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

[Jay]

I could also recommend to use a 0,068uF cap for presence instead of the 0,1uF stock value. This helps to tame the fizzy sizzle.

This is a good one too. Very nice with the smaller pot value.

[Jase01]

Great thanks.. Next n00b question... Whats the Cap #?

[Jay]

C21 for the 22H

[käsebrot]

[käsebrot]

[Jay]

Ok, here once again:

In my opinion, there is no need to change a lot of the things in a 22H.

But then again, others like the basic, inexpensive platform and find that these mods get them closer to their ideal tone. And a lot of us here just like to tinker and see what changes do what to each aspect of the amp. You can tell someone what each change will do until you are blue in the face. Ultimately, doing the mod and HEARING the difference is what determines if there was justification in the change. All in all, let's all just have fun tinkering.

[Jay]

And I definitely concur that the JJ803s is wonderful in the PI of most amps I have tried them in.

[käsebrot]

Ok, here once again:

In my opinion, there is no need to change a lot of the things in a 22H.

But then again, others like the basic, inexpensive platform and find that these mods get them closer to their ideal tone. And a lot of us here just like to tinker and see what changes do what to each aspect of the amp. You can tell someone what each change will do until you are blue in the face. Ultimately, doing the mod and HEARING the difference is what determines if there was justification in the change. All in all, let's all just have fun tinkering.

You're right Jay!

Here in Germany, there are also a lot of fans of the JCAs. And I have recognized, that so many of them just want to sound their JCAs exactly like a SLO does - but haven't played a SLO before. Just think "hey it's a SLO - this has to sound good!" because of the famous name.

But not everything on an SLO is perfect (just think about that horrible effect loop - when using pedals), especially it's not voiced for that modern core sounds you will hear everywhere. It's more something for Hardrock and "Hair-Metal". That's my opinion.

I have seen many guys, who have modded their JCAs in SLO direction and don't like them better after that. Also talked to amp techs, who complained about their customers coming with that "Predator Mod" on papers they've found in the net and wanted to do them exactly this mod. There was no one, who liked they way the amp sounds after that! This is just, what I've been told.

Sure, that's a matter of personal taste and maybe there will be some guys out there, who really want their amps to have even more gain, mud and fizz, maybe for certain styles of music. Who knows.

I just wanted to tell, what I have done with my amps - and I have tested a lot of several mods. So this would be my personal recommandation. That's all. : )

[Meelocheck]

Oh - and of course:

Put in better tubes and set the bias properly (I like it best at 18mA)!

I recommend JJ EL84 for power amp.

For preamp you could also use JJs - they are cheap and have a good quality!

For PI, a JJ ECC803S or Sovtek LPS is very nice.

For V1 you could also try a chinese one, like a Ruby 12AX7 AC5, gives a little bit more string definition.

For what it is worth, I bought a "matched" pair of EL84's by Mesa from a GC around the corner and they made a huge difference. I know different tubes have a different effect on the amp but the Chinese ones shipped with mine were really fizzy up top and muddy on the bottom. The bias was way off as well (one was at 20mA while the other just a hair above 12mA). With the Mesa tubes I re-biased after installing and they were off only .8mA instead of 8mA and I settled on 20mA for the bias setting. I have the components to do the depth mod, which seems to be the easiest one, and it seems to make a big difference. I did get a 250k pot instead of the 1Meg one I see others using. Anyway, I am just worried about voiding the warranty should something go wrong with the amp itself. Maybe I Should just grow a pair and dig in?

The thing that makes the biggest difference to me is the guitar - or should I say the pick ups in the guitar. I have an Epi LP Custom, the cool ass Silverburst one that is a couple years old now. Anyway, it is a lot meatier down low and still has a slightly muddy sound to it. I don't know exactly what pick ups it has in it, but they just sound a little blah. I can get it to sing if I crank the treble way up and push the presence above 7 or 8, but then I lose a little of the definition and punch down low. Tough to find a happy medium sometimes...I will say it sounds really good when I record though - totally different from the sound I get out of the cab here in my room.

I also have an Ibanez EX Series from the early 90's (maybe 92 or 93) that I have had since it was new. I don't know what pick ups it has in it as they are simply labeled XH1, XS, XH2 (2 humbuckers and a single in the center)...I have never had them out of that guitar to see what it says on the back or anything...They are much brighter and are nowhere near as muddy as the Epiphone. Totally different sound and a lot easier to dial in IMO, for me anyway. Sounds better out of the amp next to me but sounds a lot brighter during playback while recording.

I have a B.C. Rich as well...It has some really cheap EMG's in it - EMG Select pick ups (bottom of the line from what I have read about them). This guitar has the best sound of all of them to my ears, which is obviously subjective. The guitar is just older than dirt (mid to late 80's) and it doesn't play as well as the others. What I may do is swap around some pick ups until I can find a happy medium between guitars and pick ups that make the amp really scream - it will only scream if you make it...Getting a guitar and pick up set up that is comfortable and sounds good is the easy part I guess...Making that bastard wail is the tough part - for me anyway.

I dunno if any of this helps anyone, but all of the above babble is based on my own personal experience. Everyone's mileage can, and will, vary...

[Hipster Salad]

Update on my SLO modded JCA100H:

Got the pots in today, from New Old Sounds. 500k PCB mount mini audio pots, cost under $7 shipped to my door. Perfect drop in replacement

Top stock (I clipped the lugs), bottom new


Left stock, right new

[Hipster Salad]

Finished product (with correct depth mod wiring this time!):

[Tortuga]

Finished product (with correct depth mod wiring this time!):

Looks great, man - what's the verdict? New pots make a difference?

[Hipster Salad]

Finished product (with correct depth mod wiring this time!):

Looks great, man - what's the verdict? New pots make a difference?

I didn't play much, but I notice it's a little brighter(?) It's been a while since I've consistently so I forget how it exactly sounds. Again, gain (even at bedroom levels) are backed off from 6 to 5, and its a slightly fuller sound. I'll be (hopefully) running it through a Bogner 4x12 this weekend so I'll have a full report and some clips come Monday

[Hipster Salad]

. . . and a crappy quick clip from my phone's camera. Volume at MOTHERFUCKING ONE!!

PRS 245 SE > JCA > Gflex 2x12

[video]http://www.youtube.com/watch?v=C980z_sCGTM&feature=youtu.be[/video]

[Jay]

Update on my SLO modded JCA100H:

Got the pots in today, from New Old Sounds. 500k PCB mount mini audio pots, cost under $7 shipped to my door. Perfect drop in replacement

Top stock (I clipped the lugs), bottom new


Left stock, right new

That's perfect, dude. Do you have a part number? We can add it to the list, or make a cross ref. to add to the Mouser BOM.

[Jay]

I just wanted to tell, what I have done with my amps - and I have tested a lot of several mods. So this would be my personal recommandation. That's all. : )

And that's what makes this place perfect. All of our experiences are here to pool together to help everyone rock harder.

A lot of what you have recommended is really good stuff, and some things I have even overlooked. Plus, for my next build, I am going to go with the MKT1813 Roedersteins. I'm very interested in those. The Marshall guys are raving over there about them.

[Jay]

. . . and a crappy quick clip from my phone's camera. Volume at MOTHERFUCKING ONE!!

PRS 245 SE > JCA > Gflex 2x12

[video]http://www.youtube.com/watch?v=C980z_sCGTM&feature=youtu.be[/video]

Very nice! Sounds like the string seperation is a little clearer compared to most of the JCA clips I've heard, too.

[Hipster Salad]

Update on my SLO modded JCA100H:

Got the pots in today, from New Old Sounds. 500k PCB mount mini audio pots, cost under $7 shipped to my door. Perfect drop in replacement

Top stock (I clipped the lugs), bottom new


Left stock, right new

That's perfect, dude. Do you have a part number? We can add it to the list, or make a cross ref. to add to the Mouser BOM.

I posted a link to the part in the DIY section regarding the SLO mod.

Two 500k PC mount 16mm (mini) audio/log:

http://www.newoldsounds.com/index.php?m ... s_id=11305

[Jase01]

Well, if you want a little more gain, try putting a 1uF cap in parallel with R4. You can also put it on a switch for when you don't want the extra boost. A lot of the 20H guys do that and get really good results. If you need more after that, we can do some more stuff.

For the NFB resistor switch, was that just ther XL mod for the Hotrods and Lead60?

Thanks I'll try that. Do I use a dpdt switch? And do I just solder the cap to the switch and run wires from R4 to the switch? ( could you please do a simple diagram?)

Not sure about the NFB mod, it was suggested as an alternative to a switchable slope mod, but I was thinking of doing both.

Oh yeah, whats the best type of capacitor to use?

I'll try and do a simple diagram. Give me some time to find/make a decent illustration though. lol

A 2 position DPDT will work. As for caps, you can use a 63v or 100v cap. I'm going to use the Vishay/Roederstein MKT1813 for my next build, or you can try the Vishay MKT368, which is very comparable to what the SLO uses. A good "poly" type will be your best bet.

Okay, try this. I hope this diagram works for you. It's my first time doing an illustration. Don't laugh. You want the capacitor to have a voltage reference, or you will get popping when you switch it on or off.

Thanks Jay, Ive done this and it works great. I just need a little bit more gain. haha.
Whats the next step? please....

[Jay]

Well, what kinds of tubes are you using? Might be able to get away with just a tube or two. And, which channel do you want more gain on? Both? OD? Crunch?

[Jase01]

Just on the crunch channel.
I've got V1-5 = Sovtek LPS / JJ/ JJ /JJ / Tung Sol.
And JJ's for the output.

[Tortuga]

. . . and a crappy quick clip from my phone's camera. Volume at MOTHERFUCKING ONE!!

PRS 245 SE > JCA > Gflex 2x12

[video]http://www.youtube.com/watch?v=C980z_sCGTM&feature=youtu.be[/video]

Very nice! Sounds like the string seperation is a little clearer compared to most of the JCA clips I've heard, too.

Does sound good, Sahl. Would you say that the pots made a difference? It seems you weren't too impressed after running through the entire set of mods required prior to changing those last parts...

[Jay]

I would almost reverse the positions of V1 and V5. I have always used the TungSol in V1 and the LPS in V5. To my ears, Long-plate tubes work best in the phase inverter. For some reason, they seem to stay more 'open' and less compressed than using short-plate tubes in the PI.

[Hipster Salad]

Ok, just cranked this baby up at Matt's house through a Bogner 4x12. WOW. Biggest difference I notice is gain usability. OD gain dropped down to 2 is still a healthy amount of gain. Overall a lot more clarity and openness. Very crisp and quick pick attack. The "sweet spot" that you usually find at 5 on these amps appears much sooner with the mod. OD volume at 3 is well saturated. More than happy with this. Pots do make a difference at gig volume. Much brighter now, even through the V30 Bogner cab. Love it, love it, love it.

[kissmyace]

Ok, here once again:

In my opinion, there is no need to change a lot of the things in a 22H.

What I would do (and have done ^^):

- C2 to 4,7nF (instead of the stock 22nF - that will bring you much more clarity and less mud and fizz)
- R26 to 39k (instead of the stock 47k - that makes the amp a little brighter sounding, slope is like in Orange or Diezel, for modern Marshall use 33k)
- R42 to 56k or 68k (instead of the stock 47k - that will push the amp towards modern mesa rectifier direction, will give a little bit more punch)
- C21 to 68nF (instead of the stock 100nF - that will reduce the fizz at presence a little bit)
- Depth Mod (I prefer a 6,8nF over the recommended 4,7nF, because this will boost lower frequencies, the 22H has enough low mids)

optional:

- change all caps up to 1nF to good high voltage ceramics
- change all coupling caps and bass and middle cap to Sozos (I like them better in this amp than Orange Drops 225 or 715 Series, for Metal use Cornell Dubilier DME)
- change all cathode bypass caps (the 1uF ones) to Röderstein or mix Röderstein with Solen Fast for more bite and clarity

- swap out R9 (this will brings more clarity and reduce the woolyness in sound)
- use C10 (stock is 1nF) in series with a 220k, 470k or 680k - the higher the resistor value, the less difference will be. With only 220k the amp would sound much brighter and has more edge in sound. If this is too much, raise C20 (stock is 270pF) to 330pF
- reduce C8 to 0,68uF (less gain, clearer sound)


I don't like all these SLO Conversations or "Predator Mod" at all. They all give this amp even more gain and "boomyness". In my opinion, these are the problems. This amp has too much gain, to much mud and fizz. All my suggestions will bring more clarity, less gain, less fizz. If you don't like this, then don't do these changes!

Do one thing after another - not all at the same time. So you will see (and hear) which mod makes which difference in sound.

And take care about the high voltage. If you have no idea about, how this works, then please let do that an amp tech.

this sounds like what I'm shooting for
Is there any way I could get some part no. I've been looking & it get confusing to a rookie