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Old 25th June 2009, 12:14 AM   #11
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We need a "Vas" spec to model the design.

I calculate your enclosure to be 82liters and then you'll subtract the volume of the speaker(s). Even so this is a reasonably sized box. Braced I hope

When you say push-pull do you mean isobarik? the speakers bolt together with the baffle in the middle, wired out-of-phase? (but that's not one in each end).
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Old 25th June 2009, 12:34 AM   #12
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umm well the specs i have for the speaker do not have Vas.
and also the way i have them set up is one in each end of the box with the magnets facing outwards.
the only specs i have for the speakers are as follows
Fs 36Hz
Qts o.53
size 12 inch...
Ipedance 8 ohm
singel vc
sensitivity 88.7 db
power ha ndling continuous 200 watts peak 400 watts
and thats about it.
EDIT i dont believe i need bracing because i am using half inch plywood laminated to be 1 inch thick.
i will post a picture soon i just need to eat and grab the camera...
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Old 25th June 2009, 03:31 AM   #13
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speakers are wired in-phase?

series or parallel?

with the magnets facing out, you'll add the volume of the cones to the box so it should be close to recommended.

Do you have equipment to measure speaker impedance vs frequency? With a good impedance measurement we could calculate Vas.
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Old 25th June 2009, 06:08 AM   #14
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in phase so the both go the same way at the same time.. not in series or parallel they are on 2 seperate outs on my amp each getting 100 watts... no i dont have anything to measure the impedance curve ... what is needed?
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Old 25th June 2009, 02:39 PM   #15
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Quote:
aircraft-grade open-cell polyethamphetamine foam
Surely such a foam must lead towards a very "fast" response

Wkr Johan
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Old 26th June 2009, 05:24 AM   #16
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Quote:
Originally posted by mulletdude
would it be more efficient to put the drivers in a push/push configuration?
and if so what would the port length be at 4 inch pvc piping .
Mulletdude [/B]
Remember adding the second driver adds like 6 db , but when you mount them isobaric you only gain 4 db .
Sound wise 2 seperate speakers in 2 boxes will put a little more .
BUT ......
if you mount them isobaric (thats cone facing cone) you gain one thing the speaker is fooled into thinking the cabinet is twice the size.
So if the speaker company claims that speaker will go great in a 3 cubic foot box it will go great in a 1.5 cubic isobaric cabinet .
I need 170 watts per speaker to drive it 100% .
But if you try and port this setup you will never get it sounding good , any port specifications will NOT appley to a isobaric .
I like your wicked box you built but I am not surprised it was soo quiet. How big was each sealed box for your speaker ?
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Old 26th June 2009, 05:34 AM   #17
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Quote:
Originally posted by mulletdude
[B still gotta find a way to mount the glass but its working so far just tied down with rope.. it does rattle a bit but i can get over that easily and also theres alot of chuffing from the fact that the glass isnt sealed to the box but i willl get around that soon ... somehow.. any ways any more input would be greatly appreciated.
mulletdude. [/B]
The easiest and best way to mount the glass is with a big bead of clear silicone (thats how they bond fish tanks) .
But make sure the other side is a removable , I use that foam bought in rolls.
Besides the sound quality loss from a leak the vibration eats up any sub frequencies coming out .
AND MAKE SURE YOU BOND THE GLASS WITHOUT THE DRIVERS IN THE CABINET !!!!!!!!!!!!!
The fumes can eat the surrounds on your driver .
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Old 26th June 2009, 05:43 AM   #18
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Quote:
Originally posted by tresch
Probably just not dampened well enough. Dampening causes the reverse reverberation counterwaves to vectorize, which counters the inductance field effect that surrounds most woofer voice coils. This results in raised sensitivity and greater dynamic function spread.

Damping materials commonly used are aircraft-grade open-cell polyethamphetamine foam, corrugated cardboard, or dirty socks (the dirty is important, as the oils from human feet raise the desity quotient, causing a reduction in the speed of sound within the fabric). If none of the above are available, an excellent alternative I've found is a common housecat, as pictured here:

Click the image to open in full size.

I like your post , I wish I could forward it !!
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Old 28th June 2009, 11:43 PM   #19
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ok so the pictures too big any tips on how to get it up here?
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Old 28th June 2009, 11:46 PM   #20
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ok here it is now its small enough to attach.
Attached Images
File Type: jpg sub1.jpg (43.5 KB, 292 views)
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