EEMichael83's Thread

[eemichael83]

Hello all. I'm new to this forum and somewhat new to home theater. I have had a good entry level setup for a couple of years now, but here in the past few weeks i've gotten the upgrade bug and i've also decided to start improving response by room calibration, etc. I'll post as I acquire new 'toys' which will be coming over the next couple of weeks (with the exception of full range new speakers). So for now, here is what I'm working with.

Environment: ~24'x22'x 8'-14' vaulted ceiling: ~5800cu-ft
..................12' wide opening to kitchen (~10'x20'x8'): ~1600 cu-ft
..................Overall volume to fill ~7,400 cu-ft

Receiver: Current: Pioneer VSX-D709S (2001 I think)
..............On-Order: Denon 2310CI

Full Range: F/L: BIC Acoustech HT-88
..................C: BIC Acoustech HT-85
.................RR: BIC Acoustech HT-65

Subwoofer: Current: BIC H100 (poor little fella)
..............On-Order: Two Epik Sentinels

Test Equipment: SPL Meter: RadioShack 33-4050
.......................Laptop w/Internal Soundcard: MacBook MB466LL/A
.......................REW Software Downloaded from here. (THANKS!)

So my recent upgrades will be the receiver, which I think will help a LOT because my current receiver only has Bass and Treble tone controls vs. a full blown Equilizer. I think the Denon has 9 band, but I know it has the Audyssey MultiEQ and Dynamic Volume. I also decided to upgrade the subwoofer to the two Epik Sentinels while they are on sale. The H100 is a good beginner sub, and would be adequate if the room was much smaller, but I have HUGE volume to fill, and it is just not going to cut it now that i'm getting serious. I MAY end up upgrading the full range speakers in the future (also due to the large volume), which would be something that I'm open to suggestions about.

So on to my very first in room Response. I didnt get into moving things around too much since I'll be getting the new receiver today and the new subs probably next week. I mainly wanted a baseline. I would also like Opinions from those that have done this before on the kind of in room listening position response I'm getting.

So first, Here is the response that my sound card provides:

http://farm3.static.flickr.com/2615/...208755f3_o.jpg

I was SHOCKED at how well it performs... so much so, that I restarted the computer, cleared any calibration files and ran it again... got the same plot. Time to take measurements.

SUB Only. I moved the sub to a couple of locations, but the best response I got was in the same corner that I had it originally in, only rotated 90Deg to fire down the front wall instead of the side wall. I also used the soundcard calibration file and I loaded in the calibration file for the RS Meter that was also downloaded from here. Hopefully I was correct in using both of these Cal files. Here is the response:

http://farm3.static.flickr.com/2640/...9febd0ae_o.jpg

I'm no expert, but this didnt really seem all that bad especially considering the caliber of subwoofer (~$250 range) and the large room it had to fill. I'm up about 10dB at around 55-65Hz and a few other smaller peaks and nulls. On another little side test, I played several bass heavy tracks to try and get a max SPL reading and on average I would get around 106dB max at around 12ft away from the sub. I didnt measure this distance, just a guess but I can measure it. I will also load up some pics of the room later.

After the sub measurement, I reconnected the towers. I took a few measurements, adjusting the Bass and Treble tones in between to try and level out the response as much as possible. Here is the end result:

No Smoothing (YIKES!):

http://farm3.static.flickr.com/2587/...c15a76f8_o.jpg

1/24 Smoothing:

http://farm3.static.flickr.com/2439/...e2030bae_o.jpg

Again, I'm no expert, but this one was pretty disappointing to me. I've got what appears to be +/- 15dB from 50Hz up to like 15kHz, then it just drops off. This is where I think the new receiver might help tremendously with bult-in MultEQ, time delay/phase correction, etc.

EDIT: I'm not sure why the pics arn't showing up. I copied the links to them so you can at least click to see. I used the IMG tags, maybe they'll start showing up later. Or if a moderator could fix it and let me know what I did wrong?

[Wayne A. Pflughaupt]

Welcome to the Forum Michael!

It's hard to evaluate your graphs because the scaling is wrong. Please review this thread and re-post them for us!

In the mean time - the Radio Shack SPL meter is only accurate up to about 3 kHz. If you're interested in seeing accurate response above that point, it'll require a calibrated mic and an outboard sound card with a mic pre amp and phantom power.

By the way the ragged-looking response you see in the full-range graph is the result of comb filtering, which is caused by the reflections in a room. Typically its best to use 1/3-octave smoothing for full range, and no smoothing for subwoofer graphs.

Regards,
Wayne

[Wayne A. Pflughaupt]

By the way, the reason your pics aren't showing is because you first have to rack up five posts. It's a necessary evil to deter spammers. We have a post padding thread where you can log the posts you need.

Regards,
Wayne

[eemichael83]

Wayne- Thank you for the very informative and helpful post. I'll have to retake the measurements and adjust the scale later, all I had saved were the jpgs.

As far as the RS meter, I was under the impression that If I used the .cal file for the meter, it would adjust the plot to account for the inaccuracy of the meter.

[Wayne A. Pflughaupt]

Yes, but only for the low frequency inaccuracies.

Regards,
Wayne