[Todd A.]

I'm about to use the ACI Excel setup sheet to get my stereo Force subs dialed in, and I'm ashamed to admit that I'm not quite clear on the process. The spreadsheet shows two SPL levels in each frequency range - measured, and compensated. A 70 Db measurement placed in all measured frequencies, (as the spreadsheet is originally supplied by ACI), results in a decidedly upswept graph in the lower frequency range. I would expect that my objective would be to create as "flat" a response curve as possible in my room, but such would require steadily diminishing output levels below 60 Hz.

So what's the objective here? Even SPL output levels at all frequencies, (or as close as I am able to achieve in my room), or a flat graph of "compensated" output?

Thanks,
Todd

[Harry P]

Todd, I think that graph compensates for the known error of the Radio Shack meter. Your goal is to get as close to a flat line as possible. If you use something other than the RS meter you won't use the compensated graph.  This is by memory, haven't looked at it in awhile

[BradJudy]

The compensation curve primarily corrects for C weighting, not the RS meter specifically, although it is thought of in this way.  The next logical step in measurement devices would be a measurement mic, pre-map and software, but that is a $150+ investment and requires a notebook computer (or computer in the listening area).  While I don't feel the RS meter is terribly accurate (even with the corrections), it isn't practical for most people to invest more in measurement hardware.  

I'm hoping that there will eventually be an inexpensive measurement setup for home audio/theater enthusiasts.  

BTW: the goal is for a flat final curve, not for the raw measurements to be flat.