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

[js635]

I recently did some work to my 20HV. New OT, Hammond choke, AT7 in the phase inverter/5751 in V1.


I'd love to get a little more sparkle/touch sensitive clean out of the amp; any suggestions?

Here's how it sounds now:
[video]https://www.youtube.com/watch?v=Q-r3Ie9lpww[/video]

[Tortuga]

Sounds fucking great, man!

Not sure what to tell you - have you checked out the clean switch & T filter? I did that to my 50H & it does resemble a Fender amp.

Haven't been able to experience a 20HV first-hand. Any idea how it compares (gain & tone-wise) to the 'normal' 20H?

[js635]

Sounds fucking great, man!
Haven't been able to experience a 20HV first-hand. Any idea how it compares (gain & tone-wise) to the 'normal' 20H?

I owned the 22H, but never the single channel. If the 20H is similar to the cleaner channel of the 22H, I can make that comparison.

The 20HV is significantly less saturated, and the overall tone is a little warmer/darker. The 20HV also has a bit of a grainy texture that I didn't detect in the 22. I think there's more overall clarity and bite in the 22H than the HV, and the latter is much less modern sounding. I found the HV to be more usable across the entire spectrum of gain and EQ than the 22H, but I play in a cover band and need some amount of clean/vintage tone I just couldn't find in the original line.

I think I might try pulling some of the lower gain glass out of the amp. It feels like it's sucking some of the character and attack out of it. We'll see.

[GuitarBilly]

I recently did some work to my 20HV. New OT, Hammond choke, AT7 in the phase inverter/5751 in V1.


I'd love to get a little more sparkle/touch sensitive clean out of the amp; any suggestions?

Here's how it sounds now:
[video]https://www.youtube.com/watch?v=Q-r3Ie9lpww[/video]

I really don't have any suggestions because I think it sounds awesome as is!!!


That said, replacing the JJ tubes with something like EHX or Mullard RIs would add a bit more sparkle to it. But I don't think it needs it honestly. Great tones!!

[Meelocheck]

That sounds really good. Damn.

[Hipster Salad]

Did a little work to Amelia . . .

Upped the gain slightly, reduced the input signal a bit to make the Clean channel a little cleaner (not demo'd though), changed a couple LEDs (still have to lower the voltage to the blue LED - it's too damn bright!), took out some flubby bass, fixed the popping noise when switching Master volumes and woila! (HUGE thanks to my bud Bryce for helping me out with these).

[video]https://youtu.be/MeQJt14TQZg[/video]

[Tortuga]

Gatdam that thing sounds so great!

Any comparison to the standard (50 or 100) offerings, or does it just blow then our of the water?

[Hipster Salad]

Gatdam that thing sounds so great!

Any comparison to the standard (50 or 100) offerings, or does it just blow then our of the water?

Seems a bit darker than the JCA50H/100 I have, and a touch more sag. I'd need a stock 50/100H to compare, but it's a little different flavor than my 'SLO' modded 50H. But yeah, I love how the Amelia sounds.

[Also Lime]

Wow that Amelia sounds great, really impressed by that clip. Definitely food for thought for myself who is still torn over which amp to go for.

For the guys that are experienced with mods I have a question, I seen it mentioned by the guy who posted the clip of the 20HV (great sounding clip again btw) that he changed the transformer to the unit that Jet City sell as an upgrade, could anyone who has done this upgrade tell a noob like myself what difference it made to the tone and feel of the amp?

[Hipster Salad]

I put the Bulldog OT in 2 of my 20 watt Jet City amps. Makes a little clearer sound; more articulate and open. Not night and day, but is a noticeable improvement.

[Hipster Salad]

js635, did you install the Bulldog yourself? If so, did you have to reverse the Brown and Blue wires on the board? I had to do that on both my Bulldog installs.

[reisG]

Hey,

new user and proud owner of the jca22h for 3 years now. Just found this thread and just finished reading the whole thing (pretty much). I gotta say it got me really wanting to have the depth mod. A user even mentioned something simpler to bring some lost bass forth at low volumes, like installing a resistor or something. I've got some basic electronic and circuit knowledge out of college (masters in mechanical engineer) but I've got no REAL technical skill and don't feel comfortable going about messing with the amp, however I'm definitely considering finding someone that does it for me. I'll settle with and EQ pedal in he loop. What I can and will do is change the tubes (still packing the stock chinese). I only play at bedroom levels, so only preamp tubes but I can't really decide on what to buy. The Sovtek 12ax7lps is a given in V5. I don't care about V3 and V4, I'll stick some cheap JJ's 12ax7 or maybe I won't even bother changing those. My problem is with V1 and V2. The amp is too trebly and I'd like to tame that (my treble knob doesn't get past 4) but don't want to loose bite, just remove fizz and those icy picky high frequencies. I hear the JJ's are really good for smoothing bright amps but I'm worried it'll add mud like some people mentioned. My playing style goes from thrash with tight and defined bottom end and bite to something like sludge with a more open, in your face, sound (think of mastodon with those big chords where you can hear the definition of every note).
suggestions?

Also anyone can recommend any good tubes dealers in Europe?

[xmugmugmugx]

New to the forum and owner of a JCA2112RC. So far all I've done is swap out the dying pilot light for the Jet City replacement and installed a Cannabis Rex. I'm generally happy with the amp but have been searching for mods tht will get it closer to the sound I hear in my head. Very interested in the JCM 800 style mods. I look forward to learning as much as I can here. And thank you in advance.

[mbranford]

See posts about the choke, the 33k slope resistor in the tone stack, and swap tubes. Another common move is to add a 220k resistor parallel across the plate bias resistor on a switch, so the total is 110k. I added an effects loop to my JCA2112RC. I was thinking about swapping the speaker for an Emminence Private Jack. Out
of curiosity, why did you choose the Cannibis Rex?

[xmugmugmugx]

I chose the Cannabis Rex after watching a lot of comparison videos. I liked the midrange response and the price. I also thought The marketing puns were great. "Adds a smokiness to your tone" and the like. The choke was my first choice for a mod. I'll check out the others and see if they get me where I'm looking to go. Did you do the depth mod, if so is it a noticeable difference?

[Tortuga]

Depth mod is really great for adding balls & body to the tone, especially at lower volumes.

Tubes are mandatory - see the many posts throughout this thread to back me up. If going cheap, at least hit V1, V2, and PI, plus the power tubes. That and setting bias correctly will do wonders.

Slope resistor mod is also really great if you're wanting a Marshall feel to the amp. Takes away the stiffness and livens it up real nice

[mbranford]

I also found the depth to be essential to eq'ing the amp to a room, which was unexpected at the time, but completely makes sense in hindsight. I jammed with some friends in a "studio" which was really a room in a concrete floor garage. Normally I don't change the depth too much, but in a room with a lot of reflective sounds, the ability to change the bass response was huge.

[xmugmugmugx]

Swapping out tubes was my first step. I originally swapped out for Sovtek 12AX7s and some JJ's power tubes. Definite improvement from the stock tubes. I experimented with 12AU7 and 12AY7s as well. I even managed to stumble across some NOS RCA 12AX7's by sheer accident. But that's what got me started down the mod path. Those changes were good, but subtle. They didn't quite get me where I was looking to go. The slope mod looks like a really great start. I've read a lot of positive things about it in this forum so far. The Depth mod and adding a choke are a bit more confusing. I understand how they work, but I'm not sure I understand the effect on the sound. I see a lot of comments about the Depth mod improving lower volume bass response, but is it as noticeable at higher volumes? and with the choke, does it make a noticeable difference as well?

[mbranford]

The depth mod effect is for lower volume, at bedroom or a medium sized room. Once you get to band level, abov a drummer, the depth mod is not needed as much because the speakers fill out the bass response,
as they will move more air. I believe this is a
characteristic of lower wattage amps,
and EL84 amps in particular. The amp still sounds better at a higher volume, but the depth pot makes a big difference during practice. I think it is essential.

As far as the choke, I also find it to be helpful. I think it makes the amp tighter, which also helps with the bass response, and creamier. The amp is less fizzy as well.

[xmugmugmugx]

That makes sense. I'll add the depth mod to my shopping list.

[Tortuga]

You mentioned changing tubes, but did you set bias? I believe that should be done every time you change tubes - especially the first time, as the amps have always been set cold from the factory.

[xmugmugmugx]

I got the amp used and did not bias it. I'll add that to the list for the next time I change tubes. I have been considering converting to cathode bias bit not really sure how feasible that is.

[xmugmugmugx]

I figured I'd throw another question out there and see if anyone has an idea. My apologies if it's been answered already. So I'm looking at the JCA2112rc schematic and there are 2 extra tubes vs the JCA20H. Now I know that one of them is for the reverb. But V2 seems to also be going primarily to the reverb stage section as well. What I'm trying to sort out is the Marshall 2204 conversion, which I believe was originally done on a JCA20H. Does anyone have experience with the 2112rc and how to approach this mod?

I also just wanted to say that I'm already enjoying this thread and learning quite a bit. Thank you everyone.

[xmugmugmugx]

Amp is now biased and running better. Had a scare or two (check the settings on your meter before testing, then check AGAIN), but no shocks. Thanks to all the various tips and safety measures I've seen on this forum. I'm still looking into which mods I want to tackle first. I think I'm leaning toward Depth Mod. I've noticed that I don't really like playing my amp at home because it sounds so thin.

[Tortuga]

Glad to hear it's working good so far.

Also good you got to read through the thread before the Photobucket fiasco yesterday. If they don't go back to allowing linked images without a ransom, I'll try to rebuild my images, but I imagine we'll have a tough time getting everyone else to do same