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Running 2 cabs in series...

Discussion in 'Amps and Cabs [BG]' started by vision, Feb 28, 2005.

  1. vision

    vision It's all about the groove! Supporting Member

    Feb 25, 2005
    Ann Arbor, MI
    okay, please tell me if this is possible. if i have two 4 ohm cabs can i run them in series and present an 8 ohm load to my head?

    and if so, how do i run them in series?

  2. The easy way is build a break out box using Radio Shack parts. The series connections are done internally to the box, and allows use of standard cab cables.

    One cable connects each cab to the box, and a third cable connects the box to the amp.

    Google for a series connection diagram. Test the final configuration with a flash light battery and both cabs connected. All drivers must move the same direction when you make the battery circuit. I suggest all cones moving forward (away from their magnets) when the Red/Plus side is connected to the battery.
  3. If you run 'em in series and one speaker blows you will have
    NO LOAD :eyebrow: on your amp !!!!!!!!!!!!
    That's bad for ANY amp..... ;) ......FATAL for tube amps !!!!!

  4. Nick man

    Nick man

    Apr 7, 2002
    Tampa Bay
    Actually you have an infinite load which does nothing to most solid state amps.
  5. andruca


    Mar 31, 2004
    Madrid (Spain)
    You have to evaluate a couple of things first:

    1) If they have different impedances, the one with the highest impedance will receive more power than the one with the least (as opossite to parallel wiring, where the one with the least impedance receives more power) and this is not always desirable (sometimes it is; I use a Hartke 4.5XL -8ohms- and 215XL -4ohms- hooked in parallel to the same amp and they sounded nice with the 215 receiving double the power than the 4.5, but results may vary).

    2) If their impedance curves are too different, you may end up having impedance peaks at way different frequencies and this causes almost all power to go into the speaker that's having the impedance peak and almost nothing to the other (this happens only at certain frequencies but if it does, it's noticieable, believe me).

    Good luck!

  6. vision

    vision It's all about the groove! Supporting Member

    Feb 25, 2005
    Ann Arbor, MI
    so if the 2 cabs are identical then i shouldn't have a problem right?

    thanks for the help...
  7. James Hart

    James Hart

    Feb 1, 2002
    Endorsing Artist: see profile
    I run a pair of 4ohm cabinets in series... no issues or problems. I ordered a custom cable to fit my exact setup from http://www.procablesnsound.com/

    For ~$50 shipped I got a "Y" cable with speakon jacks for each cabinet, a 1/4" for my Tube Head, a 1/4" to speakon adaptor for use with my backup poweramp and made out of some Coleman 12 gauge 2 conductor SJEW power cable.

    Talkbasser "Biker4him" hooked me up with them. Nice people, great service!

    as far as system failure... lots of things will kill a rig. THAT is a good reason to make sure all you gear is in proper working order.

    any 4 driver cabinet will have a couple in series... it's common place in most cat's rigs.
  8. RobertUI

    RobertUI Thumper Supporting Member

    Apr 7, 2005
    Herndon, VA - NoVa
    I know that I am resurrecting a VERY old thread, but I have a question with regards to this. I did search (for a while) and this was the thread that most closely matches what I want to know.

    I have 2 4ohm avatar cabinets and a GBE600 head which is 2ohm capable. I know that I can safely and effectively hook up the 2 cabinets (either cascading or each to the amp) and work with no problems. This setup gives me HUGE volumes which is great.

    If I wanted to (via a series box or cable) run the 2 cabinets in series it would bring me to an 8ohm load. This would (according to the manual) decrease the power output of my amp from 625W to to 275W.

    Can anyone tell me what the effectiveness of doing this would be? I know that this would equate to a decrease in volume, which is why I am even considering it, but I am curious about how this would affect tone.


  9. crazyhorse


    May 28, 2006
    i also have a question about this

    i have a 4ohm head running a single 4 ohm cab

    i also have an 8 ohm 4x10 i would like to hook up in there

    if i hook it up would it be ok to run in series?

    if so should i go into the 4 ohm cab first then the 8 ohm cab?

  10. Herman


    Dec 25, 2005
    Lynchburg, VA
    Yes, it would decrease the power that your amp puts into your cabs.

    In your case, with 2 4 ohm cabs and a 2 ohm capable amp, I can't think of any good reason why you'd want to connect your cabs in series. If you want to decrease your volume with your cabs in parallel, why don't you just turn down your amp's (or bass') volume knob?
  11. RobertUI

    RobertUI Thumper Supporting Member

    Apr 7, 2005
    Herndon, VA - NoVa
    guys, i'm not asking for advice here, this was a practical question. i work with some electrical engineers here who are NOT audiophiles or musicians, so it was a question regarding practicality. this wasn't intended as a stupid "Can I hook up my 4 4 ohm cabinets to my new combo amp?" kind of question. the question had to do with tonality. what i proposed is valid and has been done, what i wanted to know was your collective thoughts on what it would do to an audio signal. my bad if i didn't phrase this correctly.

    and crazyhorse you really want to pick on me as a non-searching noobie with your 2nd post to this forum?
  12. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Wiring cabs in series will double the system inductance and reduce high frequency response.
    You should only series wire identical cabinets, and then only if there's no alternative.
  13. What if you run two 4 ohm cabs with a series/parallel cable? Won't you get a 4 ohm load that way?
  14. Herman


    Dec 25, 2005
    Lynchburg, VA
    First, I wouldn't connect any cabs in series unless I had to - i.e. my power amp wasn't rated to handle their parallel load.

    Second, there are two cases to consider - matched cabs and unmatched cabs.

    If matched (best if they're identical), then tone shouldn't be a huge issue unless your amp runs out of juice in trying to compensate for each cab getting only 1/4 the power they'd get if they were in parallel. In a pefectly matched case, the power to each cab will be equal no matter what audio signal is being fed to them from the amp and this won't adversely affect the tone unless the cabs are such that they don't really "shine" (tonewise) until driven to a certain volume.

    In the unmatched case, I think tone could really suffer since the impedance (over frequency) of the two cabs will be varying "out-of-sync" with each other. Unlike the matched case, the power to each of the cabs will no longer be equal - the power each cab dissipates will be different depending on the frequency makeup of the audio signal they're being fed by the amp. The effect of this, I think, would be unpredictable peaks and suckouts in the frequency response of the overall system (amp + 2 cabs in series).
  15. RobertUI

    RobertUI Thumper Supporting Member

    Apr 7, 2005
    Herndon, VA - NoVa
    Bill... Awesome (I actually debated PMing you on this)... this is what I was curious about. I am a SW guy, so I don't really understand the technical specifics, but you just gave me a perfectly understandable explanation. Thanks!

    Thanks to you as well Herman!

    This also brings to mind the question of why you would use 4 16ohm speakers in parallel vs 4 4ohm speakers in a parallel/series configuration I assume? It seems to me (based on this practical response) that the ideal situation is to have EVERYTHING wired in a parallel configuration?

    Good to know.
  16. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    So that the people on the assembly line won't screw up the wiring. Ampeg didn't go with a 32 ohm driver in the SVT because it worked better. In fact, a higher impedance driver also has higher voice coil inductance (Le), and that hurts high frequency response. Using lower impedance drivers in a series/parallel wiring would work better, but opens up a very large can of worms as far as the manufacturing process goes. Cabinet wiring is a minimum wage gig, so KISS is mandatory.
  17. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    You can run them in series or you can run them parallel, but you can't do both at the same time. 2 and 8 ohms are your only options.
  18. RobertUI

    RobertUI Thumper Supporting Member

    Apr 7, 2005
    Herndon, VA - NoVa
    Awesome again! You learn something new every day. I always understood the simple instructions... ie, if you want 2 4 ohm cabs you need an amp with a 2ohm capability, but its nice to understand some of the technical considerations! Thanks again!
  19. Hmm. I thought I read something about a series/parallel cable in bass player magazine one time. IIRC, the whole point of it was so you could run two 4 ohm cabs while keeping the 4 ohm load on the amp.

    Have to go back through past issues of BPM...:meh:
  20. You might be thinking of the series/parallel setup of internal wiring of multi-driver cabs, Chris. Maybe...