DVD-A Bass management

[PeterWhite]

I'm new to surround sound, so this question may be completely off the wall. I've read that DVD-Audio does not support bass management. I have recently bought the Onkyo SR805 receiver and the **504 DVD player, which supports SACD and DVD-Audio, as well as just about everything else besides Blu-Ray. I need to select "Multichannel Direct" on the receiver in order to get all of the surround sound channels to work. I'm using the analog connections for the DVD player, since the receiver has only three HDMI inputs and they're used for a Panasonic Blu-Ray player, Direct TV and Apple TV sources.

I have two subwoofers placed on opposite sides of the room. Sound quality with movies is very good. But very often, bass quality in music sounds better without the subwoofers in the system, particularly organ music. I'm a big fan of Herr Bach. The main speakers are Martin Logan Vistas which measure reasonably flat to 40hz. The receiver has only one subwoofer output. In the receiver setup, I can set bass management settings for each speaker. But I suspect that when using "Multichannel Direct" all of those settings are ignored. I have a few DVD-Audio discs, none of them organ music, and frankly the sound is quite good. When playing two channel CDs the bass can get muddy when I use a mode that includes the subwoofers. I can easily switch the subs out by choosing the Pure Audio mode. But I'm wondering what's likely to happen if I get organ music on a DVD-Audio disc. The Pure Audio mode will drop all but the two main speakers if I'm playing a multichannel disc. If the music is mixed to require a subwoofer, and the subs are fighting with the main speakers, I may wish I'd never bothered. ;-)

Am I imagining a problem that doesn't exist?

Thanks for reading.

 

[mr-ben]

You are correct in that "multichannel direct" bypasses all the bass management (and other stuff) in your receiver, effectively turning it into just a volume control. It's forwarding all the sound from your player directly to the speakers.

Where the bass goes therefore is entirely up to the disc, and your player. Some players are capable of bass management within them, giving you control over this (e.g. the Denon 3930Ci ), but most of them are not. Luckily many DVD-A discs contain both 2-channel and multi-channel mixes, and the 2-channel is almost certainly going to have all the bass available to your mains. The multi-channel mix may or may not, as there are no standard rules.

 

[j_garcia]

The issue is, DVD-A and SACD are handled differently than DD/DTS tracks. DD/DTS have an automatic +10dB added to the LFE channel as part of their spec - this is due to how they are mastered. SACD and DVD-A specs do not, so what you end up with when passing fully analog signal to a receiver is the .1 channel ends up being too low. Some players and even some receivers have added a compensation for this for hires audio (most of the Denons, some others).

While not all players have true bass management, more or less all of them will allow you to adjust the levels of each channel, and this is what I had to do on my 2900 - I adjusted the LFE channel +5dB on the player relative to the other channels. I also have the ability to adjust the input levels for my multichannel analog input on the receiver side, so I use those to do the final tweak to get the levels I am after.

 

[PeterWhite]

The issue is, DVD-A and SACD are handled differently than DD/DTS tracks. DD/DTS have an automatic +10dB added to the LFE channel as part of their spec - this is due to how they are mastered. SACD and DVD-A specs do not, so what you end up with when passing fully analog signal to a receiver is the .1 channel ends up being too low. Some players and even some receivers have added a compensation for this for hires audio (most of the Denons, some others).

Interesting! I had the idea that the LFE channel was simply the composite of the low frequencies of all the other channels, and that this composite was created in the processor part of the receiver, based on the settings in the bass management. I had no idea that the LFE channel was a part of the mix, except perhaps in the case of DVD-A. I don't understand SACD at all! ;-)

While not all players have true bass management, more or less all of them will allow you to adjust the levels of each channel, and this is what I had to do on my 2900 - I adjusted the LFE channel +5dB on the player relative to the other channels. I also have the ability to adjust the input levels for my multichannel analog input on the receiver side, so I use those to do the final tweak to get the levels I am after.

Can you count on the recordings not to be compensating for these differences already? In other words, are there discs that seem to already have the bass boost in them, done by the recording engineer? Or are you getting consistent results with the 5 db boost?

Thanks!

 

[j_garcia]

LFE, or the .1 channel, is a completely separate channel with multichannel music (SACD and DVD-A). In other words, it is actually mastered that way. When you play a CD in stereo but you are using bass management to utilize the sub, that bass is NOT a discrete .1 channle that is recorded, it is a composite of the bass from the two channels as you mentioned. I ultimately end up with a +8dB boost to get me to what sounds right, and yes it seems to work for all of the titles I have. For these types of discs, the 10dB deficit will be consistent IMO (for those that have a .1 channel that is), however the level of that channel will vary obviously based on the way they mixed it. Of note, the Denon 2200 that I had before the 2900 had a +10dB adjustment for this, while the 2900 does not, thus why I have to use channel levels to compensate.

 

[PeterWhite]

Great! I'll check the Onkyo DVD player tonight to see if it has that capability.

Thanks for your help!