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Going the preamp/poweramp route... have some questions

Discussion in 'Amps and Cabs [BG]' started by matt_chew, May 2, 2004.


  1. After reading many great reviews and gathering enough money, im going for the preamp/poweramp. Im going to get the BBE Bmax and QSC 1450. My GK 700 RB just wasnt cutting it with my cabs. Now i have some questions.

    My cabs are both 8 ohm older model avatar cabs. I was planning on running the poweramp bridged at 4 ohms into my cabs and read that speakon cables must be used to accomplish this. My avatar cabs only have a 1/4 inch jack. Will i get the same output if i buy a Speakon to 1/4 inch cable?

    Also, Im kind of clueless about speakon cables, i know that their not as simple as 1/4 inch where you just plug them in and go correct? You have to set them up a certian way? Im still unsure about this.

    Im also unsure how to connect 2 cabs for running a bridged mono 4 ohm load. In the manual it explains how to connect 1 cab for a bridged mono load but not 2. Would i just run the speakon cable to one cab and then run another cable from the jack of one cab to the other?

    Im sorry if i sound clueless here, im just trying to find out as much as i can before i buy.
     
  2. MJ5150

    MJ5150 Terrific Twister

    Apr 12, 2001
    Lacey, WA
    Yep.

    That would be correct.

    You're being very smart asking all of these questions before you go drop a couple thousand bucks on gear. No need to apologize bro. All of us have been in your shoes before. :D

    -Mike
     
  3. lowb1970

    lowb1970 Supporting Member

    Feb 29, 2004
    Columbia SC
    You could also just run the amp normal into 2 8ohm speaker cabs and it would work at 4ohms. that should be plenty of power for you. I have run this way for many many gigs. I use a sansamp RBI and a QSC........can't beat the sound...........well unless you use ashdown, or aguilar.........but hey, that's some serious bucks there.
     
  4. Im thinking of going the same route...but talk about clueless, Ive always been a plug-n-play bassist. You know, just a head and cabs. Where can I learn from the ground up about the more complex gear setups such as Pre/Power amps and such?
    Anyone know of a website or another thread on this?
    Thanks in advance....Ive learned more about gear in a couple weeks here at TB than in my whole career as a musician!
     
  5. Spanky, almost everything i have learned about bass guitar ive learned here at talkbass. I know you dont really have any idea what questions to ask, but do a search pre/poweramp and im sure you could find a whole lot. If you dont find anything, dont be afraid to ask questions, because as i have found, people are incredibly helpful here and wont hesistate to help.
     
  6. Well, the thing is i was going to buy the QSC and bridge it because as it is right now, i am seriously underpowering my avatar cabs with the GK head, and im having to turn my amp up way too much and clipping it.
     
  7. NJL

    NJL

    Apr 12, 2002
    San Antonio
    i run my 1450 bridge mono into either 1 avatar 410 (newer design) or my avatar and hartke - the only problem i have is with my SVP - the vibrations mess with the pre so i have my rack on the ground. this is way more power than i need, but that's the point - i likey having headroom.

    BTW, i use two auralex GRAMMA's under the two cabs or one under one cab.
     
  8. Craig Garfinkel

    Craig Garfinkel

    Aug 25, 2000
    Hartford, CT
    Endorsing Artist: Sadowsky Guitars
    Actually Matt, speakon cables are used exactly the same as 1/4 inch cables. Just plug 'em in and go. The speakon is merely a new and more secure method for making the connection. Techies may jump in here and say they are more efficient, etc., but for us non-techies, they perform exactly the same function and are as easy to use.

    Speakon to 1/4 inch cables are fine. I could be wrong, but with your QSC bridged, you still should be able to use both speaker outputs (?). If this is the case, I'd run seperate speakon to 1/4 inch cables, one to each cab.

    Enjoy your new rig, and welcome to TalkBass.
     

  9. I think i read that only one speaker output works when you bridge the amp, so correct me if im wrong, that would mean run the speakon to 1/4 inch cable from the amp to one cab, then use another 1/4 inch cable to run from one cab to the other.

    Also, i was reading in another post, that a specific speakon cable is needed for bridging, saying it had to be wired a certian way and that it needed to be wired a specific way at the speaker end as well.... Do i have to buy a cable that is specifically for bridging?
     
  10. Craig Garfinkel

    Craig Garfinkel

    Aug 25, 2000
    Hartford, CT
    Endorsing Artist: Sadowsky Guitars
    Matt, you're absolutely right. A special speakon connector is required for the QSC when bridging, and I saw (after my post here) that same thread you did. Fellow TB'er Bob Lee (QSC) is the man to contact to explain exactly what you'll need. Sorry to steer you wrong with the QSC assumptions...but once you get the right speakon, you'll see what I mean about its "ease of use". You'll wish your cabs had speakon connections too.
     
  11. Planet Boulder

    Planet Boulder Hey, this is a private residence...man Supporting Member

    Nov 10, 2001
    6,482 feet above sea level
    I once had impure thoughts. Oh, and I pluck my ear hair.
    Hey Matt - have you considered using your GK as the preamp? Not sure if you're also looking for a completely different vibe, but if you dig the GK, you could save yourself some bread and use it as the preamp. Maybe use the extra $ for an even higher powered power amp.

    Just a thought.
     
  12. There is a couple of different ways you can wire this up. The easiest way would be to get a bannana to 1/4 cable. Plug the bannana into both (RED) posts and the 1/4 into you cab. Then chain the 2 cabs together with a 1/4 to 1/4 speaker cable.

    If you dead set on using speakon, you'll need a speakon to 1/4 cable with the speakeon wired +1 and +2. Plug the speakon into channel one and the 1/4 into the cabe. Then chain the cabs together with a 1/4 to 1/4 cable.
     
  13. E.O.M.

    E.O.M.

    Dec 7, 2001
    Grand Rapids, MI
    Does chaining two 8 ohm cabs together like everyone has been mentioning give the amp a 4 ohm load or a 16 ohm load?
     
  14. Chaining two 8 ohm cabs together produces a 4 ohm load. BTW the amp reads this the same way if there is 1 cab or 100 cabs.
     
  15. Another thpught. As mentioned earlier you can use a head's pre-amp out to send signal to a pwer amp.

    I only have one experience with this. I used an Ampeg B2r to a QSC USA 900. The signal sounded good and loud but it wasn't enough to drive the QSC to full power. I don't know if this is a situation with the B2r or all heads though. I will say it sounded good and is definately a worthwile option.
     
  16. I like the idea of using the GK preamp and QSC poweramp, but right now im just looking to try something completely new and different. I wanna see what else is available, because the GK is the only amp ive really had any experience with.