The beyma has quite drooping bass but very good midrange exension, this blue trace is shown in all the other graphs as reference. Measurements were made using XTZ Room Analyzer II, microphone at 80 cm distance on axis and with the horn propped up on a 50 cm high table (to reduce early reflections)
Next up is the Fane Crescendo 80W, an other pro element but with a higher Qes. Notise the incease in bass output
I have 10" bass drivers with what I thought was good slam, but horns are something else. Now I am thinking about building a pair. With some twist and turns of course. Just the basshorn is 40 kg adding top and driver the Klipsch La Scala is 78 kg, this is way to much in my taste. Replacing the MDF with 12mm plywood would cut the weight in half but it would also be to flimsy, a lighter structure either require a very different layout or fancy material that is both light and stiff.
I am sure that the midrange output can be affected a lot but changes in throat geometry, subbaffle thickness and so on. But I think some general conclusions can be made. For maximum over all output PA drivers are what you need. However, in a domestic setting were the demand for output is far less HiFi drivers might be better. The PA drivers tend to fall of in the low range.
The low pass frequency is way higher than the mass roll off that LP=2 x Fr/Qes. This does not mean that it will sound good to 1 kHz just beacuse it has output to that range. Other have found that simulation of drivers with modest BL work really well in this horn http://www.linnaraudio.com/simuleringar/kuben/index.htm
One way to tame a horn driver with to low Qes for the particular application is to add some series resistance.
Adding 0.7 Ohm as in an average crossover does not change much
These Thiele-Small parameters suggest a closed box in the 60-100 range, marginal for bass reflex and absolutly not a classical horn driver.
Excellent analysis, thank you very much!ReplyDelete