Apogee DAX Crossover Reviewed

Published On: February 13, 1989
Last Updated on: October 31, 2020
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Apogee DAX Crossover Reviewed

Although it is actually a crossover for use with the Apogee Divas and Grands, it has graphic EQ capabilities usually found on a preamp. Obviously, if you have an Apogee Diva you want to use this instead of the stock passive crossover unit, if you can find one.

Apogee DAX Crossover Reviewed

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Two types of add-ons are immune to the antipathy caused by such 'evils' as graphic equalizers or click suppressors. Most diehards will forgive/approve of dedicated extras of any type because they can be regarded as extensions of the basic components rather than as sonic intruders. The other 'okay' black box is the more sophisticated, usually external crossover system which allows the user to bi-amplify his or her speakers. As the latter most often tends to be the former, you can assume that most hi-fi casualties approve of dedicated crossover systems with even greater vigour than they'd show for 'universal' crossovers.

Additional Resources
• Read reviews of floorstanding speakers from HomeTheaterReview.com.
• Read stereo preamplifier reviews by the staff of HomeTheaterReview.com.

After a flurry of activity a decade ago, when 'active' and 'bi-amping' were hot buzzwords, the hi-fi community reverted to the simpler, less costly path of conventional or single-amplifier
operation, partly because of a growth in popularity for bi-wiring. Virtually a halfway house between the amp-per-driver luxury of bi-amplification and the mundane operation of conventional wiring, bi-wiring swept the industry in the best trickle-down manner; it's now found on quite inexpensive two-way box speakers. Among the champions of bi-wiring was Apogee, whose complex full-range ribbon systems benefitted immeasurably from the technique. It also served as a respectable compromise for Apogee owners who couldn't afford a second high-current amplifier and outboard crossover for true bi-amplification.

Although a number of companies, like Audio Research and Krell, produce active outboard crossovers of a universal nature, the design team at Apogee accepted the premise that the best crossover is dedicated to the speaker with which it will be used. Even the easy-to-access specifications of crossover points and slopes will not guarantee a perfect match, and simply setting a universal active crossover network to suit a speaker with, for example, a 6dB per octave slope at 2kHz won't necessarily result in the ideal pairing. Apogee felt that good as some of the currently available crossovers may be, they cannot optimize a system unless they've been designed specifically for that system.

In addition to offering attenuation of up to 6dB in 1dB steps for the woofer and the mid/tweeter, the company's DAX (Dedicated Active Crossover) allows the user to adjust the balance between woofer and mid/tweeter in 0.2dB steps and to adjust the 'rake angle', a sort of 'hinge' in the tonal balance which tips the midrange above 1kHz in +/-0.5dB steps at around 5kHz. The DAX also provides facilities to match the crossover to the amplifiers for input impedance loading, gain characteristics (for using different amplifiers top and bottom) and for using single-ended or balanced operation. Because of the way the various DAX controls interact, the unit can vary the group delay, important when sculpturing the gain vs. phase relationship -- and one aspect of DAX-equipped Apogees is near-perfect phase response.

By addressing both the requirements of only three specific loudspeakers (you order your DAX preset for Caliper Signature, Duetta Signature or Diva) and allowing for matching to any amplifier, the DAX provides what amounts to total control for biamplifying their speakers. This in turn enables the listener to tailor the sound for both the electronics and the listening environment, beyond the obvious tweaking one can perform by speaker positioning, cable selection and wholesale changes of hardware. In the case of the Diva, the DAX takes over from the passive box with its four toggles for boost or attenuation at four frequencies, but the switch for the tweeter on the passive box remains operable. This is because the DAX is a two-way crossover while the Diva is a three-way system. The DAX sees the tweeter and midrange as one section; the toggle on the passive box allows the user to cut or boost the tweeter by 2dB in addition to shaping the operation via the DAX.

The Diva's passive box therefore takes on a different role and no less than three-and-a-half pages of the owner's manual deal with converting it for use between the DAX and the Diva. You don't have to worry about this because your dealer will undertake the conversion, which involves replacement parts supplied with the DAX and the bypassing of much of the passive enclosure's innards; remember, the bulk of its functions are now controlled by the DAX. Still, if you enjoy spending a couple of hours inside a nest of wires, be my guest. With the Duetta, instructions are also supplied for user conversion, but the Caliper must be modified by
the dealer.

Speaker conversion aside, the actual installation is a doddle if you've ordered your DAX correctly. I asked for a version set up for using single-ended amplifiers, the same top and bottom (two Aragon 4004s), but even if I decide to change, the manual covers the range of adjustments which are accessed via dip switches inside the DAX. If you want to mix amplifiers, you'll have to know the gain characteristics, while choosing between balanced and single-ended operation merely involves flicking the toggles to the left or the right. As for input impedance matching, the DAX arrives in standard form with 80k ohms preset for single-ended operation or 10k ohms for balanced. Four other values are available for either mode. (See specifications below.)

The DAX slips into the system just where you'd expect it to, between the preamplifier and the power amps. I ran the Audio Research SP-9 into the DAX and the DAX into the Aragons via
Master Link cables, with Lieder speaker leads connecting the amplifiers to the modified passive boxes. The gold RCA sockets on the back of the DAX are clearly marked, the rear split into left and right halves, so feeding the four signals from the DAX is no more confusing than wiring up a conventional stereo set-up.

The DAX itself is one of the most attractive pieces of high-tech hardware I've ever seen. Apogee has come up with a satin black finish which screams of luxury, visual confirmation that this is one high-priced goodie. The fascia is split into three sections, the left and right thirds containing four rotary controls each while the centre consists of what might be the most useful
display yet to grace a hi-fi component. Left-to-right, the groups of knobs include woofer attenuation, woofer-mid/tweeter balance, mid/tweeter attenuation and rake, with separate knobs for each channel. The Hewlett-Packard display, glowing a fetching green (which must be this year's colour as the Aragons, the SP-9 and the CAL Tempest II power supply also glow green), gives you digital read-outs of every setting, again separated into left and right. With this bank of controls and the digital confirmation, it's possible to set up the system for sonically asymmetric rooms using test tone generators and spectrum analyzers, or you can (as you'll see) use it to compensate for recordings with any previous settings being easy to note. Power to the DAX is via an outboard unit a third the size of the DAX. This houses the on/off switch
and a front-panel LED; it connects to the DAX with a locking cannon plug.

Apogee presupposes that its customers know what they want to hear, so instructions for setting the controls amount to little more than doing it by ear. I did manage to find out how Apogee's Jason Bloom approaches the problem each time he sets up a DAX and his advice means less to-ing and fro-ing. Future DAX owners, take note:

1) Adjust the mid/tweeter attenuator, which is another way of asking yourself, 'Do I need to cut the upper frequencies?' (In the unlikely event that you need to boost those frequencies, there's still the toggle on the passive box.)

2) Adjust the balance between the woofer and the mid/tweeter. This maneuver attenuates either portion in 0.2dB steps. You won't believe it until you hear it, but this operation is audible
enough to change the character of the system from forward-sounding to muted, despite the seemingly limited operating range. And only a deaf person or a reactionary/liar would deny the audibility of a change of even one step.

3) Adjust rake angle. By tipping the response up or down in 0.5dB steps, it's possible to compensate for brightness or dullness without any loss of information or frequency extension. I've a feeling that owners of Quad electronics will find this not a little familiar.

4) Adjust woofer attenuation. This is especially useful for those who would have Apogees in small rooms. (No, there's no woofer boost because it's unlikely that anyone would ever need it. And if they do, they can always go back to steps 2 and 3.)

But here's where it gets bizarre. Word had reached me that the DAX, even with everything at '0', improved the performance of the Divas beyond the gains that you'd expect from mere biamping. That struck me as odd until I accepted that the DAX -- two amplifiers instead of one notwithstanding -- is a vastly more sophisticated crossover than the passive box supplied as standard. And not only does it do a better job of signal splitting, the DAX also optimizes the interface between amplifier and speaker, allowing the amplifiers to see a trouble-free resistive load instead of the complex impedance of passive-crossover'd Divas. But the reason it bothered me is because I preferred the DAX at '0' on four out of five recordings. Like most of you, I refuse to believe my good fortune when I find that my system and/or room needs no help.

And so it came time to play...

Read about the DAX's performance on Page 2.

Here's where I usually go crazy and tax Roget to the limits. It's also the point where I regret that specialist magazines haven't taken note of what's going with graphic novels, because I sure could do with some help from the likes of Alan Moore. Picture a frame-by-frame EC-type cartoon of KK, saliva dripping down his stubble'd chin, eyes wide and nearly touching his Zeiss lenses. The hair -- what's left of it -- is up on end and a balloon from KK's mouth reads 'YAAARGH!' or some such exclamation. Yeah, the DAX is like that. If this wasn't a family magazine, I could really go to town, but it is so I can't and besides, Editor Harris prefers to have contributors of sluggish pulse.

Well, THAT'S TOO DAMNED BAD!!! The DAX is simply the niftiest little marvel I've ever used, a jolt of steroids which boosted a system that I thought could only be improved by tiny increments. It is to the Diva what spinach is to Popeye. And it's Kryptonite
to everyone else.

Listen: When I set up the DAX, I was also playing host to somebody who has no reasons for wishing success on this product. I won't embarrass him by revealing his name; all I'll say is that he's from the competition. Anyway, we put on some serious music -- Billy Cotton's Wakey Wakey Show and George Melly on C5 Records -- and he just looked at me, uttering a British expletive which rhymes with 'buckshee' and grinning from ear to ear. We fiddled with the knobs, cranked up the volume, dug out some naff mono CDs of ultra-thin-sounding British pop from the 1960s. We rocked. And we heard the Kinks' 'Waterloo Sunset' like it's never been heard before.

What the DAX does is turn the Diva from a simply magnificent speaker system into some kind of limitless performer which virtually defies criticism. Auditioning the system with music of
utter familiarity, I was embarrassed at how much more the Diva could offer. And the areas which benefitted most were areas which I didn't think need any improvement.

The most blatant manifestation of the DAX is the way it allows the Diva to present deep bass notes. I admit that, on occasion, the Diva can sound a bit overwhelming, with bass which thunders and roars. Suitably DAX'd, the Diva's extension remains constant but the bottom octaves acquire a sensation of greater control. That's with everything set at '0'. You want to tighten things up even more or recess the midband for reggae or House at the max, a touch of the controls will shift the balance to suit your tastes.

Equally chilling are the gains in soundstage creation, image placement and specificity. The Diva, sans DAX, is simply one of the best imagemakers I've used; the DAX opens the sound and removes and last vestiges of texture to the silences between instruments and players. What the controls do is allow you to dial in the most realistic stage depth in a manner not unlike that of the control unit for the Infinity IRS Betas.

And the more you learn about the controls and their capabilities, the more they take on the nature of a focussing ring on a camera lens. What they do is nudge the sound one way or the other in tiny, repeatable steps and without any sense of added noise.

But here's where I find myself at cross purposes with the whole concept of active crossovers. Until the DAX arrived, I thought of trick crossovers as a way of optimising the speaker, something to set once and leave alone. Because I reviewed the system with such a wide range of material, from LP transfers of 78s from 1926 to too-hot-to-handle club mixes to purists' delights, I found myself using the DAX to compensate for the recordings rather than the hardware or the room.

The DAX is ghostly quiet and absolutely precise in everything it does. Although it doesn't have an instant bypass mode to allow the user to compare settings in A/B fashion, the digital readout means that you can tweak something and return to a previous setting for comparison purposes with absolute accuracy. Starting each LP or CD with the readings at '0', I then altered the sound as per the above-mentioned steps. After a few hours, I was able to ignore the four-step procedure and go straight to, say, woofer-mid/tweeter balance or rake if I knew that the other controls didn't need adjusting. Judicious use would suppress ludicrous sibilance (some Juice Newton and Poco recordings) or restore weight to thin recordings (most Beat Boom UK pop).

What I don't want to do is give the impression that the DAX works like a dream-world equalizer or even like the rather splendid Cello Palette. The effects are most assuredly audible, even those 0.2dB changes, but the adjustments to the sound are too subtle and too precise to suggest any gross tampering. What it becomes, then, for an Apogee owner is the ultimate surgical instrument.

Which leads me to the two questions I asked Apogee. The first is whether or not they'd be offering it with remote control, because it sure would be handy to be able to adjust it from the listening position. They have thought about it, but the price -- already breathtaking at #4500 -- would have to go even higher and they're not certain the demand is enough to warrant the option; call it a 'maybe'. The other question is whether or not Apogee would consider making a version for use with other makes of speaker, but -- in line with their arguments about the need for absolute dedication ot each model -- this would be too impractical and probably too much hassle in simple political terms.

So that means that this joyous device is only available to Apogee owners. All I can say to those who possess Duettas, Calipers or Divas is that you must forget about everything else in your upgrade progression and put the DAX at the top of the list. And here's a justification if you need it:

In the year I've been using the Divas, I've tried them with single amplifiers (in bi-wired mode) running to over #10,000 per pair. The DAX offers such a transformation with even the affordable Aragons that two Aragons plus DAX at a grand total of #8100 is preferable to any other non-DAX combo I can name. What I have yet to experience are the gains of going to balanced operation, and I still want to try the mix'n'match flexibility, especially as the DAX renders the system 3dB more efficient and therefore even safer with big valve amplifiers. As it stands, the DAX is nothing less than the most exciting development yet for Apogee owners, a device so clever that I wish other manufacturers would offer similar units for their bi-ampable speakers. #4.5k for a black box? Yes. And it's worth ever single penny.

Additional Resources
• Read reviews of floorstanding speakers from HomeTheaterReview.com.
• Read stereo preamplifier reviews by the staff of HomeTheaterReview.com.

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