This is a known problem and all over the internet A/V chat sites.

Matter of fact...I threw the same problem at Home Theater...and got what I think is the wrong answer. What I think is the correct answer is that the DVD 5.1/SACD outputs are not compatible with the DVD THX bass management system and suffers from a minus 10dB on the LFE channel.

See below



December 10, 2002

Editor,

I have my receiver set up for both 7.1 home theater and a 5.1 SACD using the analog inputs of my B&K receiver.

After untold hours of experimenting, I cannot get the sound levels of the speakers to match up with the two competing bass-management systems. The receiver, of course, has bass management for THX, and the Sony SACD has an internal BM system, which is needed as the receiver has a "straight through" 5.1 analog input.

In the initial receiver setup I adjusted the speakers for equal 75dB sound levels and then when I checked the SACD sound levels (using the similar SACD player's BM system), the subwoofer is about 13dB too low. If I set up the SACD BM first, I get the opposite problem -- the bass volume on the movies is way too high. I've played with changing the speakers to small, large, direct, you name it, doesn't matter.

At first I thought I had a defective Sony SACD and returned it -- but got the same result. A call to Sony tech support ended with the technician blaming the receiver. I called B&K and they said the 5.1 is straight through.

But a trip to my dealer was informative. He has a different receiver for the SACD demo in the showroom (a Sony). We ran through the SACD player's internal BM six-speaker white-noise speaker-level volume settings in the store and when it came around to the subwoofer -- bingo, hardly any sound. Just like my problem at home! So -- whatever I'm doing wrong, my dealer is doing the same thing! Can you shed light on our confusion? I don't think even the Outlaw ICBM can make up for this 13dB bass shortfall.

Dennis Laslo

This is an easy one. The LFE channel, when set to flat in the Sony's bass-management system, is correct when routed through the B&K's analog pass through. The specified 10dB boost (Dolby's LFE specification) in the software you play will compensate, so that what you actually hear is correctly balanced. With movie soundtracks, the LFE is setup to play 10dB louder than the main channels to compensate for the bass output of the other speakers in the system. However, you don't need to set the LFE 10dB louder! When you play back an actual movie this is part of the soundtrack's spec. Set it to flat and listen to a disc and it should all sound correctly balanced....Jeff Fritz