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DDRC-88A BM, MSO and Dirac's 10dB LFE boost 2 months 6 days ago #62289

  • asx77
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Apologies first off as I know this has been discussed previously but reading those posts I'm still a little unclear.

I've recently got a ddrc-88a with the Bass Management enabled.

I use an Oppo BDP with 6 channel out. The Oppo does not boost the LFE.
The mains are sent directly to the 88A then onto an old AVR that has a 6channel input. The signal is not processed by the AVR other than volume control before its internal amps are used.

Now heres a complication but it works. I've got two passive subs each driven by a channel of a power amp. The Oppo LFE goes to the AVR 6channel input first for attenuation and then from the AVRs sub output to the 88A. Sub and Mains signals pass through the AVR and 88A, they just follow a different order but everything seems level and I get to use the display of the AVR for volume control.

Before running Dirac or setting the LFE Mgt tab, I took individual measurments of subs and 3 front large speakers, put these through MSO and created independant output for the two subs. Also I let MSO choose different HPF for the 3 mains. All MSO setting are applied to the output tabs.

Next I use the LFE Mgt tab and create LPFs on the mains to combine with the Oppo's LFE. These LPFs are basically the inverse of the HPFs chosen by MSO. Oh and I dont set HPFs here as they're already on the outputs.

'LFE Mgt' then has its own dirac channel assigned, labelled as a subwoofer, and since MSO did its calculations assuming the three fronts would be playing with the subs, I let the Dirac subwoofer channel 'see' the subs and the 3 fronts as a cohesive whole when it does its sweep.

I've told you all that as I'd be interested in your thoughts - Essentially anything below 120Hz is shared across two subs and 3 large fronts and MSO has worked out how to get them all playing nice together (at least as far as my limited MSO skills allow).

But my actual question because I cant get my head around why the tutorial tells me to do this is.... If neither the Oppo or the AVR apply a 10dB boost to the LFE, then why in the LFE Mgt tab do I need to set the signal from the mains thats joins the 'LFE Mgt' channel at -10dB? My thinking is that because my AVR is not adding any intentional 10dB boost then I do not need to apply -10dB to the mains in the LFE mgt section. Or do I need it because the LFE on the BR disc itself is -10db?

Sorry for the long message and thanks for reading this far!

Appreciate the above is too long a read and puttin people off. Probably I've rambled too, so tried to be more succinct here:

Warning: Just because I'm a 'Platinum' member, doesn't mean I know what I'm talking about... It just means I've asked too many questions!!

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Last edit: by asx77.
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