Power Setup and equipment for home theater build

Discussion in 'AV Receivers' started by Highplainsdakota, Jul 5, 2014.

  1. Highplainsdakota

    Highplainsdakota Stunt Coordinator

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    Hi all,

    I'm building a new house and installing a home theater. I need some help with the "basics" of more complicated power equipment to drive my speakers. (more than just "buy a receiver with X watts / channel"). Thanks to this forum I've decided on my low end (Infinite baffle with 4 x 18" Fi audio IB318 in two manifolds entering just below my projection screen). I'm in the process of picking out some speakers in another thread (building floorstanding speakers into the wall, am I crazy).

    Assumptions:
    I currently have an Integra DTR 50.1 (130 watts per channel 7.2)
    Assume the following speakers need to be driven:

    Floor standing left/right loudspeakers with suitable amp power range 15-350 watts, maximum input power 230 watts, impedance (compatible with 8 ohms)

    Center channel: 15-300 watts suitable, 210 watts maximum input,

    Rear surrounds: 15-180 watts suitable, 130 watts maximum input

    Direct left/right surrounds: 15-160 watts suitable, 110 watts maximum input

    4 x 18" subwoofers, single 4 ohm, RMS 550 W @ 20 Hz


    So here are the questions:

    I was going to use a Behringer inuke 3000DSP two channel. (1500W into 2 ohms per channel) My IB sub system needs 1100 watts per manifold (2 x 4 ohm subs in parallel = 2 ohms; 550 RMS x 2 = 1100 W). Run one channel to each. Is this the right choice?

    What is the deal with speaker "Maximum input" vs "Suitable Amplifier Power Range"?

    If my receiver is 130 watts per channel will it under power the floor standing L/R and over power / possibly ruin the left/right surrounds? Does the receiver adjust automatically or based on the channel outputs?

    What is a pre-amp, vs receiver, vs amp?

    Does it matter from which source my speakers receiver their wattage? will they sound different?

    Should I buy a dedicated amp for my front L/R? maybe the center channel as well?

    I'll hold off on the other questions until I get this figured out... Thanks, and bring it on.
     
  2. schan1269

    schan1269 HTF Expert
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    *The only two specs that matter in speakers...1. Ohm load2. Efficiency The efficiency of a given speaker has more to do with overall volume than the amount of power.
     
  3. Highplainsdakota

    Highplainsdakota Stunt Coordinator

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    Ohms and wiring I can figure out. I don't really understand the relationship between sensitivity, watts max, and watts suitable. The loudspeakers in question have a sensitivity rating of 92 dB (room), 89 dB (anechoic, whatever that means)

    So they would be highly efficient? That means louder with the same amount of power?

    If I turn my amp up and I'm running out of watts, but the speaker can handle it, what happens?
     
  4. schan1269

    schan1269 HTF Expert
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    You need to understand power and SPL doubling.Run out of power? Clipping happens.92 is reasonably efficient. (Anechoic means in a chamber meant to absorb backwave) So...BD is mastered to have 20db of headroom. Most people listen with @ 105db peaks.So, that means 85-105.To produce 85 DB, a 92 DB speaker blisters along at 1/4 of one watt*.The 105db blisters along at roughly 20*.Every 3db is 2x power.Max/suitable means absolutely nothing, at all.Is this 200 watts at 1kz? 20Hz? 20Khz? If you don't know, they don't say...it is useless information.*That is at 1 meter, or 3 feet. Every meter reduces volume 3db. So 3 meters at your seat means you need 4 watts to produce 92...So that 85-105, at 3 meters is 1 watt and 80-ish.
     
  5. Highplainsdakota

    Highplainsdakota Stunt Coordinator

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    So paying $200 for that 10 extra watts per channel is totally ridiculous. That would buy you about 5" of listening distance...
     
  6. Highplainsdakota

    Highplainsdakota Stunt Coordinator

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    So the Fi audio IB318 subs quote Spl: 89.1 dB 1W/1m. That would mean 32 W in order to achieve 104 dB @ 1 meter, and 256 W at 4 meters.

    If I drive two subs, each at 1 W (2 different channels) I would get 92.1 dB from the manifold at 1 meter?


    This also means my primary listening position at 12-13' would require ~160 watts in order to obtain those peak 105 dB, right?

    I guess I'm asking you to check my work...
     
  7. schan1269

    schan1269 HTF Expert
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    Subwoofers aren't "that exact" like the rest of the speakers. Properly designed, they only operate below 80hz (most .1 material is black hole above 120hz).The f3 and f10 are critical. The f3 is the point the enclosure creates a frequency roll off of- 3. F10...is 10db.So if your chosen enclosure (this case...IB) has a f3 of 28 and a f10 of 20...If it takes 1 watt to create 92db at 50hz, it takes 10 to create 20hz.So then 102 DB needs 10 for 50hz....100 for 20hz.
     
  8. schan1269

    schan1269 HTF Expert
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    So, in other words...30Hz is the baseline. Most $500-ish subs packing 400-600 watts have no issues hitting 30hz.Every 1hz, down to a theoretical max of 16hz, requires...roughly, another 200 watts.
     
  9. Highplainsdakota

    Highplainsdakota Stunt Coordinator

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    Ok,

    So back to floor standing towers. Now that we have discussed power from the amp, let's talk about the effect on the speaker with multiple drivers. What's the difference between a multi driver 3-way speaker rated at 100 watts, and a similar speaker with better/more drivers rated at 300 watts if they both receive a signal from a receiver giving 130 watts per channel.

    What happens from low to high gain?
     
  10. schan1269

    schan1269 HTF Expert
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    Forget power ratings. You've been told, numerous times already, they are meaningless. From now on I'm ignoring anything to do with it.But for sake here, If both have the same efficiency (do they? Again...that matters 1000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000x more)100 vs 300 means the 300 can receive enough power to be 4db louder.Big fucking deal. You got 130. And, again, you DO NOT HAVE 130 x 5.
     
  11. Highplainsdakota

    Highplainsdakota Stunt Coordinator

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    You keep saying "If you want more power". I'd like to get that figured out before I flush $K down the toilet buying something that's less than what I want/need/should have had, or ruin my speakers because of AMP clipping (not sure how that affects speakers then). HOW DO I KNOW I WANT MORE POWER? If all the numbers mean shit except for sensitivity, I'm guessing you're saying volume (SPL) is the only difference.

    Turn my receiver up until the amp clipps before I get to your desired volume GIVEN THE FACT the speakers have high enough sensitivity to play that loud (Then I buy another amp and use the pre-outs on my receiver for that channel/channels).

    OR

    Turn my receiver up until my speakers max out because I have plenty of power. (I assume I'd hear that, probably like a metal on metal bottoming out sound?)

    So what you're saying or suggesting, is that I wait until it's all hooked up and test it out. If my receiver clips before I get to my maximum desired listening volume then I go buy an amp to give additional power to the speakers.
     
  12. schan1269

    schan1269 HTF Expert
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    Exactly.For there to be a noticeable volume increase from what you have, you have to triple to quadruple your power.So, let's say the Integra you have pumps out 80x5.That means your amp has to be 250x5-300x5 to gain 4 to 6 more DB.So, once you are at your max(If you get there)...Every 3 more DB is...16032064012802560
     
  13. schan1269

    schan1269 HTF Expert
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    That is also why buying a dedicated 2 channel amp is worth it. Your AVR probably can do 130x3. So, if you bought a 150x2 amp...If 690 isn't enough...you are just trying to go deaf.
     
  14. Highplainsdakota

    Highplainsdakota Stunt Coordinator

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    I assume most people who are running pre-out to a sub and front L/R get two separate amps to do this?
     
  15. JohnRice

    JohnRice Lead Actor

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    Subs are virtually always from a pre-out to a powered sub or to a DIY type of sub with an external amp like you are thinking of making. Only cheap cheapest, garbage all-in-one systems have power for a sub built into them, as far as I am familiar with. And yes, they are typically different amps. Since subs require a LOT of power and aren't full range, you can use a "lesser" but more powerful amp for them. As far as the L&R pre-outs, pre-outs MUST go to an amp. That could be a powered speaker or an external amp, but pre-outs are line level and can't drive a speaker.

    I don't plan to participate in this thread beyond this one reply. I just wanted to say a couple of things. You were talking about finding the clipping point of your receiver. I wouldn't do that. When an amp clips, it can sometimes destroy the voice coils in your speakers almost instantly. Sometimes not, but it can cause damage. Believe it or not, it isn't always obviously audible either.

    Personally, I have the philosophy that, in a sense, you can't have too much power. There's a limit, like if you have 100dB sensitivity speakers, you don't need 300 wpc amps. But in my experience, an amp can't just be reduced to a single number, their rated power output. Sam and I disagree on that and I'm not getting into that pissing match again. I do agree with the idea of using an external amp for at least the L&R, and center if it's feasible. It takes a significant load off the receiver. I also observe that higher quality amps can make an improvement in the reproduced sound, but if and how much depends on so many other things as well. From the other electronics to the speakers. You seem to want to not worry about the capabilities of your system. There are many good 2 and 3 channel, 200 wpc amps out there. You might just want to go for one of them.
     
  16. Highplainsdakota

    Highplainsdakota Stunt Coordinator

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    To explain my obsession over the power issue: I bought my Integra 50.1 amp 4 years ago thinking I wouldn't ever need more power than that. Now with all the wireless additions, HDMI 2, and 4K rolling out right when I'm finally designing a theater area, it's looking like I may need to get a newer model receiver. I just want to make DAMN sure I don't end up with two amps with major shortcommings. From the sound of it, I probably won't need another receiver in terms of power unless I want crazy volume (much more than a home theater would need). That is steering me away from just adding an amp to my front L/R (maybe center). According to what I've learned from Sam, spending another $600 for the same receiver with a measly 10 extra watts / ch (rated, which isn't nearly true apparently either) is stupid.

    Options:

    Deal with what I have (receiver programs/capabilities), add an amp if I REALLY need more volume which also may future proof my power needs.

    Buy a new receiver for the capabilities, and consider a lesser model to save a few $, spending that on an amp for the same reasons above.

    Spend all remaining budget on quality (highly sensitive) speakers and room treatments.
     
  17. Highplainsdakota

    Highplainsdakota Stunt Coordinator

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    John, thanks for the info and reply. I'm really getting it narrowed down at this point. Just looked for amps and some are quite pricey in the $5-6K range. Seems like a long run for a short slide. I won't be "Looking" for the clip point, but I don't want to reach it accidentally either. From the sound of things I probably won't get there even playing music quite loudly.
     
  18. JohnRice

    JohnRice Lead Actor

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    You need to stop using the terms "Amp" and "Receiver" interchangeably. They aren't the same thing.

    Surround Receivers and Pre-Amps become outdated. Amps (as in Power Amps) don't. It's common to invest in a good, powerful amp for your main speakers and keep it through several receivers. The only requirement is that the receivers need to have pre-outs for the power amp.

    Yes, spending an additional $600 just to get an additional 10 wpc is a complete waste of money. Of course, in the real world, spending an additional $600 on a receiver will typically get benefits beyond the 10 watts. The 10 watts itself will make no difference. However, spending money on a higher quality, equally rated, external amp might give benefits. This is where the argument always starts.

    Just as an example. I used the same external amp for 20 years to power my L&R. That went through different systems including receivers and separates. Having that amp took the power output variable out of the factor when I was considering receivers.
     
  19. JohnRice

    JohnRice Lead Actor

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    You don't have to spend anywhere near that much. I have a lot of Emotiva, and you can get a 3 channel, 200 wpc amp for around $700. Look also at Outlaw and Adcom. There are dozens of others.
     
  20. JohnRice

    JohnRice Lead Actor

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