Originally Posted by Zee-man
Newbie here with a few questions. I have a 2.2 system and I want to measure and find the best spots for my two subs. I've read quite a bit of this post and used AustinJerry's REW guide to get everything fired up, but I still have a few questions based on my specific task of measuring the subs.
What is the best way to measure and graph - L+subs, R+subs, and then L+R+subs? Is it better or even possible to only measure the subs?
Should I run tests with and without Audyssey? When running Audyssey, do I turn off dynamic EQ and dynamic volume?
With my PSA XV15se sub(s) gain set at 2:00, Audyssey set my level to -9. I confirmed with my Umik that the -9 setting matches the SPL of my mains, but I bumped the sub level to -3 to suit my taste. Should I use the -9 or -3 setting when taking measurements?
What specific measurements or graphs are are the most important for subs - waterfall, decay, spectrograms, ETC? I have two possible locations for the subs and one of the options have them placed inside built in cabinets. I've heard this is a big no-no and I'd like to see some measurements to back that up. Is there a specific graph that will show the "boomy bass" that everyone says is going to happen?
Should the Umik with the factory calibration file be set horizontally?
Thanks in advance.
OK, I'll try to address your question, maybe not in the same order as asked. It is nice that you have two subs, because you will likely be able to get better bass response with two vs. one sub.
When approaching a sub placement exercise, there are going to be some obvious placements that should be better than others, based on the characteristics of your listening room. The dimensions of the room will determine the axial standing waves in the room. You can download an Excel worksheet that will calculate your room modes here
. Typical sub placements are in the nulls of room modes. The mid-point of a wall is a in a null, as are the 1/4 and 3/4 points along a wall. The placement exercise is to locate a sub in one of these spots and measure the results. Keep experimenting with different placements until you get the best measurements.
When experimenting to find the best location, measure each sub individually, then both subs combined. The main speakers should be turned off (carefully disconnect the wires). Measurements should be taken with Audyssey turned off? Why? Because an Audyssey calibration is good for only one speaker configuration. The minute you move a sub to a potential new location, the calibration is no longer valid. Optimize sub placement first, and then run Audyssey. And if anything changes, re-run the Audyssey calibration. Final measurements should always be taken with DEQ and Dynamic Volume turned off.
The gain setting on the subs does not really matter with respect to the smoothness of the frequency response. Make sure your mic is calibrated, and turn the gain on the subs enough that you are getting a level reading of 85-90dB. It is important, however, to make sure the two subs are gain-matched. If you go to the Audyssey thread, the Audyssey FAQ has an excellent write-up on how to properly gain-match your subs. The trick is to achieve a matched gain that also measures close to 75dB for the Audyssey calibration.
Optimize your sub locations by measuring frequency response. The waterfall graph is useful to assess bass resonance once you have found the best sub locations. If resonance is bad, it can be controlled by treating the room, not by moving the subs around. And the ETC graph is to measure higher frequency reflections, and is of no value in placing the subs. And when measuring, make sure the mic is in the MLP, pointed towards the ceiling, with the mic tip exactly at ear-height. Use the 90-degree calibration file.
There are several poor locations for subs. Inside a cabinet would be near the top of the list. Corner placement is usually not the best location either, although there may be exceptions. So, if you try placing them inside of a cabinet (ugh!), then what does "boomy bass" look like? The frequency response will be poor, and the resonance (waterfall) is probably going to be terrible. And most importantly, it will sound terrible.
So, you need to resign yourself to the fact that the best-sounding location for your subs may not be the most esthetically-pleasing location. Since you didn't comment on what your room looks like, and what freedoms you have in placement, I can't predict how easy this exercise is going to be. Getting good bass is a lengthy exercise--it took me several years before I could say that I had what I was looking for.
Good luck, and report back with progress and questions.