The Avantgarde Duo's are a very well thought-out design, but like all speakers embody compromises.
You see, it's not possible to build a reasonably compact woofer that goes deep, has high efficiency, and matches the radiation pattern of the horns. Not even close!
Avantgarde has opted for a fairly compact woofer that goes deep, which is probably the best decision, and provided a separate power amp and plenty of flexibility in the controls for dialing in the best possible overall sound.
Let me describe the two areas where the woofer system has compromises (this is not a criticism, just a description - compromises are inevitable in speaker design).
First off, there is a significant discrepancy between the radiation pattern of the woofer and of the horns. The horns produce an approximately 60-degree radiation pattern, and the woofers are approximately omnidirectional. Let's look at the implications of this - if the woofer level is set so that its first-arrival sound is at the same level as the horn's first-arrival sound, then the reverbrant sound in the bass region (resulting from that omnidirectional bass pattern) will be about 9 dB louder than the reverbertant sound in the mid & treble region. So, the bass will be overpowering.
Conversely, if we set the level of the woofer so that the net in-room volume level of the woofer and horns are the same, the first-arrival sound of the woofer will be about 9 dB down, with a resulting loss of impact (these numbers are estimations, but the trend they illustrate is valid).
So the woofer level setting is an inevitable compromise between a thick bass on the one hand, and weak bass impact on the other.
By the way, a bass horn would be the obvious solution because it could match the directional characteristics of the mid & treble horn, but bass horns are about the size of refrigerators.
Looking more closely at the wooferbox itself, there is an inevitable tradeoff relationship between box size, efficiency, and bass extension. Avantgarde has gone with a reasonably compact box size and deep bass, which means the efficiency is fairly low. Now, there is a correlation between efficiency and dynamic contrast, so we would expect the woofer section not to have the wonderful liveliness and dynamic contrast of the horns. While I'd have to say the woofer does better than expected in this area, there still is an audible dynamic discontinuity - the bass just isn't as lively as those horns.
Now, we all have differing degrees of sensitivity to different colorations and imperfections, so until they build the perfect loudspeaker, we're left to pick the set of imperfections we find least objectionable. If you are epecially sensitive to the lack of coherence between the horns and woofers, you might consider the Classic Audio Reproductions T-1.
The CAR T-1 has a very efficient woofer but it doesn't go as deep as the Avantgarde woofer does, and the box is quite a bit larger. The midrange horn used in the T-1 also has a wider radiation pattern than that in the Avantgardes, so there is less discrepancy between woofer and horn. I would say the CAR's are a more coherent loudspeaker in the bass, while the Avantgardes are more coherent in the high treble. I think the CAR's have some of the best bass I've heard come out of a box - they sort of shattered my anti-reflex-box prejudices.
I don't sell either of these, but I admire both the Avantgardes and the Classic Audio Reproductions speakers.
You see, it's not possible to build a reasonably compact woofer that goes deep, has high efficiency, and matches the radiation pattern of the horns. Not even close!
Avantgarde has opted for a fairly compact woofer that goes deep, which is probably the best decision, and provided a separate power amp and plenty of flexibility in the controls for dialing in the best possible overall sound.
Let me describe the two areas where the woofer system has compromises (this is not a criticism, just a description - compromises are inevitable in speaker design).
First off, there is a significant discrepancy between the radiation pattern of the woofer and of the horns. The horns produce an approximately 60-degree radiation pattern, and the woofers are approximately omnidirectional. Let's look at the implications of this - if the woofer level is set so that its first-arrival sound is at the same level as the horn's first-arrival sound, then the reverbrant sound in the bass region (resulting from that omnidirectional bass pattern) will be about 9 dB louder than the reverbertant sound in the mid & treble region. So, the bass will be overpowering.
Conversely, if we set the level of the woofer so that the net in-room volume level of the woofer and horns are the same, the first-arrival sound of the woofer will be about 9 dB down, with a resulting loss of impact (these numbers are estimations, but the trend they illustrate is valid).
So the woofer level setting is an inevitable compromise between a thick bass on the one hand, and weak bass impact on the other.
By the way, a bass horn would be the obvious solution because it could match the directional characteristics of the mid & treble horn, but bass horns are about the size of refrigerators.
Looking more closely at the wooferbox itself, there is an inevitable tradeoff relationship between box size, efficiency, and bass extension. Avantgarde has gone with a reasonably compact box size and deep bass, which means the efficiency is fairly low. Now, there is a correlation between efficiency and dynamic contrast, so we would expect the woofer section not to have the wonderful liveliness and dynamic contrast of the horns. While I'd have to say the woofer does better than expected in this area, there still is an audible dynamic discontinuity - the bass just isn't as lively as those horns.
Now, we all have differing degrees of sensitivity to different colorations and imperfections, so until they build the perfect loudspeaker, we're left to pick the set of imperfections we find least objectionable. If you are epecially sensitive to the lack of coherence between the horns and woofers, you might consider the Classic Audio Reproductions T-1.
The CAR T-1 has a very efficient woofer but it doesn't go as deep as the Avantgarde woofer does, and the box is quite a bit larger. The midrange horn used in the T-1 also has a wider radiation pattern than that in the Avantgardes, so there is less discrepancy between woofer and horn. I would say the CAR's are a more coherent loudspeaker in the bass, while the Avantgardes are more coherent in the high treble. I think the CAR's have some of the best bass I've heard come out of a box - they sort of shattered my anti-reflex-box prejudices.
I don't sell either of these, but I admire both the Avantgardes and the Classic Audio Reproductions speakers.