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Author Topic: 6th Order Bandpass  (Read 6156 times)

Andrew W

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6th Order Bandpass
« on: July 16, 2004, 06:19:41 am »


Hi there,

I am still using front loaded 18 boxes, and have been thinking about building LABs for sometime. In reality I probably only need that sort of output 5-6 times per year - hardly justifyable.

Anyway, a couple of years ago I thought about building 4 single 18 inch bandpass boxes. Some people love them, so hate them - those who hate them complain about the trasient response.

I have noticed "lots" of banpass boxes getting around in rigs from Nexo to Mackie to JBL etc, and I am thinking about building them again. You know the drill - maximum output, smallest size.

Are bandpass now in vogueAndrew Watts
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ChainedDragon

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Re: 6th Order Bandpass
« Reply #1 on: July 19, 2004, 12:58:29 am »

I was thing about iso loading a decware "house wrecker" band pass box


I dont have the know-how, or money to build the labs (seeing how you need a set or more to hit good)
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danfowler

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Re: 6th Order Bandpass
« Reply #2 on: July 19, 2004, 09:59:43 pm »

Hi Andrew,

Band pass boxes, in my opinion, are as hard if not harder to build CORRECTLY than the Lab Sub. The 6th order you refer to has 2 resonant chambers, one tuned to one freq., one to another, each to theoretically cover a wider frequency band. Hard to mate a "off-the-shelf" driver to that with those peculiar parameters AND high power handling.

Most of the BP boxes I've heard sound terrible (with the exception of a NEXO S.2) and don't go very low in the small box designs. They seem to "latch" onto one note in the program material and moan away at that one frequency. The more of them you stack together, the worse it becomes. Maybe I just haven't heard a good design implemented yet. I've only mixed 2 1/2 decades now.

I found it difficult in the extreme to mix on Manifold boxes in the 80's and 90's, and that was, I think, the pinnacle of BP box development. The drivers were always blowing and sound companies were always showing up with 2 or 3 drivers working in a box.
I ALWAYS went to the crossover and created a "hole" at 150 to almost 200hz if I could. The quantity of bass was great and it reproduced the kick signal with abandon. The bass guitar response SUCKED. Wolf notes everywhere. It was just a complete nightmare if the room co-resonated (in clubs usually the long wall distance in feet x 2, a la 200 hz) and they usually DID co-resonate a LOT. I could almost NEVER get smooth freq. response in the majority of the venue. There was always this "sweet spot" and most Sys. Engineers made sure mix position was there! It always formed a triangle with equidistant sides with one side being the center distance between the 2 stacks. Outside that triangle there were all kinds of cancels, nulls, buildup nodes, you name it.

Try to mix on that every day!

The reason the NEXO works so well is it only performs in one octave (32 to 64) and it is electronically controlled, actually making it a 7th order BP. It distorts, no doubt about it, you just can't HEAR the distortion very well in that octave. It arrays and throws well, packs good on the truck, and only weighs 187#, so it is a "good" BP box IMO. Only thing that takes getting used to is it's a 3 ohm box. It takes a big mondo amp to drive it.

Is there a design you've found and prototyped that works to your satisfaction?

Dan 0;)
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Andrew W

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Re: 6th Order Bandpass
« Reply #3 on: July 21, 2004, 05:48:04 am »

Thanks for the detailed response.
I was considering building somelthing like the X1 from the speakerplans.com website.
If only there was a horn loaded box that ran 40hz to 100hz that was really compact - ah well, we can't defy the laws of physics!
Andrew
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Re: 6th Order Bandpass
« Reply #4 on: September 28, 2004, 05:05:56 pm »

Ask Bill.

http://www.billfitzmaurice.com

particularly, check into the Tuba 24. When loaded with the Eminence HL-10 (the smaller brother of the LAB driver), supposedly it is excellent through that range. You may want to put a subsonic filter on it at 35-40 Hz, though, to maximize headroom. For really light (musical instrument) duty, it can even work with a Beta-10, and demolishes a Peavey SP-series 18" sub in both loudness and extension, at the same time. I think I still have the AudioXPress magazine where details about the Tuba 24's design process are given. The plans aren't in there, though they're only $10 from the Bill F. website. Bill F. also designs W-style horns for musical instruments, but the Tuba 24 box can also find use as a sound reinforcement sub.

Its usefulness is limited by the fact that it is really only a single-10" even though its horn uses innovative design to fit enough horn into that space to provide the extension you need. The HL-10 is 8 ohms and has only 300 watts power handling, so it takes lots of amp to drive into those 8 ohms unless you stack two of them vertically per side for 4 ohms. At the price, though, you can afford to do that as long as you've got transportation. They should fit together well if you turn the upper one upside down so the two horn mouths integrate better.
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Re: 6th Order Bandpass
« Reply #5 on: September 29, 2004, 07:36:52 am »

Update: Bill Fitzmaurice says that his Tuba 24 horn, loaded with a HL-10, can be used to replace a dual-18" bin, in terms of output. So for those looking for a smaller alternative to something as big as the LAB sub, the Tuba 24 (because its external dimensions are 24"x24"x24") with the HL-10 should fit the bill nicely as a SR sub.
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