I thought discussions of other speakers were off topic to the forum and not associated equipment, but since a Super Moderator suggested this thread be created here it is. Thank you, Widget! Because this topic is more general than any specific speaker or brand, I have placed it in General Audio Discussion.

I am talking about Hammer Dynamics Super 12 speakers in particular here, but by way of comparison this could be all over the map. This realm is called Full Range Drivers and is almost identical and coincident with Single Driver speakers. Open Baffle is an installation subset of this field. Let me speak generally about Full Range and with the background in place the Super 12’s might make some sense.

One of the problems with multi way speaker systems, that would be two way, three way, four way, etc, is the crossover point(s) always dividing the really important frequencies where the fundamental tones of musical instruments and voice reside. Not the deep bass or the highs, but where the heart and soul of the music lives. Thus the famous phrase, “We live in the midrange.” As will be noted by the development of bypassed and charge coupled crossovers, dividing frequencies with networks (crossovers) gives rise to certain problems that affect music reproduction. We are always trying to minimize these side effects, but when great sources, great amplifiers and decent listening rooms and hearing are brought together, we can hear these effects and given a comparison to listening experiences where this is not the case they sound bad. They get between us and our music, and after all this pursuit of ours is all about the music.

What are these better listening experiences where this is not the case? Live music and full range driver reproduction where any crossover points fall outside the range of frequencies where our sensibilities are offended if the reproduction is compromised in some jarring way. The reason for multi way speakers is to use a mix of transducers that by their specialized nature allow better reproduction of each selected frequency band. Good idea, but not quite so good if we make two or more frequency bands out of the range where our music appreciation “lives”. This problem manifests itself not only with crossover distortions but also with different individual transducers, often even different types of transducers, non identical at least, producing adjoining frequencies. In reality, they are not only adjoining but also overlapping – even with very steep crossover slopes. When you have a bigger cone and a smaller cone, a cone and a compression driver, a conventional driver and a helium tweeter, whatever, these different versions of the same frequencies and of adjoining frequencies create problems. All this should sound inaccurate and strange, and it does. Yet another set of differences between live music and our reproduction of it.

So why are stores not full of Single Driver systems? Well, they once were. Then music reproduction went from 60-9000 hz to 20-20000 hz to 16-45000 hz. Designing a full range driver with good sound for 60-9000 was hard enough. Any more range and the compromises ruin the sound. Now there are still attempts at Single Driver systems, but Full Range plus some help on the low or high end are what is happening more and more.

Widget mentioned the Lowther and Fostex based systems. These cone speakers are still being installed in an endless parade of enclosures designed to overcome their sonic problems. Especially in the case of Lowther, a very old design that is very expensive to produce properly, the bass response of these small, stiff cones falls off the table as high as 300hz. Rather than dropping like a stone, it was noticed that the response falls in a curve. Steep, but a curve that does go below 80hz. What is required here is a very complex horn that has a rising rate bass response exactly opposite the falling response of the driver. If you think designing enclosures for multi way systems is challenging, try this hair pulling exercise. They are still trying to get it perfect, but of course nothing is. People familiar with great sound but not with these systems often hear another issue immediately. The direct sound from the cone sounds different from the horn output in many respects. Essentially two different sounding transducers; a single driver two way system.


So what are we to do? Give up? No, there are other workable solutions. Design a driver full range from 100hz on up and use a sub. Omega makes a range of small speakers like this, and home built Fostex and Lowther systems go this way sometimes. JBL used to make a speaker that was superb at this, but it is I understand long gone. The library has specs for the LE8T. http://www.lansingheritage.org/html/...-comp/le8t.htm


Another solution is to make a larger driver and use a super tweeter instead of a sub. There is one example I am personally aware of, and this brings us to the Hammer Dynamics Super 12.