OK Where are the Pro's? got a ? for you

PolkinHarley

Ok I was reading that a -3db difference in speaker Efficiency
needed double the power to produce the same SPL readings..

Now giving that this is the case wouldn't there be a Big Issue when choosing speakers for a HT system?

example of why I ask is my RTi12's and CSi5 is rated at 90db Efficiency..
then the RTi4's and FXi5's are rated 89db, Thus to me these should need a little more power??

the way I see it a -1db diff in the Efficiency of speakers would need 1/3 more power to be eqaul.
so with a hundred watt system you would need a extra 33 watts going to the 89db speakers then the 90db to make the SPL reading the same for the both..

Does this sound right to you pro's?

gatemplin

Theoretically yes. But wattage ratings ( and possibly efficiency ratings?) are often inflated and almost no one listens to their amp and speakers maxed out. BTW I'm not a pro so I could be wrong, just tryin to help.

wlrandall

Those are measurements made at one meter in a special test cell (anechoic chamber). Your actual in-room response will probably differ a lot due to the increased distance, room acoustics and a realistic amount of power applied.

weavercr

one db is not that much of a difference, but RTi55 91db vs KLF-30 102 db is night and day a/b'ed off of same amp.

3 watts to the Klf-30 will need 60 watts to the RTi 55 for the same spl level.

Tour2ma

Again, no pro here, but a couple comments...

You are correct in that the power requirements will be slightly different based on the difference in speaker efficiency, but as pointed out above other factors will impact each channel's power demand. For the same source signal, e.g., calibration tone, the distance to your listening position leads the way.

Say your mains are on the short wall of a 12 x 24' room. If your listening position is mid-room, then while the mains and rears are equidistant to you, the side-surrounds will be around half as far away. The sides' power demands will then be roughly 1/4th that of the mains/ rears. Calibration with a good test DVD and SPL meter addresses all set-up inequities.

As gatemplin ponted out, don't fixate on the max output of your AVR. Calibrating at a typical level of 85 dB means the maximum your speakers will be asking for only a couple watts per ch.

PolkinHarley

Thanks to you all for the input on this, sometimes with all there is on the market it can be a puzzle..
I do not get into to much of the techno stuff but I was wondering on this one after reading some old posts..

Thanks again!

Happy Holidays

Dr. Spec

Originally posted by Tour2ma
Calibrating at a typical level of 85 dB...

This is the key. Balance all the channels with an SPL meter and you will correct for the differences that disparate efficiencies and varying speaker distances have created in your system.