Is it wrong to sue a PA amplifier with subwoofers?

Discussion in 'Archived Threads 2001-2004' started by NathanP, Jan 22, 2002.

  1. NathanP

    NathanP Supporting Actor

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    I'm using a 600 watt p/a amp to drive my dual subwoofers.

    I've been told that I won't get the very best out of the subs because P/A amps's are made to play high frequences such as vocals and not to play the very low bass of a movie.

    A friend I purchased these subwoofers from says that they sound much better in house house then in mine.

    Keep in mind-

    1.He has a Dolby Digital 5.1/DTS reciever with a dedicated LFE and I only have a DPL reciever with a mono-output for subwoofers.

    2.These are some pretty cruddy subwoofers, until I upgrade to some madisound's or better this is what I got.

    So, is my P/A amp not "good enough" for a subwoofer?

    Nathan
     
  2. NathanP

    NathanP Supporting Actor

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    Also:

    The measurement's of my room are 11X13 and his are 11 or 12 X 14

    Could that be the diff right there?
     
  3. peter_anderson

    peter_anderson Stunt Coordinator

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    what exactly did your friend mean by "designed for vocals"?

    electronically, physically, what is different? if the power supply is not as beefy because it doesn't need to be for pure vocals, then yes, that would be bad for pushing two subs.

    i heard through the grapevine that "pro" equipment often isn't made to the same specs reqarding deflecting EMI/RF.

    Other than that, if it sounds good to you, that is all that matters! (of course it would also be good if you weren't creating a fire hazard by over-driving the amp)
     
  4. Patrick Sun

    Patrick Sun Studio Mogul

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    I don't think a self-respecting lawyer would take this case. [​IMG] (check the thread title)
     
  5. Ryan T

    Ryan T Second Unit

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    I'm the one that said Nathan should get a better amp. When I had the subs in my room (it is 10 1/2x14) they did not sound that bad besides the lack of really low bass. Now when there in Nathans room they sound really muddy and undifined to me. I suggested that he get a better amp because the only major change between my room and his room is the amp. and I figured that is what is causing the bass to be muddy. Also even though my receiver is DD/DTS the sub sounds pretty much the same with DPL or DD so I highly doubt that his DPL decoder is the problem.

    Ryan
     
  6. jeff lam

    jeff lam Screenwriter

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    Lots of guys use PA amps around here. SVS even recommends their samson PA amp over their plate amps due to the power and headroom. PA's have subs too you know. The same amps are used for subs there as the mains. My brother was the head sound tech for a small college and in their autotorium, they had a rack of QSC powerlite amps. One for 2-18" EAW subs, 2 for 4 EAW mains, and I think two more for monitors. Anyway, They were all QSC powerlite amps just the sub amps were higher power that's all.
     
  7. NathanP

    NathanP Supporting Actor

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    Yah,

    I mean, the band at my church uses 2 12" EV Elimnator subwoofers.

    I suppose Ryan was wrong.

    Nananananana!
     
  8. John A. Gordon

    John A. Gordon Stunt Coordinator

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    Amps can be desined to play mid and high frequency's only, as they can be designed for low freq. only. But practically every stand alone amp on the market, pro or consumer will deliver the 20Hz - 20kHz spectrum.

    I can assure you that QSC amps will perform very well for subwoofer use as well as others here at HTF can confirm.

     
  9. Lewis Besze

    Lewis Besze Producer

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  10. Ryan T

    Ryan T Second Unit

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    Lewis,

    It's funny you should ask but no i'm not from the car audio circle. I'm 16 years old and do not even have a drivers permit yet. I'm not saying that my room and Nathans room are the exact same but our setups are very close. The main diffrence between my room and Nathans are as fallows.

    Nathans room has poster on all the walls my room does not have any posters. His room has a bunk bed as a couch my room has a regular bed as a couch. other than that are rooms are very very closed to the same setup.

    I still think that the amp is the reason that the bass does not sound to good to me. I'm not saying that PA amps are bad for reproducing bass I just suggested that his might not be the best for bass.

    Ryan
     
  11. Patrick Sun

    Patrick Sun Studio Mogul

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    Take Ryan's receiver to Nathan's place, and then compare the bass with Nathan's amp.

    DPL receivers are a different creature compared to DD/dts 5.1 receivers when it comes to bass management.
     
  12. NathanP

    NathanP Supporting Actor

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    Maybe, it's Ryan's amp?

    When he does out from the DD reciever to the sub, he powers the sub with some 100 watt shelf system..

    Wait!

    Maybe, because I'm overloading the subwoofers with 300 per speaker (dual subs in 1 box) when they're only 160 rms?

    Could that be the reason?

    Oh, and about the room..

    Ryan's room is longer, but less wider then mine and our stuff is positioned differently.

    He prefers bookshelf speakers all around (Pardigim Titans) and I have Sony + Kenwood Towers all the way around along with a seperate equipment rack (Ryan's is an entertainment center) and movie posters.

    It could be the room.
     
  13. Ryan Hawke

    Ryan Hawke Agent

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    What amp do you have exactly? Pro amps vary a lot from brand to brand. If you have a QSC PLX or something, then I'm sure you won't have any problems with it. Also, is that 600W number RMS? or peak? Also, I would try and move the sub around the room to different places. I heard of one way to find the optimal place (not sure if it works, but it kinda makes sense in my head). What you do is set the sub in your listening position and then you crawl around on the floor for the place with the best bass. This place will be where you set the sub. Try it out, nothing is lost if it fails! Good luck.

    --Ryan
     
  14. Ryan T

    Ryan T Second Unit

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    Nathan,

    I do not have an entertainment center I have a TV stand and a seperate equipment rack. I will try and bring my amp over to Nathans house next time I visit, and the road gear subwoofers are 80 watts RMS not 160. Also my amp that I used to power your subs is not a "shelf system" it is a stereo amplifier with 100 per channel. I don't know to much about room accoustics but I supopose that or the amp that Nathan is useing is the reason the bass sounds muddy.

    Ryan
     
  15. Bob Christensen

    Bob Christensen Stunt Coordinator

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    Many pro audio amps have built in high and/or low pass filters. Make sure that you have it set right.
     
  16. Patrick Sun

    Patrick Sun Studio Mogul

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    Pro amps may need a higher input level (from the signal from the receiver) to get the proper amplification. The DPL sub-out is probably not copecetic with the P/A input level requirements.

    Thus, I'm thinking it's the DPL receiver that's responsible for the lack of performance.
     
  17. Ryan Schnacke

    Ryan Schnacke Supporting Actor

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    Pat has got a really good point. Digital receivers all tend to have fairly well developed bass management. But the Pro Logic recievers with subwoofer outputs often had some really weird stuff going on. Like crossovers at 200Hz. And possibly sending the bass to both the subwoofer and the main speakers. It would be pretty easy to get a big, bloated hump in the mid-bass region.

    With a DD/DTS receiver, good placement and calibration I'm sure the subs will sound just as good, maybe better than they did at your friend's house, despite using a PA amp.
     
  18. Dan Hine

    Dan Hine Screenwriter

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    Here are a few other things to consider.

     
  19. NathanP

    NathanP Supporting Actor

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  20. BrendanL

    BrendanL Agent

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    I'm late to the discussion but I wanted to chime in. I use a large PA amp to make my Shiva move. Its a Crown CE2000.

    Wow is it mean. I have a madisound swan on the other channel, I'm going to build either another Shiva or a tempest. For high power, there isn't a cheaper way to get there than large external amps. I got it from the woodwind and brasswind, they are largely a mail order band instrument company but they had it for $650 or so.
     

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