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Help! What 15 inch cab can I buy without blowing it up?

Discussion in 'Amps and Cabs [BG]' started by dbull, Mar 31, 2009.


  1. dbull

    dbull

    Feb 26, 2009
    North Carolina
    I have an Ampeg SVT Pro-4 and an Ampeg Pro Series 4x10. I want to get a 1 x 15 inch cab to run with the 4x10 for performance, and alone sometimes for practice. The Amp puts out the following power according to the manual:

    300 x 2/900 (mono-bridged 8 ohms)
    490 x 2/1200 (mono-bridged 4 ohms)

    I've never been clear on the whole 2/900 thing, but I want a good solid sounding low end for the 4x10 that I won't blow up. Any math wizard that can help me this this would be greatly appreciated.
     
  2. bongomania

    bongomania Gold Supporting Member Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    I suspect you're reading it wrong. It should read something like:
    "300 W per channel when you're running it as a two-channel unit, connected to two 8 ohm loads;
    900 W total when mono bridging the amp into one 8 ohm load;
    490 W per channel when run as two channels into two 4 ohm loads;
    1200 W total when mono bridging into one 4 ohm load."

    Whether you do or don't blow up any cab is wholly dependent on how you use it, not what the wattage ratings are. The ratings are just a general vague guideline. That said, if you want to play it safe then get an 8 ohm cab which can handle 300 W or more, or a 4 ohm cab which can handle 490 W or more.
     
  3. Assuming your 410 is 8 ohms, any 15 that can handle 490 watts with an 8 ohm impedance will work.
     
  4. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    The math that you should be concerned with has nothing to do with watts. It's driver displacement, Vd, which is cone area (Sd) multiplied by excursion (Xmax). Vd is what limits the low frequency output of a speaker.The average 4x10 has a total Vd of 400 to 500cc, the average 1x15 only 250 to 300cc. What the math tells you is that if you want to get more low end to go with your 4x10 the best way to get it is with another 4x10. If you want a modular system make the second cab a 2x10, so you have the choice of small, medium and large.
     
  5. Rick Auricchio

    Rick Auricchio Registered Bass Offender

    But, as Bongo said, you can destroy any speaker with way less power than printed on its nameplate.

    1. Most cabs won't handle their full power rating before farting out. If you let the farting continue, the speaker is destroyed mechanically, not burned out.

    2. Most cabs reach the point of power compression, where extra power doesn't get louder. It creates heat, which can destroy a speaker.

    There's no magic to this.
     
  6. dbull

    dbull

    Feb 26, 2009
    North Carolina
    What it actually says is:
    "1600 watts mono-bridged at 4 ohms
    1200 watts mono-bridged at 8 ohms
    2 x 900 watts @ 2 ohms (600 watts continuous)
    2 x 625 watts @ 4 ohms (490 watts continuous)
    2 x 350 watts @ 8 ohms (300 watts continuous)

    The 15 inch I am looking at is the Ampeg SVT-15E, but it says on the website that his rated for "RMS Handling 200 watts". This is my concern, but I can't see that Ampeg makes a bigger 15 inch cab.
     
  7. bongomania

    bongomania Gold Supporting Member Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    Well that tells you that you shouldn't buy an Ampeg 15 for this amp. :p For a different brand of cab, what is your max budget, and do you have any restrictions like it has to be available by mail order to Croatia?
     
  8. dbull

    dbull

    Feb 26, 2009
    North Carolina
    No. Just mail order to North Carolina. I was look to spend $300 or less used, which usually means the same as 700 or less new.
     
  9. brianrost

    brianrost Gold Supporting Member

    Apr 26, 2000
    Boston, Taxachusetts
    Run the 15 with just one of the two amps (i.e NOT bridged mode )...then you have 300W continuous into a 8 ohm cab rated for 200 watts, no sweat.

    Saved bridged use for when using cabs that handle more power.
     
  10. rpsands

    rpsands

    Jul 6, 2007
    Phoenix, AZ
    If I'm reading Bill right, and the eminence charts right, the VD of a Kappalite3015LF is 848cc.

    Why don't you get an LDS 3015LF cab and use that? Pretty sure they'll make you one for cheap, with or without a 6" mid (with would be my recommendation so you have a standalone cab).
     

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