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Old 21st February 2013, 06:36 PM   #1351
xrk971 is online now xrk971  United States
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Quote:
Originally Posted by KLBIrd View Post
Here is my venture into the world of foam enclosures. Its the Admiral 1970s Tunnel Reflex also known as the Bull Horn. I was in engineering at the time and we had to get a license from General Dynamics to use the design. They had bought Stromberg-Carlson and owned the labyrinth patents. The tunnel is lined with 1/2" blanket batting and is not to be stuffed as the tunnel has to be open all the way. I will use a Visaton FR 10 and take some measurements.
Reminds me of my much smaller 3-fold MLTL made of cardboard - uses 3.5 in driver. Post #1089 Foam Core Board Speaker Enclosures?

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Old 21st February 2013, 07:02 PM   #1352
xrk971 is online now xrk971  United States
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Originally Posted by MrMag2001 View Post
This is scary
But I have been thinking in the same trail (?), but I never though to use foam board so my project come to a halt.
This is what I have in the project box for this one...

\M
Is that a TPA3110 amp? Where did you get the active crossover designs? Looks interesting - don't forget that foam core can be curved to make very compact channels.
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Old 22nd February 2013, 12:28 AM   #1353
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Admiral had a plant in Shelbyville, IN where all TV and stereo cabinets we made until they shut down in 1978. I was in field engineering at the time and made a visit due to some QC problems with color TV cabinets. They made the Tunnel Reflex there also, as I recall it was 3/8 plywood with a vinyl wood grain covering. The speakers were from a plant in Taiwan, not Japan. I remember seeing pallets of them ready for loading in the cabinets. I only had one set, ditched the cabinets and sold or traded ( cant' recall which) with some guy on line in the 90s.
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Old 22nd February 2013, 01:51 AM   #1354
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I cooresponded with the daughter-in-law of the guy (Jack Virva) who got the patent that these were based on.

I also got a pair of the drivers in those pallets. A variation on the ones i have pulled out of the actuall speakers i've gottenmy hands on (25+ pairs). All were versions of the Foster 4" driver known generically as the FE103A (same basket as the Fostex FE103 variants made until circa 2000 when they changed to the current basket. Foster has/had factories in Taiwan & S Korea for the less expensive stuff.

There was also a larger version with a 5" driver (a Coral OEM i believe)

dave
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Old 22nd February 2013, 02:06 AM   #1355
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Originally Posted by planet10 View Post
Jack Virva ... patent
US4164988

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Old 22nd February 2013, 09:33 AM   #1356
xrk971 is online now xrk971  United States
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Quote:
Originally Posted by KLBIrd View Post
Here is my venture into the world of foam enclosures. Its the Admiral 1970s Tunnel Reflex also known as the Bull Horn. I was in engineering at the time and we had to get a license from General Dynamics to use the design. They had bought Stromberg-Carlson and owned the labyrinth patents. The tunnel is lined with 1/2" blanket batting and is not to be stuffed as the tunnel has to be open all the way. I will use a Visaton FR 10 and take some measurements.
How is the foam tunnel reflex coming along? I never knew there was an FR10, it looks like it is only available in Europe. Interesting 4 in with a whizzer? Looking forward to your first sound impressions.
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Old 22nd February 2013, 12:57 PM   #1357
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The Visaton FR 10 is available from MCM part number 55-4610.
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Old 22nd February 2013, 01:51 PM   #1358
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Thanks for the tip Ken!

There is a 4 ohm variant that looks real good. This driver looks like a real great value.

Have you used it before because the specs look really good for a $12 driver - maybe competition for my favorite Vifa TC9FD. Lower fs, lower Qts, larger Sd, larger xmax of 4 mm! Same price! It certainly appears to compete with Tang Bands in the $30 to $40 price range. PE should have carried this and I would have seen it sooner. Maybe the peaky high end and lack of really high end above 10 kHz is the problem?

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FR 10 - 4 Ohm

Visaton 4 Inch 20W 4 Ohm Full Range Dual Cone Speaker | FR10 2020 | Visaton

Below are the specs for others who may not have noticed this gem of a budget driver:

Rated power 30 W
Maximum power 50 W
Nominal impedance Z 4 Ohm
Frequency response 80–20000 Hz
Mean sound pressure level 86 dB (1 W/1 m)
Opening angle (-6 dB) 113/4000 Hz
Excursion limit +/−4 mm
Resonance frequency fs 92 Hz
Magnetic induction 0,95 T
Magnetic flux 180 Wb
Height of front pole-plate 3 mm
Voice coil diameter 20 mm
Height of winding 6 mm
Cutout diameter 100 mm
Net weight 0,38 kg
D.C. resistance Rdc 3,2 Ohm
Mechanical Q factor Qms 2,29
Electrical Q factor Qes 0,7
Total Q factor Qts 0,54
Equivalent volume Vas 2,3 l
Effective piston area Sd 50 cm
Dynamically moved mass Mms 5,7 g
Force factor Bxl 4,6 T m
Inductance of the voice coil L 0,2 mH

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Old 22nd February 2013, 02:08 PM   #1359
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I have four of them and one in a .4 cu ft box with 1 inch port they sound great. They do need some high end and I have a box full of 3/8th" dome auto tweeters that work well with them with 4.7 uF cap. Like you, my high end is becoming limited each year. I am now at 14K. Have yet to load them in the finished reflexes. We had 8 inches of snow yesterday so my path to the shop has to be dug out before I can get back at them.
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Old 23rd February 2013, 04:24 AM   #1360
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I just plugged the FR10 params into the BIB calculator: 37 in tall x 5 in wide x 7 in deep with driver 14.5 in from the top. This could be a fun build in foam core. I would have to join some pieces to get the 37 in length though. Might sound real good for a $12 driver. Has anyone built a BIB with this driver?
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