Selecting speaker wattage - AVS | Home Theater Discussions And Reviews
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Old 06-23-2007, 09:33 AM - Thread Starter
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The more I read, the more confused I get. Since different writers have opposite views, what is the truth? Should speaker wattage ratings be higher or lower than receiver wattage? For example, with a 100 watt receiver, would I get better sound with 75 watt speakers or 125 watt speakers? Which would be louder for a given volume setting? Which would have less distortion?
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Old 06-23-2007, 09:37 AM
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You should take a different approach. You should go audition speakers that sound good
to you and then buy good amplification to power them, having alot more power than
the speaker ratings isn't a bad thing, in the majority of cases, it's better.



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Old 06-23-2007, 09:47 AM
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Quote:
Originally Posted by thylantyr View Post

You should take a different approach. You should go audition speakers that sound good
to you and then buy good amplification to power them, having alot more power than
the speaker ratings isn't a bad thing, in the majority of cases, it's better.

I agree 100% with these statements. Good Advise.
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Old 06-23-2007, 10:03 AM
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Speaker wattage ratings are nearly meaningless. A speaker may be able to handle a 500 watt peak for a few milliseconds, but it may burn up if you put 75 watts into it for one minute continuously. And the frequency makes a difference. A speaker may handle gobs of power at 700 Hz, but one-tenth as much power at 70 Hz. To make matters worse, sleazier speakers claim "500-watts" when they can't handle nearly that much. (Marketing watts are higher than real watts.) Add to this the tendency of blowing tweeters more often by driving an amp into clipping, and you can see how many variables and marketing lies are involved.

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Old 06-23-2007, 10:12 AM
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Yes, you will probably find that most speakers' continuous wattage ratings are taken at 1khz, which is not indicative of anything except power handling at that particular frequency. Some manufacturers have plots for the entire range, but this is rarely the case. The same is often true for amplifiers, but it varies much less dramatically, especially in the case of decent quality class-d amps.

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Old 06-23-2007, 10:57 AM
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Audition a few sets of speakers within your budget, and try to do so in a room that is similar in size to your room at home. If the speakers are able to play loud enough in that room, then they have the capacity to play loud enough at home. Ask the salesperson what the power rating is on the receiver or amplifier being used, and if possible try to have one used that is within your budget. In any case, when you find some speakers that you like and that can play loud enough, take a look at the power handling and sensitivity ratings (either the store should have a pamphlet, a manual, or you can look on-line). If the speaker is very efficient and you don't play at really loud volumes, any well built receiver will likely do (if the speaker's impedance is 8 ohms).

A rough guide to sensitivity:
< 85 db/W, you will need a lot of power.
< 88 db/W, you will want a lot of power unless you don't play them loud.
~90 db/W, will play loud enough for most people with a mid-priced receiver.
91-95 db/W, most receivers unless room is huge or volume must be really loud.
> 95 db/W, any receiver.

The above does not imply that you should get really efficient speakers and buy a poorly built, off-brand receiver. Distortion will damage almost any speaker. If you have lots of clean power, the speakers can usually have their rated capacity exceeded on short peaks without damage, but if you have a low powered receiver and turn the volume up really high, it will clip (distort) the signal and this will damage your speakers.

So, it's a question of whether a speaker that you like the sound of has the combination of efficiency and power handling to be able to produce the volume levels that you want in your room, and then whether you can afford the amount of power required to achieve that volume level.
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Old 06-23-2007, 01:10 PM
 
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I found this thread on speaker wattage rating at the av123 forum interesting. One of their reps responds to why they don't post wattage ratings for their speakers.

http://av123forum.com/showthread.php?t=22196
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Old 06-23-2007, 02:58 PM - Thread Starter
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Auditioning speakers is a problem. HT-in-a-box systems and Bose speakers are all that are available locally [110 miles]. The Klipsch dealer-finder shows two within 300 miles, but I have no idea which models they have in stock when I get there, even when calling ahead. "Just sold that model this morning" was what I found last time. Have another trip coming up so maybe I'll luck out and find something like the Klipsch RF-10 or RF-51 systems. BTW, my room is 12x22 with an 8ft. window on one side wall; receiver is 7.1x100w Sony. Any suggestions?
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Old 06-23-2007, 03:42 PM
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You should not choose speakers based on the receiver you have. You should choose them based on sound quality, power handling, and sensitivity. You basically want good sound quality, high power handling, and high sensitivity, no matter what your receiver.

You should not look at the power handling of speakers relative to the receiver!!!
It doesn't matter if it is higher or lower than what you receiver can put out, as long as it is as high as possible.

A mistake in thinking that people make goes something like this:
Quote:


Low powered amps clip. Clipping damages speakers. Therefore, it is always better to have the amp wattage greater than the speaker wattage to avoid clipping and speaker damage.

Here is why this is wrong:
Low powered amps only clip because people turn them up too loud. People turn up low powered amps too loud because they want a volume level that their amp can not deliver. Assuming an equal sensitivity, no matter what speaker is being used, the maximum volume will always be the same. Because of this, no matter what speaker is being used (assuming equal sensitivity) people will always turn the low powered amp up to the point of clipping. Speakers with a lower power handling will be more easily damaged by this than speakers with a higher power handling, so therefore it is better to get speakers with a greater power handling, even if this is greater than the wattage of the receiver!

Here is the trick: the sensitivity of speakers is not always the same. Speakers with a lower sensitivity tend to have higher power handling (it takes more power to move the cone, so the speaker can handle more wattage), and speakers with a higher sensitivity tend to have lower power handling (1 watt really pushes the speaker cone hard, so 100 watts is likely to push it too hard). So, lets say you get a speaker with very high sensitivity. The low powered amp would be able to drive it loud enough with the volume knob only part way turned, so the amp wouldn't clip. The power handling would also be low, so other people would instantly think, "it hasn't blown because the power handling of the speaker is lower than the receiver," which is wrong. It is the fact that you have kept the volume knob low which has saved the speaker from blowing, and that is a result of the high sensitivity, not the low power rating. If you were to turn the volume knob all the way up (as you would with a speaker with higher power handling, but lower sensitivity) the speaker would blow.

When looking for speakers for a low powered amp, sensitivity is more important than power handing. This way it will get to the volume you like, but won't tempt you to turn the amp up too loud.

It is not clipping which damages speakers, it is the volume knob being too set too high.

EDIT: The best way too choose speakers for a low powered amp is to listen to speakers that sound good and get much louder than you will ever need them to get, and then choose the speakers with the highest sensitivity, and from those (if you have a choice) pick the speakers with the highest power handling. After that, NEVER turn the amp up past a particular volume which you have determined is much lower than the volume you auditioned them at. This will give you speakers that will be loud enough, but less likely to blow.

For a high powered amp, sensitivity is not as important. Assuming an infinitely high powered amp, you would choose speakers by narrowing it down to speakers that sound excellent, narrowing it down further to the speakers with the highest power handling, and then (if you have a choice) choosing the speakers with the highest sensitivity. This will give you speakers that sound great, can get very loud, and are very unlikely to blow.

If you can't audition, you will be sacrificing sound quality. In this case, just look first for speakers that have high sensitivity ratings, and then choose among those by the power handling.

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Old 06-23-2007, 04:36 PM
 
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If finding speakers to audition locally is aproblem, than I would seriously look at the Internet direct companies. Several have no risk trials where you can try them for 30 days and they will even refund shipping charges. For example, Aperion does this:

http://www.aperionaudio.com/home.aspx

********** offers this on their bookshelf speakers. Here is an example:

http://www.**********/products_produc...s&product=82.1

There are a few others as well.
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Old 06-23-2007, 04:54 PM - Thread Starter
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Quote:
Originally Posted by greeniguana00 View Post

If you can't audition, you will be sacrificing sound quality. In this case, just look first for speakers that have high sensitivity ratings, and then choose among those by the power handling.

The center channel Klipsch speakers I have been considering have sensitivity ratings from 95 to 98. Is there a real difference between those numbers?
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Old 06-23-2007, 08:31 PM
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There is a large difference between 95dB sensitivity @ 1w 1m and 98dB sensitivity @ 1w 1m.

Say you have about 20 watts powering the 98dB @ 1w 1m speaker, and it is at a decent volume level. For the 95dB @ 1w 1m speaker, you would need 40 watts to get the same power.

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Old 06-24-2007, 06:38 PM - Thread Starter
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I find that most packaged systems have a center channel speaker with higher sensitivity and wattage than the voice-matched front speakers. I know the receiver can ballance them for volume, but what is the reasoning for this? I would think that being the same would be best.
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Old 06-24-2007, 06:59 PM
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I've also seen the opposite, with centre speakers having a lower sensitivity. This happens because it is most often the woofer that determines the overall sensitivity of a speaker; the woofer is usually the least sensitive driver. To get the midrange and tweeter to match, often resistors are placed in the signal path to lower their effective sensitivity. Usually, when you make a speaker cabinet larger the sensitivity goes up, but since centre speakers are often placed in smaller cabinets, the sensitivity will often be lower (if they use the same woofer as the main speakers). If the centre uses a smaller woofer, or a mid-bass driver, this may be a more efficient driver than the woofer in the main speakers, and so it will not be necessary to attenuate the midrange (if present) and tweeter as much, if at all. In such a case, the centre speaker will have a higher sensitivity, despite having the same tweeter and possibly midrange as well.
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