Would appreciate if someone could explain the meaning and/or difference between the two frequency response specs listed on the Axiom Tower Spec. Sheet (i.e., M-60's: Freq. Resp. +/- 3db (Hz) 37-22K, and Freq. Resp. +3db/-9db (Hz) 27-22k).

Thanks.

that means that if you are listening at say 90 dB, the frequency response would be down to 37hz up to 22 khz, with a variation of + or - 3 dB (so between 87 and 93).

the response would be down to 27 hz and up to 22 khz between 83 and 93 dB

correct me if i am wrong, but i think this is right.

Joe, Ian or Alan would probably have to describe the exact conditions under which Axiom made the measurements, but in general the plus or minus 3 db would indicate that from whatever frequency happened to measure as a high point(say 800hz)that all the other frequencies from 37hz to 22Khz fell no more than 6 db below that( therefore making a +/- 3 db "window"). Almost always it would be the lowest frequency(37hz)where the response would be 6db down. The additional +3/-9 measurement would indicate that at 27hz response was down an additional 6db from what it was at 37hz, i.e. a total drop of 12db from the high point.

Bear in mind that these measurements were most likely made under anechoic conditions and that the room gain when listening in an average room would boost the bass response significantly.

JohnK is pretty close here to how it works. The starting point though is the average db output across the frequency range above which point the low frequencies have reached there full output. This means that the +3db point may never be reached in the actual amplitude response of the speaker. The -3db point will always be achieved because of the drop off in the bass response above the low end of the specified window of 20Hz to 20kHz. Good bass from a speaker is usually achieved not by how low a frequency it can reproduce within the 3db range but rather by how steep the roll off is below the -3db measurement point. The -9db specification gives us a look at this roll off. Considering JohnK's point about the room affects on anechoic measured specifications, the roll off becomes even more important in achieving low bass response. In other words the room will not boost non-existent frequencies.

okay, i was REALLY wrong..

that's why i'm no scientist!

Thanks for the info Ian and JohnK. You too Ravi...nothing ventured, nothing gained!

Cheers.