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

[mrfret]

Just stick a pot in there to fill the hole. Nobody will ever know that it doesn't do shit.

I thought about that. Just putting the MV pot back for looks lol. I also thought about a fender style jewel light

[capota]

Hi, I finally made a quick video demo of my new Jet city Custom 22 by Martin Kidd

Here it is: [video]http://youtu.be/Ugfe5DyHr6g[/video]

[StanD]

Mesa 3077. Thanks. You are so right the depth mod saved this amp for me. I now have adequate low end. I play pretty clean and needed the boost. Used a 250k pot and went with a 5800pf instead of 4700pf.

The gain redux reduced the gain a lot!! Like down to barely audible. Weird? I did not keep it.

Keep slope, low end boost and depth.

With my flux capacitor faceplate I'm pretty good for now.

So did you experiment with different pots for the depth or just go straight to the 250K ?

I just went with the 250k per your suggestion. It's very useable. All the way up when I'm using a 1x12 cab (4 o'clock) at low volume. Backed off to noon with my 2x12 with the volume cranked. Added the knob next too the presence knob.

[StanD]

Can anyone point my to how to adjust the high freq on just the lead channel or just the rhythm channel. I can't handle the diff between the two it renders one channel or the other useless for me. I need to shave off some high end off the lead. Or I could add some to the rhythm channel then roll both channels down with the treble knob. I am not a able to read amp circuits and interpret. I only read and learn from you guys. Thanks.

I'm done the depth, low end boost and slope mods already.

I wish this 33 page post was its own forum. This awesome amp deserves it!

[capota]

Can anyone point my to how to adjust the high freq on just the lead channel or just the rhythm channel. I can't handle the diff between the two it renders one channel or the other useless for me. I need to shave off some high end off the lead. Or I could add some to the rhythm channel then roll both channels down with the treble knob. I am not a able to read amp circuits and interpret. I only read and learn from you guys. Thanks.

I'm done the depth, low end boost and slope mods already.

I wish this 33 page post was its own forum. This awesome amp deserves it!

"So, finally I've got new tubes, all JJ.

changing the valves made a diference in sound, but biggest diference was when I did the BIAS on the amp (21/22ma) and lifted a leg on the C6 (c6 acts as a bright cap over the gain knob, so taking it out would create less brightness).

I can tell you, it's a new amp!! Great sound

I can now use the treble and the presence pot a lot. On my gig it went well, i used the volume on 3 and it was a bit less fizz, but the changes I did yesterday on the BIAS and de C6 Cap where immense."

[Tortuga]

Can anyone point my to how to adjust the high freq on just the lead channel or just the rhythm channel. I can't handle the diff between the two it renders one channel or the other useless for me. I need to shave off some high end off the lead. Or I could add some to the rhythm channel then roll both channels down with the treble knob. I am not a able to read amp circuits and interpret. I only read and learn from you guys. Thanks.

I'm done the depth, low end boost and slope mods already.

I wish this 33 page post was its own forum. This awesome amp deserves it!

Welcome, Stan - I hope Capota's response is helpful. Sorry I don't know directly how to help you with that. If not, you may want to post a new thread asking directly - unfortunately, there's not a ton of activity in this thread anymore.

As for the 'own forum', did you see the index I posted (and try to keep updated) on page 1?

[BowerR64]

I can confirm that the Zoom Multistomp MS-50G works with the JCA50H with no issues. Cool pedal has a bunch of different stuff in it its more like a larger multi effects pedal but in the size of a single pedal.

You can program it so that with each press of the button it cycles threw 4 different saved patches and each patch you can program up to i think 7 effects, amp modelers, modulation, delays reverbs even an A/B switch and EQs pretty nifty.

[marnold]

In the FWIW category, I had tried a 5751 in the V1 position on my JCA22H, trying to get a little more headroom on the crunch channel. I found that while it didn't affect the low end of the gain knob much, it definitely took it off the top end (basically the distortion with the preamp gain set at "9" was about the same as it was at "6" with a 12AX7). I put in the spare JJ 12AX7 I bought and I like it a lot better. The amp just sounds more lively, for the lack of a better term.

[heavyredmetalneck]

Soooooo, have you ever seen the new Jet City Custom 22 by Martin Kidd??

This is what it looks like from the inside



http://extrazoom.com/image-48876.html?s=huln50x50

The crunch channel is much cleaner and the whole amp is more to the British side of things. I Just got it las Friday and haven't had the time to test it properly.

I'll do a video review as soon as I can, and as soon as I cab take it to a place where I can play it LOUD as this amp screams for volume and its freakin loud to play at my apartment.

I sure would love a schematic for that thing, would love to tweak my 2212c to it's specs. not that I want more gain out of the OD channel. I'd love to plexi-fy the crunch and hot rod 800 the OD

[maynardo]

Soooooo, have you ever seen the new Jet City Custom 22 by Martin Kidd??

This is what it looks like from the inside



http://extrazoom.com/image-48876.html?s=huln50x50

The crunch channel is much cleaner and the whole amp is more to the British side of things. I Just got it las Friday and haven't had the time to test it properly.

I'll do a video review as soon as I can, and as soon as I cab take it to a place where I can play it LOUD as this amp screams for volume and its freakin loud to play at my apartment.

A LOT of changes, can't see the values on the caps tho, a picture a little bit from the side would be awesome. This guy uses a ton of electrolytic caps

[Shinigami75]

Hi guys,

I just joined the forum and I own a Custom 22

I recorded a short home video to provide "bedroom" players with some audio samples.

In the video I mention a Mesa ECC83 in V2 but now that I think about it there's a stock Chines tube in there for everything else:

V1 Mesa
V2 China
V3 TAD selected
V4 and V5 Mesa

I will be reading all the previous pages to learn more about this amp which I think it's very nice for the price you pay. I wish the gain on the overdrive channel was more usable since past 5 doesn't sound too nice. Plenty of it though. Since for home practice with the volume at 1.5 and gain at 3 the sounds is really good

Here's the video:

http://vid1356.photobucket.com/albums/q ... og0uuh.mp4

P.S. I forgot to record some sample with the bright switch off and the mid boost on...I'll do it asap!

Have a nice day folks

Luca

[xxmicrocutsxx]

Hi all,

Firstly, this thread has been a god send for learning about not only what mods can be done but also what they do and how they do it which for someone who wants to learn more has been great, so thanks!

Now on to my problem...... I finally got around to modding my JCA22h on the weekend and have run into a little issue. The mods I made were the SLO mod (changes to VR1, VR2, R5, R9, C5 and C6), the front panel channel switch mod (SPDT switch from the backline.tk blog) and also a DPDT switch with both a 33k and 47k on it for the slope resistor at R26.

The mods are working but I appear to have introduced a "POP" in to the amp when switching channels. I think it may have something to do with the channel switch mod (http://toboy-diy.blogspot.co.uk/2013/09 ... witch.html). I can't find anyone online having had the same issue as myself after doing this mod. Could this issue have something to do with the other mods I made? I'm wondering if the cap changes at the crunch and OD gain pots could be causing any issues?

Any help with this would be greatly appreciated! When I have some time tomorrow night I think my first port of call will be to reverse the channel switch mod and see if that gets rid of the "POP". If not then at least it will narrow the search down.

I did make a new thread for this issue just in case no one checks into this thread, it's been a while since people have posted anything.

Thanks

[sefloval]

Long time lurker of this forum/club? and thought I'd say hello! After looking at Jet City amps for literally years, my curiosity finally got the best of me and I couldn't resist ordering a JCA50H! At the price they are new, I had to get one.

So far, I have just replaced all tubes with the low gain JJ retube kit from Euro Tubes. There is a lot of gain on tap, and this kit plus a 5751 in V4 got me where I want to be.....and it's still a ton of gain!!

I'm running it through an Avatar Bluesbreaker style 2X12 loaded with a Vintage 30/K-85 mix which is my favorite speaker combination I've tried to date. My main guitar is an Ibanez Prestige RG2550Z and has been my "go to" guitar for some years now.

The first thing I've noticed, is this amp likes volume and wants to be cranked! Yes, the master volume works incredibly well, but it gets sweeter with more volume and really starts to breathe and open up with the master past 3-4.

I play in a band for fun with some buddies and we have originals and play covers of Pennywise, Bad Religion, etc. When at home, I like to wank away on 80's metal and this thing does it very well The clean channel is no slouch either as long as you keep the preamp crunch low. Will have my first band practice with the JCA50H in about a week and can't wait to turn this beast up!

My humble rig,
Cheers!

[Tortuga]

Nice rig. I've heard several times that this amp seems to be made for the V30. Never have tried it, but sure would like to.

Make sure you check the first page of this thread. That's the fastest way to get to the mods and other tech postings within this and other threads. Great info in this 33 pages!

I'm a huge fan of the depth knob and slope resistor mods. Brings out the balls and marshall-y mids. Also, make sure you get the bias set for your new tubes.

And, fuck yeah it's a lot of gain. One of the things I really haven't liked about it, to tell the truth. I'm still wanting to do the SLO mod to my 50H, but haven't gotten around to it yet.

[sefloval]

I'm a huge fan of the depth knob and slope resistor mods. Brings out the balls and marshall-y mids.

Good to know and thanks for the welcome! I've read through pretty much all 33 pages before I got the amp so I feel as I already know you
Will definitely bias the amp ASAP. After a few band practices and getting a feel for the amp, I'll have a better idea of what kind of modding I might want. For now, I'm just going to turn this bitch up and rock it

[Tortuga]

[fajen]

Hi all,

I have some Troubles with my JCA 22h that I have modded.

I have applied the Marshall mod that Jay mentioned in an earlier post but now the amp is quite hissy if I turn up the gain. Much more than before.

Any suggestions how to quiten the beast?

[Meelocheck]

What Marshall mod? What exactly did you change.

FWIW, I have done the depth mod and I have pulled one leg of C6 and put it on a switch. Allows a little darker tone on the OD channel. I also changed the slope resistor tho I can't recall the value off the top of my head.

I also changed out R21 and R9 to 470k, R25 to 220k and R6 to 100k. I then changed every one of those back to stock values because the OD channel sounded a little flat and lost a lot of harmonics.

With the 3 changes mentioned above this amp already has a slightly pissed off Marshall tone. I still get a bit of flub when palm muting and chugging tho, but it does sound better than the stock amp to my ears.

[fajen]

Thats what I have done after I had applied the SLO mod.

Change R9 to 475k
Change C5 to 1n or 2n2 (I kept it as 1n, but 2n2 also works nice)
Remove C6 or put it on a toggle for a "bright" switch
Change R16 to 2k7
Change R17 to 475k with a 1n cap in parallel
Change R18 to 68k
Change R23 to 2k7
Change R42 to 68k
Change C21 to 680n

[Meelocheck]

I'm not sure what the problem could be but at least one of the changes you made is pretty drastic...You took R18 from 1M to 68k, that's a pretty huge difference in values. Even R9 from 1M to 475k seems a little drastic to me but I am no expert. I tried R9 @ 470k and didn't like it at all so I changed it back - no off sounds or noises tho...I would start reversing the changes you made, one at a time, until you find the one, or ones, responsible for the added hiss/hum. It's possible you just missed something too. Maybe someone with a little more experience will chime in. Anyway, good luck.

[maynardo]

I'm not sure what the problem could be but at least one of the changes you made is pretty drastic...You took R18 from 1M to 68k, that's a pretty huge difference in values. Even R9 from 1M to 475k seems a little drastic to me but I am no expert. I tried R9 @ 470k and didn't like it at all so I changed it back - no off sounds or noises tho...I would start reversing the changes you made, one at a time, until you find the one, or ones, responsible for the added hiss/hum. It's possible you just missed something too. Maybe someone with a little more experience will chime in. Anyway, good luck.

IF this is the jca22 we're talking about... then yeah, thing is this dude went crazy with the cold clipper in 3rd stage, taking that thing down from 39k to 2k7 gives you stupid amounts of extra gain, with that R9 to 68k he is just dumping a crap ton of gain in the 2nd stage to compensate.

With the SLO mod with Depth and taking the first two coupling caps (C2 and C9) down , specially the first one to something like 2n2 or less people are going to get as metal as they need, no need to go so creative.

[sefloval]

Just up update on my JCA50 head. Had a local amp tech bias my amp today as I recently replaced all the power and preamp tubes.
He texted me that the bias was set so low he couldn't believe it was even working? He said it was at about 10ma and raised it to 60ma and playing good now.
Before I gave him the amp I had played it for a couple weeks before biasing and it was a fizzy/fuzzy mess on the overdrive channel. Now it's much clearer sounding with more definition and punch.

I should have biased as soon as I got the new tubes, but didn't have time till this weekend. Anyways, just wanted to share that it's sounding great now!

[Tortuga]

Just up update on my JCA50 head. Had a local amp tech bias my amp today as I recently replaced all the power and preamp tubes.
He texted me that the bias was set so low he couldn't believe it was even working? He said it was at about 10ma and raised it to 60ma and playing good now.
Before I gave him the amp I had played it for a couple weeks before biasing and it was a fizzy/fuzzy mess on the overdrive channel. Now it's much clearer sounding with more definition and punch.

I should have biased as soon as I got the new tubes, but didn't have time till this weekend. Anyways, just wanted to share that it's sounding great now!

Good to hear it's working out for you, dude.

Now, go back and actually read this thread . I'll bet the words "bias + new tubes" are mentioned at least 100 times in these 30+ pages. There's a hell of a lot of good info here.

[Nproctor]

I'm a new owner of the JCA100hdm. I love the amp but want to fool around with some preamp tubes. I have done a bunch of research online and I cannot find a confirmation on the tube positions when looking at the front of the amp. Does anyone know for sure? I assume it's L-R V1 V2 V3 Then I'm not sure if it's the tube for the loop or Phase inverter or cathode follower.... And does anyone know what roles V1 V2 and V3 have? I.e.: clean, overdrive, etc.??? I'm totally lost!

[sefloval]

"And does anyone know what roles V1 V2 and V3 have? I.e.: clean, overdrive, etc.???"

I want to know this too! I can't find exact documentation on this anywhere.
I'm thinking of trying either a 12AU7 or a 5751 in V1 to try and tame the beast a little. I put a 5751 in V3 position which helped a little.
V1 starts to the far right when you're in the back of the amp replacing tubes.