TOPIC:

I've had a 2.1 home theater for years with no plans to expand to 5.1 or more. I have a few 4K HDMI sources that route through my Denon AVR. The Denon does bass management and down mixing of multi channel sources (mostly Apple TV 4K movies/netflix/etc). Speakers are set to small, crossover set to 80hz, center and surround channels set to "None", and subwoofer hooked up via LFE preout. I'd like to upgrade to better room correction like Dirac Live instead of Audyessey MultiEQ.

My thought is I could change the config on the AVR to set speakers to large and no subwoofer. This way, the full range of all channels plus the LFE content is sent to the front left/right speakers/preouts. Then use the FL/FR preouts to hook up a DDRC-24, which would be configured like www.minidsp.com/applications/digital-roo...rc-24-for-2-1-system.

My goal is to not lose the LFE content from multi channel sources. Does anyone have experience with a setup like this? Anything I'm not thinking of? The other option is to use the DDRC-88A, but it feels like such overkill when I only need 2.1 setup.

I've simplified my question to this - In a 2.1 system, how does using the DDRC-24 and following the setup as described here www.minidsp.com/applications/digital-roo...rc-24-for-2-1-system compare with using DDRC-88A + BM where you take a multichannel signal and use bass management to downmix to 3 channels (2.1) and each channel gets its own Dirac filters applied? I assume the end result would be very similar. Maybe the main difference is in how easy it would be to get everything dialed in.

I think there are two potential issues: 1. whether the AVR downmixes the LFE correctly and 2 whether you will run into level/clipping issues because of the 10 dB offset on the LFE. So even if it works for one person it may not work for you.

Thanks, John. To clarify, the correct way for an AVR to downmix LFE is by applying the 10 dB gain to the LFE channel, correct? Could you explain what you mean by level/clipping issues because of the 10 dB offset on the LFE?

davekaro wrote:

Thanks, John. To clarify, the correct way for an AVR to downmix LFE is by applying the 10 dB gain to the LFE channel, correct?

Yes, but it's being mixed down to two speakers. So.. to do what you want, it would need to be mixed at +4 dB to each speaker. Then when you recombine you get the +10. However if the LFE signal were being sent to two actual speakers, the acoustic signal won't sum back to +10, so the manufacturer may have decided to mix higher than that. Or they may have gone the other way and decided that putting LFE into consumer speakers was going to end in blown speakers and they would be blamed, so they reduced the level or highpassed it. I suspect the only way to know would be to measure it.

Could you explain what you mean by level/clipping issues because of the 10 dB offset on the LFE?

If the LFE is mixed into the speaker signal at a higher level, this effectively reduces the maximum signal level to the speakers. Combine with the 10 dB of headroom that (IIRC) Dirac wants you to allow and it's possible that levels will not be high enough. However it's not as severe as I thought when I first posted as a. I had "10 dB" in mind and b. a lot of the LFE is being removed from the speaker channels again. As usual though you need enough gain (post processor) on the sub channel.

This helps a ton! Helps me to decide that I really do want an AVR/processor with Dirac Live built in, or use the DDRC-88A. Thanks again!

I'm doing almost exactly what you're talking about. AVR receiver, speakers set to large, subwoofer to "no", LFE mixed to mains. I use the stereo pre-outs as inputs to a 2x4HD, that I send to 3 amps (main L/R, and 2 mono sub amps).

You have to pay attention to your crossovers and filter slopes carefully (do some REW sweeps before hand) but once that aspect is dialed in implementing DIRAC is a breeze.

I have not come close to overloading due to clipping/etc, this could partly be because my DIRAC curve only moderately boosts (mostly some cuts to get to my target curve) and partly because my sub amps are ~4x as powerful as the L/R amps, so minimal signal is needed for significant output. I have found this combination to be very rewarding to listen to, fairly easy to implement once you take the plunge, and fairly inexpensive, especially in light of the quality of sound.

There are also many ways to tweak, with respect to setting up stereo vs. mono subs, individual sub delays, etc. I have a hard time imagining more fun for less money in this category.