Voigt pipe vs open baffle - what to expect?

[sonorsnoopy]

Hi, I have an 8" full range driver in this OB enclosure Pic1

http://www.methe-family.de/picture/OB Classic 10.jpg

and would like to try an other OB design with wings Pic3
openbaffle

or a voigt pipe - a cain & cain abby clone Pic2
Voigt Pipe

The driver is: Davis Acoustics 20 de8 Pic4

Fs: 33.38 Hz
- Re: 6.51 ohm
- Res: 29.29 ohm
- Qms : 1.83
- Qes : 0.41
- Qts : 0.33
- Vas : 175 L
- Mms : 9.5 g
- Cms : 2402 microM/Newton
- BL : 5.64
- SPL : 93.9 dB
- S : 213 cm2

I want to try a voigt pipe just for the looks and for better imaging (narrow vs wide baffle). The question is if the imaging with a voigt pipe will be better, and if there will be more mid bass output with the voigt, and if the timing of the bass output will be as accurate as with the OB?

I want to use the design of this link: http://www.parow.no/Lowther/voigtpip.html
and would like to know if i must adapt certain dimensions (Port diameter=SD?, any other?) to my specific driver.

I have no experience in speaker design / calculation at all and would be very happy if you could give me some useful hints and links.

Thank you

 

[DanHat]

That driver has a rather large vas spec. Any type enclosure sealed or bass reflex or mltl is going to be large. Have you considered adding a woofer or subwoofer to your ob? The qts spec of the driver is fairly low so I doubt wings would make that much difference to the bass output. Have a look at Martin Kings site "quarter-wave.com".

 

[picowallspeaker]

Sort of a voigt pipe is the mass loaded transmission line ( MLTL )
with a duct at the end to mimic an acoustic resistance 😕

 

[Greg B]

That Davis driver has a low Qts for either OB or Voigt pipe. They both generally work much better with higher Qts IME. A quick check shows max flat BR is 90 liter tuned to 41Hz. What I would suggest for this driver is an ML-TL (tower reflex). A good starting point for simulation would be an ML-TL around 1m tall with a cross section of 35cm x 38cm in 19mm material. This will have much stronger midbass and better extension than either Voigt pipe or OB.

RE imaging: Any monopole speaker will interact with the room in a completely different way than a dipole OB. Whether one has better imaging than the other is at least partly room dependent. Since larger FR drivers are relatively directional, a narrow baffle is less of a benefit than it is with say a dome tweeter.

 

[sonorsnoopy]

Well Greg you are probably right, Davis Acoustics has found that this driver works best in a box with a vent and without any baffles inside or stuffing:

But before they have released that speaker they have displayed the driver on the high end show in munich in an large open baffle. There is also a OB Kit available:

An externally hosted image should be here but it was not working when we last tested it.