Hi Spirit,
The Radio Shack SPL meter is a very handy tool for both two channel and multi channel/home theatre systems.
The SPL meter became popular with the advent of home theatre as it provides a fairly accurate means to achieve balanced SPL's on all those speakers and subs when used with the built in test tones of the pre/pro/AVR's.
It also can serve as a rudimentary spectrum analyzer when used in conjunction with a test CD containing test tones running the gamut of the frequency range 20hz to 20khz+. The Stereophile test discs are fine for this purpose. Seamless calibrating of the x-over and levels on a sub in a two channel/sub set up can also be achieved with the 20hz-100hz test tones.
Using the SPL meter is fairly straightforward. Set the "weighting" to "C" and response to "slow". At the listening position, using a tripod or holding the meter in your hand pointing at the mid point between your speakers, at ear level, slightly angled towards wall/ceiling juncture set the system to your normal listening level. You need to now set the "range" on the meter so that the needle hovers back and forth between the 0db level. Usually this means the range is set at 70 or 80 db.
As the test CD plays each frequency tone, assess and document the db level for each test tone. This is labourious as you will need to repeat tracks and adjust the meter's range up or down depending on the in-room response. Once completed you now have an in-room frequency response for your system detailing all the peaks and nulls for the frequencies represented on the test disc. You may be surprised at what frequencies your system is emphasizing and de-emphasizing!
Another use for the SPL meter is determining L/R balance and energy propagation into the room. Using the pink noise tracks on the test CD, from the listening position, point the meter directly at each speaker and see if you are achieving a balanced presentation. Now sweep the meter around the room and see if there are wide variances in levels.
The key to a spectacular sounding system is balanced energy propagation into the room.
All this is for naught if there is not a practical solution, as in no added EQ or room treatments, to resolving peaks, nulls and propagation issues.
Acoustical analysis of the room is the answer. I can determine the exact location for the L/R speakers where the room's impact on the sound system is minimized and the room is energized evenly, the "zone of neutrality" Smoother bass response, realistic sibilants, increased inner detail and greater dynamics are the end result.
If you have the opportunity, measure and document your system's current in-room response and I will drop by and acoustically analyse your room. We will relocate your speakers accordingly and you will hear the results immediately.
Of course, if you have the speakers close to the correct location the improvements will be noticeable just not as dramatic!
Hope this was helpful.
Best Regards
Neil
