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Power amps are comlicated!

Discussion in 'Amps and Cabs [BG]' started by Thunderbird91, May 4, 2006.

  1. Well i guess not that bad... I want to know if I can take my 125 watt GK backline head and add a power amp (thinking 300 bucks for this http://www.carvin.com/products/single.php?ItemNumber=HD1800&CID=PWA is one heck of a deal) and then possibly have a avatar neo 1x15/4x10 stack underneath it. Would that be good?

    I understand how regular ohms work but what is the deal with bridged vs. unbridged?

    What is continuous RMS?

    What are all those different types of cables?

    If there is a faq for this please just link me
  2. Name Changed

    Name Changed Banned

    Apr 22, 2006
    actually yeah that would be cool.
    that would be quite possibly the best power amp and cabinet rig ever for that price range.
    GO FOR IT!
    btw the hd1800 doesnt have speakon outputs, but thats ok!:bassist: :bassist: :bassist: :oops: :scowl: :D :D :D :D :D :hyper:
  3. steveb98

    steveb98 [acct disabled - multiple aliases]

    Mar 15, 2006
    Venice, CA
    Well if your head has pre-amp out you could use it drive the power amp. Lots of other ways to front-end the power amp.

    It is a two-channel amp, you can BRIDGE the two channels to make one big one channel amp.

    RMS is a way of measuring output. In general they are saying they are giving continous average power rating, not the power of a burst.

    FAQ - Google or Wikipedia is your friend when in doubt.
  4. :eek: really?

    :hyper: yay me!
  5. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    I think power amps are confusing because they are designed to be flexible. One example is... a stereo power amp contains two amplifiers, but there are applications such as bass guitar that call for a monaural amp. A typical PA power amp can run in two modes:

    1. Stereo mode, which is two inputs and two outputs.

    2. "Bridged mono" mode, in which the two amplifiers operate together from a single input signal to produce a single output delivering much more power.

    This makes more sense for the manufacturer than having two product lines for stereo and mono.

    For bass amp use, you should probably assume that you want to use bridged mono, so you are just looking at the amp's specs for bridged mono mode. It looks very much from the specs that in bridge mono mode, driving two cabs (i.e., 4-Ohm load), the HD1800 is an 1800-Watt amp.

    "Continuous RMS" is explained in Carvin's fine print: It just means that the amp can deliver its rated output continuously, rather than just for a brief time period.

    Reading this same forum, I gather that it is common for bassists to have an amp that can overwhelm the power rating of the speakers. I don't do this myself. Part of doing this is exercising the necessary caution to avoid blowing speakers. Make sure you get some advice on this forum before going down the "overpowering" road.

    There is a chance that 1800 W is too much for your use. You can always us just one side of a stereo amp, and save the other side for something like running a vocal PA or monitor speaker.
  6. thanks. How would you hook it up for "mono-bridged" mode with two speakers?
  7. the manual for any particular amplifier will tell you how to operate in bridged-mono mode. it is critical that you read and understand it before trying to use the amplifier. it's also a good idea to read and understand it before buying the amplifier.

    as far as hooking up to cabinets, the best way is usually to connect a cable from the power amp output to an input jack on cabinet A, and then use the second jack on cabinet A to connect an input jack on cabinet B.

    some people prefer to use two cables from the power amp, but that's probably not what you want to do.

  8. MakiSupaStar

    MakiSupaStar The Lowdown Diggler

    Apr 12, 2006
    Huntington Beach, CA
    I did this. It worked, but here's what I found. I felt like I was building the tower of babel. Here's the whole story. l I stumbled upon a Behringer 1x15 600watt cabinet for 200 bucks. So I added it to my rig and ran two cabinets, my Carvin 4x10 RedEye 600Watts and my Behringer 1x15 600Watts. Well this combination was too much for the little Carvin head. I lost all my headroom. My solution (here's where my point comes in) was to buy a Carver 1000Watt power amp wired to run 1000Watts mono to power that second cabinet. I ran balanced line out from my Carvin head into the input of the power amp. It worked well. I had a lot of juice now. Essentially 1600 watts. So that took care of my head room issue.

    Still I wasn't happy with my sound. So I ended up ditching the Carvin for a Ampeg SVT-BSP preamp to sit in front of the Carver 1000W poweramp. Now I'm happy. It simplified my sound and my rig. Yeah, I know that the underlying moral of the story is that I was really seeking the warmth of a tube all along, but I also felt like the whole set up with the head and the power amp was a bandaid or a stepping stone to setting up a proper pre/power set up. But to answer your question. It can be done.
  9. So I probably wont be happy with the sound of the gk through the power amp?
  10. CamMcIntyre


    Jun 6, 2000
    I've got one of their other line of poweramp-a DCM2000. Plenty of flexibility and the thing sounds just fine.

    take it easy.
  11. 62bass


    Apr 3, 2005
    It should be plenty loud. The sound will depend a lot on the preamp of the GK Backline. Myself, I'd go with a different preamp. I like GK but I am not fond of the sound of the Backline series. GK does make a dedicated preamp but it's not cheap.
  12. hmm... what would you recommend as a preamp?
  13. MakiSupaStar

    MakiSupaStar The Lowdown Diggler

    Apr 12, 2006
    Huntington Beach, CA
    In theory it would sound exactly same, just louder, right? But it never seems to work out that way. For me I found that I didn't like my Carvin R600 when it was coupled with all that power. That's why I switched out to an Ampeg pre amp.

    You can find a good used Ampeg preamp, depending on model, for somewhere between 200 - 400 bucks. I'm playing a Ampeg SVP-BSP pre amp and I frickin' love the thing. Super happy with it. Other people swear by their SVP-CL preamps, others by their SVP-PRO. You're gonna have to research a little. Look at who you're favorite players are, and what they're playing through. That's a good place to start. I just noticed that all of my heros are playing through Ampegs, so I checked it out and found that it worked for me.

    But I will say this. I'm definitely a LOT happier with a pre/power set up.
  14. cheezewiz

    cheezewiz Supporting Member

    Mar 27, 2002
    While I just hate to contradict the wise expertise of Mr. Name Changed, I wouldn't think that'd be a very good sounding rig. You'd be using the Backline 125 as a preamp, and for not much more money, I'd guess there are a lot better sounding preamps out there.
    It's certainly doable, and worth a try, but I think MakiSupaStar is on the right track. You may be better off with a cheaper pre/power setup.
  15. MakiSupaStar

    MakiSupaStar The Lowdown Diggler

    Apr 12, 2006
    Huntington Beach, CA
    Yeah my pre/power set up is all used and cost me a total of 450 bucks. You can always upgrade later.

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