Looking at compact horns etc and wondered what system Bose use in their Bass enclosures- is it a type of horn/transmission line system? I am guessing its one-eighth wavelength but might be completely wrong.
Searching will find it - I think it's a small-multiple wavelength with the driver some 1/4 way along it.
googled some more- when Bose did the proto they basically fitted a 2 metre length folded system into a tiny box. So must be quarter wave length tuned for around 40 hz or so
something to note is that you dont see people DIYing these. I would instead start from a required cutoff,SPL and volume of enclosure. Then proceed to driver availability.
Hi,
It varies.
Many Bose LF systems are bandpass. This goes both for pro and "lifestyle" systems. These are usually tuned for maximum efficiency and do not go very low or very wide bandwidth, so they usually play a good one or two note bass.
The "wavecannon" was/is basically a quarterwave pipe with the driver near 1/3rd of the pipe (so there are actually three resonances) without damping, so plays a lovely three-note bass.
The waveradio uses a variation of the wavecannon, but it has zip low frequency output that I could detect, based on what I heard not even 100Hz. Well, it is a very small thing and you cannot cheat physics. What little upper bass was there was again very "a few notes".
With all due respect, the only thing IMNSHO that one can learn from Bose LF systems is how not to do it...
Ciao T
It varies.
Many Bose LF systems are bandpass. This goes both for pro and "lifestyle" systems. These are usually tuned for maximum efficiency and do not go very low or very wide bandwidth, so they usually play a good one or two note bass.
The "wavecannon" was/is basically a quarterwave pipe with the driver near 1/3rd of the pipe (so there are actually three resonances) without damping, so plays a lovely three-note bass.
The waveradio uses a variation of the wavecannon, but it has zip low frequency output that I could detect, based on what I heard not even 100Hz. Well, it is a very small thing and you cannot cheat physics. What little upper bass was there was again very "a few notes".
With all due respect, the only thing IMNSHO that one can learn from Bose LF systems is how not to do it...
Ciao T
Bose uses an 8th order bandpass for most of their small subs. Very tricky to get right, but it can extract a lot of output from very modest drives.
I remember reading Weems, perhaps it was this one Designing, building, and testing ... - Google Books Where he discussed how the higher the order of rolloff the lower the perceived quality of the sound. It may have been another book though its been 6years since I read it. Also interesting articles on panel resonance and FEA
Seems to me that the cheapest way to get deep controlled bass from a small enclosure is the aperoidic route. A large driver in a compact 'leaky' box..
Im not sure, the leaks will just make it halfway between an open baffle and a sealed box,like some one who cant decide which is best.
Infinite baffle =
Even a few car audio 12"s with a higher Q should perform ok due to having large Xmax.
Yes, if you start with a low enough Fs, high enough Vas and Qts driver. Unfortunately, only DIY drivers are suitable AFAIK, i.e. mass loaded HE woofers and these don't have enough Xmax to play loud enough for most apps in singles.
GM
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