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A Secrets SSP Benchmark Review
 

Anthem Statement D1 Surround Sound Controller, Audiophile Preamplifier, and Home A/V Control Center

 

Part II

June, 2004

Brian Florian

 

Speaker Setup

The real plum of the speaker setup is the "Room Resonance Filter", better known as the subwoofer single band parametric EQ we've been begging manufacturers for.  It is a simple, straightforward tool with settings for center frequency, width, and attenuation.  By design, it cannot provide a boost, only a cut.  Every room in the world will have its share of nodes, but there is always that one that ruins your day.  If it's deep down, you get a fat, burpy sound from your sub.  If in the upper bass, it ends up drowning out the really deep notes.  I won't bog down this review with the details of how to go about measuring your room and dialing in the filter.  Suffice it to say, this one feature can make the difference between "ok bass" and a subwoofer really living up to its potential!

In the D1, you may specify a completely different speaker configuration (large/small etc) for "Music" (the first setup then becomes known as "Cinema").  Then, it is a simple matter of specifying in each input's configuration menu which speaker layout that input is to employ.

You may elect to send the surrounds from the 5.1 analog input to either the sides or rears.  For any source you can elect to copy the surrounds to the rears, essentially using two speakers for each surround channel of 5.1 sources (including Pro Logic II).

At any time, using either the remote or the front panel, you can trim, in the range of -10dB/+10dB, any of the channels.  This is separate from the master speaker level calibration and is retained by the playback mode.  So if you decide you like the surrounds artificially high for Pro Logic II, you can boost them, and that boost will be retained.  The exception is any and all THX modes:  While you can trim a channel, it will always revert to 0 after the power cycle or even just the input cycle.  This is correct and by (THX) design:  When you press that THX button, part of the whole point of it is that you know the soundtrack is not being altered by any superfluous adjustments or processing.

Bass Management

And so it has come to this:  Bass Management gets its own heading in a review.  It probably should not be this complicated, but then again, I think about my days in the Boy Scouts.

Everyone had to have a Swiss Army Knife, and like everything else, they ranged from the mundane "knife and bottle opener", to models a full inch in width with saw, wrench, and tooth pick (tooth pick!?!), to name just a few of the items.

Truth is, there came a time, perhaps even just one time, that each of those tools came in handy.  All except that tooth pick.  As rough a bunch as we were, nobody dared to whip out their knife after a meal, extract the tooth pick, and go to work with it.  Yet there it was, and remains today . . . just in case.

And so it goes with some of these advanced bass management features.  Many we may never use, but if you are going to turn out the proverbial Swiss Army Knife of SSPs, you'd better have it all.

There are two "levels" of Bass Management in the D1.  Taking the simple route, each pair of speakers and the center channel can be set Large or Small.  "Small" crosses over that channel to the subwoofer (or large front speaker if there is no subwoofer) via the THX spec slopes of 2nd order high pass/4th order low pass.  There is a selection of crossover frequency from 25 Hz to 160 Hz in 5 Hz increments.

The D1, like the AVM-20, gives you the option to use a variable phase control on the subwoofer.  This sort of control is fairly common on subwoofers because prior to comprehensive time alignment in SSPs, this was the only way to "line things up" in terms of the in-room response of the sub/sat crossover.  For the most part, it is a little outdated in that respect, but there may be cases where its a handy final tweak.  Time Alignment delays the entire signal sent to the subwoofer (to correct for the distance it sits relative to the other speakers).  What a variable phase control does is selectively apply a group delay to the subwoofer's output that's proportional to the implemented phase shift. Think of it as a delay only around the crossover frequency. This allows you to adjust the phase of the subwoofer relative to the output you're trying to match.

Academically speaking, if you have THX speakers, there should be no need for the phase control (the linear delay is all we need).  In that scenario the electronic and acoustic slopes sum to be in phase.  With non-THX speakers where the high-pass characteristics of the acoustic slopes of the loudspeaker itself don't fit into the crossover scenario, simple time-alignment doesn't guarantee the optimal phase relationship.  In that situation, it may be beneficial to apply group delay (our aforementioned continuously variable phase control).  While we still hope for the day when Anthem will provide a 4th order high pass option (at which point you need only set the crossover frequency about an octave above the speaker's -3dB point), until then, the phase control option might just be the thing to dial the subwoofer in.

Under Advanced Bass Management, the crossover frequency for each pair of speakers and the center can be different from one another.  Somewhat counter intuitively, setting up a 5.1 or 7.1 system with a mix of crossover frequencies is not a sure bet to audio nirvana.  In our essay "Miscellaneous Ramblings on Subwoofer Crossover Frequencies" we point out that a mix of crossover frequencies will leave the room with an uneven bass response from the various channels because only one low pass is applied to the subwoofer, a fact which will leave you with either holes in the response of some channels, or overlap between some channels and the subwoofer (or a combination of both).

Despite what you may have read on certain forums, Anthem's bass management is not "flawed" or "incorrect" in this regard.  The slight holes or overlaps, created by fussing with a mixture of high pass frequencies in the D1, are at least smooth, like a tone control, and is the very reason Anthem gives you the ability to create holes and/or overlaps:  The room itself and its effect on system frequency response are often more influential than a less than perfect crossover configuration.  With some care, patience, and a great deal of expensive MLS type measuring equipment, it may in some rooms be possible to overcome some of the room's effect on the spectral response of the system as a whole by fudging the individual highpass points this way or that.  We offer this up with the caveat that it is either the measuring equipment or the ear which should make the final call and not mere academics.  A selection of high-pass points based solely on such things as speaker low frequency extension will almost assuredly not yield the best results.  Beyond all that though, there is no "correct" alternative way of doing it.  You cannot take a 60 Hz low-pass, an 80 Hz low-pass, and add them to an unfiltered LFE channel and expect to get anything remotely resembling the original soundtrack.  Because we are talking about summing electrically, if a manufacturer went this route, you would end up with comb filtering of the subwoofer signal, plain and simple.  You would "damage" the signal before it gets to the subwoofer, and the correct energy is no longer there to acoustically mate with the speakers in the room.

In the D1, Anthem now gives you the option to disable the low-pass normally applied to the LFE channel of 5.1 material.  Actually, it's not really disabling it, rather it simply adds the LFE channel to the subwoofer signal after the low-pass is applied.  In so doing though, you introduce the potential for phase response error (see above).  It is for this very reason that the LFE channel is normally combined with all the other material destined for the low pass.  Anthem tells us they play with the phase of the LFE channel to partially address these issues, and an impromptu sweep on that channel turned out nothing too odd, but it's not categorically correct.  So why is this option even offered?  The fact is, if you are going use an inordinately low crossover (say, 30 Hz) this is the only way to get the whole LFE channel.  Your call.

To try and put a wrap on Advanced Bass Management, the standard default settings, the 'standard' way to do bass management, was established out of a whole lot of work by some very smart people who took a very comprehensive look at real world scenarios. The ability to customize to your heart's content is a powerful tool, but one capable of drastic steps backwards if not used judiciously.

Remotes (Yes, that's Plural)

The remote is identical in form and function to the one supplied with with the AVM-20, except that two are included with the D1.  No, it's not in case you lose the first one, it's for Zone2 or 3.

The remote is fairly large, and every function of the D1 can be controlled with it.  An "All-in-One" remote, it has built-in codes for virtually any mainstream CD/ DVD player, VCR, TV, Cable box, Satellite dish, and so on. With the abundance of buttons available, I found it covered more of my equipment's functions than any other such "multi-function" unit I've ever seen. This comes at a small price though: The remote can only put on one hat at a time. It is either "the D1 remote" or the "TV remote" or the "DVD remote" etc. as selected by the buttons at the very top. The exception is the volume control which you can set to always correspond to the D1 no matter what other hat the remote has on. The buttons are a little mushy, leaving me uncertain as to whether I've pressed one or not, but it does illuminate whenever you are using it. It's nice because there are so many buttons, and finding the one you want by feel would be next to impossible. You'll still need to memorize which button does what since labels for many functions are not on the button but on the background, and thus invisible in a dark room despite the back light.

At this level of product, it's hard to be too critical of the supplied remote.  About 99% of the time, in only has to get you by until you set up the wand of your choice, be it a Harmony, Pronto (my favorite), an AMX system, or whatever.

All 24/192, All the Time!

Nothing else distinguishes the D1 more from its predecessor than this.  The D1 uses Analogue Devices AD1896s sample rate converters to take everything coming in to 24/192 regardless of input sampling frequency, including Dolby Digital and DTS after they've been decoded into discrete channels, and any digitized analogue material.  Quick sidebar:  Though the ADCs themselves are capable of 24/192, the maximum rate offered by Anthem is 24/96.  When we asked Anthem why this is, the answer was simple enough:  they found no benefit to digitizing all the extra ultrasonic noise.

The term "Upsampling" has been slapped around the last few years, and esoteric types have either touted it as the end-all, be-all, or as a carnal evil.  For our part, we've found more examples of it being poorly implemented or simply just not working to our satisfaction.  In my Onkyo receiver for example the upsampling yields noticeably different results when Pro Logic II decoded (and that just should not be).

But let's not allow a few bad apples spoil the barrel.  The truth is, sample rate conversion has been around forever (in digital years).  Early digital recorders ran at 50 kHz, while playback on CD was at 44.1, and 48 kHz is still the standard in movie sound, not to mention 14 bit, 16 bit, and so on.  An SRC (Sample Rate Converter) used to cost 50 grand, but of course, times have changed.

But why do it? The full-time 24/192 output allows Anthem to use a 3rd order Bessel filter which has the reputation of yielding the best phase response (and frequency response) of anything out there.  For those who are keen on this subject I suggest an excellent paper by the folks over at Rane which, although written in the context of speaker crossovers, explains the inherent virtues of the Bessel with more detail than I have time for here.

One could just use, as has been done for decades, more and more oversampling to get enough room to use the desired filter, but upsampling adds a couple bonuses in that bit to bit phase errors are reduced, and the process inherently provides a stage of jitter reduction which Anthem feels is enough, without getting into a big buffer, which would actually be a problem in A/V as the sync gets thrown off. 

The D1's DACs also have 128x oversampling (oh yes, still have to oversample) bringing the overall Fs to 24.576 MHz.   I'm not going to sit here and regurgitate Anthem's literature, but if you want to double check the math you'll find that for all intents and purposes, the audio range is practically untouched by the reconstruction filter.

What we should be left with is pure audio, nothing more, nothing less . . . literally.

Go to Part I - Introduction, The Design, and Functionality

Go to Part II - Speaker Setup, Bass Management, and Upsampling

Go to Part III - On the Bench, The Sound, and Conclusions

 

Copyright 2004 Secrets of Home Theater & High Fidelity
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