Apogee Duetta II loudspeaker George Graves part 2

One of the more curious aspects of the Duetta II design is that Apogee provides no way of bypassing the speaker's built-in crossover. So even though there are separate sets of terminals for the woofer and tweeter on both speakers, it is impossible to actually bi-amp them. The Apogee instruction book does show how to use double amplifiers with a separate amp for the woofer and tweeter, but these amps are both fed a full-range signal from the pre-amp without the use of a low-level crossover. I can see no real advantage to this scheme except in the case when one's amplifier size is marginal.

Though the Duettas are less of a problem to drive than some of the older Apogee models, they still require gobs of current. Apogee recommends a minimum of 100Wpc, but after living with them for a while, I recommend at least double that. It's not the power that the speakers need so much as it is the current. Amplifiers get their power ratings by figuring the power using the output device's voltage swing across the load (usually 4 or 8 ohms), expressed as Power (P)=Voltage (V) squared, divided by the load Resistance (R). It should be obvious that an amplifier's power supply must be able to supply enough current for the voltage to swing high enough to develop its power rating across the load, but often, due to cost restraints in a very competitive market, a power supply will be designed to do this with little or no reserve. When the impedance drops below 4 ohms or so, the power supply just cannot provide enough current, and the DC voltage available across the output devices drops. In this case, a current-hungry speaker like the Duetta should be given plenty of watts in order to be assured of enough current.

When you try to drive these speakers with less than about 200Wpc, they suffer in dynamic contrast. It might be advisable (for cost reasons if no other) to purchase a duplicate of one's current amp and double-up by using one channel of each amp to drive the woofer, and the other channel to drive the tweeter. This will divide the load evenly between the two available channels, thus reducing the power requirements on each. By dedicating one entire stereo amp to each speaker, you will end up with the advantages of a "dual-mono" amplifying set-up as well.

The sound: First of all, the most striking aspect of the Duetta sound, and the one that first assaults the sonic senses, is the bass. It is, in a word, unbelievable. In my main listening room, the -3dB point seems to be about 25Hz. The bass is not only plentiful, but is tight and quick to boot. Organ music is visceral in a way that I would have thought impossible from bipolar speakers.

In large measure, the manner in which a bipolar speaker couples to the room determines the ultimate low-frequency performance which can be expected. As stated earlier, the Duettas like to have lots of room around them. When I first set up my pair, I placed them the same distance from the back wall as I had placed the Magneplanar Tympani 3Cs which preceded them. The low end was impressive enough, but the midbass between about 80Hz and 120Hz exhibited a slight, broad peak, which, although it did not give the feared "one-note-bass" effect, was nonetheless unpleasant. I found that in my listening environment, it was necessary to move the Duettas out to about 40" from the rear wall to totally remove this midbass hump. This experience, of course, merely reinforces the fact that bipolar speaker placement is largely a matter of experimentation, and what works or doesn't work in my listening room has little to do with what might work in yours. I can promise you bass extension rarely heard in audiophile speakers these days, and I can tell you that the quality of that bass can be startling.

The midrange in the Duettas is also excellent. After fixing the aforementioned cable problem, the midrange glare was replaced by a finely balanced midrange which has the rather unusual ability to really belt when called upon to do so. If you've ever been in a room where live brass are playing, you have probably noted how really "brassy" they sound. The sound just sort of blats at you in a rather loud and raucous manner, and is anything but polite. Very few speakers can capture this blast of wind and make the listener sit up and take notice. The Apogees do this very well. They also have the ability to separate instruments and delineate dense orchestral textures. It seems that no matter how loud and complex proceedings become, the speaker never loses composure, and things never become thick and congested.

The high frequencies are, of course, the range of the Duettas most affected by cable differences. With the Symo cable the highs are flat (with the tweeter switch in the up position) and well-extended. (Measuring nearfield frequency response with a calibrated microphone coupled to a Hewlett-Packard model 400 audio voltmeter and a swept frequency source, I was unable to correlate MC's rolled-off highs in Vol.10 No.1, finding the -3dB point to be at 18kHz (MC measured -3dB at 12kHz). Jason Bloom explained that this was due to the fact that these speakers have been improved considerably since MC reviewed them, and in fact not only have much improved highs, but are 5dB more efficient across the board as well!)

The most impressive characteristics of this speaker's top end are the speed and the utter lack of coloration. The high-frequency detail is astounding. The tweeter ribbon's ability to recreate the resinous quality of properly miked strings gives me goosebumps, and triangle and bells have the proper attack and decay (very difficult for most speakers; the only other speakers I know of which have this quality are the ribbon-tweetered Magneplanars and some electrostatics). Very impressive.

Conclusion: Apogee Duettas are capable of near-state-of-the-art performance, but are so sensitive to cables that without the right ones, you won't get the performance you paid for. They are also amplifier-sensitive. To sound their very best they need a good power amp with lots of current-sourcing capability. If in doubt, don't buy these speakers without first hearing them with your own amplifier. My experience with dipole radiators is that even though they are room-placement-sensitive, it is a rare room indeed where there isn't a place where they will sound satisfactory. Be prepared to experiment.—George Graves

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