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Power Amps

Discussion in 'Amps and Cabs [BG]' started by Mr. Pickle, Apr 19, 2006.


  1. Mr. Pickle

    Mr. Pickle

    Aug 20, 2005
    ok, i'm in need of some assistance.

    i am currently using a qsc850 and i need a little more juice. here's the thing, i can get a more powerful crown power amp for about the same price of my qsc (i'm currently using 4 ohm bridged). i'm sure there are some quality aspects of the qsc that outweigh the crown, but should i really look the other way when it comes to crown? are they like another behringer? (even though every piece of behringer equipment i've owned has never had a problem) keep in mind that i take very good care of my equipment, so if durability is one of their flaws, i should be fine.

    also, do power amps really mess with your tone that much? i know ss vs. tube is a different story, but what does a power amp really do in terms of sound and what factors determine what kind of sound you'll get?


    k,
    me
     
  2. vooch311

    vooch311

    Aug 28, 2001
    Wilmington, NC
    hi

    well a whileback i was searching for a power amp and read just about every post on here related to them.
    Almost every time the Crest CA-9 was recommended, so i got one and i see why.
    Tons of clear, pristine power and built very well. Mine was dropped by UPS very hard (bent the rack ear) and still no probs.
     
  3. BBMS

    BBMS

    Jun 29, 2005
    I have used a QSC USA850 for over ten years without a problem. I was going to use it at a school dance, but the tech guy said,"don't bother, use the PA system." The PA system was a Crown CE1000 and some Bose speakers. I really didn't crank it up that much (clipped, but turned it down). The Crown went into protect mode and never recovered. I replaced it with the QSC, and it hasn't missed a beat since (three months ago).
     
  4. Mr. Pickle

    Mr. Pickle

    Aug 20, 2005
    well, i think it's kind of obvious by my first post that that's a little out of my price range. thanks though.
     
  5. emjazz

    emjazz Supporting Member

    Feb 23, 2003
    Brooklyn, NY
    I can't say that I think it was obvious by any means.

    I will say that a Crest CA4 would still do the job extremely well. Check around for a used one.
     
  6. srxplayer

    srxplayer

    May 19, 2004
    Highland, CA
    I own and use several Crown CE 1000 & 2000 and XLS 402 & 602 amps and I wouldn't recomend them. I have a lot of trouble with them. They are supposed to be good products but my experience has not been very positive. The XLS 402 & 602 I have each have lost a left or right channel and they are less than 6 months old. I have evaluated over & over how we are hooking them up and if they are getting banged around but they are not. I keep them racked in SKB casses but they still fail on me. Crown won't cover them under warranty because they said we damaged them. Thats a bunch of crap! The conditions they have been run under havent pushed at all. In fact they were running in a rack that never moved and never got puched beyond 50% of the amps capacity. I have checked the ohm loads, connections, etc and we can't see what we are doing wrong.The CE 's are usually racked in permanent racks in a church but they too have failed on several occasions.

    I have several QSC RMX series amps. 1450, 2450, and 4050's and I ask them to do the same thing that the Crowns do and they don't quit on me. The only down side to those is the weight but the weight benefit didn't out weigh the cost difference with the PLX. I am happy with the RMX's and highly recommend them.

    I would stick to the QSC's you can get good deals on the 1450's.
     
  7. Mr. Pickle

    Mr. Pickle

    Aug 20, 2005
    well, i was talking about power amps that were in the same price range as my qsc, i thought it was basically implied, sorry.



    any experience and/or comments about this?

    click


    basically, i'm looking for a powerful power amp on a pretty low budget. i'll probably end up going with the next size up qsc, but i just wondering if there are any PAs out there that could fulfill my purpose w/o spending as much.
     
  8. Mr. Pickle

    Mr. Pickle

    Aug 20, 2005
    also, to emjazz, that still kind of out of my price range (new or used) and as in power output, would it be all that big of a step up?
     
  9. emjazz

    emjazz Supporting Member

    Feb 23, 2003
    Brooklyn, NY
    The CA4 is still a REALLY loud amplifier.

    I know that there's a tber selling a Crest LT1000 for $300. Let me know if you're interested and I'll give you his info. The LT1000 is a great amp and would definately be a big step up from what you have.
     
  10. Mr. Pickle

    Mr. Pickle

    Aug 20, 2005
    alright, this might help me understand power amps. the ca4 and rmx850 are SIMILAR as far as wattage goes right? (4 ohm bridged) if they are, what would make the ca4 louder than my qsc? or are u just saying it is really loud, but your not making a comparison to the qsc?


    danke
     
  11. emjazz

    emjazz Supporting Member

    Feb 23, 2003
    Brooklyn, NY
    I'm not familiar with the QSC amps. I have heard the CA4 and I just can't imagine needing more volume than that amp puts out. I've owned a CA6 and it was silly loud. If you ask anyone with a CA9 they'll tell you that they can hardly turn those amps up. Most everyone uses only one side of the amp. It's just that those amps are so well made and so solid.
     
  12. how about input sensitivity? for example, the CA4 is .775V (0dBu) sensitive, which means it takes only .775V to drive it to full power. the RMX 850 and RMX 1450 are both 1.15V (+3.4dBu) sensitive. it takes more than 3dB of extra output from your preamp to drive them to full power.

    i am going to guess that you're not fully driving your power amp. with a modification to your power amp, you'll find it's much louder. unless you're already lighting clip LEDs, which means you're driving it to full power already.

    the funny thing about comparing CA amps to PLX or RMX amps is that you have scale back the input level of the CA amps to match gains with PLX or RMX amps, even much more powerful ones. if your preamp even comes close to fully driving a PLX 2402, you will have trouble using the a CA amp without turning down its attenuators quite a bit.

    this doesn't mean the PLX and RMX amps aren't "loud", though. they're just designed to a different paradigm than CA amps. unmodified, CA amps are a much better system match for most instrument rigs than PLX amps because of the input sensitivity. for many, the weight savings is worth it for a PLX, and it's relatively easy to make modifications to preamp or power amp to make PLX and RMX amps better suited to the application. there are some QSC dealers who sell PLX amps pre-modded. i modified the output of my preamp to drive my crest Pro 7200 power amp -- so it's not a brand-specific thing. (although it should also be known that i have worked for both crown and peavey/crest in the past...i'll get to qsc eventually.)

    robb.
     
  13. Justice

    Justice

    May 24, 2002
    Houston TX.
    I have been using a Behringer EP1500 (running 4ohm bridged) amp in my bass rig since they first came out, they have proven to be solid reliable amps. My first EP1500 was almost 3 years old when it was stolen from me, still working perfectly and never had an issue. I replaced it with another EP1500 which i have had since January in my new rig. We use two of the EP2500 amps in our PA system. They are one of the best values for the $$ in power amps, especially if you are on a budget.

    I'm not familar with the Samsom amp you linked, since i have never used one (or known anyone else who has) But you could get the Behringer EP2500 for less and have a more powerful amp.
     
  14. rockstarbassist

    rockstarbassist Banned

    Apr 30, 2002
    The Woodlands, TX
    Endorsing Artist: HCAF
    Check out some of the Stewart Audio stuff. You could get a 1.2 or 1.6 for a pretty reasonable deal, I'm sure. Plus, 17lbs (or less in the 1.2's case) is awesome, considering the power you get!

    I have a 2.1 on the way right now. Can't wait to get it in and REALLY thump with my Schro 410!!
     
  15. Mr. Pickle, a bit larger amp isn't going to do what you want.

    Let's do the math:

    RMX 850 bridged into 8 ohms = 600 watts
    PLX 3402 bridged into 8 ohms = 2200 watts

    dB = 10 LOG (Power1 / Power2)

    Using the above two amps, the big expensive PLX is 5.64 dB more powerful than the 850. What this demonstrates is the rapidly diminishing returns from increasing amp power.

    Worse, there aren't many speaker cabs capable of handling a full 2200 watts without power compression, or melting into goo.

    Your solution is
    1) more speakers
    2) more efficient speakers

    For #1 add cabinets
    For #2 use bass horns
     
  16. MacGroove

    MacGroove Brother of the Groove with a 'Pocket Full of Funk'

    Oct 5, 2005
    Calif.
    IMO yes, simply, there are watts and there are WATTS.
    Weather you're comparing ss to ss or tube to tube, a good power amp will, IMO, give you a better front end (tone).
     
  17. emjazz

    emjazz Supporting Member

    Feb 23, 2003
    Brooklyn, NY
    Agreed.
     
  18. Mr. Pickle

    Mr. Pickle

    Aug 20, 2005
    alright, thanks people.

    does a more 'powerful' power amp help with clipping? thats starting to become a problem. clipping is basically driving the power amp too much right? (in a nutshell) one of my biggest problems is i'm running out of headroom, so wont a bigger power amp help?


    btw, i'm running my qsc850 into an kappa pro 410 (4 ohm)
     
  19. Planet Boulder

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

    Nov 10, 2001
    6,482 feet above sea level
    I once had impure thoughts. Oh, and I pluck my ear hair.
    Every now and again, you can find a NOS E&W power amp on ebay for cheap (I got a 1600 watt AL1600 for less than $300.00 shipped) and they are well made power amps (do a search and you'll find a thread or two). Plenty of power (bridgeable to 4 or 8 ohms) and nice tone. Heavy as hell, but I carry it in a separate rack anyway.

    As for the tone issue, I also have a Carvin FET1000 power amp and a Trace Elliot RA500 power amp and all three possess different tonal qualities.

    I replaced my Carvin, which had a sort of dull tone that didn't really do my Eden pre justice, with the E&W and the difference is noticeable.
     
  20. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    A more powerful amp will put out more audio signal power before it clips. A little clipping is nothing to worry about, but prolonged or very frequent clipping means you need more amp power and/or more loudspeakers (or more sensitive speakers).

    Is your amp an RMX 850 or a USA 850?
     

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