I have a pair of vifa p21wo-10-08 8inch drivers that I would like to use in a subwoofer project.
Here is the datasheet;
http://nedlab.com/wp/wp-content/uploads/2014/06/Vifa-P21WO-10-08-woofer.pdf
Does anyone know of a suitable box design, or some pointers?
They are 8ohm but I will run them in parallel at 4ohm for use in my car.
I'm looking for low, musical bass (lowest I can get for 8s anyway) as I have polk audio 6.5inch and 6x9 for mid bass and above.
I have the tools and the box building skills, but not the knowledge on box design.
Any help appreciated.
Here is the datasheet;
http://nedlab.com/wp/wp-content/uploads/2014/06/Vifa-P21WO-10-08-woofer.pdf
Does anyone know of a suitable box design, or some pointers?
They are 8ohm but I will run them in parallel at 4ohm for use in my car.
I'm looking for low, musical bass (lowest I can get for 8s anyway) as I have polk audio 6.5inch and 6x9 for mid bass and above.
I have the tools and the box building skills, but not the knowledge on box design.
Any help appreciated.
Somewhat of a learning curve to learn basic speaker alignments.
And WinIsd is a popular free download.
Which can auto calculate basic alignment's.
I did run the numbers for this woofer
A straight forward sub type alignment like a BB4
called for 48 liters (1.7 cubic feet) for one driver tuned to 34 Hz
The response is pretty good -3 dB at around 41 Hz
48 liters is very large though for a 8" so power handling before distortion
would not be very high.
Then you start dealing with tradeoffs for 2 drivers, to make a box that
would sound good and fit in a car. Since almost 4 cubic feet is way to large for 2x 8"
drivers and power handling would not be to spectacular
Something tolerable would be a box around 58 to 65 liters for 2 speakers
and tune to 27 Hz
With a 2.5" to 2.7" inch single round port. Manufactures vary from 63 to 68mm
the overall length would be around 47 to 48.2 centimeters or 18.5 to 19 inches
of course it would be better to calculate yourself once you have actual port size. to tune around 27 to 30 Hz
What I recommended is somewhat small port area, but velocity wont be too high.
With the amount of power they likely tolerate.
And WinIsd is a popular free download.
Which can auto calculate basic alignment's.
I did run the numbers for this woofer
A straight forward sub type alignment like a BB4
called for 48 liters (1.7 cubic feet) for one driver tuned to 34 Hz
The response is pretty good -3 dB at around 41 Hz
48 liters is very large though for a 8" so power handling before distortion
would not be very high.
Then you start dealing with tradeoffs for 2 drivers, to make a box that
would sound good and fit in a car. Since almost 4 cubic feet is way to large for 2x 8"
drivers and power handling would not be to spectacular
Something tolerable would be a box around 58 to 65 liters for 2 speakers
and tune to 27 Hz
With a 2.5" to 2.7" inch single round port. Manufactures vary from 63 to 68mm
the overall length would be around 47 to 48.2 centimeters or 18.5 to 19 inches
of course it would be better to calculate yourself once you have actual port size. to tune around 27 to 30 Hz
What I recommended is somewhat small port area, but velocity wont be too high.
With the amount of power they likely tolerate.
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With 2 woofers the first thing you want to seriously consider is to mount the drivers push-push to take advantage of the active reaction force.
I will look more closely but first pass suggests 90 litres tuned to 25 Hz will get you into the mid20s F10. Fairly slow roll-off to match (estimated) room gain. ROom gain is quite variable depending on room and placement.
dave
I will look more closely but first pass suggests 90 litres tuned to 25 Hz will get you into the mid20s F10. Fairly slow roll-off to match (estimated) room gain. ROom gain is quite variable depending on room and placement.
dave
Mobile audio app, so typical room modes, box alignments don't apply. 🙁
Need the vehicle details to find how much cabin gain it might have.
Are the Vifas even suited for mobile audio?
Need the vehicle details to find how much cabin gain it might have.
Are the Vifas even suited for mobile audio?
For a standard tuning of 2 of those in one cabinet to 30Hz i come to a big 180L cabinet with 2 10cm round ports of 21.7cm And i would also do like Planet10 says, configure them in push push if you put 2 in one cabinet. But like GM said, in a car room gain comes to play so this may not work there. First you need to know the cabin gain in the car before you can tune the sub to that.
And this driver may not be suited to cars, as the conditions (mainly temperature) can be very drastic in change and many hifi drivers like this one can't deal with that.
And this driver may not be suited to cars, as the conditions (mainly temperature) can be very drastic in change and many hifi drivers like this one can't deal with that.
Too good to use for car audio IMO and there are better drivers around for car use.
I'd use a single 10" rather than two 8s
I've got a sextet of car 10s on the shelf but SWMBO says there's no room for sub boxes in the new car.
I'd use a single 10" rather than two 8s
I've got a sextet of car 10s on the shelf but SWMBO says there's no room for sub boxes in the new car.
I've heard them in a very large ported box and more suited to that I think.
Vas is large for a small woofer.
Vas is large for a small woofer.
I already have them from another project so they are free, plus I already have plenty of wood, wire, tools etc.
And imo there is no such thing as "too good".
Its a 2004 bmw 3 series touring, so it has a big boot area, but I will take measurements tomorrow.
Alternatively I will put it in my 2003 bmw 3 series sedan, but obviously a smaller boot.
I dont see why the vifas cant work for mobile audio, if they are wired for four ohms?
I have some vintage Alpine v12 amps running the polk audio's, and a third v12 spare for the subs.
Thank you for the knowledge.
A push push design sounds fun to build. Is it better to have both speakers facing out, or both speakers facing each other with some kind of slot or port? I'm not at all opposed to complex designs as I like the challenge, and my woodworking skills are pretty high.
Its possible to use them.
The large vas demands a large box.
They are more suitable for large door speakers, or mounted to a rear deck.
Since the volume of a door, or a rear trunk is suitable for the volume they want to see.
The performance would be similar to good performing 6x9 mounted in a door
or on the rear deck.
As mentioned to get a good response, a pair needs a very large box.
around 65 to 100 liters.
xmax is 3mm so power handling is about 30 to 50 watts.
they would sound good in a car, consider them similar to large door speakers.
or mounted to a rear deck for good midbass. not sub
cabin gain for mid sized vehicle is around 40 to 50 Hz
The large vas demands a large box.
They are more suitable for large door speakers, or mounted to a rear deck.
Since the volume of a door, or a rear trunk is suitable for the volume they want to see.
The performance would be similar to good performing 6x9 mounted in a door
or on the rear deck.
As mentioned to get a good response, a pair needs a very large box.
around 65 to 100 liters.
xmax is 3mm so power handling is about 30 to 50 watts.
they would sound good in a car, consider them similar to large door speakers.
or mounted to a rear deck for good midbass. not sub
cabin gain for mid sized vehicle is around 40 to 50 Hz
Yes, and titghtly coupled.
Cabin gain in a car (windows closed) is significant, means that, AFAIK, a sealed box with a slow, slow roll-off will have a flat (or even raised) bass response Anything that tries to drag more bass, like a reflex, will have too much gain.
The biggest issue i see with these is finding enuff room to fit the box which will be big.
Using the boot by itself as a leaky box might actually work out best.
dave
You're welcome!
Ideally measure it, though you can get a 'close enough' one based on these measurements: https://farm4.static.flickr.com/3194/2516534482_b0d155d5ac_o.jpg
Mainly because of the large Vas and the need for a big box to obtain deep bass, but as you say they are there and paid for.
Even taking room gain into account if you need to put them in small sealed boxes go ahead and experiment.
Drivers aside have you decided on a crossover for the sub yet?
I have some spare 10" car drivers here if you were interested in a swap
Even taking room gain into account if you need to put them in small sealed boxes go ahead and experiment.
Drivers aside have you decided on a crossover for the sub yet?
I have some spare 10" car drivers here if you were interested in a swap
Quick and dirty in a small sealed box
Add room gain to get an idea. Low X-max limits power handling
Add room gain to get an idea. Low X-max limits power handling
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Thanks for everybodies advice and support.
For crossover points;
The polk audio 6x9 rears are these ones;
Polk Audio MM691 6"x9" 3-way car speakers at Crutchfield
And the polk audio front components are these ones;
https://www.crutchfield.com/S-KqKPFBu7ugF/p_107MM6501/Polk-Audio-MM6501.html
Polk don't provide detailed info on frequency response, so hard to know where to cross over, but most likely where the polks start to roll off, so the polks carry most of the mid and lower bass, and the vifas can just handle the really low stuff.
All my alpine v12 amps have parametric equalizers and adjustable crossovers so should be pretty easy to setup.
For box size, if I use the sedan boot, I can probably get away with up to 180 litres without annoying the wife too much. Thats taken from a rough measure of 90cm x 50cm x 40cm, but final design can be a different shape or size. It doesnt matter to me if its an odd shaped box, if it gives a better sound.
For crossover points;
The polk audio 6x9 rears are these ones;
Polk Audio MM691 6"x9" 3-way car speakers at Crutchfield
And the polk audio front components are these ones;
https://www.crutchfield.com/S-KqKPFBu7ugF/p_107MM6501/Polk-Audio-MM6501.html
Polk don't provide detailed info on frequency response, so hard to know where to cross over, but most likely where the polks start to roll off, so the polks carry most of the mid and lower bass, and the vifas can just handle the really low stuff.
All my alpine v12 amps have parametric equalizers and adjustable crossovers so should be pretty easy to setup.
For box size, if I use the sedan boot, I can probably get away with up to 180 litres without annoying the wife too much. Thats taken from a rough measure of 90cm x 50cm x 40cm, but final design can be a different shape or size. It doesnt matter to me if its an odd shaped box, if it gives a better sound.
I'll PM you pictures.
I'm cooking dinner at the moment and drivers are in the shed
A general use driver with good X-Max
No brand stuff salvaged from my home theatre sub boxes when the amp section died, pretty good actually in 30 to 35 sealed, but one on its own would be equal to the pair of Vifas
Picture of driver in the box tho
I'm cooking dinner at the moment and drivers are in the shed
A general use driver with good X-Max
No brand stuff salvaged from my home theatre sub boxes when the amp section died, pretty good actually in 30 to 35 sealed, but one on its own would be equal to the pair of Vifas
Picture of driver in the box tho
