The legendary +10 dB LFE specification was ONLY FOR THE Mixing Engineer "When using an RTA" (Real Time Analyzer) - please read below*.
((no longer available in their website)
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*Dolby Digital Professional Encoding Manual
2.5.6 Subwoofer Calibration
(pg. 2-27)
"When using an RTA, proper alignment of the subwoofer requires setting the subwoofer within its bandwidth, typically 25-120 Hz, 10 dB higher than the same bandwidth measured for the Center channel. For example, when measuring the Center channel, if the average value of each third-octave band (between 25 and 120 Hz) is at the 0 dB datum on the RTA display, adjust the subwoofer so that the average value of each third-octave band is at the +10 dB datum."
(pg. 2-29)
If an RTA is not available, setting the subwoofer channel 4 to 6 dB higher (e.g. 89 to 91 dBc for the subwoofer channel when the Center channel measures 85 dBc), can give an approximate level on an SPL meter.
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NOTE: I use +2 dB or 77 dB AVG (NEW SVS 25-31PCi 04-11-02 ) **
I did not need much for my SVS 25-31PCi!!!
** My LFE needle swing is 3 dB, lowest 76dB, highest peak 78dB - in my 20' x 30' HT/family room.
(Your results may vary due to room integration.)
You need to carefully integrate your Sub to your room and speaker crossover, where either situation, can contribute to over bloated, boomy unatural bass.
(from SMR Home Theatre website @ http://www.smr-home-theatre.org/Interface.html)
Click right arrow button to read:
"High level description of the Low-Frequency Effects channel"
(You'll need Acrobat Reader - PDF: 17KB)
(Click Secrets Image above)
After calibrating my AudioSource SW Fifteen to Dolby Digital 5.1 using Video Essentials DVD to 79 dB AVG. (w/highest deflection just touching the 82 dB tick mark - updated 12/18/00): it took about another 15 - 20 mins. to integrate it in my 20' x 30' w/10' vaulted ceiling HT/Family room! Careful placement is required to eliminate bloating or boomy bass, so I started @ my usual location, once occupied by my Sherwood SP210W 100w 10" sub.
I started about 1' away from the front right side corner wall, and eventually moved it to it's final placement, . . . about 7" away (back of the sub) from the front wall x 10" away from the right front side wall. I used various source materials, from Music CD's to 3 (Dragonheart; Tomorrow Never Dies - SE; Armageddon) Dolby Digital DVD's, to verify room placement and to make minor Sub/LFE Level adjustments with the Sub & my Yamaha R-V905 AV Receiver.
Performance = Outstanding!! Compared to my 100w 10" sub, moving up to a bigger and more powerful subwoofer gave me an increasing sense of acoustic depth and envelopment. Actually, the basic extension of the system hadn't changed all that much, due to my careful calibration & room integration location. The overall volume levels were exactly matched vs. my 100w 10" sub, but my SW Fifteen subwoofer increased the overall dynamic capability of my system. The SW Fifteen also extends the low-frequency bandwidth as well, so, . . .I did not have to increase the overall volume level to get the benefits. In other words, the SW Fifteen subwoofer allows my system to go both louder and deeper. - yeah!!! The SW Fifteen has impressive sub-sonic impact, coupled with clear, full-frequency balanced with my JBL HT speakers!
One of the first things I noticed was what I was missing with my 100w 10" sub, . . . the aftershock and decay that the SW Fifteen easily delivers! I felt the oomph and decay when the DD-5.1 DVD material called for it and it also blended nicely with my Rippington's or Yellow Jacket Music CD's.
If you carefully calibrated & install/integrate your subwoofer, there will be no intrusion on the upper ranges of your system and it will (if your sub is big enough), . . .shake your structure, the earth, and leave an aftershock, which is "Most Glorious". To quote "Tom Nousaine" in Sept. 1997 Stereo Review - "No aftershock, no decay, means no lows. Contrary to popular myth, there is no such thing as a "fast" subwoofer." (unquote)
Take the time to locate and calibrate your sub, if it's done just right, . . .it's capable of pulling you into the sound and the story by moving the floor under your chair, and giving you the natural decay that comes with powerful low-frequency information.
Included is step by step instructions to Calibrate using Yamaha's "SWFR" & "LFE" trim levels.
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