How to diagnose the need for room treatment?


I have my stereo setup in the family living room (30x14x8 ft). I have done some work around speaker placement, and treating 1st reflection points, but don't know if I need to do more. I often read room treatment being crucial. So while my system sounds good to me (I'm new at this), it might be able to sound a lot better.

How can I come up with a diagnose, short of trial and error of every posibility?

Thanks!
lewinskih01
Newbee -- I don't think you are missing the point, you are just making some additional points.

To re-state my basic point, room effects at mid and high frequencies are heard differently by microphones + sound level meters than by the human hearing mechanism. The human hearing mechanism tends to some degree to "latch on" to the leading edges of transient waveforms, and give them greater emphasis than what may follow a few milliseconds later. I think that is pretty well recognized. But a microphone + sound level meter monitoring a continuous frequency sweep, or a series of tones covering the different parts of the spectrum, will not do that -- the late arriving sounds at any given frequency will be taken into account, so to speak, simply based on their amplitude. Therefore, whatever the desired tilt of the fr may be, tuning the room or the system to provide it on the basis of that measurement technique will not give the desired result when listened to by a human.

Regards,
-- Al
How about a dumb question :)

I am going to try Room EQ wizard with a good microphone placed at ear level where I normally sit. Do I aim the microphone at the front of the room (HDTV) or do I aim it at the ceiling?

I will be trying to analyze (and perhaps improve) my 5:1 theater system.
Hi Ghstaudio, I assume you are using the Radio Shack microphone/Spl meter (although you did say a good microphone so its probably not Radio Shack). But If you are buying a microphone and you need a SPL meter, just buy the Radio Shack unit. It is more than adequate and the freq correction is done by the REW set up. Also many/most use this combination, myself included, and help in setup is freely available.

Point it straight ahead. It mut be on a tripod at where your head is.

When you get your Freq response graph, waterfall and RT60, please post them here for interpertation. That will be interesting.
Bob
If you are trying to assess room acoustics based on system throughput, aiming the mic forward, or at any speaker, biases the results to the performance of that speaker. Pointing it upwards makes for the least biased results. Also, averaging more than one mic position helps.

Kal