Guitar Gear Forum

Would they need a tester/donor amp to make sure they fit? If so I'd loan them mine . . .

I am very seriously considering going for a Jet City amp, though I don't forsee myself doing any mods aside from Tube swapping, and even then I'll likely drop in JJ's and call it a day

Long thread, sorry for asking, but I'm also looking into picking up a Jet City amp and the JCA20HV sounds interesting. Did this model ever materialize? I see it on their site and there's a couple of phantom yt clips (at shows but not in an actual consumers hands, lol). This one has my attention, hope it hits streets soon (if not already). Thanks

MacaroniSalad - you won't be disappointed. As popular as this thread is, it should be an indication to the love of these amps. Highly recommended for many reasons. Price, tone, customer service, reliability - these amps have it all

Derek - yes the HV is in production

http://www.jetcityamplification.com/2012/07/28/jca20hv/

Groovy! Thanks. Looks classy (but hope it sounds at least a little mean ).

edit: I'm hoping this model will make for a great pedal friendly amp (seems as though it would based on the specs).

I'm excited that it will get me back into the Soldano ball park, but at a fraction of the price of getting my SLO back hahaha

Jay wrote:Okay guys. I got an email back from Heyboer for a 50w and 100w Transformer set. I gave them the dimensions that Grime and Sahl gave for their respective amps. They can make the them as drop-in replacement based on the bolt pattern given. These guys should bolt right in, have enough capacity to run ANY of the big octal tubes and they are inexpensive. $200 for the set for the 50w and $220 for the set for the 100w. I didn't ask about the choke, mainly becuase I forgot. lol But I'm sure it can't be more than $30.

I'm still on the hunt for a decently priced JCA 50 or 100 so I can test the waters first, but I think this is a really feasible (albeit - major) mod that can open up more possibilities for the big JCA amps. I may even try to find a 22H at some point and see if I can squeeze some of the bigger tubes in place of the little EL84s.

I'm still going to contact Edcor about some custom winds, but so far I'm really psyched about Heyboer and how quickly they responded.

Sounds great, Jay - this may be something I attempt later this year, once/if I have some funds available. I'm extremely interested in how this pans out - would be so cool to be able to change tube types. A couple of questions:

* Would there be any other changes required to the amp for this mod? Just change out transformers and I can swap / rebias on the fly?

* If I changed out one or both of the transformers, would they improve reliability and/or tone on their own (without changing tubes)?

* Did you happen to catch my prior question about an external bias adjuster / bias probe terminals? What is involved?

Thanks, dude - I can't wait for you to get your own amp to continue this chapter!

GRIMESPACE wrote:

Jay wrote:Okay guys. I got an email back from Heyboer for a 50w and 100w Transformer set. I gave them the dimensions that Grime and Sahl gave for their respective amps. They can make the them as drop-in replacement based on the bolt pattern given. These guys should bolt right in, have enough capacity to run ANY of the big octal tubes and they are inexpensive. $200 for the set for the 50w and $220 for the set for the 100w. I didn't ask about the choke, mainly becuase I forgot. lol But I'm sure it can't be more than $30.

I'm still on the hunt for a decently priced JCA 50 or 100 so I can test the waters first, but I think this is a really feasible (albeit - major) mod that can open up more possibilities for the big JCA amps. I may even try to find a 22H at some point and see if I can squeeze some of the bigger tubes in place of the little EL84s.

I'm still going to contact Edcor about some custom winds, but so far I'm really psyched about Heyboer and how quickly they responded.

Sounds great, Jay - this may be something I attempt later this year, once/if I have some funds available. I'm extremely interested in how this pans out - would be so cool to be able to change tube types. A couple of questions:

* Would there be any other changes required to the amp for this mod? Just change out transformers and I can swap / rebias on the fly?

* If I changed out one or both of the transformers, would they improve reliability and/or tone on their own (without changing tubes)?

* Did you happen to catch my prior question about an external bias adjuster / bias probe terminals? What is involved?

Thanks, dude - I can't wait for you to get your own amp to continue this chapter!

I would assume changing the SGRs and that might be it after dropping in the new trannies. I remember that being required on my XXX if I wanted to run EL34L tubes.

Hi guys, I'm still trying to get my head around the decadence mod. I was looking at both the 50 and 22 schematics but still cant seem to figure it out.
I've done a very crude diagram, am I on the right path?

Am I the odd man out/lone wolf here because I love the way my Jet City Amps sound and have no desire to mod them at all? I bought my JCA100HDM with a saturation mod that someone else had previously performed and it's interesting but nothing I'd run for any amount of time. Seems to be a simple resistor/capacitor circuit hooked into pin 8 of V4 (if memory serves - might be V3 or V5 -- I'm writing from memory).

Do people do mods just because they love they science, love to tinker, etc., or is the feel that there really IS something lacking in the amps?

Cheers,

Race

racerevlon wrote:Am I the odd man out/lone wolf here because I love the way my Jet City Amps sound and have no desire to mod them at all? I bought my JCA100HDM with a saturation mod that someone else had previously performed and it's interesting but nothing I'd run for any amount of time. Seems to be a simple resistor/capacitor circuit hooked into pin 8 of V4 (if memory serves - might be V3 or V5 -- I'm writing from memory).

Do people do mods just because they love they science, love to tinker, etc., or is the feel that there really IS something lacking in the amps?

Cheers,

Race

thats what I am curious about too. I can appreciate the modding if its because its a simple, fairly inexpensive platfor. Based on FPRC's demos, it seems like it should pretty much smoke off the shelf.

Jase01 wrote:Hi guys, I'm still trying to get my head around the decadence mod. I was looking at both the 50 and 22 schematics but still cant seem to figure it out.
I've done a very crude diagram, am I on the right path?

Jase - as with the SLO clean/crunch switch, you have to put part of the switch between the cap and resistor, as I've show below - I placed an 'X' over the wire you drew in that is wrong and another 'X' where you have to interrupt the connection between cap and resistor. The other line is where you need to connect back to R42.

My suggestion of lifting the one side of C2 (which is C30 on the 50/100) and soldering the switch to that still stands. I can't speak to long-term reliability, since you'll now have a component half-hanging with a wire attached to it, but from a circuit perspective, it should be kosher. If nothing else, I'd zip-tie the wire to something sturdy (ie: another component) near C2 - just make sure you cover the wire/cap connection with shrink tubing.



Let us know if this is still not making sense to you. I think I can draw it another way, and will try to do so in the next day or so if it's still not clear.

Man, trying to do some research on the JCA20HV and can't find jack about it...though it sure seems available, plenty of sites have it in stock. Weird. No yt demo clips with audio, very little forum talk, nada. Hmm, makes me wonder.

racerevlon wrote:Am I the odd man out/lone wolf here because I love the way my Jet City Amps sound and have no desire to mod them at all? I bought my JCA100HDM with a saturation mod that someone else had previously performed and it's interesting but nothing I'd run for any amount of time. Seems to be a simple resistor/capacitor circuit hooked into pin 8 of V4 (if memory serves - might be V3 or V5 -- I'm writing from memory).

Do people do mods just because they love they science, love to tinker, etc., or is the feel that there really IS something lacking in the amps?

Cheers,

Race

Honestly, they are killer right out of the box. I had mine for 2 1/2 years before I started with mod(s) . That being said, the Depth mod is about the only thing it really needs if you're playing lower volume stuff, the rest is just because I'm a tinkerer.

MacaroniSalad wrote:

racerevlon wrote:Am I the odd man out/lone wolf here because I love the way my Jet City Amps sound and have no desire to mod them at all? I bought my JCA100HDM with a saturation mod that someone else had previously performed and it's interesting but nothing I'd run for any amount of time. Seems to be a simple resistor/capacitor circuit hooked into pin 8 of V4 (if memory serves - might be V3 or V5 -- I'm writing from memory).

Do people do mods just because they love they science, love to tinker, etc., or is the feel that there really IS something lacking in the amps?

Cheers,

Race

thats what I am curious about too. I can appreciate the modding if its because its a simple, fairly inexpensive platfor. Based on FPRC's demos, it seems like it should pretty much smoke off the shelf.

That's exactly it. They do kick ass out of the gate. Modding them just makes them more "yours" I guess. Sort of a Signature touch. And yes, most of us here like to tinker.

sahlomonic wrote:I would assume changing the SGRs and that might be it after dropping in the new trannies. I remember that being required on my XXX if I wanted to run EL34L tubes.

Well, on the XXX, the screen grids were good for most EL34s and 6L6s. They were just too small for the E34Ls because they draw a bit more current on the screens. I know, not important here in JCA land, but now you know! lol

GRIMESPACE wrote:Sounds great, Jay - this may be something I attempt later this year, once/if I have some funds available. I'm extremely interested in how this pans out - would be so cool to be able to change tube types. A couple of questions:

* Would there be any other changes required to the amp for this mod? Just change out transformers and I can swap / rebias on the fly?

* If I changed out one or both of the transformers, would they improve reliability and/or tone on their own (without changing tubes)?

* Did you happen to catch my prior question about an external bias adjuster / bias probe terminals? What is involved?

Thanks, dude - I can't wait for you to get your own amp to continue this chapter!

There are a few resistor changes for the control grids and screen grids for the power tubes. I'll post up the changes when I get home and can check my notebook. Other than that, I gave them the specs for the voltages and the dimensions that you and Sahl posted up, just with the increased current to accomodate the other tubes.

The Heyboer Transformers are very rugged but toneful units. Splawn uses all Heyboer stuff, if that gives you any idea. They actually went from Mercury Magnetics TO the Heyboers. A lot of the testimonials and blind test that I have read through all say the Heyboer Iron has great harmonic detail, but does not get annoying or stiff. Apparently the Mercury stuff can be overly stiff and rigid, especially if you play with lower gain.

So, if you just swapped in one of the Heyboers, and stuck with the 6L6s, it would improve reliability and probably tone as well.

As far as the external bias pot/probes, it will be cheap and simple. Parts should be under $5. I'll try and draw a diagram or something later.

Drill three holes for probes, one for trim pot, solder in a pair of 1R resistors and the extension wires for the trim pot and bias circuit.

Dude here at work won a 50H off of the 'bay......so I might hit him with a tire-iron and take his amp.

MacaroniSalad wrote:I'm excited that it will get me back into the Soldano ball park, but at a fraction of the price of getting my SLO back hahaha

If you look through some schemes and diagrams, it's very easy to turn the preamp into the SLO. Just a few caps and resistors, and 'viola!

GRIMESPACE wrote:

Jase01 wrote:Hi guys, I'm still trying to get my head around the decadence mod. I was looking at both the 50 and 22 schematics but still cant seem to figure it out.
I've done a very crude diagram, am I on the right path?

Jase - as with the SLO clean/crunch switch, you have to put part of the switch between the cap and resistor, as I've show below - I placed an 'X' over the wire you drew in that is wrong and another 'X' where you have to interrupt the connection between cap and resistor. The other line is where you need to connect back to R42.

My suggestion of lifting the one side of C2 (which is C30 on the 50/100) and soldering the switch to that still stands. I can't speak to long-term reliability, since you'll now have a component half-hanging with a wire attached to it, but from a circuit perspective, it should be kosher. If nothing else, I'd zip-tie the wire to something sturdy (ie: another component) near C2 - just make sure you cover the wire/cap connection with shrink tubing.
Let us know if this is still not making sense to you. I think I can draw it another way, and will try to do so in the next day or so if it's still not clear.

Yeah Grime, if you do another diagram that would help me more, I kinda get it but aren't certain and don't start something until I am,
Would the crunch channel gain mod still work with this? Sorry for being such a dumbass!!
Oh and I'm still keen on multiple switches for more options with the slope mod so If anyone out there has any ideas I love to hear them.

Heres my idea for a switch setup for mulitple slope mod options. As you can tell, I'm no artist and if you've read my earlier posts you'll know I'm no electronics dude either!
Or is there a single toggle that will do 3 or 4 switchings?

thinking of selling my jca50 and 2x12 cab : ( seen some guys talking about wanting to buy one,
mines the one from a couple pages back with the black and pepper grillcloth and white piping.
New tubes, biased, depth mod. pm me if your interested.

When posting mods, if possible can we have pictures and a parts list to accompany them? It seems simple enough figuring out what caps and resistors for the SLO mod, but if adding the clean/crunch switch, what switch do I need to look for and how is it wired?

<-- modding n00b

And for reference, my plans and progress:

SLO mod
Simple scoop mod
Normal/Overdrive channel switch
Clean/crunch switch
Overdrive LED indicator (like the HDM)
Depth mod = done

I'm also interested in the slo mod, and would like to see pics. I probably wouldn't do a switch, though.
I did the depth mod, but can't hear a lot of difference. 22h, by the way

kissmyace wrote:I'm also interested in the slo mod, and would like to see pics. I probably wouldn't do a switch, though.
I did the depth mod, but can't hear a lot of difference. 22h, by the way

Man, when I did it to my 22h the difference is amazing. Maybe you've done something wrong, but I'm defiantly not the person to ask here! haha Grimespace seems to be super switched on.

Jase01 wrote:Heres my idea for a switch setup for mulitple slope mod options. As you can tell, I'm no artist and if you've read my earlier posts you'll know I'm no electronics dude either!
Or is there a single toggle that will do 3 or 4 switchings?

How noticable a difference are we talking about here? With the 33k I seem to get some more higher mids maybe and a bit less bottom end than the stock 47k. Does that about right to you guys? The more I played the more diff I noticed..