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BM analog inputs (1 Viewer)


Stunt Coordinator
Apr 3, 2000
Hi All,

I read much about BM not being implimented on the 5.1 inputs of a rec or pre/pro. Why is this such a problem? Why don't we rely on the player, to provide the BM and the receiver or Pre/Pro just do a pass through? I must be missing something.


Dave Milne

Supporting Actor
Jul 2, 2001
I assume the "BM" you're talking about is "bass management".

The problem is... players don't do "bass management". The ".1" output of the player is the "bass effects channel". It contains only the bass special effects (typically band-limited to below 120Hz) that the studio put there.

The other five channels have full range information, ie. lots of bass! Very few of us have five speakers that can faithfully reproduce signals down to 20Hz and below. We choose to have the receiver's "bass management" strip the deep bass off of the five channels and send it to the sub (along with the original ".1" bass effects information).

Actually in my 7.1 system, I run two "front" subs (L and R) and an additional sub (built into the seating riser) for the .1 effects --all with separate power amps, of course. Sophisticated bass management in the pre-pro allows me to do this --including selecting different crossover frequencies (in 10Hz increments), and distance delays for each speaker and sub. Crossover slopes are selectable as well. Try doing this with a DVD player...

Daryl Furkalo

Second Unit
Dec 8, 2000
The BM on analog inputs really is mostly related to DVD-A and SACD players that up to now, rarely provide any bass management on the players. For DVD-Video, DVD players that have built-in DTS or DD decoders, do have time alignment and bass management capabilities, so they are not affected. I have both a RP-91 DVD-A player and SCD555-ES SACD player that I want BM on the analog inputs for ... so I bought an ICBM to do this. Time alignment isn't a problem for me, since my speakers pretty close to evenly spaced around, since I have a dedicated home theatre room.

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