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Old 10th November 2010, 10:57 PM   #1
ArtL is offline ArtL  United Kingdom
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Default Subwoofer for my Warfdales

Hi, I'm new to WinISD and loudspeaker design, contemplating my first build, would appreciate your thoughts/comments :
A Skytronic 902-222 in a vented* enc. of (design1) about 8.5cu.ft tuned about 25Hz, 2 ports of 2.5inch dia x 3inch long.
Perhaps a little bit big, and a volume reduction to (design2) 6cu.ft, 29Hz, 2ports 2.5in x 3.3in might fit the domestic a bit better without sacrificing too much,
it would still give a useful addition below 50 Hz to the present setup.

Background story :-
I have a pair of Warfdale black boxes dating from the mid 70s, yes ok I know ! stay with me :-
They are nice enough to listen to in a domestic environment (ie no roof shaking disco style emanations!)
but they could do with a bit of extension down the bottom end.
It would be nice to hear a bit more of the lower reaches of classical organ music for example.
So whilst browsing the catalogue of a UK supplier of loudspeakers, and expecting to have to pay lots of ££,
I was surprised to find the above low priced 12inch that, when I plug it in to WinISD, seems to give a quite reasonable extended low freq. response, am I deluding myself or missing something ,,,

They would be driven by their own amp. off an active crossover/pre-amp from the source to the main amp.

PS *the EBP quoted by WinISD v0.43 of 40.8 suggests a Closed Box design but the resulting plot is not very impressive being 3db down at 42Hz already,
compared to about 21Hz for 8.5cu.ft and 26Hz with a bit of lift for the 6cuft design. (both of which seem amazingly low and probably lower than I actually need!)

thanks for reading ,,,
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Old 11th November 2010, 01:07 PM   #2
ArtL is offline ArtL  United Kingdom
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Apologies, I should have included my project file, but I had probs with the files on my puter, and now I have prob with attaching a .wid, the board says "invalid file" !
Back later after scratching my head ,,,,,
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Old 11th November 2010, 01:43 PM   #3
ArtL is offline ArtL  United Kingdom
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if I wrap the two WIDs in a zip,
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Old 11th November 2010, 02:56 PM   #4
sreten is offline sreten  United Kingdom
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Hi,

Your boxes are massive for a 12" driver, that comes from trying to vent
a driver that should be used sealed, I cannot find all the specs,
Fs and Qts, Vas is apparently 130L and sensistivity at 91dB / 8ohm
very high for a "subwoofer", another reason big boxes are needed.

Check out the parameters of typical 12" 4 ohm car subs, they work into
1 to 2 cuft boxes typically. Fs around 30Hz, Vas 50L, and Qts usually
a little too high for my liking, 0.6 to 0.7, 0.5 is better for venting.

IMO take a decent 12" car sub, put it in around 40/50L sealed and
add a subwoofer amplifier with optional bass boost at 30Hz or so.
(If building the c/o yourself make this a peaking 2nd order high
pass filter with Q around 2, possibly make Q adjustable.)

Alternatively this package is good value :
WHARFEDALE DIAMOND 9.1 SPEAKERS & SW150 SUBWOOFER 2.1 SPEAKER PACKAGE - available from Superfi UK Visit http://www.superfi.co.uk/index.cfm/page/moreinfo.cfm/product_id/7065 for details

rgds, sreten.
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Last edited by sreten; 11th November 2010 at 03:02 PM.
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Old 11th November 2010, 04:08 PM   #5
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There are only certain file types you can attach.

sreten makes a good point. Do you realise how physically huge 6 cu ft box is? And how heavy it will be with all the necessary bracing?
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Old 11th November 2010, 04:58 PM   #6
GM is offline GM  United States
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Quote:
Originally Posted by sreten View Post
Your boxes are massive for a 12" driver, that comes from trying to vent a driver that should be used sealed, I cannot find all the specs..........
FWIW: http://avslgroup.com/cdn/downloads/t...all_902127.pdf

GM
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Old 11th November 2010, 06:08 PM   #7
bjorno is offline bjorno  Sweden
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Quote:
Originally Posted by ArtL View Post
..It would be nice to hear a bit more of the lower reaches of classical organ music for example...
Hi, You wont regret if building a T-TQWT with Skytronic 902.222 driver

b
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Old 11th November 2010, 09:35 PM   #8
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Hi,

It sounds like you're setting off in a similar way to I did. I actually bought the driver after being convinced by the sims that it'd go flat out to 30Hz. The box was large, though. Needless to say, I didn't build the large box, and bought one of these pre-made car "sub" boxes. It wasn't very good. Hit you in the chest at 80Hz, but very little below that.

So, I tried again, this time, I did some research into bass from smaller cabinets (for a bedroom system). Came up with 2x8" drivers, 42L sealed, with a Linkwitz Transform circuit to get the bass nice and low.

Anyway, here's a link to a supplier that delivers pretty quick (linked to the page with lots of Visaton woofers - they're not the best, but parameters are available, which is a plus...).
Your Search Results | CPC
Visaton - Lautsprecher und Zubehör, Loudspeakers and Accessories

Chris

PS - it'd help if you told us your budget, musical preferences (and at what volume!), what size space are you attempting to fill... What will you drive this with....
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Old 11th November 2010, 10:12 PM   #9
GM is offline GM  United States
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Quote:
Originally Posted by bjorno View Post
Hi, You wont regret if building a T-TQWT with Skytronic 902.222 driver

b
Yeah, as soon as I saw that the specs had TL 'written' all over them, I figured that if you hadn't simmed something by the time I got done with rearranging leaves...........

GM
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Old 11th November 2010, 10:27 PM   #10
ArtL is offline ArtL  United Kingdom
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Thanks for your thoughts folks, a few in return :

sreten> "that comes from trying to vent
a driver that should be used sealed"
Yes, that is what puzzled me and why I added the PS in my orig. post
about the closed box that WinISD proposed, didnt
look as good, to my untrained eye, as the vented
proposals.
see my new attachment, in which a closed box of 2cuft is shown

>"IMO take a decent 12" car sub"
any recommendations in this price range ?
I originally started with the idea that I might spend
much more on a single 15" or 18" common to the two
channels, till I saw the 'bargan deal' on those
Skytronics! Looks like on advice I may need to reject
them then ?

richie>"Do you realise how physically huge 6 cu ft box
is?"
Yep! In another room I have a pair of 5.6cuft
containing electrostatic mid-top and 15" cone base,
built for me 35y ago and only moved once :-!)
Those are in the main domestic region, this project is
for my hobbies/refuge/retreat room

bjorno> "T-TQWT"
errr ? I found TQWT via google but what is the T- bit ?
I fear that my woodworking skills may not be up to
that ! Perhaps for my second project LOL! and those
resonances/comb structure looks a bit fearsome.
I will have to do a lot more reading on that, thanks for
the pointer tho.

Chris : thanks, good questions!, I prepared the above for dialup posting before I saw your post, will get back to you shortly on your questions ,,,,
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