#1
Hi,

Today I got a new Jet City JCA2112RC, because my last one had some problems so I decided to just send it back since I only had it for a week and a half. There's a couple things though that I've noticed on this new one.

1) When I'm playing, and then I turn down my guitar volume, there is still a low hum coming from the speaker, it's not effected by the guitar vol. at all, so I think that is ruled out. It's not that big of a deal, but it kind of bugs me. It is more obvious at higher volumes, and I never noticed this with the other one I had.

2) There is also a slight rattle from inside the amp (I'm guessing the tubes?) when I play at loud volumes. How do I go about fixing that?

Are these things bad? If so, how would I fix them? Thanks
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#2
1) My JCA50H is the same. A noise gate will (should) solve this problem if it's really bothering you. My 5150 is loud as hell just from turning it off standby, almost completely silent since I got my decimator. I've actually not used it on my JCA yet though....

2) Never owned a tube combo amp but I've read this is a fairly common issue. I think if you get those little spring things that go over tubes it helps but I'm not completely sure on that.
#3
Quote by ChrisBW
1) My JCA50H is the same. A noise gate will (should) solve this problem if it's really bothering you. My 5150 is loud as hell just from turning it off standby, almost completely silent since I got my decimator. I've actually not used it on my JCA yet though....

You still get them hum on the JCA even when the guitar volume is on 0 right?
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Fender Deluxe Roadhouse Strat
Ibanez RG4EXFM1
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Dunlop Original Crybaby Wah
Fulltone OCD Overdrive
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MXR M-148 Micro Chorus
Jet City JCA2112RC 20W
#4
'Twer it me I'd put bigger filter caps in it. That's an area amp manufacturers often skimp on to save money.
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#5
Yeah even when there's no guitar volume. As long as it isn't a problem when you're actually playing you should be ok.
#6
what was wrong with the first amp?

amps hum

if it hums really loudly then maybe the amp or the guitar are not grounded properly. Try a different guitar. Try your amp in a different room or a different location altogether.

tube rattle can by annoying but it won't hurt anything. If your amp can run an extension cab as I believe it can, try plugging a cab in and then listen (or record) for the tube rattle while it is a far distance from the combo. get an oven mit - does the rattle if you push down on the power tubes? you can also tap on the tubes with a pencil (eraser) and listen for that tapping coming out of the speaker. Again this is easier to determine if the speaker cab is separated a fair bit from the amp.

it may simply be an overly microphonic preamp tube - which is easy to test and replace. you should have 1 extra preamp tube laying around at all times anyway.

i just re-read that your 1st amp did not have this problem. this would tell me that your guitar and power are fine.
#7
one of the EL84's in my first one was red plating and blew and I guess that I could have done damage to the screen grid resistor so I figured instead of spending 30 bucks on all new tubes and stuff I'd just send it back and get a new one cause I had only had the other one for about 14 days prior to that going wrong.

and yeah I don't really care about the tube rattle, and as far as the hum goes, it just sort of was bugging me because I don't remember hearing it before, (maybe I never noticed it haha) so I was just wondering if it was a big deal.

thanks for the replies guys
Quote by Robchappers
Ha ha love you to dude ;-)

Quote by fearofthemark
10/10 Slater is amazing

Fender Deluxe Roadhouse Strat
Ibanez RG4EXFM1
Washburn D46S
Dunlop Original Crybaby Wah
Fulltone OCD Overdrive
Boss SD-1 Overdrive
MXR M-148 Micro Chorus
Jet City JCA2112RC 20W
#8
Also, if you are standing near your amp facing it, it can introduce hum. Try walking away from it and face your guitar away from it.

May not be your issue but I had a customer that had this issue and thought it was a problem with the amp so I thought it would be worth mentioning.
#9
Amps hum, even high fi $1000 stereo systems hum at high volumes, just it's very slight. They hum even more with distortion. If you are playing with single coils, it'll hum, if you have a dirty power supply, it'll hum, if you have a computer, or fan running near it, it'll hum.

Humming doesn't mean there's something wrong with the amp, unless like 311 said, if it's loud humming.