Pro audio amps for Home theater?

Discussion in 'Archived Threads 2001-2004' started by Billy Gun, Nov 25, 2001.

  1. Billy Gun

    Billy Gun Stunt Coordinator

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    I was wondering if pro-audio amps could be used in a home theater setup?

    What are the differences?
     
  2. SamRoza

    SamRoza Stunt Coordinator

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  3. Dan Hine

    Dan Hine Screenwriter

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    I agree! There are many amps used for pro audio that are really really good. QSC, Crown, Crest etc... And they aren't that expensive. I priced 3 QSC RMX 850's (which would give me 6 channels of 200watts) for only $900. And I've heard these amps myself and they sound great to me. Some complain about fan noise but I can't hear them. However, coming from the pro-audio field perhaps I'm just used to it?

    To agree with what Sam said, make sure if you choose one that it has compatible connectors. If you don't have XLR and that is all the amp has then you will not be better off. Most amps though have 1/4" inputs that accept balanced AND unbalanced so a simple RCA-1/4" cable would work.

    Are you considering buying an amp that is typically used for pro-audio? If so which one?

    Curious,

    Dan Hine
     
  4. Danny Owens

    Danny Owens Agent

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  5. Dan Hine

    Dan Hine Screenwriter

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    Danny,
    Yes but....[​IMG]
    Then you have one more thing that you have to buy and wire up and you don't gain much (notice I said "much" b/c I do kind of agree with you) since the signal coming from the pre-amp is an unbalanced signal to begin with. Since you can get GREAT amps that have 1/4" inputs I think that is just a better way to go.
    Dan Hine
     
  6. Danny Owens

    Danny Owens Agent

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    Dan,
    I see and understand your point. In fact, I was adding the second paragraph in my post while you were posting your reply. The problem is that the consumer level (- 10 dbv ) is in my opinion way to low to wake up the input stage of the amp. It is much (notice I said much [​IMG] ) better all around if the signal is at +4 dbv. Just because a signal is unbalanced doesn't mean it is level matched. Balanced simply means that the signal has both the signal, and the inverted signal. The inverted signal is inverted yet again at the input to the balanced component and summed with the + signal. The common noise on both lines is cancelled at the inversion. Un-balanced is just a + signal and a ground. Even then, the pro audio unbalanced level is above that of the consumer level.
    I'm not trying to talk down to you because you probably already know this stuff; I'm just covering it to insure that we are all agreeing or disagreeing on the same base of information.
    Danny
     
  7. SamRoza

    SamRoza Stunt Coordinator

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    I respectfully accept your disagreement. [​IMG]
    And in fact, I agree with you, but I assume that most consumers won't know the ins and outs of pro audio equipment, impedance matching, and input matching, so I mentioned it.
    Sam
     
  8. Dan Hine

    Dan Hine Screenwriter

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    Danny,

    I know you're not talking down to me. And in fact I appreciate your input. I did "know" what you are talking about but honestly never really put it all together. Your points have been very valid and I appreciate them! Thanks.

    Dan Hine
     
  9. Vince Maskeeper

    Vince Maskeeper Producer

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    Well, Billy, since the other two resident pro audio soundguys have chimed in, I geuss I should too.
    Many people already use pro style amplifiers for their HT subwoofers. If you check the Hardware Archive, there are a few archived posts about budget amplification from the professional arena. Most people will shy away from the Pro stuff, because it is pretty expensive.
    http://www.hometheaterforum.com/htfo...threadid=26716
    http://www.hometheaterforum.com/htfo...threadid=26718
    http://www.hometheaterforum.com/htfo...threadid=26717
    http://www.hometheaterforum.com/htfo...threadid=26711
    I have personally used QSC Powerlights on my SVS sub, and have gotten good results. In addition, I have a set of Ashly FTX-2001 amps (great amps, highly underrated in my opinion) that I will probably use in my HT system, once I have the cash to pick up a pre/pro I'm happy with (I had a Lexicon MC-1 on loan for a while, now I can't settle for anything less!)
    As Danny said, you do have an issue of input voltages to contend with- but the majority of home receivers I've played with put out PLENTY of juice to get inputs on a pro amp hopping. Again, I suggest a trip to the hardware archives, there was a whole thread discussing (in "dummies terms") the whole issues of -10db vs. +4db, input sensitivites and what they mean.
    As Danny suggested- you shouldn't be running your outputs at +10 or anything (if you have to crank beyond +5 to get ref level out of a decent amp, then you'll need some help- line level shifter like the Balance Buddy).
    -Vince
    PS: Hey Dan, I changed the R-H in my quote from your sig to Renkus-Heinz, for the uninitiated. [​IMG]
     
  10. Tim Kilbride

    Tim Kilbride Stunt Coordinator

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    I know this is probably going to put me in the doghouse here...but here goes. First of all, just to state a fact, I own a Pro Audio Company in New Orleans w/ warehouses in Metairie, Lafayette, and Alexandria, La. I own over 50 EAW KF850 boxes w/ SB1000 Subs and a 70 box Klipsch KP-600 Pro System. I use QSC Amps exclusively in my company.

    We also do about 2-3 large home theater installs a year. We have been using QSC and Carver amplifiers on installations for years. The reason being is that we have ZERO service calls on these units. As for the input (-10/+4) sensitivity argument...thats null and void. You can order most pro amps with different input sensitivities set at the factory, or in most QSC's you can even set it in the field.

    I personally use 3 Carver PM300's in my home theater. They are small (1 rack space), use convection cooling (no fan noise), and offer 1/4", XLR, and terminal inputs on both channels. They are more than what 90% of home theaters would ever use. I feel any and all amps that are used should be chosen by listening to them. They do sound different. The Carvers sound completely different than the QSC's. It all personal taste. If you like the way it sounds, buy it.

    A quality installation, with the proper setup should last and serve you well for years. If you're a gadget type and want the latest greatest, then upgrade, please!!! I love it when my clients upgrade...I get some great deals on equipment that comes back to the warehouse...

    Respectfully Submitted,

    Tim Kilbride
     
  11. Dan Hine

    Dan Hine Screenwriter

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    Tim,

    You don't own Pace do you? Just curious.

    Dan Hine
     
  12. Billy Gun

    Billy Gun Stunt Coordinator

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    OK....

    Here is some more backround on where my question is coming from:

    I am using Klipsch KLF-30's (102 db effecient.) for my left and right channels.

    I am powering them with an Adcom 555 two, which is 200 watts x 2, but I don't like the "Hiss" I hear during completely quiet passeges in movies.

    I love the speakers, so I'm considering using something else to power them so the hiss hopefully becomes inaudible.

    Please advise........
     
  13. Tim Kilbride

    Tim Kilbride Stunt Coordinator

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    Dan,

    No, the company is The Sound Source. We are also the exclusive Sound/Lighting/AV Provider to the New Orleans Convention Center...

    Billy,

    Unplug the inputs to you amp, with the amp set at the normal levels...if the hiss goes away, the hiss is coming from another component in your system...if the hiss continues, its your amp. In my experience, the Adcom is a very stable and quiet unit. I would be curious to see if the hiss is coming from the amp.

    Tim
     
  14. Danny Owens

    Danny Owens Agent

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    Tim said:
     
  15. Tim Kilbride

    Tim Kilbride Stunt Coordinator

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    The reason the amp manufacturers offer different inputs is because none of the processing manufacturers (BSS, Klark Tek, Yamaha, XTA) can seem to agree on a standard. Some use Pin 3 hot, some Pin 2...some use .775v = 0db some use 1v = 0db, and so on. In pro audio most line level sources are -10db/.775Vrms, balanced (using summing op amps or transformers to achieve a positive signal). So sending consumer equipment (preamps, etc.) into pro amps will not raise the noise floor, if anything you won't be able to turn your preamp over "4" on the volume control. The preamps are mostly +4/unbalanced. Therefore, if anything, the mismatch would be too much signal to the amps. The correct wiring would be the + wired to the high side of the amp, the - wired to the neg side and ground of the amp. Some of the high end preamps do offer balanced outputs (XLR/-10db), which of course would be no issue whatsoever. I don't personally know of many transformers or magic black boxes that change unbalanced +4db to balanced -10db...you can get +4db to -60db (mic level), which incidentally is not enough signal for the amps. We could go on indefinitely...I do respect your opinion and understand your valid points...I just feel that the consumer manufacturers have a lot more "Smoke and Mirrors" to their marketing plans. The jist of the matter is that 99% of the consumer equipment outputs more than enough signal for 99% of the pro amps...

    Thanks again,

    Tim K.
     
  16. Vince Maskeeper

    Vince Maskeeper Producer

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  17. Gregg Loewen

    Gregg Loewen Video Standards Instructor, THX Ltd.
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    Im currently trying out some QSC DCA amps. I like them alot. 215 wpc x 6, 350 wpc x 2 for the mains, and 1200 wpc for the subs. My Sonodome is rocking!!

    Issues for me right now are:

    1. Fan noise (not really an issue as the amps are in a different room)

    2. A little bit of a grounding hum. I just got some Furman Line Conditioners today, and will be running some new 110 20 amp power lines tomorrow. Hopefully this will fix this problem.

    Gregg

    Almost in HT Nirvana...
     
  18. Gregg Loewen

    Gregg Loewen Video Standards Instructor, THX Ltd.
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    LOL, I just saw Vince's last post.

    Actually Im using a Sony 9ES DD processor for now until the new Outlaw 950 is released (hurry up Outlaw!!). I am well with in my limits for my individual line levels.

    Gregg
     
  19. John A. Gordon

    John A. Gordon Stunt Coordinator

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    Gregg,

    I'm curious about the hum you have. Do you have cable hooked up to your system? If so, disconnect the cable and see if it goes away.

    As for the topic of this thread. Yes, pro amps can be used in a home theater--and by searching the forum, you will find it is very common indeed--with great results. I have 3 pro amps in my system--QSC DCA amps.

    Many good things have been said. But I lean the same way as Vince, in that with my experience, hooking up a receiver or pre-amp/processor with pro amps, have never been an issue with regard to getting enough volume. A benefit you have with pro amps are the gain controls. With proper set-up/calibration, you would be hard pressed to ever clip the amp.

    But as I've said before, and for those who are not aware, gain controls are not volume controls. Regardless of where the gains are set, you still have the capability of the full power output of the amp. By having the gains, let say set half way, does not mean you are only getting half the power. You still have full power capability.

    By all means, if you want a pro amp in your system, use one. It is always best to purchase gear that will make you happy.
     
  20. Billy Gun

    Billy Gun Stunt Coordinator

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    Which QSC models are great for home theater?

    Are there any other makes/model #'s that are great for theater applications?

    The "Level" thing has me confused???

    Can someone explain this to me in lamen's terms?

    I'm afraid to make a purchase and end up with exessive noise/hiss!!

    Please advise?
     

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