Another Zu Thread

The Pros have much more output potential and can be infinitely tuned in the bass. The 1.5's have a useful bass attenuator but I was never able to get them to pressurize my leaky room.

Kirk,

I think that you would prefer the Def Pros if you are a "hands-on" audiophile. If you are more inclined to set and forget your system, them the Def 1.5 might be a better choice.

The Pros offer more versatility but require more equipment, and thus, more investment. With the Def 1.5, a small integrated amp is all you need to attain world class performance.

Thanks for clearing that up for me. I was confused by thinking the 4 woofers were limited above 40hz but it appears that it is only the internal amp that has the limitations. Is this correct?

Thanks,

RWWMS

Ron,
As I understand it, the full range drivers roll off naturally in the range of 40 hz.in both models. With the 1.5, there is a choke which prevents the rear firing woofers from reproducing anything above 40 hz. With the Pros. you have the option of setting the upper reach of the rear woofers at any frequency that works for you in your room. Mike posted at one point that he crosses his over at 65 hz. so as to unburden his low output triodes and put more responsibility on the woofer amp. I can definitely imagine the benefits in such a decision.
In my case, I have experimented but always return my upper shelf to the 50 hz. range.
This has got to be the world's best reggae speaker.

With the 1.5's, natural response of the rear drivers is flat-ish in response and does not need EQ. I don't think flat-to-20 hz is an expectation with the 1.5's but most folks aren't too concerned with that. They are crossed steeply above 40 hz and only an attenuator is available to adjust their output. A person could probably dig into the speakers and change that XO point/slope but I'm not adept enough to try it.

The Pro subwoofers are professional drivers, capable of significantly more output than the 1.5 drivers. However, their response curve is ragged and must be EQed. Without EQ, they run to 1 khz and fall off sharply from there.

With my TacT I can adjust the main XO point/slope as well as that for the subs. While a certain amount of shared output (bipole) is useful, i.e. shallow XO slopes, doing too much like running the mains down to 40 hz will muddy the sound. Further, getting the little main amp out of the bass zone makes it perform even better higher up.