Hi,
I have a couple of Kef B200's, ex Monitor Audio MA5's, and was wondering if I could put them to use in a subwoofer. Please excuse my lack of knowledge if this is a stupid thing to ask, but is this realistic, and does anybodu have any experience of this, and could perhaps suggest suitable designs?
Thanks
Stuart
I have a couple of Kef B200's, ex Monitor Audio MA5's, and was wondering if I could put them to use in a subwoofer. Please excuse my lack of knowledge if this is a stupid thing to ask, but is this realistic, and does anybodu have any experience of this, and could perhaps suggest suitable designs?
Thanks
Stuart
Hi,
which version of the B200 was fitted to the 5?
Some data for your drivers would help. I think there are 3 or 4 versions on this forum.
which version of the B200 was fitted to the 5?
Some data for your drivers would help. I think there are 3 or 4 versions on this forum.
Hi spikey,
Not much x-max on those Kef but good parameters otherwise.
There are several iterations of this woofer B-200-A,B,G etc, which is yours?
With several units in a large box total displacement can be good anyway.
How many units do you have? Can you tolerate a large box?
Not much x-max on those Kef but good parameters otherwise.
There are several iterations of this woofer B-200-A,B,G etc, which is yours?
With several units in a large box total displacement can be good anyway.
How many units do you have? Can you tolerate a large box?
They're SP1014s, and I have 2 of them. I wouldn't be looking for lots of power, but I would like a clean sound if that helps.
Hi,
http://homepage.mac.com/planet10/TLS/drivers/images/B200_SP1014.gif found in http://www.diyaudio.com/forums/showthread.php?s=&postid=731448&highlight=#post731448
That 10Vrms for 96db is ~=85db/2.83Vac@1m.
Xpp=6mm is Xmax=3mm.
Q=.51 suggests sealed box.
Don't apply any Linkwitz transform nor similar EQ to extend the low bass, you'll run out of travel at very low volumes.
I did a search on sp1014 and found five other threads.
http://homepage.mac.com/planet10/TLS/drivers/images/B200_SP1014.gif found in http://www.diyaudio.com/forums/showthread.php?s=&postid=731448&highlight=#post731448
That 10Vrms for 96db is ~=85db/2.83Vac@1m.
Xpp=6mm is Xmax=3mm.
Q=.51 suggests sealed box.
Don't apply any Linkwitz transform nor similar EQ to extend the low bass, you'll run out of travel at very low volumes.
I did a search on sp1014 and found five other threads.
Thanks Andrew T.
This is all new to me, and I don't yet fully appreciate what those specs mean. Are you saying that I wouldn't be able to get much deep bass out of these drivers, and therefore that they aren't the most suitable to use?
This is all new to me, and I don't yet fully appreciate what those specs mean. Are you saying that I wouldn't be able to get much deep bass out of these drivers, and therefore that they aren't the most suitable to use?
Hi,
input the driver data into a sealed box modelling program and look at what Q you end up with for different sized boxes.
For lowish bass you need a big box, roughly equal to Vas in volume. This will not go loud but it might sound nice if you can disguise it as a coffee table or TV stand.
You could try diysubwoofers.org and use their sealed box model. and read the two sets of design notes (general+sealed).
input the driver data into a sealed box modelling program and look at what Q you end up with for different sized boxes.
For lowish bass you need a big box, roughly equal to Vas in volume. This will not go loud but it might sound nice if you can disguise it as a coffee table or TV stand.
You could try diysubwoofers.org and use their sealed box model. and read the two sets of design notes (general+sealed).
Thanks for being so helpful Andrew.
Now I've got somewhere to start! The Subwoofer DIY page looks useful.
Cheers
Now I've got somewhere to start! The Subwoofer DIY page looks useful.
Cheers
So.....
Well I've done the numbers, and it's clear that to get a decent response from these drivers in a sealed box the enclosure size could lead to domestic difficulties. Looks like I'll knock that idea on the head and have a rethink - still that's something I've learnt today.
Well I've done the numbers, and it's clear that to get a decent response from these drivers in a sealed box the enclosure size could lead to domestic difficulties. Looks like I'll knock that idea on the head and have a rethink - still that's something I've learnt today.
Hi spikey,
Andrew T wrote:
Agree and suggest that if you include the effect of box enlargement from the stuffing, its possible to use about 15% less, e.g. if Qtc = 0.707 is the goal for B200 then the volume should be about 142.6 L - 15% = 121.2L + bracing volume = 124 L.
I dug up a TL I have made near a dozen of (1970-1980) since B200 could be purchased.
It may be used as a closed box or TL and if used as a sub lower than about 120 Hz, you can place the driver/port almost anywhere on the baffle.
b
1(2)
Andrew T wrote:
Agree and suggest that if you include the effect of box enlargement from the stuffing, its possible to use about 15% less, e.g. if Qtc = 0.707 is the goal for B200 then the volume should be about 142.6 L - 15% = 121.2L + bracing volume = 124 L.
I dug up a TL I have made near a dozen of (1970-1980) since B200 could be purchased.
It may be used as a closed box or TL and if used as a sub lower than about 120 Hz, you can place the driver/port almost anywhere on the baffle.
b
1(2)
Attachments
spikey said:
Yes, a decent sealed box for the B200 is BIG. Give nice response to the mid 40s + room lift thou.
When a sealed box is too big, time to start thinking aperiodic.
dave
Hi,
If one closed box is sufficient and since you have 2 drivers there is also the possibility to mount drivers in isobaric configuration (face to face) and half box volume requirements.
But one box and low displacement capabilities will limit sound pressure.
I was hoping that you had one the lower Q variants, yours is box volume demanding as pointed out already.
If size is tolerably, bjorno's TL would probably give the best overall results for your driver.
If one closed box is sufficient and since you have 2 drivers there is also the possibility to mount drivers in isobaric configuration (face to face) and half box volume requirements.
But one box and low displacement capabilities will limit sound pressure.
I was hoping that you had one the lower Q variants, yours is box volume demanding as pointed out already.
If size is tolerably, bjorno's TL would probably give the best overall results for your driver.
Thanks for this bjorno,
It looks interesting, but unfortunately although I could see how to fit it into our living room I am sure that my wife could not!
4fun, I am interested in your comments about isobaric configuration - that could be worth looking into, thanks
It looks interesting, but unfortunately although I could see how to fit it into our living room I am sure that my wife could not!
4fun, I am interested in your comments about isobaric configuration - that could be worth looking into, thanks
FYI: added Acoustic dampening to the aperiodic and isobaric B200 box.
Acoustic Qm dampening applied close to the basket of a driver is the best of all methods to for lowering the Qt of a driver in a box.
All other methods suffer from more efficiency and bandwidth loss when comparing (Richard Small).
b
1(1)
Acoustic Qm dampening applied close to the basket of a driver is the best of all methods to for lowering the Qt of a driver in a box.
All other methods suffer from more efficiency and bandwidth loss when comparing (Richard Small).
b
1(1)
Attachments
Hello:
I have just "inherited" a Fried Model H subwoofer enclosure. Minus the KEF B200's SP1022 models. I am wondering if I can find suitable replacements for the SP 1022's and use the perfectly great condition Model H enclosure.
Cambe
I have just "inherited" a Fried Model H subwoofer enclosure. Minus the KEF B200's SP1022 models. I am wondering if I can find suitable replacements for the SP 1022's and use the perfectly great condition Model H enclosure.
Cambe
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