silly question about amps

Discussion in 'Archived Threads 2001-2004' started by tom_furman, Aug 3, 2001.

  1. tom_furman

    tom_furman Stunt Coordinator

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    i have a sony db-840 receiver that i use to power my speakers...my friend just gave me his used QSC EX1250 amp..
    how exactly do i hook the amp up to power my front towers? like what inputs do i use?
    sorry for the stupid question!
     
  2. GarryW

    GarryW Stunt Coordinator

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    Tom:
    There is no such thing as a stupid questions, just stupid answers! [​IMG]
    Here is what you need to do:
    You need to run an RCA type cable from the pre-outs on your Sony to the Amps Signal IN inputs. Then connect the + and - speaker wires to the amp. You will then be using the Sony as a Pre-Pro which may give you better quality sound. You can connect up to 5 channels out from to the amp's IN if these are available on both pieces of equipment.
    I say "it may" improve sound quality as I am unfamiliar with both the Sony and the amp you mention. Maybe others on this board can share some of their experiences.
     
  3. DaleB

    DaleB Stunt Coordinator

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    Hmm. Interesting amp. Have not a lot of info on it. Did you get a manual with it? It's commercial grade I take it.
    Anyway, if your receiver has preamp outputs for your front left and right channels, wire those over with 2 interconnect cables to the inputs of your new amp, and move the speaker outputs for the same L and R front speakers to the speaker outputs on the new amp.
    That's it in a nutshell. Of course, do all this with everything powered off, and perhaps even unplugged and make sure all your connections are correct and secure before powering back up.
    Then there should be nothing else you need to do. You should have more power now available to your front channels.
    Maybe someone here has more info on this amp, like if it can be triggered to ON by your receiver. This only works if your receiver has a trigger output. Otherwise you have to power it on each time you turn on your system, or waste electricity and have it powered on all the time, except for vacations when everything should be powered off.
    You did not provide a wealth of information, so I am not sure your receiver even has preamp outputs, as I do not have much info on it. If it does not have a preamp output, then you have a problem. Not one that can not be overcome, but it gets more complicated.
     
  4. tom_furman

    tom_furman Stunt Coordinator

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    so i might not even notice a difference huh? i figured the extra power, plus the fact that it SHOULD be cleaner power would make a difference.
    if amps might not make a noticeable difference why do some people use like 5 amps to power all their speakers?
     
  5. David Judah

    David Judah Screenwriter

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    Tom,
    Many of us have added external amps to receivers with positive results, so I'd definitely say give it a try.
    DJ
     
  6. Dan M~

    Dan M~ Second Unit

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    Be carefull with (off-brand) pro amps... they may play louder, but they often have very high distortion numbers! Night clubs and disco's are about dB's and not quality (I'm sure there are exceptions).I have not heard the QSC amp, is this the amp that Parts Express sells? It may work better as a sub amp where distortion numbers are more tolerable. Don't expect pro amps to sound better in the home enviroment, thats NOT what they are designed for.
    Good luck,
    Dan
     
  7. John Garcia

    John Garcia Executive Producer

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    The DBs use most of the amplifier section of the ES gear, so you probably won't see too much improvement, unless the QSC is putting out a lot more power. For you to really notice it, it would have to be a significant jump in power.
    Do the DBs have pre-outs?
    ------------------
    All progress is based upon a universal, inate desire on the part of every organism, to live beyond it's income.
    ITRCA ** Honda/Acura Club ** Speedring (sorry, car guy)
     
  8. Dan Hine

    Dan Hine Screenwriter

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    First off, QSC is definitely not an "off brand" amplifier. Yes they are pro amps, but very good ones.
    Here is some information about QSC's EX-1250:
    - 275watts per channel @ 8ohms
    - 20hz-20khz .1% THD
    - THX approved for cinema applications
    That is just what I thought might be relevant off hand. To see much more on this amp (and other QSC amps) follow the link.
    http://www.qscaudio.com/support/library/specs/specs.htm) and connect them to the barrier strip.
    2) Get two 1/4" to XLR cables and two 1/4" to RCA adapters
    However, both of these options may quite possibly degrade the signal to the point that it would negate any good the amplifier may do you. Try it and see what you think. If you don't think it sounds better at least you have a good amp you could sell! [​IMG] And with radioshacks 30day return policy you would only be out the RCA cables you cut. Have fun....
    Dan Hine
     
  9. John Garcia

    John Garcia Executive Producer

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    Based on those specs, I'd say you'll definitely hear a difference. [​IMG]
     
  10. Vince Maskeeper

    Vince Maskeeper Producer

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    quote: I have not heard the QSC amp, is this the amp that Parts Express sells?[/quote]
    Either that or they're one of the top 5 largest professional amplifier seller on the planet that has been around for 30 years, the largest- by far- provider of power amplifiers to the cinema market as well as a good portion of professional touring amplifiers...
    QSC offers the largest range of THX-approved amplifiers for the cinema market with its DCA, ISA, USA and MXa Series amps- all are THX cert (they carry like 18 models that are THX certified).
    2500 dealers, almost 30 regional offices around the country. They supply audio to many of the major sporting arenas and parks (Safeco Field in Seattle for example) - even supplied all the amplification for the Superbowl.
    Even folks like the Tonight show use QSC.
    Either that or they're that part express stuff you mentioned [​IMG]
     
  11. Andrew Pratt

    Andrew Pratt Producer

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  12. AVspec

    AVspec Supporting Actor

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    Well all I use is QSC amps in my Digital Vortex theater and they are GREAT!!!
    I have 3 QSC EX800's and 1 QSC EX1250! They can pump into 2ohm loads without even blinking!!! I am using one channel of the 1250 to power my new dual SVS subs in parallel which is a 2ohm load which gives me 600watts from the QSC amp and it does not even break a sweat.
    And as for the sound? They sound great!!!! A good friend of mine from my old company told me that the EX line (which is now discontinued unfortunately) is one of the best audiophile grade pro amps made.
    And yes they are THX approved.
    Just check out my web site with newly updated pictures of the theater and you can see all the QSC EX amps. And hey if you want to get ride of the QSC I will take it! Can always use a spare! [​IMG]
    ------------------
    -Mark
    **** Digital Vortex ****
    The Digital Electronic Site
    www.digitalvortex.com
     
  13. Dan Hine

    Dan Hine Screenwriter

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    hahah...Vince, I knew you would chime in here somewhere! I definitely agree. Professional amps have a very bad reputation for some reason. Personally, I love them. I don't have them in my home yet, but I use them at work a lot. Crest amps, QSC's, Even have some older AB Logic amps still going strong.
    Dan Hine
     
  14. John A. Gordon

    John A. Gordon Stunt Coordinator

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    Hello Tom,
    Glad to hear you are an owner of a QSC amplifier. There is good information on above posts on connecting your Sony to the QSC EX 1250. If you want specific options on connecting the amp, please provide more info:
    - do you have pre-outs on your receiver
    - will you use the EX 1250 for L&R mains
    - or will you use the 1250 for sub(s)
    As mentioned above, the 1250 is rated for 275W at 8 ohms. If you choose to bridge the amp in a mono sub configuration, you are now looking at 800W, 8 ohms, .1% THD.
    Do not believe the fallacy of "pro-amps" cannot sound as good as consumer hi-fi amps. Night-clubs or discos are not even a close equivalent to camparing pro-amps to consumers. Read the posts above by Dan and Vince (thanks guys). I will gladly test QSC amps against any amp on the market, consumer or pro, for sound quality with the confidence QSC will be the winner.
    For those into the numbers, QSC is the largest manufacturer of pro amplifiers, we have more THX certified amplifiers (we were the first btw) and we are in more cinemas than any other amplifier brand. So, QSC is not an off-brand.
    Until then, enjoy your new (used) amplifier.
    ------------------
    John Gordon
    QSC Audio Products, Inc.
    Costa Mesa, CA 92626
    (714) 957-7100
    www.qscaudio.com
     
  15. Charbel

    Charbel Agent

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    Is anyone familiar with Crest Audio amps? My friend used to work on them and he said they were monsters. Very popular, for rock concerts,shows and the like. How do they compare?
     
  16. Vince Maskeeper

    Vince Maskeeper Producer

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  17. Dan Hine

    Dan Hine Screenwriter

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    I won't get into the "which is better" discussion since that has largely to do with personal preference, cash flow, and loyalty [​IMG] among other things. But put simply... Crest = [​IMG] [​IMG]
    Dan Hine
     
  18. Steve_D

    Steve_D Second Unit

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    My biggest concern about pro-amps is the fan noise. I'm very sensitive to spurios noises.
    Those of you with Crest, Crown, etc...Can you hear the fan?
    ------------------
    http://www.sdiver.org
     
  19. Dan Hine

    Dan Hine Screenwriter

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    Steve,
    Well, I only had two amps handy to listen to. A QSC RMX 2450 and a QSC USA 1310. From about 6ft away with subtle background music I could not hear the fan in the RMX 2450. This (I believe) is the largest/most powerful of the RMX series amps @500watts a channel. Perhaps a lower model would be even quieter? Don't hold me to that though. The USA 1310 had a noticeably louder fan but still not too bad. For an easy listening music system it might be too loud, but for a rockin' home theater, I doubt you would notice it. If you do...live a little, its the round knob marked "volume". [​IMG] Just Kidding.
    On a side note, speaking of no one in particular, I find it amusing how some people get annoyed by fans in amplifiers while others will buy an extra fan to suck out hot air from their equipment rack. Even more odd are those that don't like fan noise AND buy an extra fan or two...Seems a little strange to me. [​IMG]
    Dan Hine
     
  20. AVspec

    AVspec Supporting Actor

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    Out of the 4 QSC EX models I have in my rack I can not hear the fan in any of them. If I put my ear to the front of the amp I can hear the humm of the transformer and I had the cover off of a few of these amps and if you ever see the size of the transformer you will see why! They are huge!
    ------------------
    -Mark
    **** Digital Vortex ****
    The Digital Electronic Site
    www.digitalvortex.com
     

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