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N00besque question about hooking up 2 cabs

Discussion in 'Amps and Cabs [BG]' started by T-Forty, Mar 17, 2009.


  1. T-Forty

    T-Forty Guest

    Mar 14, 2008
    Up until now I've played through an 810 or one 410. I've never had to hook up two cabs to one head before and never thought to check out other bandmates set ups. DOH!

    The gear:

    SVT-450 head (225 watts at 8ohms, 450 watts at 4 ohms)
    SVT-410he cab (8 ohms)
    SVT-15e cab (8 ohms)

    The rear panel can be seen in this PDF:

    http://www.ampeg.com/pdf/SVT450H.pdf

    I am using speakon cables to connect the cabs. The head only has one speakon out, which means I will have to run the cabs in series, right?

    So I should run one speakon from the head to the speakon in on the first cab (which should be the left input, yes?) and then from the right input connect the other speakon and run it to the next cab?

    Also will the head automatically realize it is powering two cabs or do I have to do anything with it?

    Thanks,
    n00b out
     
  2. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    The speakon is strictly for bridged mode, so if you want to run your amp in bridged mode, you would have to chain your speakers together (that's not called "series" but "daisy-chaining"...series is a way to wire the jacks or speakers, but your stuff is wired parallel so never mind about that). If you want to hook it up in stereo mode, you would need 1/4" jacks for the amp. Either way will work for you just fine. The amp automatically detects the impedance and adjusts it for you.
     
  3. T-Forty

    T-Forty Guest

    Mar 14, 2008
    Are there any major differences between bridged and stereo mode?

    The speakon inputs on the cabs aren't marked in or out. Does it matter which one I used as in/out?
     
  4. I am speaking merely from my experience with my SWR cabs, which are not the same animal, but, here goes.

    If you are hooking them up in series, you will increase the OHM load from 8 ohms a piece to 16 total. To figure out your ohma in series you simply find the sum of the total ohms of your speakers.

    I will assume your speakers have parallel outs, which then will decrease your ohm load from 2 cabs at 8 ohms, to 4 ohms. Wiring in parallel (assuming you have matching resistance levels of speakers) you divde your original ohm load by the number of speakers. 8/2=4 ohms.

    Therefore, you will have a 4 ohm load. Your amp will automatically put out more juice because there is less resistance, and therefore you won't have to adjust anything.

    If your speakon jacks are not meant to run parallel, which again depends on the cabinet manufacturing, you may use your standard jacks instead. You have two speaker outputs that will run parallel, lower your overall amp load to 4 ohms, so you are getting max power.

    Sorry, I am an education major.
     
  5. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    No major differences as you're using them, unless if you have a separate volume control for each, then you can control the volume of each cab. I don't know if your amp has that or not.

    And no, it makes no difference which is in/out on the cabs.
     
  6. T-Forty

    T-Forty Guest

    Mar 14, 2008
    So you are saying if I use the cabs in series (dairy chained) using speakons I won't be getting the full power, and in order to get full power out of head you need to run it in parallel (stereo) which for my head is only available using 1/4" jacks?
     
  7. T-Forty

    T-Forty Guest

    Mar 14, 2008
    p.s. i hate this stuff. haha
     
  8. Implosion

    Implosion

    Oct 19, 2007
    Finland
    Daisy chaining isn't the same thing as "in series". Daisy chaining is an expression that is used when cabs are connected to each other with a cable. Series and parallel are expressions that are used when circuits are being discussed. To over-exarregate a little, 99% of the time cabinets are connected in parallel. This is also true in your case. With speakon connect your amp to cab #1 and then cab #1 to cab #2. Left/right doesn't matter. When connected this way, your head will recognize it as a 4 ohm load and both cabinets will recieve 225 watts.
     
  9. anderbass

    anderbass

    Dec 20, 2005
    Phoenix. Az.
    Yes, the "dual parallel" speaker jacks most all cabs have are simply wired together inside, (including yours and this applies to both the speakon and 1/4" jacks) so it doesn't realy matter which are used for input or output.

    The only time this might any any issue at all is if your cabs dual speaker jacks had been modified/wired to be in series instead of the normal parallel method they originally were.

    Your amps dual 1/4" speaker jacks are also simply wired together inside the same way so for instance if you used 1/4" speaker plugs you'd be achieving the same thing by running each cabs speaker cable directly to the amp. If your amp happened to be equiped with dual Speakon's, they would work the same way.


    Yes, simply plugging two 8 ohm cabs into your amp presents a 4 ohm combined load to its single channel poweramp. Your amp model does not have any switch that needs to be changed for this but some other amp models do.

    Your amp model has a single channel poweramp, so there is no Bridged Mode issues or connection options to consider here.

    You'll find allot more info about all this ohm stuff in the TalkBass ohm sticky thread found at this link: http://www.talkbass.com/forum/showthread.php?t=166225
     
  10. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    Oops! Sorry bout that T...I mistakenly thought it had a bridged mode. I guess the way the speaker jack panel looked threw me. I'll got put on the dunce cap and sit in the corner now ;)
     
  11. T-Forty

    T-Forty Guest

    Mar 14, 2008
    Thanks!

    The reason I was using the series/parallel terminology is because I googled this question and found a site which used this terminology. Thanks for the clarification.
     
  12. T-Forty

    T-Forty Guest

    Mar 14, 2008
    Well written and easy to understand. Thanks!
     
  13. Scootr117

    Scootr117

    Mar 11, 2009
    Would you want to use a shielded or unsheilded cable for the 1/4 connections?
     
  14. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    Unshielded for speakers always.
     
  15. RickenBoogie

    RickenBoogie

    Jul 22, 2007
    Dallas, TX
    +1 Use Speaker cable only, always, forever. NOT instrument cable.
     
  16. T-Forty

    T-Forty Guest

    Mar 14, 2008
    I use speakon cables, but thanks!
     
  17. Holy War

    Holy War

    Sep 18, 2008
    VA Beach
    this thread was very handy in answering some of my questions...thanks for the info, and thanks for a great in house search engine
     
  18. RickenBoogie

    RickenBoogie

    Jul 22, 2007
    Dallas, TX
    Speakon speaker cables. Or, what was your point.
     

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