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Question - Connecting 2 Bass Cabs from Amp in Series

Discussion in 'General Instruction [BG]' started by ADHD_4Ever, May 12, 2011.

  1. ADHD_4Ever


    May 11, 2011
    Ok, so I just got my hands on an old Fender 300 PS ('78?) which is in great shape for its age. Had it serviced and retubed (saved the original GE 6550A's). It's 300w at 8ohms, all tube. The problem I'm having is that I know eventually I will want a full stack, but almost all 8x10's are 4ohms, and if I daisy chain in parallel with 2 4x10's at 4 or 8 ohms I still will be under my minimal impedance. So I think my best choice is to go with 2, 4x10 4 ohm cabs and run them in series, although I know this is not a common setup. I have seen a few diagrams online on how to make a series speaker cable to run from my amp to the input on both cabs (power Y adapter?), but nothing conclusive for someone with minimal electrical knowledge. I guess my main questions would be 1) Could someone point me in the right direction for directions to make the Y adapter in series and 2) how to hook up said adapter to the cabs - do i need anything else besides the output on the amp and the 2 inputs on the cabs? *Side question - I have have heard most cabs are wired in parallel/series - does this matter to the amp as far as load is concerned when combining 2 cabs? Sorry for the length of this whole post, but I am very confused on this matter.

    Edit - I may want a 4x10 and 1x15
  2. Just a suggestion, but how about rewiring the cabs instead? That way you won't have a problem if you forget or lose your special series connection cable. It should be possible to rewire a 4 ohm 4-10 to 16 ohms. Do that twice, and you have an 8 ohm load when you daisy chain the two cabs in parallel.
  3. JTE

    JTE Supporting Member

    Mar 12, 2008
    Central Illinois, USA
    A. You'll probably want to get a mod to move this from the music theory forum to the amp forum- you'll get a lot better and faster responses.

    B. Series has some issues. You need a special cable, if one cabinet fails the whole system quits, etc. Rewiring a cabinet 4Ω to 16Ω makes more sense, depending on the actual impedance of the individual drivers in the cabinets.

    C. Most cabinet jacks (and amp speaker jacks too) are electrically in parallel. Whether you daisy-chain from the amp to the first cabinet and then to the second, or if you run a Y-cable off the back of the amp (the 300 PS only has one speaker jack I believe), electrically it's still a parallel connection.

    D. However, there are multiple ways to wire up an 8x10 to get a 4Ω load, so you'll have to find out exactly how the ones you're looking at are wired internally. Could be eight 32Ω speakers all in parallel, or it could be combinations of series/parallel with other speaker impedances to get a net load of 4Ω.


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