Good evening

I purchased a pair of KEF B200 SP1039 drivers a while ago to repair a pair of KEF 104ab speakers, and now have a single spare functioning driver. I would like to use this to make a 2-way speaker for use in the garden for a (not so wild) summer party, and then use it in my 7x4m log cabin workshop/home office (with a basic solid state class AB amp). As a result, there are no WAF limits!

I was going to ask for suggestions for a tweeter to accompany the SP1039, but my first stumbling block is the enclosure. The data sheet for the SP1039 indicates typical enclosure volumes of 20-25 litres for a closed box, and 30-40 litres for a reflex cabinet. However, playing with online calculators suggests a need for larger volumes. I presume I am making a basic error, but I can't fathom it, so any pointers would be appreciated.

I used this site https://www.diyaudioandvideo.com/Calculator/SpeakerBoxEnclosure/

If I enter the data sheet values (Vas 130 litres, Fs 25 Hz, Qtotal 0.45) and a system Q of 0.707, I get given a volume of 88.5 litres for a sealed box.

If I enter the effective diameter of the driver (about 16cm) and calculate a ported box, the suggestion is 186 litres.

Clearly these are way off what the data sheet suggest. So, please someone put me out of my misery, where am I going wrong?

Thanks for any help.

I purchased a pair of KEF B200 SP1039 drivers a while ago to repair a pair of KEF 104ab speakers, and now have a single spare functioning driver. I would like to use this to make a 2-way speaker for use in the garden for a (not so wild) summer party, and then use it in my 7x4m log cabin workshop/home office (with a basic solid state class AB amp). As a result, there are no WAF limits!

I was going to ask for suggestions for a tweeter to accompany the SP1039, but my first stumbling block is the enclosure. The data sheet for the SP1039 indicates typical enclosure volumes of 20-25 litres for a closed box, and 30-40 litres for a reflex cabinet. However, playing with online calculators suggests a need for larger volumes. I presume I am making a basic error, but I can't fathom it, so any pointers would be appreciated.

I used this site https://www.diyaudioandvideo.com/Calculator/SpeakerBoxEnclosure/

If I enter the data sheet values (Vas 130 litres, Fs 25 Hz, Qtotal 0.45) and a system Q of 0.707, I get given a volume of 88.5 litres for a sealed box.

If I enter the effective diameter of the driver (about 16cm) and calculate a ported box, the suggestion is 186 litres.

Clearly these are way off what the data sheet suggest. So, please someone put me out of my misery, where am I going wrong?

Thanks for any help.