Analog vs Digital Bass Management

[Eric_C]

I've had my setup for just about a year now and I'm amazed I'm just finding this out.

Ever since I bought my Yamaha RX-V2600 and Deftech 7002's I've been disappointed in the 2 channel audio. I have the match center and rears also.

It always sounded hollow and lacking bass. I've done the speaker adjustments and all that but still when compared to playing movies or DVD Audio/SACD after the installation of my ICBM, 2 channel just plain sucked in comparison.

The ICBM for those that don't know used to be made by Outlaw audio. Its a 8 channel analog cross over for people who listen to DVD-A and SACD. The DVD-A/SACD spec calls for 5 full range speakers and no sub. No one really has that setup so it lets me cut off my rears at 100hz, my center at 100hz, and my fronts at 80hz and pipe the remainder into a LFE channel for my sub.

I always thought it was odd but a easy fix was to run things through the ICBM. I guess I never realized something until tonight. I "thought" that because I picked multi-channel input that it went into some kind of PL II arrangement. It always sounded better than 2 channel and I found it more that acceptable.

Tonight I was playing around with arrangements and swapped over to HDMI audio(from optical) and still found it lacking. I played with my speaker levels on the unit including the sub output and found nothing.

I later found out when playing around with my Yamaha C950 DVD player that it defaults to PL II, not STEREO.

So I swapped it over to Stereo and tried both STRAIGHT and 2 Channel stereo settings on my RXV2600, better but still no life or punch.

Then I turned on the multichannel inputs and discovered it never was the receiver doing the PL II, it was the DVD player.

Setting the DVD Player to STEREO and running things via the ICBM which basically cuts off my mains at 80hz and creates a LFE channel for me left me amazed.

I played with the receiver for nearly an hour and a half with all kinds of settings, none of them matched using the ICBM as the bass manager for 2 channel audio.

I always thought something was odd but never really looked into it because I listen to alot of DVD-A and SACD which prompted me to buy the ICBM in the first place. DVD-A and SACD sounded horrible without the ICBM and took it to such a higher level than 2 channel. Now my 2 channel matches my multichannel.

So my question is...why is the digital side not as effective? I've used YPAO, I've tried doing it myself but no oomph to the music like when using the external bass manager.

My worry is that HDMI 1.3 receivers and DVD players will now make my multichannel inputs obsolete since they will pass the lossless via digital. How can I match the sound quality I get with the ICBM using the digital portion?

I know I'll now spend the next few weeks listening to my entire 2 channel collection again.

All this time I've seen people post how they mostly listen to 2 channel and don't find multi channel hi-res so impressive and always wondered why. Guess I have my answer tonight

Thanks

[gianni]

For what it's worth:

I use the M&K BMC mini which is a simple version of the ICBM. I have found that 2 ch does sound better using this anaolg filter than using my Rotel's built in bass management and it does allow for bass mamagement using the multi-inputs.. There are pros and cons to both and benefit will vary by system. For movies, I just use the on board as it makes more sense.

[ThomasW]

Outlaw discontinued the ICBM quite a while ago. For some reason it still shows up on their products page. But if anyone tries to buy one it shows up as discontinued.

[Eric_C]

I was lucky. Bought mine just a week before they canceled them.

It worries me more since I am lead to believe Rotel is one of the higher quality brands out there and if your doing better with a analog cross over than their digital stuff built in now I really wonder what will happen when things go HDMI 1.3 and TrueHD.

[Ovation]

My Integra receiver can (if I select it) digitize the input entering the 5.1 analogue inputs and then apply bass management and (important to me) time alignment (but not level settings; that I have to do in the player) and I've compared it to the player's own bass management and time alignment (which the player can NOT do for SACD). I find the time alignment crucial and the receiver's steeper xover slope preferable, even after the A/D/A conversion of the hi-res signal (with multiple Wolfson 192/24 DACs doing the work, it sounds great to me). I think many factors come into play and the digital/analogue issue, while important, is not necessarily the most important one at play.

For two channel playback, I do NOT use the A/D/A (I use "pure audio"--a total bypass of all processing) as I have a different player for 2 channel CD playback that can be configured for 2.1 playback. Its bass management and DACs sound better to me than my receiver (and time alignment is not an issue in 2 channel), so I let the player do the work. So, as you can see, for some situations, the digital option in my system is the better option, while in others, the analogue option is better. Experimentation is the key.

Early on, I'd given some thought to getting an ICBM, but in the end, the lack of time alignment was the deal breaker for me, once I found a receiver that could provide it for me (my room is such that I need the time alignment to compensate for the lack of space for a proper ITU configuration). As for setting different xovers per speaker, I think the phase issues that would introduce, as well as the variable peaks and nulls, outweigh the flexibility inherent in such a feature. But then, different strokes for different folks.

[Eric_C]

What kind of equipment are you using on the CD/DVD side?

Granted my setup is on the cheaper side but this was a first round try and as long as their is stuff out there that will address the issue then I'll be ok. I also use pure direct which on the Yamaha just turns off the video processing. Its already bypassing the digital processing because I'm using the multichannel in.

I was looking around at dedicated CD players but did not find one on the higher end that also did DVD-A that would address this digitally.

I continue to go through my collection and really am amazed at the difference. I had completely given up one some older CD's.

I haven't gotten to the point of time alignment and have not heard the term but taking a guess I'd say that is keeping the rear speakers in phase with the front dealing with the speaker distance issues?

[Ovation]

What kind of equipment are you using on the CD/DVD side?

I have a Marantz DV6400 that I use exclusively for hi-res audio playback (and, on rare occasions, when a scratched rental DVD causes my other player trouble, I run it through this one--its PQ is slightly worse than my other player and its layer change is slower, but its error correction is higher). I have a Cambridge Audio 540D that I use for DVD-V and CD playback (I was looking for a dedicated CD player and was told to audition the 540D for CD playback and, after a head to head comparison with the 540C, as well as two NAD players--my "final four", if you will--I went with the 540D. As a bonus, it can be configured for 2.1 CD playback, so that's how I use it.)

I haven't gotten to the point of time alignment and have not heard the term but taking a guess I'd say that is keeping the rear speakers in phase with the front dealing with the speaker distance issues?

I'm no engineer, but that is how I understand it as well. My general understanding is the ideal setup would be five full-range speakers, all equidistant from the listening spot, with a sub and no processing (no bass management, no time alignment) in an ITU configuration. In the real world, very few people have that as an option. I have fiddled with various settings and found that time alignment is more important, to my ears, than keeping the hi-res signal (PCM or DSD) "pure"--it appears the DACs and processors in the player and/or receiver (depending on what I'm doing and with what source) are transparent enough that time alignment becomes the biggest single factor in need of adjustment after bass management in my system. So I engage in the heresy (to some ) of applying an A/D/A to the hi-res signal coming out of my Marantz. Now, if the Marantz did time alignment on SACD, I'd likely go with that (but it doesn't). If I could have an equidistant setup for the speakers, then the ICBM option would be better than mine, as it would not require an A/D/A, but I can't set my speakers that way. And, someday, I hope to have set up that allows me to use either an HDMI or firewire connection to do everything in the digital domain, and avoid extra conversions. But the sound is quite good from what I have right now, so I'm no hurry to upgrade on the audio front.

[Eric_C]

This whole "cd transport" thing is new to me.

I've seen that bass management is the big problem...I've also heard of this external DAC's.

Can someone give me the quicky on that?

If you have an external DAC does it just send the CD data outboard to it and it does the work?

When you say 2.1 option on your setup does that mean it has a crossover, does bass management and sends data via LFE or you have some kind of external cross over? Is that work done in the amp?

My wonder is how is all this going to hook up?

I really cannot believe the difference in listening to this on Pure/Direct with the ICBM. I can hear there is more to be had and now I want it

Thanks!

[Ovation]

My 540D is a DVD-V/DVD-A/CD player with a 5.1 analogue output. I use it for movies (it's region free, does a great PAL>NTSC conversion (works in both directions and outputs PAL natively for those with projectors who can take that signal) and has internal bass management and time alignment) and for CDs (I use the Marantz for DVD-A purposes). In the 540D, I select SMALL for the front L/R, OFF for the centre and rear L/R and ON for the sub. The xover is fixed at 80hz (which works fine with my speakers) and I send those three channels to my receiver's 5.1 analogue input (I use a switchbox for those three channels for the 540D and the Marantz). When I listen to CDs, I select "pure audio" and the player does all the processing. When I watch DVDs, the signal goes to my receiver via digital output and the receiver does the processing (DD, DTS, etc.).

If you connect your player to your receiver with analogue cables, then your player's DACs are doing the work. If you connect via digital coax or toslink to your receiver, your receiver's DACs do the work (they are, in effect, outboard DACs from your player's POV). An external DAC would be a box in between your player and the receiver. In some cases, a receiver (or pre/pro) will take the analogue signal (like mine) and redigitize the signal. That uses an ADC and then a DAC (or several of each, as the case may be). My receiver gives me the option to redigitize any analogue input. "Pure Audio" bypasses all of that. Some pre/pros (Anthems, I believe are among them) redigitize ALL analogue signals by default.