Cab cutting out

Discussion in 'Amps and Cabs [BG]' started by basspla915, Mar 10, 2001.

  1. basspla915


    Mar 28, 2000
    Bangor, Maine
    I have had a problem with one of my rigs for the last two gigs. My set up is an Ashdown ABM900 amp, (two channel), XWire wireless (line runs from unit to passive imput), Euphonic Audio XL208 and Bag End S15XD (coaxial) cabs. Basses are both active - Musicman Sterling and Pedulla Rapture J2000.

    The problem is this: I will start the night off and all is well, great sound, plenty of punch....suddenly the bag end is gone, no sound. I am getting a reading on my xwire and on my amp to show that the signal is ok. The EA is fine.

    I tried changing speaker cables... the connection on the Ashdown appears not to be as tight as it should be. Initially solved the problem, then it came back. What is also interesting, is that it happens more when I am playing the Musicman. I normally run active basses through the passive imput, but is this causing some type of problem where I am using the XWire?

    Any thoughts would be greatly appreciated.
  2. ;) sounds like a nice rig!

    It probably doesn't have anything to do with the wireless or the inputs or the basses. It sounds like an output, speaker cable or speaker problem. Is it a biamped system? (pardon the ignorance, I haven't seen many Ashdowns). If the other cab is fine it suggests that there's a problem with the output driving the bagend. If it's biamped, it could be the amplifier driving the low end, a loose output jack, or a loose connection in the bagend. If it's an intermittent problem it's probably not serious, just a bad solder joint or a 1/4 inch jack with not enough tension on it. Does your sound have more bottom end when you're using the musicman? The extra vibrations caused by that could trigger the problem. If the low end's about the same, maybe it's just a fluke that it happens more with the musicman. Hope this helps and keep us posted. Wait a while and you'll probably get posts from some of the tech gurus on here (Joris, Mikey D, Pkr2 and others I'm forgetting) cheers!
  3. basspla915


    Mar 28, 2000
    Bangor, Maine
    Thanks, Spacegoat. Some great places to start. It is not biamped, there are two separate channels. I suspect that the problem is a loose fitting 1/4 jack.
  4. Had that prob recently, cab cutting out. Drove me nuts. It was a corroded Monster speaker cable (the kind with side-by-side zip-cord-like conductors). The speaker cable had transparent insulation, but the corrosion had been hidden by the plug cover.
  5. mchildree

    mchildree Supporting Member

    Sep 4, 2000
    ...ditto what others said...and it could be that your Stingray is creating more low-end, and therefore more vibration to cause the intermittant connection to fail more often. I've had many problems with cab and guitar input jacks being smaller than the plugs on certain cables. As the jack is used more, the tension of the connector is lessened even more and exacerbates the problem.
  6. Getting a little off the topic of speakers cutting out, but still related (and something I recently became aware of) is why I should go to the considerable trouble of converting to a Speakon connector (aside from the fact that they're hard to disconnect accidentally).

    Andy Lewis had told me to run 12 gauge cable to my Acme Low B-4. The used cab came to me with a couple of woofers blown, and when I opened it up to change the drivers, I found smaller cable. I figured why not bigger inside, too? So I was in the middle of rewiring the innards of my cab with heavier cable when I thought, hey, maybe I should update the connector from 1/4".

    One thing I didn't know (but should have thought of): how much current can a given connector pass? Then Jon Risch (thanks, Jon!) whacked me with the clue stick: "1/4" phone jacks by Switchcraft, not cheap imports, are only rated to carry 3 amps of current. The Neutriks are rated for 15 amps or more, per contact. If you use the NL4 types, you can double up on the contacts, or bi-wire with ease."

    Well, I don't know how my Carvin DCM1000's 1000 watts (bridged into 4 ohms) divide up in terms of voltage and amperage, but 3 amps <i>does</i> seem rather skimpy. However, five times anything seems significantly better, so I figure 15 amps will do me just fine; I'll wire it however the cab end is wired to the new crossover (no space on the old one for the connector) and screw down the bare ends at the other.

    Andy, as you probably know, acts like his cabs are his kids and owners of his cabs are their adoptive parents. So even though he knows I bought used, he's helping me get that Speakon worked into my cab (for anyone who's considering buying an Acme, buy new, free shipping, to get the Speakon connector and also to make sure you're getting perfect drivers--I should have).
  7. pkr2


    Apr 28, 2000
    coastal N.C.

    An intermittent problem can make the best tech in the world cringe. They nearly always only show up at the most inoportune time plus you almost never know for certain whether you have actually repaired the problem untill you wring everything out under actual operating conditions.

    My suggestion would be to move the speaker connection from the offending channel to the channel that works properly. In other words swap ch A with ch. B at the amp output. If the problem now goes to the opposite cab, you know that the prob has to be in the amp. If the prob stays in the same ch., the prob will be in the cab, connectors or speaker cable.

    Be sure to make only one change at a time and don't clean or repair anything untill you are reasonably sure that you have isolated the problem.

    Mchlree came up with an excellent comment about the vibration difference between the two cabs possibly being a clue. I'd never considered that before.

    There's an old cliche in electronic diagnosis called "divide and conquer". It means exactly what it says and is THE most powerful diagnostic method thats ever been discovered.

    Hope this helps, Pkr2
  8. My speaker cut-out prob was intermittent in a really bizarre way. I could fire up the rig and play, then it would start distorting, then cut out with only a tiny trace of fuzzy sound left, so quiet it almost wasn't there. A while later, it would work again, then the same problem would crop up. Hard to believe it could be the cable, which I always wrongly supposed either worked or didn't, but it was.

    So from now on, a fresh cable will be my first substitution for any kind of power deficiency problem where the ladder lights are showing just fine and there's no obvious shortage of mains voltage.

    Hey basspla915, let us know what it was when you fix it!
  9. basspla915


    Mar 28, 2000
    Bangor, Maine
    Thanks for the advice, gang. It really appears to be an speaker input connection, i.e., the connection to the cab is good but appears somewhat loose into the amp. I have replaced the speaker cable with a Tara Lab cable which has a speakon connection on one end and 1/4 on the other. This appears to create a better connection.

    I am practicing tonight and hope to give it a good run. Will let you know if it works.

    Thanks, again!
  10. P=I^2 x R

    1000 = I^2 x 4

    250 = I^2, so I = 15.8 Amps RMS

    P=IV, 1000=15.8 x V, so V=63.3V RMS

    Now you know. :D

  11. Saved to disk and thank you so much!