speakers efficiency

Myraj points out that I wasn't clear in something I said.

Let me try re-writing the second to last paragraph from my post above:

"Now make sure that the manufacturer is really claiming 89 dB/1 watt EFFICIENCY. If it's a 4-ohm speaker, the manufacturer may be claiming 89 dB/2.83 volts SENSITIVITY. While 2.83 volts into 8 ohms is 1 watt, 2.83 volts into 4 ohms is actually 2 watts, so in the latter case the speaker would actually be only 86 dB/1 watt efficient even though it's 2.83 volt sensitivity is 89 dB."

Hope that helps.

Duke

See http://www.welbornelabs.com/recomendspeaks.htm

Scroll down to end of Recommended Speakers & before Raw Drivers.

Well I just wanted to point out that to have good dynamic range is essential to a good system. while you may only listen at an average 92 dbs but peaks could be much higher than this (especially on a well built system) this is the area where your amp could run into some trouble on a hard to drive speaker. These peaks could also (most probably) cold be at a frequency where impedence is also high, which is a real strain on the amp. For example using the above info (4 watt = 93db @ 1 meter) this figure probably means 90 db at listening position so in reality to listen at 93db average at listening postion you will need 8watts (with 8 ohm speakers). But for the amp to be able to handle dynamic peaks there needs to be headroom. If the peak is 12db the amp must cleanly without clipping put out 128 watts (8@93, 16@96, 32@99, 64@101, 128@103). Also factor in that this peak could be at frequency that the speakers impedence has dropped to 4 ohms or less even on a 8 ohm speaker and you need twice the 128watts or 256 watts@4ohms to cleanly play your wonderful uncompressed audio material at the average of 93 db at the listening postion. Of course good amps can also double in power as impedence goes from 8 to 4 ohms.

think i read somewhere that JA at Sterophile's database of past measurements indicate the avg sensitivity of the speakers evaluated by the mag has been 87

Duke,

You seam to know a bit about pro audio as well. Do you have any information on absorptive properties of crowds and rooms with large volume? I know that Master Handbook has some info on this but I have misplaced my copy.

Thanks!