Twin 4" bookshelf enclosure

[Philthy]

I'm building a pair of bookshelf speakers with 2x 4" woofers (jaycar cw2151), and a tweeter in each. According to the spec sheet, each driver wants a 5L vented enclosure tuned to 50Hz.
Now, I want to have both woofers in the same enclosure (mainly for ease of building, but also so I only need 1 port), so plugged all the specs into the box building program I've always used and it came up a 20-something L box.
I'm pretty sure my free downloaded program is lying to me, and was hoping to find answers here. How do you go about designing enclosures for more than one driver?

The only set measurement is that they will stand 40cm tall.

[HCVP]

I'll post back, i didn't read your post properly..

[Philthy]

Cheers HCVP
Also, the sensitivity of the woofers is 85 dB (2.83V/1m). How do I figure this out at 1V/1m so I can sort out the tweeter attenuator when I build the crossover?
And how do I have to adjust the attenuation since I am using 2 drivers? The program only gives me resistor values for single woofer/tweeter crossover networks

[Philthy]

Bump. Getting back onto these this week.

[AmmoJammo]

got any speaker specs?

[Philthy]

Umm, not right now. I'll try and dig them up. They are the 4" bronze-coloured woofers and ribbon tweeters from jaycar. They don't sell either of them anymore and weren't on their website last I checked

[Philthy]

Found the specs. Its too cold to go out to the shed and find the tweeter part number though

[AmmoJammo]

one issue with tuning a 10 litre enclosure to 50Hz, is that if you use a single 50mm diameter port, it needs to be nearly 200mm long...

[Philthy]

one issue with tuning a 10 litre enclosure to 50Hz, is that if you use a single 50mm diameter port, it needs to be nearly 200mm long...

Is it a 10L enclosure though? Do you simply double the box volume for 2 drivers?
The box is already going to be fairly deep. I'm making it as narrow as possible. I have no problems with using 2 smaller ports either

[AmmoJammo]

yes, its 10 litres.

you could tune higher, say 55Hz, as they won't do any ground shaking bass anyway.

[Philthy]

I'm not after bass from them anyway. They are just a better alternative to laptop speakers when I want (quiet) music in my bedroom. I can always add a little sub later on if I need to.

Does anyone know anything about converting the sensitivity units so I can sort out the attenuation?

[AmmoJammo]

run the two woofers in parallel.

this gives you 91dB at 2.83 volts.

if your tweeter is 8ohms, then, 2.83volts is 1watt into 8ohms, so match the tweeter at the same voltage...

what impedance is the tweeter? whats its sensitivity?

[Philthy]

run the two woofers in parallel.

this gives you 91dB at 2.83 volts.

if your tweeter is 8ohms, then, 2.83volts is 1watt into 8ohms, so match the tweeter at the same voltage...

what impedance is the tweeter? whats its sensitivity?

I can't even remember the tweeter model. Its all out in the shed. Pretty sure they are 8ohm though