Newbie design

[mikec]

Hi.

I am new to speaker building so I want my first project to be mainly a learning exercise.
Therefore I have decided to try and make a Subwoofer out of parts I already have.
A friend recently gave me a set of speakers with 12 inch Dai1chi 120 watt speakers, plus I have a couple of reasonable quality 300 watt stereo amplifiers, so hopefully I can make something that doesnt sound to bad.
I would like some advice on what would be the best way to go:

Sealed or vented sub?
Dual 12inch drivers in one sub or two small subs?

Any existing plans that you know of that may be suitable would be greatly appreciated.

Thanks

Mike C

 

[sreten]

Without the driver parameters we cannot help,

sreten.

 

[mikec]

After much searching, found the following info on the drivers
(Made a mistake in my last post-100W not 120W)

12" WOOFER 100W
Paper Cone.
Foam Surround.
Z 8W (7.2Wdc)
Freq. 33®4KHz
Fo 32Hz
Sens' 93dB
Magnet 30 Oz
Voice 38mm
Power 100W nom.
Qms 1.42
Qes 0.47
Qts 0.35
Vas 188.56L
Code SP12-100

Thanks

 

[mikec]

After much searching, found the following info on the drivers
(Made a mistake in my last post-100W not 120W)

12" WOOFER 100W
Paper Cone.
Foam Surround.
Z 8W (7.2Wdc)
Freq. 33®4KHz
Fo 32Hz
Sens' 93dB
Magnet 30 Oz
Voice 38mm
Power 100W nom.
Qms 1.42
Qes 0.47
Qts 0.35
Vas 188.56L
Code SP12-100

Thanks

 

[sreten]

some alignments for one driver, sreten.

 

[sreten]

Xmax is not given but here are some isobaric pair alignments,

sreten.

 

[sreten]

JMO but a single 300w amplifier is way more than enough,
IMO you'd be a lot better off with the facilities provided
by a mono plate amplifier circa 150w for both drivers, e.g. :

http://www1.jaycar.com.au/productVi...&pageNumber=&priceMin=&priceMax=&SUBCATID=443

Note that an isobaric pair will be 1/4 of the size of a pair
used in parallel, but maximum output will be 6dB lower.

IMO the isobaric ~ 2 cuft ~ 60L tuned 30Hz looks good,
unless a big box is not a problem, then ~ 6cuft ~ 200L
tuned to 28Hz, drivers in parallel is the way to go.

sreten.

 

[mikec]

Thanks steren for the info, much appreciated.
A couple more questions:

With the isobaric option, does the box volume stay the same if you dont have the drivers configured in a clamshell arrangement, instead have one behind the other (cant remember what they call this config)?

Also I was trying to match your results by putting the driver info into WinIsp but my results never seemed to match yours- mainly in the single driver option- box always came out at 118 ltrs- This is the first time I have used this program so I guess I am doing something wrong or misinterpreting the driver data.
Can you show me the data you entered into the driver parameters?

Thanks again.