How can I change my SVT 4X10 cabinet from 8 ohm to 4 ohm

Discussion in 'Amps and Cabs [BG]' started by FrankieBaker, Mar 5, 2006.

  1. FrankieBaker


    Mar 5, 2006
    Hello everyone
    I have two SVT 4X10 Classic cabinets. They are wired 8 ohms each right now (factory setup). I also have an SVT4 head. I would like to change the two cabinets to be 4 ohms each instead of 8 so I can get the full power from my amp. Ampeg has 4X10 cabinets at 4 ohms but they weigh a lot more than the ones I have and I didn't want to have to deal with the extra weight of the cabinets. Their 4 ohm cabinets have the same speakers as the 8 ohm version. How can I change my 8 ohm cabinets to 4 ohms?

    Any help would be greatly appreciated!

    Frankie Baker
    Bass play for TAKEN (
  2. Is your cab the SVT 410HE? If it is then it is not possible. The 410HE contains 4 32ohms speakers. The speakers in the 410HLF are the same size but different specs.
  3. uglycicles

    uglycicles Supporting Member

    Dec 10, 2003
    Southwest Chicago
    Are you bridging your 4Pro? If so, then if you use your existing two 8 ohm cabs connected in parallel, then your amp is seeing a 4 ohm load, and you are getting the most you can out of the amp.

    Maybe I'm not understanding your question?
  4. If he wants to use the SVT 4 Pro in bridged mode with his speakers he needs to get a speakon cable made up for the head to first cab.

    On the connection to the head the speakon needs to be wired 1+ possitive and 2+ neggative and the connection to the cab 1+ possitive and 1- neggative. The cable from the first cab to the second cab is a normal wired speakon.
  5. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Short answer: you can't. Suggest you read impedance threads in the FAQ section.
  6. illidian


    Jul 2, 2004

    Your SVT4PRO is already giving all it can.
  7. Unfortunately, no 8 Ohm 4x10 cabinet can be rewired to be 4 Ohms without replacing the drivers (or disconnectig 2 :p). It can be done with a transformer (autoformer) but the expense and weight wouldn't be justifiable.

    I think you can run the 4-pro at 4 Ohms in bridge mode though. If you did that you'd get the full power of the amp.

    Ah, Uglycicles beat me to it except that when you chain the two cabs together they're actually connected in parallel. The load is still 4 Ohms though.
  8. HunnaThaStunna


    Mar 5, 2006
    same question, but different implications. i have a svt 4x10he AND a 4x10hlf. my head is an svt3pro. obviously, it doesn't have enough power to rock em both at full capacity. however, i was wondering if anybody knows where i can find the schematics of the 4x10he because i have an electrician buddy that says he might be able to jerry rig something until i can afford a second head or a power amp that my line out will slave drive. my intent is to run a wet dry rig with a clean 4x10hlf and a highly overdriven 4x10he with a tech21 psa-1 preamp for an all bass guitar death metal project i'm writing.

    any help fellow bassists?
  9. HunnaThaStunna


    Mar 5, 2006
    in liew of my prior post, anybody know where to get and the cost of new drivers for the 4x10he might be?
  10. illidian


    Jul 2, 2004
    You could wire the two in series, but that would give you a twelve ohm load. Safe, but not as loud.

    I believe Ampeg has schematics available on their website. If not, send them an e-mail and they probably will be happy to send you schematics.
  11. mlwarriner

    mlwarriner Supporting Member

    Nov 8, 2003
    KC, MO, USA
    install the accu-switch in both cabs. :D:D:D
  12. illidian


    Jul 2, 2004

    :p :p :p

    I posted that in the last thread reguarding this topic, so I sat this one out.
  13. HunnaThaStunna


    Mar 5, 2006
  14. illidian


    Jul 2, 2004
    AccuGroove, for a while, put a switch on the back of their cabinets that they claimed would change the impedance of your speaker cabinet, without it affecting sound (tone, quality, or loudness) whatsoever.

    Then some reports came out, claiming that the AccuSwitch went against the rules. Once these became popular, AccuGroove stopped installing AccuSwitches in their cabinets.

    Okay, that's not so bad, right? The stink that most people have with the whole situation is they haven't (at least to my knowledge) came out and said anything about it. No, "Yes, it was all a bunch of bull****," or, "Hey, it actually works - look at these tests." They just stopped marketing it altogether once these repots came out.

    Disclaimer: I have tried to simplify the situation and give the brief facts. For more information, feel free to use the search function.
  15. Jerrold Tiers

    Jerrold Tiers

    Nov 14, 2003
    St Louis
    OK, as noted 8 to 4 does not happen unless you change the speaker drivers, in which case you may as well get another cabinet...

    But, the 4PRO drives 4 oms in mono. Two 8 ohm cabinets in parallel, which is what happens if you "daisy-chain" them (plug one into amp, and the second into the first), results in 4 ohms, which is perfect for max power.

    Is that not what you want?

    If you want 1 cabinet to be 4 ohms, so you can get max power into it, that's not a good idea, AND the 8 ohms can't be re-wired.

    The 4PRo full power and the classic cab speakers are not a good match for lots of low end. They are not speakers designed for lots of cone movement. Using only 4 would stress them.

    And, if you had two 4 ohm cabs, you still wouldn't bget max power in stereo mode, since the amps can each drive 2 ohms....

    Also, you couldn't use mono mode with both cabs, which is when you'd want to use both. But they would be 2 ohms, which the amp shouldn't drive in mono.

    Honestly, it looks like you have what you need now, if you can use the amp in mono.... single 8 ohm for smaller gigs, both for full power at larger gigs.

    Am I missing something here?
  16. mlwarriner

    mlwarriner Supporting Member

    Nov 8, 2003
    KC, MO, USA

    i just couldn't resist :)