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

[Jay]

Ceramic caps: inexpensive, good for anode bypass and bright caps. Can be a bit on the gritty side under high voltage. Just think of them adding "texture"

Mica caps: Bright, can be kinda sterile. Similar to the ceramic caps without the grit, but they are rather expensive in comparison.

Polyester: Smooth and creamy. Sometimes too smooth for my taste. Good to mix with Polypropylene for a good "balance" of tone.

Polyproylene: Bright, tight, articulate, good harmonics. Some people say they are "harsh" for a Poly type cap.

[Jase01]

Good job. The t-filter is something that soldano took that was inspired by an older amp (can't recall which one off the top of my head right now).
For me I love the clean+scoop mod, get me a very touch sensitive sound. What values are you doing with the slope switch? You into clean tones alot or no?

Hiya, Edge - glad to see you. How'd things go with the internship at Fender?

Thanks for the compliment - it means a lot coming from you. Slope switch is 47k (stock) and 33k, as noted above. I've heard that 39k is also being used by others, but I really like the vibe I get with leads on the 33k. It took a while for me to get into the clean mod, but after playing more and more with my Fender Pro Reverb, have found that the JCA is getting pretty close to that tone. As I also said earlier in this thread, I'm glad I put the scoop on a separate switch because I like both settings - normal (no scoop) is big and beefy; scooped is thinner / more chimey, with greater dynamics.

I know most would join in my appreciation for your pioneering work with these mods, Edge! I hope you do find time to come back, at least occasionally.

<<<and now that I'm done smooching up >>>

I've been holding off building a JCA mod thread in the DIY area, hoping you'd be able to do something with it. This JET CITY LOUNGE thread was really intended as a general gathering place, to find information about what others are doing with their amp (not so much how, just getting ideas), and where to find more information. That said, I think it's real important that someone who has the time to keep a new mods thread updated (especially the first few postings, as you've done in the past) start the thing. I'd be happy to do so - I've already grabbed snapshots of a lot of the content over at HCAF, just in case the thing did a Titanic on us, and could put together a consolidation / summary of the good stuff so's we can start getting more technical without overburdening this thread.

So, what do you think? If I start it, you'll have first say on anything that goes on the first few threads I reserve, but won't have to worry about keeping it up. Let us know.

...and to the rest of you Jet City Pirates , what do you think about it? DIY thread for the tech-heavy stuff? I've got some how-to's that I've been anxious to post but haven't yet - I'm sure a bunch of the rest of you do, too.

I'm all for a DIY section, consolidate all the mods together. Would make it easier to navigate I think. Is there anyway to link the separate mods, so you didn't have to trawl thru lots of different posts looking for relevant info. I'm new to all this so excuse my ignorance

[Hipster Salad]

I have a written list for the parts for the SLO mod, but have to post it up here. I'll link to all the parts you need on mouser, so it makes things easy.

I bow to you, good sir. I guarantee my parts list on Mouser for the SLO mod (and a couple others) is a complete compared to yours because I'm still green to all of this haha

[Jack Tone]

here's my depth mod(phone pic, sorry)
can't figure out why it doesn't do anything
cap is wired between 1st 2 lugs (left- rt) blue wire from fb on 1st, to sp on 2nd, 2nd/ 3rd lugs bridged together

I did the mod on my 100 and my 20 head. Made a huge difference on both. I just took the 20 apart to check, and for what it's worth, the second and third lugs on my pot are not bridged, and I have a 250 audio pot. If I remember right, Dusentrieb who I think made this mod, said that a 250 worked best. A 500 had less sweep. I'm not sure why I see pics of a 1 meg pot being used. Also, I've got the wire from the second lug connected to the 8 ohm tap, not the 16 where it came from.

[justinjag77]

Hey guys, been lurking ever since someone posted a link to here on HC. My new JCA22H with 1x12 arrived earlier this week, and I think it's the perfect amp for me. (Also the first tube amp I've felt like keeping after a few failed attempts to jump from modelers. HT5 suuucks.) However, I do want to make some tweaks and I'm not sure where to start. Remember this thing is brand new, stock tubes, speaker not broken in, etc. I'm playing with the master below 4 too.

Basically two things are bugging me. One, it's too bright. It's not so bad with the presence at zero but I feel like I'm constantly moderating the treble and some of the mids back. Don't know if this is a dialing in problem or what. Number two, there's some fizz in the gain and I'd really like it to be smoother. I'm wondering if I can solve both of these problems with new tubes. I keep hearing that the JJ ECC83S will darken things up, but people complain that they're flat and dead sounding. (What about the long plate ECC803S?) Maybe TungSol 12AX7 would be a better choice? I'm also not sure how things will change as the speaker works in.

Wow, I have the exact opposite problem with mine. It seems to be very dark and boomy, I personally like highs in my sound, i really would like to get that razor marshally sound out of it.. but IDK . I've got a broken in V30 in my cab that gets me close

[Jay]

SLO mod thread

I'll try and find suitable toggles also

EDIT: My second post here makes thing easier.

[käsebrot]

Vishay/Roederstein MKT1813: I have not tried these, but they are axial Polyester caps and I hear lots of good things.

I have changed all non-electric caps (value > 1nF) to Rödersteins in one of my JCAs. They are really good. Like it a lot better than the Mallorys or 715/225 Orange Drops. Just in a few positions I replaced them with Sozos and Cornell Dubiliars. But this isn't neccessary.

Especially they work great as cathode bypass caps.

[Tortuga]

Vishay/Roederstein MKT1813: I have not tried these, but they are axial Polyester caps and I hear lots of good things.

I have changed all non-electric caps (value > 1nF) to Rödersteins in one of my JCAs. They are really good. Like it a lot better than the Mallorys or 715/225 Orange Drops. Just in a few positions I replaced them with Sozos and Cornell Dubiliars. But this isn't neccessary.

Especially they work great as cathode bypass caps.

Hiya, käsebrot - welcome to the new club!

[käsebrot]

Hiya, käsebrot - welcome to the new club!

Thank you very much! : )

[Jay]

Vishay/Roederstein MKT1813: I have not tried these, but they are axial Polyester caps and I hear lots of good things.

I have changed all non-electric caps (value > 1nF) to Rödersteins in one of my JCAs. They are really good. Like it a lot better than the Mallorys or 715/225 Orange Drops. Just in a few positions I replaced them with Sozos and Cornell Dubiliars. But this isn't neccessary.

Especially they work great as cathode bypass caps.

Which Cornells? The brownish-orange square/rectangular caps that resemble the ODs? I hear their DME series is actually pretty good for high gain stuff.

I've also been trying to track down the original type of caps that were used in the SLO (since they changed manufacturers/brands/etc about five times) and I THINK they are the Vishay MKT368. Between starting out with the Philips MKT, then going to the Mallory PVC 4211 and PVC 4147, then the Vishay/BC Components type 368, it almost seems like the MKT368 is the most current iteration.

So, if anyone wants the more "authentic" Soldano type tone, that may be the way to go. I'm still trying to hammer it out though.

[Jay]

So, after geeking out about capacitors, I found that the closest match to the older Soldano SLO types are the Sprague 6PS Polyester Film and Foil for coupling and the Vishay MKT368.

Also, since there has been much controversy about using KT66s in these amps, it seems the TungSol KT66 is the only one that will be safe to use. KT66s usually draw 1.3a of heater current, and the TungSol draws .9, same as the 6L6. Apparently, it's not a true KT66 as it is more of a "hot-rod" 6L6, but with bigger lows and mids. So, if some of you guys want the bigger-bottle tubes, but don't want to change your Transformers to keep up with the extra current, you have this option.

[käsebrot]

I've talked about the Cornell Dubilier DME series, they are coloured winered and have quite the size of Orange Drops 225 and are polyester film too.
And yes, if you would use only these caps as coupling caps, your amp will scream at hi-gain settings! So I've just tamed that a little bit by putting in some Sozos and Rödersteins. With CD DME only, it's a little too brutal for my choice. But there are other amps, which show how that would work like f.e. Splawn.

[kissmyace]

thought I would share a pic of my 22H. Just took the big badge off & put some chicken heads on (red= masters)
pic quality is terrible, but......

[Jay]

I like the chickenheads. The red ones remind me of the safety for nitrous systems on race cars and missle control on a jet fighter. The only thing about the JCA amps I don't like is the blue tolex. Some salt n pepper grille cloth would make that thing look sweet!

[marshallnoise]

I am in. I have a second run of the JCA20H with the rocker switches and integrated light. Have the depth mod and the choke mod.

Currently surfing through the old HC thread to see if I can pull off the Brown Eye and Saturation Switch mods.

[Jay]

JCA 100HDM schematic

[Jay]

I am in. I have a second run of the JCA20H with the rocker switches and integrated light. Have the depth mod and the choke mod.

Currently surfing through the old HC thread to see if I can pull off the Brown Eye and Saturation Switch mods.

Noice! After I finish my little clone, I'm going to work on some additional mods. I still keep thinking I should just get one to tinker with. But I have some cool ideas for the little ones on the horizon.

[marshallnoise]

I am in. I have a second run of the JCA20H with the rocker switches and integrated light. Have the depth mod and the choke mod.

Currently surfing through the old HC thread to see if I can pull off the Brown Eye and Saturation Switch mods.

Noice! After I finish my little clone, I'm going to work on some additional mods. I still keep thinking I should just get one to tinker with. But I have some cool ideas for the little ones on the horizon.

I gotta say, doing those two mods was such a piece of cake with this board. Everything is clearly labeled and appears laid out very clean too. For as cheap as the amps are, I see no reason not to pick one up. I think I got mine for $200 shipped. Hell of a deal.

[marshallnoise]

As I said, I am rereading the whole HC thread digging for Brown Eye info...but I gotta say, M-Theory is such a magnificent tool. What a dick.

[Tortuga]

JCA 100HDM schematic

Well, HELLO!!! Been waiting a long time to see that. Quite a difference from my 50H, that's for sure!

Notables (from my first perusal):
* Soldano is using a .1uf cap inline with the depth mod, purportedly for eliminating scratchiness when adjusting the control. I've got one, and I do recall hearing a positive difference after doing so.
* Interesting how the 50W switch cuts the two tubes. I wonder how it deals with the change in impedence (wouldn't it double or is it halve the impedance when removing tubes like any other amp?) - perhaps something trick with the transformer?
* Different wiring for the footswitch - can I tie a light directly to that in my 50 as well, so I can see the channel change whether I switch via my panel or footswitch? I think Jay said something about this a few posts back (dam my shitty memory!)

Jay - how's things coming on picking up a 50? And, any news on the transformer front? It got kinda quiet this past week - are you in the dungeon getting ready to kick our asses with something cool?

I've done some research on the Bias test points and alternate methods of setting up bias adjustments (dual controls - 1 for each power tube). The test points look pretty straightforward - just connect a 1 ohm resistor between pin 8 of the power tubes and ground, and wire the test point such that it measures voltage across the new resistor. Assuming this is correct, what wattage resistor is needed, and what can be done to adjust the bias to either tube, since this design only has a single adjuster? Also, what needs to be done (if anything) with the wiring between resistor and test points on the rear panel to make sure I'm not introducing a new source of hum?

CTN / Blakkwater - you still out there? I'm really interested to hear a report on the 5751 replacement you were supposed to get.

And, in other news, I heard from Edge11 yesterday. Sounds like he might be making some time to get his mod stuff moved over in the near future. Can't wait...

[marshallnoise]

Jay, can you help me out with the Brown Eye Mod?

I have pretty much figured out all of the changes but I am paranoid about the wattages for the resistors and the voltage ratings for the caps. I have read such conflicting information on what wattages are acceptable and what is not.

Here is what I found (as in another dude on HCAF):
• First stage:
o Anode - 220k in series with 100k // 500p -- very interesting!
o Cathode - 2.7k // .68 -- standard marshall
o then into 2n2 coupling cap then into 68k/68k voltage divider.
o then into 33k which is soldered straight to the grid of the next gain stage
• Second stage:
o anode - 100k (this one already exists in the amp and is not changed)
o cathode - 2.7k // .68
o then into 2n2 coupling cap
o then into the standard 470K/470K divider with 470pf treble peaker (it think the actual value in the amp was 500p silver mica)
• 3rd stage:
o anode - 100k
o cathode - 820 // 22u

Tone stack values changed to stock marshall -- slope R 33k, treble cap 500p mica

So here is my parts list based on the above:
o 2 x 680nf (.68uf) capacitors – 250v
o 3 x 500pf Silver Mica capacitors – 500v
o 2 x 2n2 capacitors – 100v
o 1 x 22uf cap – 500v
o 2 x 2.7k resistors – 1/2 watt carbon comp
o 1 x 120k resistor – 1/2 watt metal film
o 2 x 820 ohm resistors - 1/2 watt carbon comp
o 2 x 33k resistors - 1/2 watt carbon comp
o 3 x 68k resistors - 1/2 watt carbon comp
o 2 x 470k resistors - 1/2 watt carbon comp

Can you change my parts list in terms of ratings to match what is said in the description of the mod up top?

Thanks a million if you can.

[sevenmusic]

Hi to all!
First steps here...
Happy to join the Jet City Lounge

[Meelocheck]

First time poster, long time lurker...

Anyway, glad to be here. I also have the JCM22H and all I have done so far is turn the thing around so the front of the amp is now what used to be the back - so you now see through the expanded metal and watch them sweet tubes glow. I plan on doing a bit of modding as well. I'm going to start with the depth mod as that one seems to be the easiest and it yields some decent results for around 8$ in parts...

I am playing through a 4x12 Ibanez cab and have recorded a few "tracks" with it so far. Before this amp I was rocking an Ibanez Toneblaster 100H - what a huge difference in sound. The tracks are really only drums (EZdrummer) and guitar. The guitar is recorded using Reaper and a shitty USB mic. I hear some of the recordings from guys here and they rock. I don't know how they get such good sounds recorded. I have the cab mic'd, albeit with a crappy mic, and it just doesn't sound anywhere near as good as some of the other guys here. What kind of interfaces are these guys using? Holy cow...I should also mention I am not using any effects - just plug and play...

My playing spans about 18 years...I do have a period of about 10 of those where I never picked up the instrument. I lost most of what I had going on during that down time. Since then I have been playing off and on the last 2 years or so, trying to get back into the swing of things...Unfortunately the fingers don't work as they once did so things are slow going. I thought the new amp and an app like EZdrummer would motivate me a bit and it has...Still, I'd like it to sound better...

Anywho, hopefully I will be able to contribute some to the forum as I learn more. I do have something in the works as far as the cover on the amps go - I have access to some acrylic, mostly black and blue, as well as a laser cutter...So I am in the process of designing some cool face plates/badges/covers or what ever the hell you want to call them. The machine is always busy so it is tough to get time on it...I will post some pics as I get them. Again, glad to be here.

[racerevlon]

If memory serves Splawn moved away from Heyboer for business reasons and is now sourcing transformers out of a new supplier from Texas. I'll look inside my 2012 Quick Rod and see if I can ID it.

[Tortuga]

Hi to all!
First steps here...
Happy to join the Jet City Lounge

Hiya, sevenmusic, welcome to the happiest place on (virtual) earth! Are you the same guy from the HCAF? If so, thanks so much for posting the HDM schematic over there! Assuming so, do you have an HDM, and would you be willing to take some gut shots of your amp for us? I'd very much like to see the labels on the transformers, inside wiring for the 50/100 switch, channel LED, and depth knob, and some shots of the PCB and back panel wiring as well.

First time poster, long time lurker...

Anyway, glad to be here. I also have the JCM22H and all I have done so far is turn the thing around so the front of the amp is now what used to be the back - so you now see through the expanded metal and watch them sweet tubes glow. I plan on doing a bit of modding as well. I'm going to start with the depth mod as that one seems to be the easiest and it yields some decent results for around 8$ in parts...

I am playing through a 4x12 Ibanez cab and have recorded a few "tracks" with it so far. Before this amp I was rocking an Ibanez Toneblaster 100H - what a huge difference in sound. The tracks are really only drums (EZdrummer) and guitar. The guitar is recorded using Reaper and a shitty USB mic. I hear some of the recordings from guys here and they rock. I don't know how they get such good sounds recorded. I have the cab mic'd, albeit with a crappy mic, and it just doesn't sound anywhere near as good as some of the other guys here. What kind of interfaces are these guys using? Holy cow...I should also mention I am not using any effects - just plug and play...

My playing spans about 18 years...I do have a period of about 10 of those where I never picked up the instrument. I lost most of what I had going on during that down time. Since then I have been playing off and on the last 2 years or so, trying to get back into the swing of things...Unfortunately the fingers don't work as they once did so things are slow going. I thought the new amp and an app like EZdrummer would motivate me a bit and it has...Still, I'd like it to sound better...

Anywho, hopefully I will be able to contribute some to the forum as I learn more. I do have something in the works as far as the cover on the amps go - I have access to some acrylic, mostly black and blue, as well as a laser cutter...So I am in the process of designing some cool face plates/badges/covers or what ever the hell you want to call them. The machine is always busy so it is tough to get time on it...I will post some pics as I get them. Again, glad to be here.

Welcome, Meelocheck - glad to have you with us! My guess is that you're having most of the problem with recording due to the USB mic - those things just aren't good for much other than the occasional Skype session and maybe recording a quick clip for remembering a new riff you came up with. I'm using an SM57 (pretty much industry-standard) and a Presonus AudioBox, and getting pretty good results. Where did you place your mic? That has a huge impact as well. I've found that aiming pretty much straight at the juncture between dust cap and speaker cone and moving back a few inches works pretty well (also found this was confirmed by CTN recently as being a pretty good placement). I'm really interested in what you come up with on the acrylic / laser cutter - perhaps you'll be able to make some custom designs for others ($$$??? )

@Marshallnoise - good luck with the mods - would love to hear clips when you're done!