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Use 2 Ampeg SVT-210AV's and NOT blow the cabs with this rig?

Discussion in 'Amps and Cabs [BG]' started by Basstovsky, Aug 6, 2012.

  1. Basstovsky

    Basstovsky Stuck on those 4-strings Supporting Member

    Feb 29, 2008
    So my favorite old cabinet finally died, and as it will be a while to find a replacement speaker, I figured I'd like to try something i've always wanted.

    I really love the sound of the old ampeg 4x10/8x10s, but I need a more portable/lightweight rig. (lots of narrow stairways) My thought is to use 2 of these 8 ohm 200 watt Ampeg SVT-210AVs in place of a 4x10, as each on its own is very easy to move. Now we arrive at the problem.

    My current gigging amp is an A.M.P. BH-420 (some info here: AMP) which outputs 200 watts into 8 ohms and 400 watts into 4 ohms. These ampeg cabinets only handle 200 watts each, and if I run a cable from the amp to each it would work out to 4 ohms so 400 watts.

    I like to run the amp somewhat hot, volume all the way up and add gain to get the appropriate stage volume (the gain is pretty much never above 1/4 of the way up) and I would expect this would blow up these cabinets.

    Is there a way to rig up these cabinets in such a way that they would be 8 ohms to my amp and therefore only receive 200 watts of power? The ampeg cabinets list something about each having an in and an out jack to be run in series instead of parallel but not sure if that would help? http://www.guitarcenter.com/Ampeg-SVT-210AV-Micro-Classic-Bass-Cabinet-105324420-i1447507.gc

    Not sure if there is any hope anyways as I somehow managed to blow up my 8 ohm speaker that was rated for 400 watts, even though the amp should have only been giving it 200 watts at 8 ohms.

    Thanks for your time.
  2. will33


    May 22, 2006
    Well, any most amp can be used responsibly with most any speaker and not blow stuff up...BUT...those amp settings you describe may be a problem.

    Amp ratings are measured (or should be) at some % distortion. Run it into more distortion and amps can produce more than their rated power, sometimes as much as double with a lot of grit/grind/distortion.

    Speakers "watt" ratings should be what they can continuously take while riding on the verge of melting/burning/shorting the voice coils. Excursion (how far they can move back and forth) is often left out.

    There are 2 kinds of excursion. Xmax...the point of 10% speaker distortion, aka, the point it can't make anymore bass. Mids and highs can still go more...hence distortion. And Xlim...the point of physical, mechanical damage. Xlim = death. You're not gonna get those specs from any amp/speaker company. Only driver manufacturers who provide complete datasheets. With the notable exception of Barefaced Bass cabs from the UK.

    Along with the thermal "watt rating" limits also comes thermal power compression. That means as the voice coil heats up, it's impedance increases, this drawing less power from the amp. Sometimes the player notices this lack of output and turns up more to compensate, forcing it to dissipate even more heat and birning up the speaker, sometimes without even exceeding any mechanical limits.

    What all this means is, with that pair of cabs, and your amp running full tilt like that, you may be riding the edge producing great sound, or you may be burning up all your stuff. It really is a fine line there.
  3. will33


    May 22, 2006
    Also ignore the dial position of your knobs. 1/2 way up doesn't mean 1/2 power, etc. It depends on how strong a signal you're sending in.

    Turning masters full up and controlling volume with input is how you run a component Pa system. It's also how any non-master volume tube amp works. If your sound is generally cleanish, you're likely within the amp and speaker ratings. If it starts to get dirty, you're likely exceeding things. Sometimes that sounds good. Too much of it can break stuff.
  4. Basstovsky

    Basstovsky Stuck on those 4-strings Supporting Member

    Feb 29, 2008
    So the only way to completely avoid destroying speakers is to give up on distortion from the amp and speakers and switch to distortion from pedals?
  5. JimmyM


    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    Or to get speakers that can handle it. I love the 210av's and use them all the time, but they're not going to handle a 400w amp cranked past the point of distortion.
  6. drea2304


    Feb 13, 2012
    Central IL
    I use two 210av's with a strmlnr 900 with no problems. Plenty of volume and I'm not pushing the head much at all. Getting some grit with the gain and pre vol. around 2 o'clock, master never past 10 o'clock.
  7. sloppy_phil


    Aug 21, 2011
    Toronto, ON, Canada
    Not actually named Phil
    I was sound-checking on Friday night with the Micro-VR full stack, and found that if I tried to push too much bass frequency from the amp itself, I would get a little bit of buzz/rattle/what have you from the cabs (not sure if stacking the cabs makes any difference). Dialing back on the bass freqs allowed me to push out more volume without any of the rattle. Not that it's a precise measure, but the gain knob on the amp was at about 3 o'clock and the volume somewhere a little past noon. And the VR only pushes 200w at capacity (with only 100w going to each cab), so I'd be a little worried about running those cabs at 400w each
  8. Basstovsky

    Basstovsky Stuck on those 4-strings Supporting Member

    Feb 29, 2008
    Well at least it seems like they sound awesome, I wish I remembered enough from my electronics classes in high school to figure out how I can run two 8 ohm speakers in such a way as to simulate an 8ohm total load instead of 4 so the amp would only put 200 watts out of it.
  9. You cant.
  10. Russell L

    Russell L

    Mar 5, 2011
    Cayce, SC
    Coupla Barefaced Midgets would do the job.
  11. wcriley


    Apr 5, 2010
    Western PA
    Am I missing something here?
    Two cabs, each thermally rated at 200 watts = 400 watts.
    Amp is rated to put out 400 watts before unacceptable distortion.

    Seems to me that the cabs will sound like crap long before there's any voice coil damage.
  12. JimmyM


    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    You can get them pretty decently loud, but yeah, I believe that to be true, Bill.
  13. Basstovsky

    Basstovsky Stuck on those 4-strings Supporting Member

    Feb 29, 2008
    So when running a 4 ohm load by using 2 speakers plugged in parallel (one cable from each cabinet to the two separate outputs of the amp) and the amp outputting 400 watts, it splits that 400 watts of power between the two cabinets and thereby gives each cabinet 200 watts of power?

    Also: does anyone know what running speakers in series is for?
    Why daisy-chain your output signal from one cabinet to the next instead of both cabinets receiving input directly from the amp?

    Man I feel dumb when it comes to amps/cabs, I thought I knew what I was doing before!
  14. JimmyM


    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    Right down the middle.

    Don't confuse daisy chaining with series wiring. Series wiring is hooking the speakers up with their negatives to the next speaker's positive, like this:

    pos. / neg. > pos. / neg > etc.

    Parallel wiring is hooking up all positives together and all negatives together.

    Daisy chain jacks in cabs are parallel wired. Series wiring is useful if you have, for example, two 4 ohm cabs and you want to use them in an amp with a minimum 4 ohm limit. You can series wire the two cabs together to create an 8 ohm load. There are a handful of other situations where it's useful as well, but I don't want to bog you down too much with info you don't need.
  15. Daisy-chaining the SVT210s sets them in parallel. It's the same as plugging each one directly to the head.

    These Ampeg have 2 x 16ohm 10" speakers wired in parallel, resulting in a 8ohm load. If you rewire those speakers in series you'll get a 32ohm cab, and two 32ohm cabs in parallel will get you a 16ohm load, unacceptable.
  16. walterw

    walterw Supportive Fender Gold Supporting Member Commercial User

    Feb 20, 2009
    A pair of 200w cabs driven by a 400w head; sounds just right to me.

    Stack 'em vertically, and don't drive the amp past the point where they start flapping.
  17. Basstovsky

    Basstovsky Stuck on those 4-strings Supporting Member

    Feb 29, 2008
    Thanks everyone, sounds a lot more do-able than I expected. I guess I should start looking around to see where they are in stock

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