Questions for Jet City JCA22h owners

[joshsc]

Hey guys I just bought a Jet City JCA22h and got a great deal on it. Unfortunately its on back order so I wont see it for a bit.. I'm planning on building a speaker cabinet for it. 2x12" with Eminence Legend speakers. I want to get started before the amp shows up so it'll be ready (or at least close to ready) when I finally receive the amp. I'm looking for dimensions for the JCA22h head. Outside dimensions of course, in standard rather than metric. I know the Jet City website says 9" x 9" x 19.5" but i'd feel more comfortable getting the measurements from someone who has one.

I'm also thinking of using a couple of 12at7's to tone down the gain on the clean(er) channel and mellow it out to use as a more respectable clean channel. Any thoughts on this?

 

[frankv]

I like the pre amp tube choice..

 

[CN24]

I have a JCA20h that is 9"x9"x19.5" , I believe they are the same dimensions.

 

[joshsc]

Yeah Franky I definitely want to get high gain sounds out of it too but it would be nice to tame the cool channel down for clean tones as well..

CN have you measured it or are you going by the measurements on the website? I'd hate to build a cabinet and have it not match the head!

 

[Pwrmac7600]

There is a clean mod that can be done to the clean channel that is supposed to turn it into a truer clean channel.

 

[CN24]

I measured it.

 

[joshsc]

Awesome thanks CN!

Do you have any more info on that clean mod, Pwrmac?

 

[Pwrmac7600]

If you do a google search you'll see it talked about. You could also reach out to Brian at BFG Amplification in regard to doing this mod. He currently has my 22H doing a whole slew of mods on it.
Member jimmer_5 could probably answer better I believe he has it done on one of his jet city's.

 

[joshsc]

Oh cool thanks! I've built a few pedals (10 or 12) and built a small tube amp in the past so I'll probably do the mod myself.

 

[Pwrmac7600]

Yeah I don't know the technicals behind it but I know it is a toggle switch, that is supposed to really clean it up. This video has a clip of the clean mod done by BFG.
[ame]http://www.youtube.com/watch?v=FJjr9m-BGu4[/ame]

 

[frankv]

Yeah Franky I definitely want to get high gain sounds out of it too but it would be nice to tame the cool channel down for clean tones as well..

CN have you measured it or are you going by the measurements on the website? I'd hate to build a cabinet and have it not match the head!

Do you have time to build me a head cabinet? I have a Studio 15 combo I want to convert

 

[joshsc]

PM sent about the cabinet mod

 

[ac/dcfan87]

I would advise against using 12AT7s. They are terrible tone generators. You're better off using a 5751 or 12AY7. I've tried 12AT7s and they sound brittle and bright. 12AT7s are better for reverb circuits and stuff.

 

[joshsc]

Cool I think i'll probably go with the 5751 if the clean mod isn't enough for me.

So far i've done a bit of research and there's a mod thats pretty simple that gives you a switch to go between a clean sound on channel 1 (the cleaner of the 2) and a sound with more gain than stock on channel 1. Neither will affect channel 2. I'll probably go with this first and then try a 5751 in v2 and/or v3 if its not clean enough.

 

[ScottMarlowe]

I just picked up 5 Used Test as New OS American GE JAN 5751s for ~$80 or so delivered from Ebay, all tested good on my end. I'm a big fan of 5751s for input stages and PIs especially NOS ones while they're still cheapish.

I too recommend using 12AY7s or 5751s in place of 12AT7s. OTOH you might stick in a 12AT7 somewhere any just love it, so I say try it and see.

For later gain stages I'm a big big fan of NOS / ANOS GE JAN 12AX7WAs. Then again I also like the Chinese Shuguang 12AX7B in those positions too. They're a bit brighter and somewhat higher gain, but work well for overdrive / high gain stages.

But play around man, you never know what tubes will work well with YOUR amp and YOUR sound until you try them.

 

[joshsc]

Thanks for all the info! I think once I get the amp I'm gonna mess with it to see if I can get the sounds I want out of it first. Then if I can't I'll go ahead with the clean/crunch mod and I'd its still not clean enough I'll get some tubes. I'll probably get one each of 5751, 12at7, 12ay7 and 12au7. That will give me plenty of variety and the ability to low gain more than one valve at a time.. I also have a Blackstar HT5 I could use them in as well..

The funny thing is that I've never really been tuned in to my amps sound that much to notice the difference between tubes. Personally I can tell the difference between say single coils and humbuckers or my Les Paul and one of my Jacksons but I couldn't begin to tell you the difference between a 12ax7 tung Sol and a 12ax7 JJ!!

 

[Big John]

Another tube that may work to clean it up is the 12DW7 (12AX7 on one side, 12AU7 on the other). In your internet search for a clean channel mod, take a peek at the clean/crunch switch on the SLO schematic. That switch drops a gain stage out of the signal path which results in a good, useable clean tone.