Friday, May 23, 2014

After time alignment, new DAC sounds even better

It turned out not to be so hard to set the time delays I needed to time alight the Acoustat panels with the subs and super tweeters using the Behringer 2469 DEQ I now use as crossover for the Acoustats.  I had previously been fooled by the fact that when you bring up the time delay dialog, and turn the big knob, it advances the "distance" (how it measures delay) in large 0.6 meter increments.  But on Wednesday night I discovered that pressing the knob in once (until it clicks) changes this default increment to 0.01 meters, which is good if not as fine as I would like (0.001 meters).

So I was able to dial in the same delays I had previously used in the Behringer 2496 DCX.  I didn't have to check my notes or this website, I just checked the DCX itself by turning the delays back on and checking the numbers I had added.

After this and other adjustments, another long unplanned listening session ensued because the sound was so good.  This time I also listened to different music, the DVD-Audio recording of Santana's Supernatural (one of my favorite sounding recordings of all, which previously I had been thinking was an SACD and therefore proof that SACD's could sound especially good…but then later pulling out the disc again, I see it wasn't an SACD after all..and now I can't think of a single SACD that is categorically better than CD, though I can think of lots of DVD-Audio discs which are).  I did not hear any of the dryness I had heard the previous night when listening to Pink Floyd Wish You Were Here, in 16 bit version through Sonos.  But I did continue to hear the marvelous dimensionality, layered imaging, and super high resolution I noticed the night before, and which I associate with the new DAC.

Additional tweaks I made were that since the new subwoofer is slightly farther back than before, I increased the panel delay by 0.05 meters (a couple inches) to account for that.  That seemed reasonable to do without measurement, but I will have to re-measure with Tact to determine the exact delays needed.  I also increased the delay on the tweeters by the same amount on average, but while doing so I made both tweeter delays the same (I hadn't remembered setting them different, but apparently at one point I had).

I messed with relative levels too, bumping the sub and tweeter levels up a dB or two, and then also moderating the massive -11dB notch at 45 Hz to a mere -8dB.  Bass had been sounding sucked out before.  But even moderating the notch just this amount, brings back massive resonance in the corners of the room and in the hallway.  But it really made the bass more enjoyable at the sweet spot.  Until and even when I can notch out the 45Hz modes more precisely, this has to be a compromise, though I also have some ideas on how the two subs can be tuned slightly differently as another strategy.

I eliminated all the sub boosts below 32 Hz on the left side sub.  They were making the bass sound congested, especially on another favorite of mine, Bass Erotica by Bass Connection, which I played on Thursday night.  Later, though, I dialed back in a 25 Hz boost on the left side in order to remove it on the right, and tuned both subs to have 2dB boost at 32 Hz.  It seemed light the right side sub was straining and shaking too much, while the left side sub, with new amplifier, seemed placid (despite having levels matched by playing Stereophile Test Disc 2).  Playing Bass Erotica was shaking walls, but I went outside to the sidewalk and nothing was audible there, or close to nothing, while the sounds of wind and AC compressors could be quite loud.  It seems like at least 15dB reduction from outside the front door to the front of the garage, and perhaps another 15dB reduction from there to the sidewalk.  I figured I could play even 10dB louder before reaching 40dB at the sidewalk.  I was playing with level at 82 (about -11dB digital) and inside levels were surprisingly low on Bass Connection…about 70dBa peak, but this recording saves all it's dynamic range for the deep bass, which doesn't show up as loud as it sounds in A weighting.

I tried temporarily rolling off the panels less by canceling one of the two 80Hz 12dB high pass cutoffs, then dialing it back in at various frequencies below 80Hz, then ultimately going back to 2 80 Hz cutoffs (for proper Linkwitz Riley 24dB/octave) which didn't sound any worse, and possibly somewhat better.

I also checked the 2nd bedroom (Queen's Room) which has "soundproof" wall and door, and you could hear that bassy music was playing, but someone not inclined to make trouble could just as well sleep through it, I decided.  So while I wish my soundproofing was better than it has turned out to be, it seems to have reached a minimally acceptable level of performance.  (Before the soundproofing, that wall would be rattling constantly at these levels, and the door might as well not be closed.)

So the new setup has been time aligned, tweaked, and tested, and it sounds good, and won't bothers others playing to 5am (as I did on Wednesday night).  A great success.

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