Rewiring a 1x18 Cabinet

Discussion in 'Amps [BG]' started by McKraut, Jan 5, 2014.


  1. McKraut

    McKraut

    Joined:
    Nov 30, 2009
    What's up all,

    I just inherited a Carvin RL118 cab for the cost of having to repair it. The problem is that it's not making any sound. Complete silence. The guy that I got it from said that he was told that he'd need to get any parts from Carvin because they have their whole proprietary parts BS going on.

    I thought about it for a second and pulled the panel with the plugs off of the back of the cab and looked at the PC board. It literally had no components, just a jumper and I suspect that it's just because it had a thru port which I would never use.

    Here are my the questions. With a single speaker can I not just run new wire from the leads of the speaker to a new 1/4" jack?

    What is the likelihood that the speaker itself is the cause of the problem? Wouldn't a speaker problem just result in crappy sound?

    Thanks
  2. Mr. Foxen

    Mr. Foxen

    Joined:
    Jul 24, 2009
    Location:
    Bristol, UK
    Disclosures:
    Amp tinkerer at Ampstack
    Should be able to wire it right to the jack/speakon, most cabs do. Probably kind of dark sounding on its own, but its designed to be used like that by the look of it.
  3. beans-on-toast

    beans-on-toast

    Joined:
    Aug 7, 2008
    + on the speaker goes to the tip on the ¼" jack.

    Test the resistance across the terminals of the speaker with a volt meter. An 8 ohm speaker should read around 5.6 ohms. It can vary through. If it read 0 you have a short, if it reads infinity it is an open circuit. Either one is a problem.

    You can also test the speaker with a 9 volt battery. Conect - on the speaker to - on the battery. Momentarily tap (quickly on and off, do not hold it) the + on the speaker to the + on the battery. You should see the speaker cone move outward. If it doesn't the coil may be burned out.
  4. Geri O

    Geri O

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    Sep 6, 2013
    Location:
    Florence, MS
    If there is an open voice coil (a break somewhere in the windings), the speaker won't say a word. That could be the problem. Check the speaker's continuity with a VOM, or have a friend that knows how check it.

    If it tests good (it should measure slightly under 4 ohms for a 4-ohm speaker, slightly under 8-ohms for an 8-ohm speaker, and slightly under 16 ohms in the unlikely event that it's a 16-ohm speaker), then simply make new leads from the jack on the cabinet that will connect to the speaker.

    Geri O
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  6. bassmeknik

    bassmeknik

    Joined:
    Nov 6, 2009
    Location:
    Fair Haven, MI
    Yes, A Speakon connector would be ideal but a 1/4" jack directly to the driver will direct wire it and eliminate the need for the circuit board. This arrangement is how my PA subs are wired and most bass cabs that don't have tweeters or midrange drivers in them. Most all single driver bass cabs are wired this way. I do recommend a simple resistance test before connecting to an amplifier (better safe than sorry). Described in earlier posts in this thread, an ohm meter or a battery will give you indication as to whether it is a working speaker. Depending on if your amp is SS or tube type either an open or a shorted driver can KILL your amp...

    Hopefully you or someone you know has a basic volt/ohm meter and knows how to use it. If not get a (known good) 9 volt battery and do the "thump test" (when hooked to a good driver the battery will cause an audible "thump" when connected). If you are unable to get your newly inherited driver to make a thump with a 9 volt battery them I would not recommend hooking it to your amp.
  7. bassmeknik

    bassmeknik

    Joined:
    Nov 6, 2009
    Location:
    Fair Haven, MI
    1. The speaker (driver) IS the most likely cause of the silence...

    2. Drivers can fail in many ways and give several symptoms, unnatural noises (you called it crappy sound) is the final stage before "death". Ultimately three things will result in "no sound": open circuit voice coil winding, shorted voice coil winding, or physically jammed voice coil. Typically jammed coil will eventually result in either open or shorted coil so... If you get either zero ohms (shorted) or infinity (oped circuit) the driver is damaged. Cone damage is bad but not to be confused with an electrical problem with the driver. A driver may look perfect but be "silent" due to electrical failure (open or shorted voice coil).
  8. bassmeknik

    bassmeknik

    Joined:
    Nov 6, 2009
    Location:
    Fair Haven, MI

    With all due respect sir this seems like BS going on... Carvin uses common parts and although you may not be able to get the exact replacement if it is the only bass cab (or sub-woofer) then an exact replacement is not necessary. The cab will likely sound slightly different with a different driver, and if you had multiple cabs like that then matching the drivers would be much more important. A single cab can be compensated for by use of tone controls or adjustment to the electronic crossover in bi-amped or tri-amped systems. The only other recommendation I might ad is that if replacement is required then the replacement driver should be recommended for use with a vented box (your Carvin cab is vented).

    MCM electronics has an 18" replacement musical instrument driver (for vented boxes) for $69.95 plus shipping... (a more expensive model from MCM is pushing the air in my 2 PA subs...I am very pleased after using mine regularly for 7 years now) just for reference.
  9. BurningSkies

    BurningSkies Supporting Member

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    Feb 20, 2005
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    Seweracuse, NY
    If it is indeed the driver, I would think that Carvin is being pretty responsible in saying that their speaker is what should be in the box, since speaker cabinets are designed around a specific speaker.
  10. bassmeknik

    bassmeknik

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    Nov 6, 2009
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    Fair Haven, MI
    Agreed, however this is no where near as big a deal in a single cab application provided that the replacement is similar. Not wanting to start a large disagreement but replacement drivers abound and if you do your homework it is possible to get good results IN A SINGLE DRIVER SYSTEM only. I do not recommend mixing brands or even different model number of drivers in a multiple driver arrangement. In a single cab set-up you can get good results if you just pay attention to T/S parameters. This means not just any 18" driver but you must get close, and the OP's Carvin cab is a common size and design so IME it is doable. YMMV
  11. BassmanPaul

    BassmanPaul Gold Supporting Member

    Joined:
    Aug 25, 2007
    Location:
    Toronto Ontario Canada
    Quickest way to test a woofer is to stick a 9V battery across the driver's terminals. If you get a thump the voice coil is continuous.
  12. will33

    will33

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    austin,tx
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    Carvin used the input jackplates with the circuitboard mounted to them even if there was no parts on it, my old V115 was the same way. It was/is cheaper for them to have a whole bunch of those made and use them on everything, even if they didn't put any parts on the board (no crossover), than to order smaller batches of speaker specific jackplates. One thing they do to keep the price down.

    Another is to order a huge lot of 2U chassis, then just drill or punch out the apropriate holes if it's going to end up as a bass amp or power amp, etc. Another way to keep the price down.

    Good advice in the rest of the thread as far as speaker testing, etc.
  13. David Jayne

    David Jayne

    Joined:
    Jan 16, 2006
    Location:
    Brookfield, CT
    Unfortunately the likelihood is extremely high.
  14. McKraut

    McKraut

    Joined:
    Nov 30, 2009
    Thank you all for the input.. Unfortunately I do not have theopportunity to test it for a few days, but when I do, I will post results.

    Thanks
  15. Forrrest

    Forrrest

    Joined:
    Mar 10, 2013
    This.
    with the battery one way it should push the speaker out a bit
    and if you flip the battery the speaker should move inwards a bit.
    if the speaker does nothing it's your speaker that's done.

    report back.

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