Simon's 3 way horn loaded mid top

Local students love to use HD15 for school dance party's. They lite and portable, with kick bass they say it gives a "party coulour" to the kind of music they play. With a tight budget It was a right choice for them when we built with very inexpensive mid tops.
Today they requested a design to replace mid tops on the end of they pole mounth.

HD15 pole mount:

HD15 with inexpensive mid tops:




I have put a design below together to keep it lightweight and compact as possible.
Expect to deliver outstanding SPL with clean transparent sound, not only in smaller configurations, possible to used with other loudspeakers to cover frequencies from 180Hz and up.
Compact arrayable trapezoid cabinet, constant 55º dispersion with three-way horn loaded system is intent to perform better without pushing any element to the limit. Switchable active/passive, with a moderate budget to build.

Following version is intent to use on the top of the HD15's pole mount with two-way active system one amp run's HD15 with active crossover from 50Hz to 180Hz (!) second amp powers the passive mid top's from 180Hz and up.
Note, ideally mid top should play from 120Hz but horn size and over all dimensions would drastically change which would be on expense of transportability. It is great compromise made to let opening frequency from 180Hz on the tops.

I welcoming all intelligent suggestions and ideas to improve this design.






Edited by cracker.a - 13 November 2010 at 12:20am

The biggest change I would look at would be setting the HF horn into the timber flares between lo mid and hi mid - this would get the HF physically closer to the hi mid to reduce lobing and allow a higher crossover frequency, and would also set it back a bit to improve time alignment.

If the hi mid driver was a closed back type, the entire rear chamber could be one, which could allow you to port the rear chamber either side of the HF flare for a little more low end extension - a relatively high lo mid to sub crossover point could limit you regarding positioning of both.

Otherwise, looks good!

soundguymatt wrote: looks very interesting - have you actually made any?

I have built and molded similar horns from fiberglass long ago. I have posted pictures on other threads. No, I have not made this particular version.
In my opinion, Fundamentals of the horn design has not changed, the difference from past to today that better transducers and more driver selection are available and amplification ratio WATT per Dollar become more affordable.

Centauri wrote: The biggest change I would look at would be setting the HF horn into the timber flares between lo mid and hi mid - this would get the HF physically closer to the hi mid to reduce lobing and allow a higher crossover frequency, and would also set it back a bit to improve time alignment. If the hi mid driver was a closed back type, the entire rear chamber could be one, which could allow you to port the rear chamber either side of the HF flare for a little more low end extension - a relatively high lo mid to sub crossover point could limit you regarding positioning of both.

I like your idea. Unfortunately this would change the over all dimensions in that case I would consider different design, please see on the picture below.
If powerful BL quality neo cone drivers are used along with custom made phase plugs this 3 way version mid top would be a very competitive sounding with Martin Audio Wavefront W8C.
This version takes a bit of woodworking skills to build, employs 12" / 8" / 1" drivers and will play from 120Hz !

Ibex wrote: Great design! Looks a little bit like a mini KF-850... What are the driver sizes? 10" LF & 8" MF?

You right ! After I browsed for EAW KF-850 I find similarity. I was not aware of this, generally EAW products would not be my first choice.
If you decide to build your opinion and feedback would be appreciated.
Size of the drivers should be on the print, design # 1 use 10" Mid Low / 8" Mid / 1" HF
design # 2 use 12" / 8"/ 1".





Edited by cracker.a - 09 November 2010 at 8:16pm

Hi Simon,

Thanks for sharing the design! Nice clear plans too

Do you plan to make the horns from fibreglass or wood?

You show a phase bung in the plans, how far along is it's design?

cracker.a wrote: I like your idea. Unfortunately this would change the over all dimensions

What I had in mind for the HF would not change box dimensions - something along the lines of


The top and bottom of the HF flare would be trimmed to suit.

Anyone care to spec drivers and do some plots for this design - looks like you could be onto something.