Originally Posted by toofast68
Well, perhaps I didn't do things correctly....but I will try again,.
1) connected sub 1 ONLY
2) placed in center of ROOM near the listening "mic"
3) adjusted to 75DB
4) repeated the same thing with sub 2 - of course in the same place with sub 1 disconnected.
5) moved BOTH subs to final resting place
6) connected them both
7) ran audyssey - SWEAR my reading was 78DB, so adjusted EACH sub EXACTLY the same to get a unified reading of 75DB with mic placed in listening position #1
8) finished setup etc.
NOW - I am new to subs and ONLY used this method as I really was confused on everything else and this made sense ?
I honestly don't know if this is best...but at the moment until I learn more I guess it is what I am going with.
Your experience with RS meter readings was completely random, as it is for everyone else.
The missing equation here is a frequency response measurement.
The rumble tone in every AVR is a bandwidth-limited pink noise from 30-100 Hz.
The SPL meter does not have a flat response in that same bandwidth.
If, for example, the frequency response at your mic with the sub in the gain matching position shows a peak at 30 Hz you will get an SPL meter reading that's dominated by that peak. With a correction factor of anywhere between +4dB to +6dB at 30 Hz for the RS meter, you can see where I'm coming from here.
Using the same example, moving the subs into position will usually drastically change the FR and you might see a very large swing in your meter reading.
Audyssey will then set your sub output hot... every time, any system. This is simply because the Aud mic has a roll off which sends a false reading to its brain. That roll off gets compensated for, resulting in a boost to the level that mirrors the mic roll off.
Since the mic roll off occurs from 30 Hz down, the boost will show up in that bandwidth skewing the SW output level.
These differences from the meter reading from the gain matching FR to the meter reading from the final resting place FR to the Aud compensation from its algorithm/mic roll off are significant, making most of this threads nit-picking moot.
Regardless of the preferred level matching method, a FR sweep is the only reliable method to gauge levels, especially after running Audyssey.
For reference, I've compared the Aud mic response to my reference ACOPacific mic (which is flat to 2 Hz with no calibration file).
I've compared close mic measurements of before and after running Aud to confirm that it a) boosts both sides of a peak instead of just pulling down the peak and b) boosts the low end proportional to its mics roll off, which frequencies are not included in the rumble tone used by most for level calibration.
I've compared the RS meter reading using the rumble tone to a frequency response with the measurement mic and the RS meter at exact positions. The result is always that the rumble tone/RS meter level is higher than the flat frequency response method, by +4-6dB.