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hiss, hum with UL502?

Discussion in 'Amps and Cabs [BG]' started by Gene Leone, Nov 10, 2005.

  1. SO finally my UL310 arrives and I hook up the UL502 to get the juices flowing.

    I hear a low hiss with an underlying hum in the background. I call Epi, talk to one of the guys who says to lower the treble on my bass. (I never keep it up much) Do that but hiss and hum continue. They say to lower the tweeter control which is too sensitive. Well that cures the problem but then I'd have no tweeter.

    Anyone experience this low grade hissing or hum when not playing but the amp is on?

    Epi says this is normal noise but I won't hear it when I am playing live? :meh:

    Next odd problem. When I switch channels using the front panel buttons I get a quick "crack" or "static" sound when the button is pushed. When I press the mid-cut button the red mute light flicks for a second along with that same "crack" sound.

    Epi says to use compressed air and try and clean out the buttons because there might be dirt in them. (The amp is about a month old)

    C'mon I'm not stupid or an amateur. :rollno:

    Before the 310 arrived I used headphones through the back and didn't hear any hiss, hum, or crack sounds at all.

    Anyone else notice these on their 502's or epi cabs or any combination of 502 & 310 together?
  2. I get some hum from my 502, and a pop/crack when switching channels too, but it's not bothersome to me. And of course the hum is inaudible when the music starts.

    By contrast, the 502 is quieter than my PLX/Bmax rack amp. I do run a pretty hot signal to the input tho, I'd imagine a normal signal would quiet things down. I don't care tho, I just want a big live sound, and the 502 works for me despite a bit of hum.

    No comment on the Epi cabs, never played one.
  3. OK Temp,

    That's what I ma trying to find out from other users. Of course I tried different basses with different pups but when used with headphones the amp was dead quiet.

    So I ma just trying to determine if the hiss/hum and the pop/crack is normal to this amp or if it needs service.

    On a side note, I was told that Epi just began the mods for the DI problem so the one I have already has the mod and I can use the DI with phantom power.

    Supposedly the mod was designe into the amp but the builder never put the circuit in. Beats me.

    But many thanks for your input.
  4. jokerjkny


    Jan 19, 2002
    NY / NJ / PHL

    mine is dead quiet, and one of the more quieter rigs i own. also, its my fav "clubbin'" rig in general when paired w/ my UL310.

    as for the switching, mine does that too, but if you hit the buttons a few times, it should discharge any static build up, and soon stop the cracking. but that cracking should be nominal. if its really loud, like "speaker damaging loud', definitely send it back.
  5. Hmmmm this is odd.

    One is dead quite, one gets a little hum, both get a crack/pop with the buttons, is that right?

    Where do you guys set the tweeter level. I had mine at normal, but had to turn it down per someone at Epi.

    When I used headphones while waiting for the 310 to arrive the amp was dead silent, so I wonder if it has something to do with the cab?
  6. The cab just reproduces what your amp is doing. Maybe the headphone out is at a different point in the signal path than the speaker outs, which could explain the added noise through the speaker cab. Also mess around with the tweeter control, if its scratchy when you turn it, it could be defective.
    When the L-pad on my Avatar cab stopped functioning correctly it ran at full open at 1/4 on, but if I turned it to 1/2 or more it sounded normal. Then it burned out all together, but thats probably my fault for not replacing it with a better one when I did the crossover mod. Best of luck.
  7. Funkyaurora


    Aug 21, 2002
    I`ve been using the UL502 frequently on gigs for about 8 months now,and have not experienced any noise or hum (nor any cracking sounds from push buttons or pots). I actually find it quieter than my previous Aguilar DB 750, which had a quite notisable fan noise (a bit bothersome when played in low volume settings and in the studio), as well as some high frequency noice from the speakers, even when the master volume was turned all the way down.

    I seldom use treble settings past 13.00 o`clock on the UL502, and preamps from my active basses are usually run with treble set flat. Passive basses however I usually run with the passive tone control fully open (full high pass). As for tweeter setting on my T310NYC ad T310UL cabs I usually set them to about 11.00 o`clock.
  8. jokerjkny


    Jan 19, 2002
    NY / NJ / PHL
    my tweeter is at noon.
  9. Yea JJ,

    I have my tweeter set at noon also but Joe and Vince said to trun it down. The only way the hiss goes is to turn it off. SO what good is it then?

    I have tried both passive and active basses and no dice.

    It's really annoying, and Epi has really become a pain with the nonsense answers that make no sense.

    I have even put the head through my power conditioner and checked the outlets. Still hiss/hum.

    I'm trying to get a hold of Nick to see what he says.

    Personally after all the crap of waiting over six weeks for the cab, multiple excuses, and conflicting answers or no answers, I'm really sorry I went with Epifani.

    However I am not sorry I came to this forum because all you guys have been excellent in responding, offering advice, and trying to help.

    Many sincere thanks to every single bass player here!!

  10. jokerjkny


    Jan 19, 2002
    NY / NJ / PHL

    recording, i dont hear nothing. and on gig, the hiss is barely audible.
  11. JJ,

    SO you are saying that when you go from head to cab using the Speakon cable you DO get a hiss?

    That's what I am trying to determine if others are getting a hiss (like WHite Noise) sound.

    Obvioulsy for recording you are going straight from the amp.
  12. jokerjkny


    Jan 19, 2002
    NY / NJ / PHL
    well, for a LONG time, i struggled w/ the fact that some of my amps do exhibit some sort of hiss.

    being tied down doing soundtrack work and stuck in my basement studio mixing down crap for soo long in that aural microscopic atmosphere/mindset suddenly made any form of hiss, whether coming from my guitar rig, bass rig, or even my laptop/sampler rig, akin to an personified stream of sailor like cursing. so, when i'd go upstairs to practice on one of my rigs, the hiss coming from my rigs would drive me simply insane! i'd do anything and everything to try to kill it, w/ better power strips, voltage regulators, newer/shorter cables, etc.

    but soon i realized that when i'm gigging, i barely notice it, my bandmates couldnt care less, and more importantly, my audience never ever ever comes up to me, and says, "wow, your rig is hissy"... ;)

    again, as long as you dont hear the hiss while recording, that's all that really matters. and if you're home practicing and the hiss bothers you, then just use the headphones as you mentioned, since that doesnt exhibit the hiss.

    and yes, i'm using a plain ol' speakon/speakon ended canare loaded speaker cable that i got from bayou cables.

    still, if the hiss is noticible while w/ others onstage during a quieter section of a particular ballad, then something may really be wrong.
  13. Thanks JJ,

    That is what I have been trying to determine. I've never had hiss in any of the amps I've had over the years.

    Yes I have a Bayou Cable too except it is Redco wire.

    I noticed when I use headphones there is zero noise at all but thought it might be because of the jack I was using. Hook up the 310 and bang..........amp has a "hissy" fit.

    Since you have the exact same rig, I guess it's normal since you are getting some hiss too.

    As always appreciate your input.

  14. gmarrazzo


    Jan 1, 2003
    Hey all
    I just picked up a used UL502 this past week.
    Does Epifani make a rack mount kit for the 502?
    I have e-mailed their service & support dept, but have yet to recieve a response :(
    Would I be better off giving them a call?
    know I'm preachin' to the choir here - I'm absolutely blown away by the sound of this thing - running through Berg HT210S.
    thanks for your help
  15. jokerjkny


    Jan 19, 2002
    NY / NJ / PHL

    check your other post. and nice rig!
  16. MacGroove

    MacGroove Brother of the Groove with a 'Pocket Full of Funk'

    Oct 5, 2005
    Hi Gene, I've used Epi cabs for about 12 years and never had a problem with any of them. As for my 502, no problems there either. By now you probably have done this, but a process of illimination, do you get hiss from the 310 when used with another amp or vice versa, 502 with another cab? If so, contact them and sent it back for them to check it out, sorry you're having a difficult time with them. But they're reliable and will make it right. I've had problems with previous gear in the past, gear you wouldn't expect it to happen to, but it happens sorry to say but they'll make it right.

    To G Marrazza, Epi makes ears for the 502, they just got back from being in Europe for 2 weeks so they've been a little hecktic around the shop, so try e-mailing again and give them a call.