I need help figuring out the ohmage on the svt pro 4

Discussion in 'Amps and Cabs [BG]' started by rickybocker, Jul 23, 2009.

  1. rickybocker


    Dec 14, 2008
    here's the deal... I pretty much get the whole ohmage thing... but my biggest question is when you run two cabs out two separate speaker out jacks does it cut your ohms??? I know some heads are run to be parallel and it doesnt effect your ohms like running to 8 ohms cabs out offthe two 8 ohm outs.... but then there are some heads that say when you run the two cabs one on each jack they sill effect the ohmage..... I have the pro 4 but it does not mention in the manual whether running 2 cabs off it effects it or not... I know there are 2 amp outs A and B so it seems as though they are independent. I have the SVT PRO 4 and i run 2x810 cabs... wondering if Im running at at 2 ohms or 4 each cab....
  2. bongomania

    bongomania Supporting Member Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    The only time a head will not connect the two speaker outputs in parallel is if it's a stereo head, with two separate power sections. Maybe there might be some exceptions, but I don't know of any.

    As it happens, the SVT 4Pro is a two-channel head. So where it says
    "RMS Power Output: 300-Watts x 2/900 (mono-bridged @ 8 Ohms)
    RMS Power Output: 490-Watts x 2/1200 (mono-bridged @ 4 Ohms)"
    It's saying that you can connect either 4 or 8 ohm cabs to each output channel, without affecting each other's total load.

    If you are running mono bridged, or if you connect both cabs off one output, then the load will change.
  3. Gearhead17

    Gearhead17 Supporting Member

    May 4, 2006
    Mount Prospect, IL
    Relax dude! The 4 PRO has two separate power sections built into it. They run separately from each other. If you run an 8 ohm cab into Channel A and run a different 8ohm cab to Channel B - each channel is seeing an 8 ohm load.

    You can run each 810e in the 4 ohm mode on one channel or both. Each power section can handle a 2/4/8ohm load no problem.

    I suggest though that you run the SVT 4 PRO in bridged mono (Channel A) at 4 ohms straight into one 810e. Make sure you use the correct cable. Two 810's plugged in for shows is a little crazy, I can understand the look of the stage with your bass gear though. But two 810's are overkill to hear yourself.
  4. bwv1013


    Mar 20, 2008
    southern cal
    edit: beaten to the punch.
  5. rbonner


    Sep 25, 2008
    The thing with the 4PRO and two 810's one to each channel and the switch in Stereo / dual mono (out) is that the amp only makes 490 Watts for each cab.

    The rig is capable of being turned ALL THE WAY UP and if you do that it will run too hot and or trip on over current. Keep the master throttle down to a reasonable setting. I wouldn't turn it over 3/4 up...

    What I found is that the amp just didn't have enough power to really whomp the 810 cab when running in the stereo mode. This is a tone issue for me. So I finally broke down and went to one amp head per cabinet.

    You will notice virtually all the guys running SVT's use an amp per cab.

    If you don't need the super volume, just remember that 3/4 on the master limit and you should be OK...

    Whatever you do do not plug from one cab to the next and run the amp in MONO-Block, it has a 4ohm limit. But a 2 ohm limit in stereo.

    Have Fun, BOB

    SPECIAL NOTE: The 1/4" jacks there are 4; two are in parallel for each channel. I use the speakons myself.
  6. rickybocker


    Dec 14, 2008
    Well I did that mono bridged into one cab and popped about 5 speakers,... so i wont be doing that again... playing thru dual 810's is awesome and I would suggest anyone do it... if you wanted to crank them and get a good gained out tone its perfect or just leave it back and use the the monster rig to help support all the frequencies that get lost... I play in a signed metal band my guitar players have mesa full stacks so it works real good.... not sure how many of yall check out the newer underground metal bands but lots of guys are doing the two cab thing either under the pro 4's or the svt classics now... its a pretty massive tone... but ya i figured those heads ran like regular steroe power amps... not lke marshall jcm heads that effect outputs... just wnated a third party to back me up on jam room discussion... thnks for the replies..
  7. Dino@Ampeg

    [email protected]

    Mar 27, 2008
    Global Product Specialist - Ampeg
    I have to concur with Bob on this one guys. Running each side of a 4 PRO into each 810 cab only yields about 490 watts per side and that's not quite enough power to really push an 810 efficiently. It can be done but your headroom is nill.
    I usually recommend running mono bridged into each 810 cab. This gives you about 1200 watts into an 800 watt cab. Remember, it's always better to have too much power and back off the gas than not enough and having to put your foot to the floor.
    However Ricky, if running it the way you are now works for you, have at it and have fun.
  8. El Kabong

    El Kabong

    Mar 25, 2008
    Central Iowa
    :rollno: Impedance
  9. Jerrold Tiers

    Jerrold Tiers

    Nov 14, 2003
    St Louis
    +1 The only way to go....... unless you really DO like the other way better.....

    BTW, the speaker-popping thing...... it's best NOT to crank too hard on the low controls (maybe not at all) with high power and substantially exceeding cabinet rating...... Especially with the lower power (classic type) 810. And do NOT use the "suck switch" (Ultra Low).

    Most speakers are more limited by speaker cone movement than they are by actual "thermal power"....
  10. Dino@Ampeg

    [email protected]

    Mar 27, 2008
    Global Product Specialist - Ampeg
    Sorry about that..... It should have read....."mono bridged into a single 810 cab"
    You CANNOT run mono bridged into two 810 cabs!!!
  11. Bijoux


    Aug 13, 2001
    I have always wondered why people don't simply read the manuals...
  12. rbonner


    Sep 25, 2008
    Because Bijoux,

    There's a lot of stuff in the manual the owner really doesn't want to know. The 4PRO is the first FULLY featured Bass amp to hit the street. She'll do almost anything, but it has a couple limits... Like shoving it into a tight rack, trying to drive a pair of 810's to full power... But now take that unit and use it within its ability and you've got a rockum sockum unit. Hook a second one, or an SVP1600 on as a slave and you will have enough power to invert the cones on two SVT-810e's. Just what ANY bassist would want to be able to do. Except trying to cook Creamettes inside while playing a gig...