Originally Posted by HopefulFred
Can we get a quick run-down of the processors and loudspeakers that are connected?
- the three fronts are M&K LCR-850 (same as the LCR-750, but with a wood veneer)
- all four surrounds are Triad OnWall Silver Surrounds
- the one and only bass is a M&K MX-150
- all connected to a Marantz SR9200
I'm not very confident that the speaker measurements you made are very close to reality. I don't know how omnimic does it's processing to generate the graphs, but I think it's getting a lot of reflection and room interaction in the measured response. I imagine that the speaker was measured installed in the false wall, to the side of the screen.
I'm not sure either, but I'm working on getting REW set up - just posted my first post on the REW forum
. I think using REW will help a lot - not only is it more well known, but I've read that it's more tuned for room-measurements (i.e. its namesake), whereas the OmniMic software is more tuned for speaker calibration, which I think is why it's missing some features found in REW...
One thing that might be relevant is that all the measurements were made using the center-channel only and it, the center-channel, was behind my Seymour Center Stage XD screen - the drivers are about 9" behind the screen. I figured this would be OK, as it might only affect the highest frequencies, but I read that AT are mostly for <400Hz :dunno:
It looks also like the measurements were taken at 75dB (according to the dB scale in the posted graphs).
I *think* so - my SPL meter measured 75dB when the pink noise was running (C weighting, slow response). That said, it seems my amp is set at -12dB, though I haven't touched it since I calibrated it (set speaker distances and loudness). I'll double-check in a little bit...
Your best bet for making your own measurements would be to drag the amp and the speakers outside - set the speaker up on a stand (a ladder should work fine, or maybe a handrail on a deck) and get everything away from the speaker so there are no nearby reflective surfaces.
Thanks for the suggestion! I will do this, at least for the center channel. I'll try to superimpose the graphs of it being behind the screen, same location but with screen removed, and outside. Given that I haven't ordered the mic or sound card, it might take a week or two...
I realize that you've built everything and set it up with the L/R outside the image. Did you guys install an AT screen with the center behind, or is it below? Reworking that would be a significant pain, I am sure, but that may be the only real option for smoothing the low end
The center channel is behind the screen, the left/right channels are not - is this a red-flag? Still, I'm not following you, what is your suggestion? - to put all 3 behind the screen? Regarding significant pain, did you catch the part where we opened up the ceiling to install a plenum to reduce air-turbulance noise caused by the HVAC (see here
)? - *that* was a royal pain, but it paid off, now we can hardly tell when the HVAC is running
It looks like (at least for the one position you've measured) you've got enough dB for bass, with the possible exception of the 32Hz null, which I still think is position related.
You mean the position of the sub, right? It's off center behind the screen - kind of at the 1/3-rd position with it's front driver facing sideways - 90-degrees from facing the screen.
BTW, took my wife out to lunch today and we discussed the theater (she was pretty happy about how The Ghost Protocol sounded last night). I tried to explain why the delay for putting fabric up - that there was an opportunity to make some small improvements to make it sound even better, such as, blah, blah, blah, put another subwoofer on a sidewall to flatten out the nodal frequencies, blah, blah, blah - she didn't even blink! Of course, she probably doesn't realize how much subs cost, but it doesn't matter now - that she didn't bother to push back means its got WAF
With that, I spent a little time today checking on if I could find another MX-150 anywhere - there are none on Ebay or anywhere else. Any idea if its OK to use mismatched subs?
Holy smoke, that thread is 131 pages! I read the 1st page and the last three pages. Mostly movie-recommendations, I'll have to come back to it later...
(some of them are on the demo disc, I think?) If you have no idea how that should be done, let's talk about it. We should be able to assess the headroom in your system and see what it really produces relative to reference.
Yes, the Reference Blu-Ray Demo Disk has a "bass" section with the following:
I'll give it a special listen in a little bit...
You've calibrated speaker output to reference (75dB at seating position is produced by 75dB signal), right? Most rooms (I find anecdotally, reading here) sound harsh at reference level. Generally, this is because their system distorts when pushed that hard (another reason we need to know some specs on your speakers and amps). If you find it sounds clean at those levels, that great news, but I think it may have something to so with the missing high end from your speakers.
I may be wrong about it being at reference level. As mentioned above, it seems the amp is at -12dB (not 0dB). That said, when we played BIG's OmniMic test-tones disk, my SPL meter measured 75dB pink-noise coming from the center channel. I haven't touched the volume level since, so I *assume* that it's still at that setting
I think I'm going to start calling you "HelpfulFred"