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Old 27th June 2014, 11:44 AM   #1
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Default cabinet response vs free air respons

20 years ago I bought a loudspeaker system from TEAC consisting of 2 satellites anda 4the order bandpass subwoofer(SW-1).
Recently the woofer broke down caused by foam rot. One speaker has a teared
conus so beyond repair.
My plan is to buy new drivers for the cabinet. There are some programs on the
net to calculate the cabinet dimentions which I use in reverse, meaning
selecting drivers to fit with the cabinet response.
Now my question is, should I take into account the free air reponse of the
driver together with the cabinet response to optain the "system" response.
I see lots of calculations on 4the order bandpass cabinets to get the response
right, but what about the free-air response of the driver?
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Old 27th June 2014, 10:48 PM   #2
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What do you mean?
What do you want to do?
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Old 27th June 2014, 10:54 PM   #3
sreten is offline sreten  United Kingdom
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Here repair / refoaming is the best option.
Torn cones can be repaired quite easily.

rgds, sreten.
There is nothing more practical than a really good theory - Ludwig Boltzmann
When your only tool is a hammer, every problem looks like a nail - Abraham Maslow
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Old 28th June 2014, 08:05 PM   #4
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Repair is no option.
What I want to do is put new drivers in the cabinet .
Included is a drawing.
Teac claimed a reponse of 50 to 200 Hz.
The TEAC cabinet has quasi same volume for front and rear chamber.

I tried some 5" drivers to calculate a cabinet for but neighter of them seem to
fit the TEAC cabinet, they all have quite different volumes for front and rear chamber in order to optain a quasi flat response (50 to 200 Hz)

Now I was thinking why driverspecs often include a free air response while this is not took into account in the calculation of the cabinet.

My question is : if I should?
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Old 28th June 2014, 10:43 PM   #5
sine143 is offline sine143  United States
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for 50 to 200 hz dont worry about the free air response too much. Get detailed measurements of you box (rear and front chamber volumes), port area, and port length if applicable.

Plug those into your sim of choice, hornresp would be mine, then just start plugging drivers in till you get something nice looking for resp and output before xmax
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Old 29th June 2014, 07:53 AM   #6
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With the T/S specs from one driver it would be easy to find replacement drivers.
If not just measure V1 (internal/liters or d1, d2, d3) and V2 (internal/liters or d1, d2, d3) for each compartment and port (1 driver) diameter and length (as was told in previous post). (This) If you have 2 drivers and two ports, if not explain. It's called reverse engineering.
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Old 29th June 2014, 03:27 PM   #7
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The Vf and Vr parameters confuse me. IS Vf the volume where the vents are or is it Vr. In my case the vents are in the space behind the speaker.
Or is Vf silply the volume in front of the speaker and Vr the volume at the rear of the speaker never mind where the vents are.
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Old 29th June 2014, 03:53 PM   #8
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The driver is located between two spaces one sealed and one reflex, can call it Vs and Vr for that mater. Vr has a Fr or frequency for the port if one for each driver (2 drivers/2 ports...etc) meaning port dimensions (internal diameter/length) to go with each Vr, for each driver.
I acknowledge, in your speaker, you have: 2 drivers, one Vs, one Vr and 2 ports. Make sure this is right to go on. Take pictures to help posters.
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