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

[spunko]

Thank you very much for the response.
I did mod the amp, with recommendations in another forum, and it drops the volume like you said. Haven't heard the tone yet. (I tried just changing R28 from 220k to 69K)

Is there any way to clean up this amp?

I see there is a super clean mod in this page, but there is no info about it. Also I can't buy it rigth now, that is why I preffer to do it by myself with instructions of course.
https://www.epic-tone.com/online-store/ ... -p87313323

This is what I have done for far. I haven't tried this mod/diagram in the amp yet.
I did install the switch and did the job (diagram), and tested with my fluke and it seems to do as I intended to, but with the amp off.
Like I said, I haven't tried with the amp powered on.

[Shask]

It wouldn't be very hard to clean it up, but you would probably completely neuter the gain sounds to do it. You could compare with a Fender schematic to get some ideas. I would probably start with changing all of the plate resistors to 100K, and change that 39K cold clipper cathode resistor to something smaller, like 2k. Clip the bright caps.

[GuitarBilly]

Bryce from Epic Tone did quite a bit of work on my JCAs. I strongly recommend his work and his pricing is super reasonable too.

[hackeiommi]

You guys are pure evil, you know it, right? Because of you, first I bought a Boss GE7 to use in FX Loop, now I began to collect effect pedals of TC Electronic! Recently I bought a dirt-cheap Vortex Flanger, and I like it!! A beast made for the Fx Loop of my JCA50H. I think next will be Corona Chorus, Pipeline Tap Tremolo, and Triple Delay. Like the Toneprint options too!

Thank you all guys!!

[GuitarBilly]

Yeah TC pedals are great with the JCA pretty much the best I've found for that amp.

[Moabman]

So I have a JCA50H head, and I would like to upgrade the caps to improve the sound quality. (I have already upgraded all the tubes in the amp)

So my questions are:

1) Which caps should I focus on upgrading?
(if you could specify which caps on the board that would be very helpful, i.e. "c15" etc)

2) What type of caps should I use?
(they also need to fit the spaces on the board)

3) Where can I purchase these caps?

Thanks!!

[Zozobra]

Component choice in that regard is very subjective and I'd be reticent to say anything was an upgrade as such. Within the same cap type you're more likely to hear the difference in component tolerance than anything to do with the branding. There are subtle differences between different types e.g., different construction types of film caps or swapping a film for a ceramic or silver mica where they overlap in values. You'll get a more reliable and consistent tonal change by changing the component value though. What specifically do you want to change tonally?

[Shask]

Yeah, I have my doubts just changing the cap type would produce a tone difference worth the effort if you use the same values. You could also look into the Epic Tones Modification kit for their Cap upgrade kit if you are serious about changing them all. Changing the coupling caps would probably have the most dramatic effect.



Funny timing of this thread popping back up! I am actually in the middle of planning multiple mods to my JCA100HDM, and wrote out a parts list yesterday. It is going to take awhile, so I am not really in a hurry. I am going to change some cap values and such, but those are easy changes. I also plan on moving to loop after the master controls where it should be, and I am going to re-wire it to a 5150-style effects loop with a global master. This will be a pain because I know I will have to cut traces and drill holes and such. I think I will do a mid-sweep control while I am in there. I will have to take the board out, so I might as well do as much as I can at once. I will probably end up tearing it apart multiple times so I can check what changes do. I want to see what the effects loop and cap changes do before I make any decisions about other changes. Honestly, if I can actually use the loop to use an EQ pedal I may decide any other changes aren't necessary.

[Moabman]

So the difference between the Soldano Hot Rod and the Jet City is the Soldano uses better:

-Transformers
-Vacuum Tubes
-Components (Resistors, caps, pots, etc.)

-I don't want to change the transformers (people who have changed them out report very minimal difference)
-I have already upgraded all the tubes.
-I would like to focus on upgrading the capacitors that will make the most audible difference in the circuit.

I can hear a big difference between different capacitor types (of the same value), and need advice about which caps to focus on upgrading.

Any advice would be greatly appreciated!!

[GuitarBilly]

So the difference between the Soldano Hot Rod and the Jet City is the Soldano uses better:

-Transformers
-Vacuum Tubes
-Components (Resistors, caps, pots, etc.)

-I don't want to change the transformers (people who have changed them out report very minimal difference)
-I have already upgraded all the tubes.
-I would like to focus on upgrading the capacitors that will make the most audible difference in the circuit.

I can hear a big difference between different capacitor types (of the same value), and need advice about which caps to focus on upgrading.

Any advice would be greatly appreciated!!

Check with Bryce at Epic Tone, he has this figured out and sells a capacitor upgrade kit for the JCA.

[Moabman]

So the difference between the Soldano Hot Rod and the Jet City is the Soldano uses better:

-Transformers
-Vacuum Tubes
-Components (Resistors, caps, pots, etc.)

-I don't want to change the transformers (people who have changed them out report very minimal difference)
-I have already upgraded all the tubes.
-I would like to focus on upgrading the capacitors that will make the most audible difference in the circuit.

I can hear a big difference between different capacitor types (of the same value), and need advice about which caps to focus on upgrading.

Any advice would be greatly appreciated!!

Check with Bryce at Epic Tone, he has this figured out and sells a capacitor upgrade kit for the JCA.

I don't want to spend $70 on a cap kit, when I could just by the caps myself, just need a bit of information. Was hoping the knowledgeable people of the Jet City Lounge could help out.

Any input would be greatly appreciated!

[Yarbicus]

So the difference between the Soldano Hot Rod and the Jet City is the Soldano uses better:

-Transformers
-Vacuum Tubes
-Components (Resistors, caps, pots, etc.)

-I don't want to change the transformers (people who have changed them out report very minimal difference)
-I have already upgraded all the tubes.
-I would like to focus on upgrading the capacitors that will make the most audible difference in the circuit.

I can hear a big difference between different capacitor types (of the same value), and need advice about which caps to focus on upgrading.

Any advice would be greatly appreciated!!

Check with Bryce at Epic Tone, he has this figured out and sells a capacitor upgrade kit for the JCA.

Bryce is the man! He nodded my DSL401 and I picked it up from him today.

[dumbmonkey]

Hey there!
I know that this group has been quiet for a while but I wanted to see if anyone had any experience with the 2204 conversion that Stump posted on page 37. I have a 20HV that I was thinking I want to try this on. I have all the parts I need, but I'm kinda wary about doing it...
I like the amp, changed out the slope resistor, made the depth switch variable, installed a choke, changed out all the coupling caps for Orange Drops, and the ceramics for Silver Mica, but I think it needs a little something something...

[theghostnow]

I think the hv is as straight as a JCM 800 preamp topology as it can be? Vs the 22h and 50/100h I mean.


I'd even try a variable feedback pot in the back. It is not the same with making the depth switch variable because it affetct all negative feedback. You can put in series with the regular negative feedback resistor. When it's full on it should block the negative feedback from going to the power amp backwards, so, you essentially defeat it. It's the rectifier modern mode lol. In essence, the pressence pot and the depth knob won't work at that point but the amp will change and become wilder, more bass and treble, rawer, less controlled. Maybe a bit boomy but you will have the bass pot to cut etc...

But it will be different, easily. Looser and more elastic to play, etc. It might be what you want or just fun to have. With the pot bypassed, you still have the stock resistor in there, so it will come back to the stock sound no harm done.

In the end there are a lot of things that you can do and maybe tweak the amp onto to your cab first and foremost. PI caps, preamp values etc. I don't know if I'd even target the JCM 800 conversion per se, it is a small EL84 power section in there.

I'd play a bit with the 3rd stage cathode value. Search for 2204 schematic that has a 10K value in there. Soldano's journey started there to be honest. You can try different values and have different sounds, you could even put a pot in parallel to a big resistor there and change on the fly but excluding to where you will mount it, it will be DC so it will be scratchy. But it will be very versatile for example.


What is it exactly that you feel it is missing? How did you find the amp changed with the cap brand change?

[dumbmonkey]

Hey!
Thanks for replying! I honestly can't tell much of a difference with the cap change, although now that I'm not playing out, and I can't turn it up too much, it's hard to discern any differences. I tried a mod that was supposed to get it close to ZWreck tones, but it was way too thin and shrill. I figured that since I'm changing it back I might as well upgrade the caps. I gotta say, this is a really great amp for big rock tones. Whenever I did get to play out, people would totally compliment me on the sound. Maybe I'll just leave well enough alone.

[GuitarBilly]

I'd leave the HV alone for sure. Great sounding little amp!

[Yarbicus]

Yeah, the 20hv is amazing. Pretty much the only el84 amp I would even consider any more.

[***1776***]

Hey guys, what power transformer (affordable) can go in a JC 50?

[Bengerm77]

Hey guys, what power transformer (affordable) can go in a JC 50?

While we're at it, what power transformer (affordable and then expensive, 2 options) will go into a JC100h? Mine's been dead for a year.

[GuitarBilly]

Hey guys, what power transformer (affordable) can go in a JC 50?

Hammond has one. Forgot the model number.. 290 something? It's the one they offer as replacement for Marshall 2204s.

[ledvedder]

Hey, am I allowed to join this lounge now?

[Tortuga]

[ledvedder]

I posted this in another thread, but figured I'd post here as well.

I had some time tonight to fire my (new to me) JCA22H up. Overall, I like it. It definitely has a ton of gain. More than I'd ever need. It came with Mesa el84's. 2 JJ's in v1 and v2. Chinese the rest. It has a ton of bass! I had the bass down to 1 to be where I like it. I'm not sure if that's a product of the depth mod. I'm not a fan of the sat switch. It drops the volume a ton and gives more gain than I'll need. I'm not exactly sure what the other switch is doing, but I'm not a fan. But overall, I like the character of the amp. I'm sire with a few tweaks, I'll get it exactly where I want it

Here's some gut shots.

[ledvedder]

A few more.

[ledvedder]

Does the depth mod need a 0.1 uF or 1 uF cap?