Why does my Jet City suck?

[Chups01098]

So our singer just bought me a Jet City Jca20h and a marshall cab with celestions. We play general rock n roll. Some pop, some heavier stuff.

I'm using either a vintage Harmony guitar i bought for a hundred bucks with almost p90 ish pickups, or a sss mexi strat with it.

It just doesn't sound too good. And I can't try high gain tones with it, because if i crank gain, i get feedback SO LOUD AND ANNOYING, its unplayable. or if i do volume, i get same. even if the strigns are muted and im not playing, if the volume knob on guitar is higher than "0", feedback out the wazoo. Why?!?! That's my main issue. Freaking feedback is sooo crazy.

So thats my question part of this.

The other part is, do you think with maybe a fuzz (big muff?) and some kind of boost I oculd start making a kinda vintage fuzzy tone, ala Black Keys or White Stripes, or Hendrix? Kinda why i bought that vintage harmony. for a vintagey type fuzz tone. What could I do to get those type of tones out of jet city, and get rid of the feedback?

And i dont think you understand what im saying on the feedback. IT IS soooooooo bad. You can be 20 feet away from it, and if the guitar volume is 1 or higher, you can't even play. it pisses me off SO MUCH.

Thanks,
Nathan

[Shugaboy]

Sounds like your pickups are microphonic. Try another guitar before blaming the amp. hope that helps

[MRscratch]

try a different guitar! also 20 watts? cranked high gain amp? with a old sears guitar? there you go.maybe back off the gain?

[Deathmonkey]

Might also be a tube issue. My coguitarist brought a JC20H to practice awhile ago, and it sounded pretty good. He didn't seem to have any problems with feedback, and we practice LOUD.

[tele_jas]

Doesn't sound like the amp is the problem to me either... Try a different guitar, other than the two you have... If it still does it, you could have a bad preamp tube.

[Sirloin]

I played on in GC one time and found the amp to be exceptionally bright in it's voicing. Not impressed with it at all.

[The Kid]

Originally Posted by Chups01098

So our singer just bought me a Jet City Jca20h and a marshall cab with celestions. We play general rock n roll. Some pop, some heavier stuff.Thanks,
Nathan

Wait... your singer bought you an amp? Most singers I know don't even own their own microphone let alone buy gear for other cats.

I think of all the money that I have invested in gear and PA to amplify their voice and they roll in with nothing but the clothes on their back... So unfair.

I should have been a singer.

[suparsonic]

[BudLite]

[QUOTE=The Kid;9467288]Wait... your singer bought you an amp? Most singers I know don't even own their own microphone let alone buy gear for other cats.

Exactly what I was thinking...

[ronmail65]

Save your money and get yourself a nice guitar.

[Endr_rpm]

+1 for microphonic pickups. Adding a fuzz to what you already have will just cause MORE feedback.

[kleydj13]

Feedback is usually not an amp thing. Check the guitar.

[fyler]

Originally Posted by kleydj13

Feedback is usually not an amp thing. Check the guitar.

this. (although what he's calling 'feedback' could be a microphonic tube 'whistling', or oscillation caused by a fault in the amp.)

i'm pretty darn sure it's the guitar, though. i used to have a Kay K300 (semi hollow w/ kleenex box pickups), and when i plugged it into my THD Flexi it would feedback CONSTANTLY at anywhere close to decent practicing (w/ a drummer) volume. those old pickups just weren't made for modern loud amps.

like already stated, a fuzz would make things worse...but you could *possibly* benefit from a noise gate...but you'd be better off with a guitar w/ a set of potted humbuckers, though.

[diagrammatiks]

microphonic pickups and tubes

if those are fixed then technique.

[Alton]

I own a JCA20H. It's actually a very, very good amp once you get to understanding it.

The first thing is you need to consider who designed this amp. Mike Soldano did and it certainly carries his "style". It was designed as more of a modern sounding high gain amp.

Inside it is very well built as compared to the "standard" Chinese fare. It's actually a simple circuit being based pretty much on the Soldano Atomic 16. Component quality is better than the average component quality found in most amps made in China. A lot of effort was put into quality control of parts supply and the manufacturing process. the weak part is, unfortunately, the tubes.

Since new tubes are in order, I would highly recommend the JJ brand for the power tubes. Of course, you will need to have it re-biased. As admitted by Doug White, head sales guy, chief ramrod for mfg. quality control and general all-around good guy, the amps come from from the factory biased toward the cold side. when you have it biased with the new tubes you or your tech should set the bias toward the warm side at between 65 - 70%..

You may like the stock preamp tubes and you might not. Since there's only 2 of them (the third is the phase inverter) it is very easy and cost effective to experiment here. If you need more clean tones you might consider a 12AT7 in V1 position. Of course, you're free to place compatible tubes in whichever position you like but since V1 is the initial gain stage you can trim back the distortion and feedback here. Be sure to use a balanced/matched tube in the PI position. Switching to a 12AT7 may prove useful here too. Avoid any long plate or 12AX7 tubes designated as High Gain. as these will sort of defeat your goal of less feedback.

When setting up your head, remember, this is designed to be a modern sounding HIGH GAIN amp. Start off with your preamp set at about 2 on the dial numbers and set your master volume at about 4. Start playing and use your tone controls to season to taste. Once you find a tone or tone range you like go ahead and sart rolling up the master volume. I don't go beyond 7 on the master. During this process keep your guitar volume pots turned down low. Once you get the amp volume/tone where you want it start experimenting with the volume and tone controls on your guitar. You'll be amazed at the tonal range you can get from just your guitar controls. Also, and this is important, distance is your friend. If you get closer than 5 or 6 feet from your amp you will get howling. Simply turn your guitar volume down before you approach the amp to make adjustments.

If, after getting the amp set up you still have howling then it's time to consider new pickups. My experience and the experience of others indicates that the JCA20H and single coil pickups aren't the best of friends. If you use P90s or P90-ish pickups you'll want to use the JCA more towards cleaner settings. It's GREAT friends with humbuckers.

The JCA is also kind of finicky about what speakers it likes. It likes Celestions which makes me very happy. I have a M 1960A with G12 T75's in it and it tended to pretty much suck with most of my other amps. It plays very well with the JCA. Today I patched up another 4x12 with an odd couple of speaker pairs (Emi. C. Rex & Bugera) and the mid response is not very good.

Definitely do the new tube thing. I just did mine and it was like getting a brand new amp with killer tone. Actually has a Marshall vibe to it.

Also, you may want to pop over to Harmony central to the amp forum there. JCA has a pretty big following over there with very useful info on tubes, biasing and mods with numerous reviews.