designing a venturi cabinet

[unclejed613]

i'm designing a bass guitar amplifier, and for the cabinet, i want to design a venturi cabinet. iirc, the BIC Venturi cabinets were a kind of bass-ackwards (pardon the pun, i couldn't resist) take on the folded horn/TL cabinet. instead of the air column widening between the driver and the outside, it got narrower, increasing the air velocity as it went. the Venturi cabinets were very efficient, and used acoustic suspension drivers (one of the first speakers on the market to do so). i plan on using a pair of 15" acoustic suspension drivers (or one, if i can make the cabinet efficient enough). does anybody have any experience disigning this type of cabinet? is it much different from designing other folded/TL/ported cabinets?

[moray james]

US Pat. 6771784 - Filed Jan 9, 2002

[moray james]

Inverted horn loudspeaker
US Pat. 4485275 - Filed Mar 25, 1982

[holdent]

unclejed613 - If I understand what you are asking about, Martin King's "Classic Transmission Line Alignment Tables" at provides the theory and a starting place for this design. Refer to Figure 1 (p. 5) - is it the top one you're referring to? If yes, Table 1 (p. 10) can be used to find the physical size of the TL and Table 4 is used to find the driver offset and so on. An example of how to apply the information starts on page 13.

[unclejed613]

it seems modeling a cabinet is very similar to modeling an antenna. i wonder if there's an audio "analog" of a "bazooka" antenna, which is an antenna with integral transmission line segments that widen the SWR bandwidth of an antenna without losses.

[Juergen Knoop]

do you have pictures of this design?
Regards
Juergen

[freddi]

hey unclejed613 - care to model the Karlson desinged in 1951? could remove shelf to simplify

http://home.earthlink.net/~buddhaboy2/K15.PNG

[Juergen Knoop]

the link doesn´t work

[GM]

Originally posted by unclejed613
it seems modeling a cabinet is very similar to modeling an antenna. i wonder if there's an audio "analog" of a "bazooka" antenna, which is an antenna with integral transmission line segments that widen the SWR bandwidth of an antenna without losses.

Greets!

Indeed it is, the B@#$ Wave Cannon is ~the equivalent if I understand the Bazooka's alignment: http://pro.bose.com/ProController?ev...annon.jsp&ck=0

GM

[unclejed613]

looks like a linear BP design....

the "bazooka" antenna was made of a piece of shorted transmission line 1/4 wavelength (corrected for velocity factor of the coax) and was tipped by a piece of wire that brought the total length to 1/4 wavelength of wire in free space (which was quite a bit longer than the coax section). the antenna had a bit of a "self correcting" property for SWR above and below the resonant length. above resonance, the capacitive reactance of the coax section corrected the impedance back down to 50 ohms, and below resonance, the inductive reactance corrected the impedance. so a dipole antenna that normally had a narrow bandwidth, had a very wide bandwidth. it was basically an impedance transformer but instead of introducing loss, the whole thing radiated....


back to the venturi idea.... i wonder if it might be a bit counterproductive in terms of SPL...... velocity and pressure have an inverse relationship....