Battery Powered 3-way Horn Loaded PA

Some friends and i intend to build a battery powered PA-system before summer. The system needs to be battery powered because it will be used outdoors and we intend to bring it to the Roskilde festival, where diesel generators are forbidden.

Our main concerns are output and sound quality, but the size of the individual cabinets should be no larger than what two persons may easily carry for longer distances. The music we play will mainly be jungle, grime, dub and garage. We hope to play for crowds of about 50-100 people.

With the system running on a limited supply of energy, efficiency of design is paramount, therefore i believe a tri-amped fully horn loaded system with an active crossover is the way to go. Ideally i would like the system to reach 30 hz, but i am aware that range in the lowest octaves is always at the cost of efficiency, therefore maybe 50 or 80 hz would be a better goal?

From what i have read the tapped horn looks like a very promising design that achieves higher low-frequency efficiency than any other i have seen. Mutual coupling also seems like a good way to achieve higher efficiency. What confuses me is that almost every TH-design i have seen uses compliance controlled high x-max low sensitivity drivers. I understand that this is beneficial when trying to reach the very lowest frequencies, but doesn't using these kinds of drivers negate the increased efficiency of the tapped horn? Would it be possible to design a TH around a mass controlled driver with higher efficiency but lower x-max? Also, are there any other high efficiency sub designs i should be considering? Are there any TH-designs that are generally considered to be superior?

For mid and top i am still quite clueless, so any and all suggestions are welcome:)

For amplification i gather that class-d tripath is the way to go when efficiency is important. If there are other ways to do this i am indeed interested.

I thank you for any response or suggestions you may have :)


2001-02-04 4:23 am
Use a MaxBass 12V processor from PPI.

Use a horn HF driver above about 2Khz.

Use a stack of six~eight midrange drivers in a vertical line, cut off around 200hz or so.

Use a tapped horn woofer with a 50hz or so cut-off.

The MaxBass will take any 30hz material and generate 90hz and 150hz that will sound like 30hz (to your ear). This is a time-honored cheat first used by organists. They were faced with music scored for a 16' stop (32hz), and only had an 8' stop instrument (64hz). By playing the third and fifth intervals it sounded like the fundamental (that could not be played on their instrument).

I own both the rack mount pro version, and the PPI 12V version. The PPI is better, and costs less.

Does it sound good?


Does it feel the same?


But it may be the best solution for you. I use it mainly for parade floats (and similar).

It is also good for environments that massive 'feel' is not tolerable (weddings, schools, etc), but yet you want it to 'sound' like you have a lot of bass.

This type of approach will yield about 10dB more output than conventional thinking for any given size and power.

The medium efficiency drivers with a Qts around 0.3~0.4 will probably work best for the tapped horn, play just as loud as you think the more efficient drivers will, and actually have more maximum acoustic output (because of their generally higher x-max).

The efficiency with a pair of 10's should be well over 104dB/2.83V, and still be able to be moved. The mid lines should be similar, if not higher (104dB and up), a 108~110dB horn will be small and affordable.

If you fill in your country of origin we might be able to recommend driver brands, and designs.
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I have a Waves maxxbass 103, would be really keen to get my hands on another one for use with 12v systems
Very impressed with the results, gives my small 8" speakers plenty of "boom" for outdoor party use (on a tricycle) - a bit artificial when listening critically, but for impact and efficiency I love it
Have you seen the boominator? Use that as guidance - making bass outdoors is hard work, especially when relying on battery power


2016-03-30 7:02 pm
Thank you for your very enlightening reply djk. Using a MaxxBass unit seems like a great way to emulate low-freq extension without sacrificing efficiency, but as chris661 pointed out they seem to be quite difficult to find. Maybe it could somehow be implemented in a minidsp?

I live in Norway, the availability of drivers here is quite sparse, so i will have to order online what i cannot source locally. My budget for the complete system is about 2500-3000 $.

I have some additional questions. Wouldn't 6~8 mid-range drivers completely out-power the bass? Also, wouldn't it be more efficient to horn-load the mid range as well?
Do you have any recommendations towards an active crossover or a dsp?


2001-02-04 4:23 am
Precision Power PPI BP.8

PPI BP.8 | eBay

"I have some additional questions. Wouldn't 6~8 mid-range drivers completely out-power the bass? Also, wouldn't it be more efficient to horn-load the mid range as well?"

A horn would be better (but huge), and would not have the same kind of bandwidth.

I have a design for two B&C 12PE32 that works well from 180hz to 1Khz or so, it is 40"x30"x24".

My 48"x36"x24" version circa 1981.

At one time I had 30 of these mid horns.

Thy are 20"x30"x24", the first one I listed is basically two-in-one in plywood (vs the fiberglass).

I prefer the short line of mids for smaller jobs, I have some quad 8" using fullrange guitar-type drivers that were inexpensive, sound quite good, and are about 102dB/2.3V and 8Ω. They are high Qts types and I run them open-back (dipole).

Lots of these type of inexpensive drivers available, Faital Pro and Tympani offer many to choose from.
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2001-02-04 4:23 am
"That PPi BP8 appears to be a narrow EQ boost, not a psychoacoustic dsp
??? "

Read the OM (linked to above), it's built under license to MaxxBass.

will introduce the first
processor to
the automotive market. The
processor is ideal for
improving the perceived bass response in door mounted speakers
without upgrading the speakers or amplifiers.

I did a TH for a pair of B&C 10NW64 that are over 102dB/2.83V, flat to 50hz, usable to 200hz (with a notch at 200hz), and are under 100 Liters (net). The design will handle 40V without exceeding x-max.
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