Wattage - Home Theater Forum and Systems - HomeTheaterShack.com

 
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post #1 of 7 Old 10-06-14, 08:56 PM Thread Starter
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Wattage

Hello all,

Looking at the specs for my Q300 bookshelves on amp requirements it says 15-120 watts. On the towers the Q700 it's 15-150. How do 3 additional drivers only need 30 more watts? Seems like it should be more
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post #2 of 7 Old 10-06-14, 09:27 PM
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Re: Wattage

Rarely do I put much faith in the "required power" of speakers. Most speakers will reach full output long before 100wats is even reached because audio signals are dynamic not a fixed frequency. What you want to make sure of is that whatever you use to power them has enough reserve to reach thos dynamics without distortion so having more is better than not enough. You run a higher risk of damaging speakers with distortion because of under power than you do by over driving them with too much.

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post #3 of 7 Old 10-07-14, 03:26 AM Thread Starter
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Re: Wattage

Quote:
tonyvdb wrote: View Post
Rarely do I put much faith in the "required power" of speakers. Most speakers will reach full output long before 100wats is even reached because audio signals are dynamic not a fixed frequency. What you want to make sure of is that whatever you use to power them has enough reserve to reach thos dynamics without distortion so having more is better than not enough. You run a higher risk of damaging speakers with distortion because of under power than you do by over driving them with too much.
Thanks. My AVR is the only thing powering them. It's rated at 130 per channel. With all channels driven it measures at 120. Considering the Emotiva UPA 700.
What factors in amp specs are most significant? When I see the higher end McIntosh amps that power massive setups with only a few watts it confuses me. Is it current? At a demo the amp was only at 3 or 4 watts powering 2 10k towers
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post #4 of 7 Old 10-07-14, 06:37 AM
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Re: Wattage

The minimum power of the amp that you need is determined by the efficiency of your speakers, how far away from them you sit, and how loud you want them to be. The maximum power of the amp should be limited by the maximum power that the tweeter circuits in the speaker can dissipate without being damaged. Buying over-powered amps is not money well spent: unused power is unused. It does nothing to make speakers "sing". That's just a myth, encouraged by expectation bias and placebo effects. Those effects are real enough. Studies have shown (using MRI scans) that a belief that something is better actually does make us feel better about it.

Harman/Crown provides a calculator which can help you to determine how much power is appropriate. See http://www.crownaudio.com/elect-pwr-req.htm

Don't forget that the advertised power of the amps in a receiver is never correct when all channels are driven The total typically is less than half of the rated power of the receiver's shared power supply, although Pioneer's receivers with digital amps can use a much larger fraction.

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post #5 of 7 Old 10-07-14, 08:24 AM
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Re: Wattage

The quoted or recommended power that's specified on speakers basically says that you need an amp rated at least this many watts for this speaker to satisfactorily work - i.e., be driven with minimal distortion. What this means is if you use a smaller amp, you won't get any great sound output from the speaker and you will end up racking up the volume causing the amp to clip and distort. The result is bad sound and possibility of tweeter damage due to the clipped signal being fed to the speaker. It might seem counter-intuitive but an under-powered amp that is clipping will produce harmonics that have enough power to heat up the tweeter's voice coil and possibly damage it. (http://sound.westhost.com/tweeters.htm). This is not to say that a high power amp will do no harm - it will do it much more efficiently and spectacularly...but chances of it being driven to clipping are much less as compared to a smaller amp.
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post #6 of 7 Old 10-07-14, 10:03 AM
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Re: Wattage

I agree with Tony. More is better than not enough. Now that doesn't mean you need a 400w amp it just means getting an amp with around 200w a channel should work well with your speakers. Also if you get an amp with a gain control you need to set it up correctly. You can find all the info you need about gain control in this thread that Wayne created. It has outstanding info. Check it here.... http://www.hometheatershack.com/foru...ontrol+pro+amp

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post #7 of 7 Old 10-12-14, 07:50 PM Thread Starter
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Re: Wattage

Thanks guys. Surprisingly my AVR that's rated at 130 per channel at 8 ohms provides 120-125 watts continously per the test bench study by stereophile.com It's always the last page of each product but is the only place I've seen the actual watts per channel with all driven & not the highly inaccurate specs that tend to leave out "with only 2 channels driven" which they're allowed to state them at due to some law (loophole) from 1975.

The only thing I'm not understanding is determining quality of the watts. Beyond the THD %, class D, Class AB, Class A, etc. It probably seems I'm over analysing this & probably am.

Thanks fellas
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