Hi Filipe,
There is only one kind of drivers well suited for a sealed box and
these are the ones with high values of Qt factor. There really aren't
many out there to meet this basic criterium. You should be looking
for any kind of driver with whatever cone type you like with Xmax
value high enough for louder playing and Qt in the region of 0,8 .
This holds true for a passive box without any kind of active bass
boosting. Don't forget that published TS parameters are often
more toward lower values than actually measured one. For example,
the specs say Qt = 0,35 but you measure Qt= 0,5
This is perfectly normal because manufacturers often change some
materials in the production process which cause TS parameters
to slightly differ.
There is only one kind of drivers well suited for a sealed box and
these are the ones with high values of Qt factor. There really aren't
many out there to meet this basic criterium. You should be looking
for any kind of driver with whatever cone type you like with Xmax
value high enough for louder playing and Qt in the region of 0,8 .
This holds true for a passive box without any kind of active bass
boosting. Don't forget that published TS parameters are often
more toward lower values than actually measured one. For example,
the specs say Qt = 0,35 but you measure Qt= 0,5
This is perfectly normal because manufacturers often change some
materials in the production process which cause TS parameters
to slightly differ.
Hi,
this will be only the case when one uses a driver with strong magnet
and accordingly low Qt factor. It seems to me that many diyers
are blinded by the common practice of building a box with low Qtc.
8" seal box woofer?
Curious, there are a few Polypro, aluminum and composite cone 8" woofers suitable for closed box applications.
It comes down to how you intend to use it. Will this be for use in a residence? Sub woofer duties, or part of a 2 or 3 way? Do you have a box size in mind? If part of a multi-way, how high do you think you need to go?
So, fill us in and I am fairly confident there is a 8" out there that will fill your requirements. You may have to consider a paper cone. A lot of strong technical reasons paper cones are the most often used.
Curious, there are a few Polypro, aluminum and composite cone 8" woofers suitable for closed box applications.
It comes down to how you intend to use it. Will this be for use in a residence? Sub woofer duties, or part of a 2 or 3 way? Do you have a box size in mind? If part of a multi-way, how high do you think you need to go?
So, fill us in and I am fairly confident there is a 8" out there that will fill your requirements. You may have to consider a paper cone. A lot of strong technical reasons paper cones are the most often used.
Where did this myth come from?
I hear it repeated from time to time. A sealed box design works with any woofer Q as long as it is a little below what you want the final Qts to be. The lower the starting Q the smaller the box can be (with diminishing returns).
Vented boxes are a little more particular about Q, but they too can be made to work over a wide range. They tend to be easier to achieve with low Q. Is that where the "high Q for sealed" myth came from?
David S.
Vifa M21WG-09-08 Woofer - Heybrook HB1, JPW P1, AP2, AP3 replacement
I use the same driver in a 2-way with a waveguided tweeter. In my room there's plenty of bass, but they wont go very loud (loud enough for me though).
EDIT: It's paper though...
Here is a 8" with a Polypro cone that "Generically" work just fine. Not recommending it, but you can run some simulations with it.
http://www.tb-speaker.com/detail/1208_03/w8-750c.htm
Also, a simple simulation can be done with this tool:
mh-audio.nl - Home
You will want to increase the QTS to about .47 or so to allow for RG (crossover Resistance Gain).
John
http://www.tb-speaker.com/detail/1208_03/w8-750c.htm
Also, a simple simulation can be done with this tool:
mh-audio.nl - Home
You will want to increase the QTS to about .47 or so to allow for RG (crossover Resistance Gain).
John
Hi,
Loads of 8" bass drivers are suitable for a closed box to be crossed
over to a sub. Its really about the 3 way design that is going to be
used that determines the appropriate quality and budget for the driver.
rgds, sreten.
The high Qts Vifa driver is a very bad choice IMO. It was used in
designs with little BSC for a highish Q "boombox" alignment to
improve the bass balance somewhat at the expense of good
bass transient performance.
Loads of 8" bass drivers are suitable for a closed box to be crossed
over to a sub. Its really about the 3 way design that is going to be
used that determines the appropriate quality and budget for the driver.
rgds, sreten.
The high Qts Vifa driver is a very bad choice IMO. It was used in
designs with little BSC for a highish Q "boombox" alignment to
improve the bass balance somewhat at the expense of good
bass transient performance.
I use mine in a much bigger, 55ltr box.
It's funny, but the Snell k uses the same Vifa driver and was one of the most popular speakers at last years Hifiwigwam show Biggest Surprises of 2012 (couldn't find last years show)
I like the flat "closed" bass. In a room a 8" should be fine. I have only 6,5" ? (Dynaudio 17w75).
For simulation try e.g. Visaton TIW200XS (quite low fs an Qts)
TIW 200 XS 8 OHM
For simulation try e.g. Visaton TIW200XS (quite low fs an Qts)
TIW 200 XS 8 OHM
Hi,
True but 55L gives a box Q of 1.1 and a mild 2dB peak 70Hz to 90Hz.
Baffle step will flatten the hump into a normal looking roll-off.
Half that, 22.5L you get a box Q of 1.5 and a 4dB peak 90Hz to 100Hz.
With no / a little BSC some people seem to like the sound of this bass hump.
It is not my cup of tea. I like bass that is deep and fast and near full BSC.
For use with a sub what is wanted here is a compact box with a Q of 0.7.
rgds, sreten.
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Why I offered the Tang Band as an example
Getting back to the TB 8" example, this driver has the kind of T/S parameters that are idea for a 40 L stuffed sealed box. F3 of about 45 Hz, 0.707 QTC (maximally flat with lowest possible FS). Nice tight and resolved mid bass with almost an octave of spare room below the 80 Hz crossover target.
Getting back to the TB 8" example, this driver has the kind of T/S parameters that are idea for a 40 L stuffed sealed box. F3 of about 45 Hz, 0.707 QTC (maximally flat with lowest possible FS). Nice tight and resolved mid bass with almost an octave of spare room below the 80 Hz crossover target.
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