Monday, November 21, 2011

New house curve

I started running the Tact Room Correction analyzer for measurements on Friday evening and into Sunday.  I decided that my living room system is measuring so good it does not need full system correction (and I will need to get better about pasting from measurement into target curve).  However, I made several important adjustments.
Final Adjusted Response, Both Channels, Nov 20

First I moved speakers slightly back and out by about 4 inches, the most available with current positioning of Belkin PureAV power conditioner.  This seemed to bring a slight additional improvement in image coherency,   The highs are also adjusted to be slightly hotter, with listening position just barely off the Acoustat beam, and flat response in the highest frequencies.  The previous speaker position is marked by tape.

To reduce bass blooming around 100 Hz, I backed down the subwoofer crossover from 84Hz to 71Hz, and changed the slope from 24LR to 48LR.

I lowered panel crossover to 80Hz, not wanting to make it lower for speaker durability.  I tried several crossovers, but decided I liked the thinking behind 24LR the best.  Years ago measurements showed the LR24 as having the nicer looking impulse than LR48, but I wonder about that now and think the the Tact impulse itself has multiple cycles, so I would have to do actual impulse measurement with other program..

To increase bass in the range 22-30Hz, which looked notably sucked out in both channels, I added a bandpass filter to the Behringer subwoofer outputs, 5dB of boost, center frequency 27Hz, Q 2.2.  It could use more boost in left channel than right, but crossover currently has this set to stereo mode.

I increased delay for panels relative to bass slightly.  I get the best measurments of bass impulse when turning off crossover.  Then put sub in one channel, panel for same channel in opposite channel, can get picture of bass vs panel impulse.  I also did this method of using two channels to measure one channel for checking crossover frequency response.

Resulting delay ia now 0.85mS in right channel (was 0.70) and 0.75 in the other (there is an extra 0.10 mS delay for right subwoofer as compared with left, same as before).  This is consistent with having listening position closer to the front, so relative distance to subs from listening chair has increased slightly.

I also tried dropping the bass level from -7.0 to -8.0, but quickly decided I wanted more bass.  Funny in the crossover picture the sub bass dominates, but that's the way it sounds best.

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