Amp advice: I need more power!

Discussion in 'Amps and Cabs [BG]' started by KampKomfort, Jul 27, 2000.

  1. KampKomfort


    Jul 27, 2000
    I have recently started to gig after several years of playing on my own, and I have found that I need much more power. I am currently using an Ampeg B1 combo (150W @ 4ohms, 12" + horn), and I love the sound I get from the tube pre-amp. However, the power amp section just isn't cutting it. It clips almost constantly.

    I have an opportunity to purchase a Sunn SPL7350 two channel power amp that produces 750 watts @ 8 ohms when bridged. It is only a few years old and in excellent condition and is selling for $200.

    My plan is to use the pre-amp of the Ampeg B1 (it is a one rack space unit), run the XLR to the bridged Sunn power amp, and then go to the 1X12 + horn Ampeg cabinet. I also have 1X15 old Yamaha cabinet that might sound good with this setup.

    Would this be a good idea? Is the Sunn amp a good deal? Is this a common solution to my problem? I'm new to the performance realm, so I need all the help I can get. Thanks for your help--I know I'm throwing alot at you.

  2. Matthias


    May 30, 2000
    Vienna, Austria
    I don't think it's a good idea to run a 750W head into 150W speaker...

    BTW 150W is not TOO little of power, your band must be very loud.
    Maybe you should try this: leave the bass knob of your EQ in flat position or even roll of the bass, boost the (low-)midrange. This should help you cutting through. (low frequencies eat a lot of amp-power!)

  3. I agree. The point to keep in mind is that the EQ which sounds great at home when you are practising alone, or which suits the studio, will NOT cut through a live mix.

  4. Munjibunga

    Munjibunga Total Hyper-Elite Member Gold Supporting Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    Actually, 150W is not enough power. If I were you, I'd look into perhaps a used head with at least 300 watts. Even a Peavey would be preferable to being underpowered. I agree that your suggested power amp/speaker setup would be ill-advised, given the power handling capacity of the speakers. Get the best head you can afford, then start working on speakers ... something like a 410.
  5. Scok


    Apr 20, 2000
    A point I'd like to bring up that is being missed.

    Your speaker is 4ohm and the bridged amp is 8ohm. If you add another 1*15 (is that also 4ohm?), this would mean you are running at 2ohm's (1/R + 1/R = 1/Rt).

    It would be OK to run your speakers in regular stereo mode on the amp (I'm assuming it's 4ohm a side). But if you run you amp bridged with you spearker impedence lower than your amp impedence you could blow your amp.

    So go for more power, but be careful not wreck stuff. [​IMG]

    [This message has been edited by Scok (edited July 28, 2000).]
  6. KampKomfort


    Jul 27, 2000
    Thanks for all of the advice. One note: My speaker (the 12) is rated at 8 ohms. The amp is rated at 150W @ 4 Ohms, which means I am probably at around 110W or so (just a guess).

    My band is loud, and I've had a hard time even hearing myself at some shows (when we aren't using the PA). I know that 750W is a lot of power, but I guarantee that I wouldn't be exploiting all of the amp's power. I just need something with a little more power than what I have.

    Also, since I am very pleased with the sound of the pre-amp section of my amp, wouldn't adding a more powerful power amp make sense? I could add a larger cab as finances allow, closely watching my sound levels until then.

    Is my logic sound? Should I look for a different power amp other than the Sunn (It seems like a good deal)? I've tried all sorts of eq options trying to cut through the mix, but I'm still struggling.

    Thanks to all for the great advice!
  7. cb56


    Jul 2, 2000
    Central Illinois
    $200 bucks for an sunn SPL 750 sounds like a great deal if it works. I'm using an Spl 6000
    600 watts 300x300 at 4 ohms to run an extension cab when I play out doors. I would not run the power amp through your ampeg speaker. Why take a chance on screwing up a great sounding amp. This is just my opinion but if I were you I'd snatch up the power amp then try to save up enough for an extension cab that will handle it. My outdoor rig (at the moment) is an SVT 200t into a410 cab and a118 cab. I run a guitar cable from my svt's line out,over to my Sunn amp into channel A and push a carvin 210 4ohm cab at 300watts with the channel A output. I'm not doing anything with the B channel yet. I don't think that will harm the amp to run only one side of it. But I could be wrong.

    [This message has been edited by cb56 (edited July 28, 2000).]

    [This message has been edited by cb56 (edited July 28, 2000).]
  8. Speedbird

    Speedbird Supporting Member

    Jul 10, 2000
    Northern Virginia
    <BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Andy Daventry:
    that the EQ which sounds great at home when you are practising alone, or which suits the studio, will NOT cut through a live mix.


    100% TRUE!

    Boosting lows (40-100ish hz) will not help you "cut" through a Marshall, it only eats up amplifier headroon QUICKLY. Try to get your guitar player to cut some mid then boost yours. It worked for me, good-luck.


  9. lowb1970

    lowb1970 Supporting Member

    Feb 29, 2004
    Columbia SC
    Well, I'm probably going to have some people mad at me for this comment, but 150 watts is not enough power for a rock band. It takes twice as much air, if not more, to push the low frequency as it does for a guitar. So, if your guitar player is using a 100 watt head, you should have at least 400 watts, if not 500 to be able to have the headroom needed to hear what you're playing in the context of a band. I have been playing live for many years, and I find that every venue is different. you have to adjust to every situation. By this I mean adjust volume as well as EQ. Some rooms are bass heavy, and others need some bass. Your settings on your preamp will determine how well your amp works. More low end draws more power. Use your ears and try not to tick off the band with the low-end thunder you will be