dougdrake Posted July 8, 2002 Share Posted July 8, 2002 NO, this isn't a my-heart-is-on-my-sleeve post. Just posting this for any insights/comments that one wants to offer... I cued up a 1150hz test track on my cd player last night, put a Radio Shack SPL meter 1 meter from one of my Chorus speakers (unhooked the other one), cranked the volume to 101db, and put a multi-meter across the speaker's binding posts. Measured about 2 volts, AC. Wondering if this is significant, as I was expecting it to read about 2.8 volts (given that the Chorus are rated at 101db 1w/1m.) Doug BTW, in case you're wondering, a 1150hz test tone at 101db is NOT fun to listen to! ------------------ My System This message has been edited by dougdrake on 07-08-2002 at 07:21 PM Quote Link to comment Share on other sites More sharing options...
fini Posted July 9, 2002 Share Posted July 9, 2002 Doug-You've got a lot of time on your hands, lately, huh? fini p.s. Don't get upset, I'm only joking,...Mr. Sensitivity! This message has been edited by fini on 07-09-2002 at 12:14 AM Quote Link to comment Share on other sites More sharing options...
cluless Posted July 9, 2002 Share Posted July 9, 2002 DOUG,DOUG,DOUGs>DOUGs>, nevermind Quote Link to comment Share on other sites More sharing options...
Klewless Posted July 9, 2002 Share Posted July 9, 2002 Doug, From what I have read, it is no easy matter to make acoustic measurements and know that they are accurate. Some factors that might make your measurement to be off is the room gain. Klipsch probably tested your speakers in an acoustic chamber to eliminate the room gain. Then there is the issue of accuracy of your input signal, your SPL meter, and multimeter. These and other variables make acoustic measurements very difficult. Plus you would probably want to run your test in different positions within the room, outdoors, and make absolutely sure that your SPL meter is exactly where it needs to be. Even an inch could affect the result. Nice work. If you are ambitious try many tests and perhaps average them. ------------------ John P St Paul, MN Quote Link to comment Share on other sites More sharing options...
Ray Garrison Posted July 9, 2002 Share Posted July 9, 2002 Room Gain Boundry Reinforcement Meter Accuracy (acoustic meter, not electrical) Meter weighting did you try moving the SPL meter around a bit while you were making this measurement? If you define a spherical surface one meter in front of the centerline of the speaker on the tweeter axis, and move the meter around on that surface with the test tone playing, and watch the response, I'll bet you get a significant amount of needle nudging (maybe as much as +/- 3 to 6 dB) at various different "1 meter" locations. Also, try measuring your Chorus with is set (1) close to the back and side walls, sitting on the floor, then (2) sitting up on top of something (stack of books?) out in the center of the room. Things like this are way a lot of folks (well, me anyway ) think you've got to treat published specs with care. Within a manufacturer's product line, you can be fairly sure that the specs provide a reasonable reference of one speaker against another (assuming that they measure their different products using the same test procedures), but across different manufacturer's products, forget about it. Ya really want to drive yourself nuts, try to measure the speakers sensitivity at, oh, say 32 Hz. Ray ------------------ Music is art Audio is engineering Ray's Music System Quote Link to comment Share on other sites More sharing options...
dougdrake Posted July 9, 2002 Author Share Posted July 9, 2002 Fini - Actually, no time on my hands, but I had the meters nearby and was just moved to do it, being the sensitive guy that I am. Cluless - Wondering what comes next. Had the makings of a good tsk, tsk, tsk followed by some wise advice. Please don't leave me hanging!! Klewless - Thanks for the useful info. I wasn't sure if the .8v difference was too big to have been attributed to room interactions and all that other stuff you mentioned, but I can see that is certainly possible. Just goes to show, once again, how specs are really just a general guideline and there's no substitute for real-world testing our own listening areas! I also played some music with the meter on the binding posts. It was interesting to watch the voltage swings from above 2 to 0.4. Just another kind of motor, right? Doug ------------------ My System Quote Link to comment Share on other sites More sharing options...
WMcD Posted July 9, 2002 Share Posted July 9, 2002 I did some math like: dB = 20 log (2.82/2.0) = 2.98 dB That is the calculation for voltage gain. So you are reading about 3 dB sound pressure more than expected on average. Speaker specs are plus or minus 3 dB from an average. So if you lucked into a frequency output is 3 dB above average, it would make sense. Of course it could be that there are room effects too. Gil Quote Link to comment Share on other sites More sharing options...
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