the tonestack, it's darker and more vintage sounding. But not my first choice for metal styles.

The only good thing of SLO Mod is changing the gain pots (as I've written already). Skip the rest.
Predator Mod is nothing you will do to your amp. That's a collecion of single conversions which don't fit to each other. I know an amp tech who has done this several times for customers who were willing to pay for - even although he advised them against this. Every single customer then hated the way the amp sounds after Predator mod.

I can tell you, Mike Soldano knows what he does. Those amps are really good. If you want to make them even better, spent your money in quality tubes and caps! A few things could be adjusted for personal likings - but I won't to too much of modding with different values. If you are into this, then better buy another amp which fits your suits as it is stock.


Thesockmonster:

I have tried Flashback, Flashback X4 and Alter Ego. They don't sound good to my ears on the bigger JCAs with this classic Soldano loop (which works with 4dB - that was my mistake in the post before). And this is really a good reason why I prefer the 22H, which has a PMV Loop (which works with 0dB).

Really not wanting go rack...thinking a multieffects may be best in this situation, like a Zoom G3 or Line 6 M9. Frustrating.

However, the Nova series...is that a better option over the Flashback X4?

My boss gt10 seems to be doing well in the loop, not to mention the versatility you get with it being able to switch amp channels, using boss's preamps time to time, fx chain routing options, good NS for this noisy ass amp....jca5012c

[justinjag77]

Issue I had with mine looks to be a faulty bias pot. I didn't pull the board to check the solder joints yet, but I tried to wiggle it to see if it was loose in any way and the thing started working immediately afterward. I am hoping/guessing I found the culprit.

Now I am going to do the depth mod which is easy enough...but a couple days ago someone posted a vid of a guy plying a JCA22 (I think, may have been a 50 or 100)...Anyway, it was fucking ripping. It is what I want my 22 to sound like. I have no idea which mods I need to do but I am looking to get rid of the fizz and tighten up the bottom end. I have no issue getting components and am going to replace some of the caps with the 715p's because it is what I can get. Will the SLO mod do what I want? The predator mod?

I so wish that I had bookmarked that video because his amp was emitting forth the glorious tone of freedom, beer and titties, all at the same time. I actually wept. I need that sound coming out of me...

I think I talked to you about the bad bias pot
[video]https://www.youtube.com/watch?v=sHW2q15FDwE&list=UUf8KpwJ3ftMFeHJR_lMxafQ[/video]
is this the tone u speak of
[video]https://www.youtube.com/watch?v=fMLDSwsn984[/video]

[shep]

.

[shep]

I run this amp at 4-5 on the gain. It's more than enough, but it's so compressed that it comes across as too smooth, like the EVH Soldano years. I think I prefer a more toothy attack.

I'll try throwing in some 100k/1.5k resistors tommorow.

i threw in a 100k on the first stage and it pulled back on the gain a bit. it adds some nice harmonics for sure. it is really nice for the lead channel. it pulls a little too much gain out of the first channel imo.

[shep]

- lowering the 1st 220k plate resistor to 150k or even 100k will reduce overall gain and makes the amp more dynamic and vintage sounding (1st plate on 20HV is 100k). It's a matter of taste. You could also go 180k and use a 1,5k cathode instead of the 1,8k, which increases gain slightly and makes the overall sound a tad darker and give you more "roarrr", fe. Splawn does so.

- the new black bias pots (not those formerly "vintage" style ones) of the JCA amps are pure crap. Sometimes just not useable. I would replace them with Piher 50k, so you could expect the bias stays in the right setting when carrying the amp around. I would trust the new ones there.

Meelocheck:

If you want to get rid of the fizz, don't use Orange Drop 715P, it will make the fizz and harsh treble even worse than it is. To tame the fizz, use good tubes and bias the amp properly. If that's not enough, increase the fizz cap a little (300p on 22H, maybe something between 56k and 100k on the 50H/100H/100HDM), also lowering the first coupling caps will help. You can also try a 56k/250pf (slope/treble cap) in the tonestack, it's darker and more vintage sounding. But not my first choice for metal styles.

The only good thing of SLO Mod is changing the gain pots (as I've written already). Skip the rest.
Predator Mod is nothing you will do to your amp. That's a collecion of single conversions which don't fit to each other. I know an amp tech who has done this several times for customers who were willing to pay for - even although he advised them against this. Every single customer then hated the way the amp sounds after Predator mod.

I can tell you, Mike Soldano knows what he does. Those amps are really good. If you want to make them even better, spent your money in quality tubes and caps! A few things could be adjusted for personal likings - but I won't to too much of modding with different values. If you are into this, then better buy another amp which fits your suits as it is stock.


Thesockmonster:

I have tried Flashback, Flashback X4 and Alter Ego. They don't sound good to my ears on the bigger JCAs with this classic Soldano loop (which works with 4dB - that was my mistake in the post before). And this is really a good reason why I prefer the 22H, which has a PMV Loop (which works with 0dB).

adding a larger bypass cap (10uF tantalum) on the first stage helped out a lot for me as far as fizzy highs. they are still there but substantially easier to tame now. it also added some more mid range bass that helped fill the tone of the amp IMO.

[käsebrot]

Thesocketmonster:

I don't have experience with Nova Series. Should work with that level - but doesn't change anything of the position of the loop.
Also I would not run a multi effects unit as the GT10 or others in the return of the amp as this runs through the amps EQ and might not sound as it could do in a standard PMV loop.
If someone just want to use a guitar amp as power amp for multi effects, I would buy another amp, which handles this quite good. Or the 20HV or 22H, if you don't need 50 watts or more.


Midnightlaundry:

Do one after one. Reducing the 1st plate to 100k will reduce gain drastically. The lower cathode resistor will increase it a bit, but not that much. You can swap R34 (resistor of crunch channel only) from 2M2 to 1M. That will tame the gain there. And decrease R28 (plate at V3a) to 100k.
If you want less buzz but more bite, swap R32 (cathode on V2b) from 39k to 10k (Marshall Style) and when doing this, swap R36 from 1M to 470k to avoid blocking distortion, as lowering the 39k will give you more gain in the coldstage.


Shep:

If you want to leave the 100k at the first plate but add some gain on crunch channel, just increase the 120p cap to 270p across the 1M in the crunch channel (on 22H there is a 470p across a 1M, which is quite enough).
I wouldn't use tantalum caps in guitar amps. A 10uF at V1a is way too much as does nothing to tame the fizz but increases mud and boosts the lows that much, that you won't here the fizz anymore, that's all.


justinjag77:

I think, this mod is just a more raw variation of the existing brown eye mod for 20H. Google it.

[Meelocheck]

Justin, THAT Was the clip. That amp just sounds mean and nasty in the clip. I am sure speakers play a part in the sound, but my amp just sounds kinda, well, fizzy. I like his tone in that clip as it sounds much darker than anything I have pulled out of this amp so far.

Meelocheck:

If you want to get rid of the fizz, don't use Orange Drop 715P, it will make the fizz and harsh treble even worse than it is. To tame the fizz, use good tubes and bias the amp properly. If that's not enough, increase the fizz cap a little (300p on 22H, maybe something between 56k and 100k on the 50H/100H/100HDM), also lowering the first coupling caps will help. You can also try a 56k/250pf (slope/treble cap) in the tonestack, it's darker and more vintage sounding. But not my first choice for metal styles.

The only good thing of SLO Mod is changing the gain pots (as I've written already). Skip the rest.
Predator Mod is nothing you will do to your amp. That's a collecion of single conversions which don't fit to each other. I know an amp tech who has done this several times for customers who were willing to pay for - even although he advised them against this. Every single customer then hated the way the amp sounds after Predator mod.

I can tell you, Mike Soldano knows what he does. Those amps are really good. If you want to make them even better, spent your money in quality tubes and caps! A few things could be adjusted for personal likings - but I won't to too much of modding with different values. If you are into this, then better buy another amp which fits your suits as it is stock.

Thanks. I am not questioning that Mike Soldano knows what he is doing. I just like to tweak things to suit my personal tastes, not his in this case. Maybe it is my speakers as well (using an old Ibanez 4x12 with shit speakers)? The crunch channel has a decent sound to it but the overdrive gets this fizzy sound to it that I am not really digging. I want to darken it up a bit and remove some of that fizz from the top...The bottom end could actually be tightened a bit as well because it starts to get flubby - again, that may just be speakers...

Thanks for the heads up on the Pred mod. Looking like the SLO isn't going to do it for me either. I guess I just need to figure out which resistors or caps are going to help with the fizz and flubbiness...

Also, I just enjoy messing with amps . I started only a year ago with modding these things and I have become addicted. Started with a Epi VJR, then went to the VHT Special 6 head. Now I Am wanting to try my hand at taming this beast to taste too...Thanks for the tips

[käsebrot]

If you like the crunch as it is but need a tighter OD, try a .68u instead of the 1u at V2. I like MKT1813 as bypass on cathodes very much, but in this case I will recommend to use a Sozo Standard, this will also smooth out the sound in OD channel a bit.

[shep]

I lied. This amp isn't done.

This amp has a ton of gain. Has anyone changed the 220k plate resistors to 100k? It would sound less compressed and more open I'm sure.

i have, and that's how i kept it. it draws a little too much gain away from the first channel. but it really helps the lead channel out. there is still lots of gain but theres more dynamics and harmonic content. you can still get super saturated if you want. still plenty of distortion. try changing the bypass cap to the first stage (10uF). it really helps the mid range bass and mids out. helps add some good clank to the chords and fill in individual notes. with just those two mods, it will make a world of difference in the tone. especially when the amp is wide open.

[shep]

Thesocketmonster:

I don't have experience with Nova Series. Should work with that level - but doesn't change anything of the position of the loop.
Also I would not run a multi effects unit as the GT10 or others in the return of the amp as this runs through the amps EQ and might not sound as it could do in a standard PMV loop.
If someone just want to use a guitar amp as power amp for multi effects, I would buy another amp, which handles this quite good. Or the 20HV or 22H, if you don't need 50 watts or more.


Midnightlaundry:

Do one after one. Reducing the 1st plate to 100k will reduce gain drastically. The lower cathode resistor will increase it a bit, but not that much. You can swap R34 (resistor of crunch channel only) from 2M2 to 1M. That will tame the gain there. And decrease R28 (plate at V3a) to 100k.
If you want less buzz but more bite, swap R32 (cathode on V2b) from 39k to 10k (Marshall Style) and when doing this, swap R36 from 1M to 470k to avoid blocking distortion, as lowering the 39k will give you more gain in the coldstage.


Shep:

If you want to leave the 100k at the first plate but add some gain on crunch channel, just increase the 120p cap to 270p across the 1M in the crunch channel (on 22H there is a 470p across a 1M, which is quite enough).
I wouldn't use tantalum caps in guitar amps. A 10uF at V1a is way too much as does nothing to tame the fizz but increases mud and boosts the lows that much, that you won't here the fizz anymore, that's all.


justinjag77:

I think, this mod is just a more raw variation of the existing brown eye mod for 20H. Google it.

i appreciate your opinion käs. i am using the jca22 now. so not sure about the first channel mod. upping the bypass cap IMO did not make the amp muddy. and yes it most likely is covering up the highend fizz. by equalizing the frequencies being amplified it allows for them to be more easily tamed. tantalum seems to work fine to me

[Meelocheck]

If you like the crunch as it is but need a tighter OD, try a .68u instead of the 1u at V2. I like MKT1813 as bypass on cathodes very much, but in this case I will recommend to use a Sozo Standard, this will also smooth out the sound in OD channel a bit.

Are you referring to C9?

Shep, which plate resistors? I am terrible at locating components without given their location. This also sounds like something I may want to try...

[shep]

If you like the crunch as it is but need a tighter OD, try a .68u instead of the 1u at V2. I like MKT1813 as bypass on cathodes very much, but in this case I will recommend to use a Sozo Standard, this will also smooth out the sound in OD channel a bit.

Are you referring to C9?

Shep, which plate resistors? I am terrible at locating components without given their location. This also sounds like something I may want to try...

it depends on which amp for the jca50/100 the resistor numbering is r46, on the jca22 its r6.

[käsebrot]

I don't know if it's C9, depends on which model you've got. But there is only one 1uF at V2, can't go wrong with this.

[shep]

c8 on jca22, c26 on jca50/100

[Meelocheck]

I love each and every one of you mother fuckers. nohomo

Thanks guys. And sorry, I should have mentioned from the get go it was a JCA22H. I'll get it sorted. I am semi-new to all of this and will eventually get my shit together. Right now I read "try changing R26 from xx to xxx for a larger penis" and I know where to look and what to do. Sometimes the stuff you guys toss around like childs play is very difficult for me to comprehend, but I am learning. Oh, and for what it is worth, changing R26 won't make your pecker any bigger. I tried several values and still nothing