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Old 4th February 2009, 03:58 PM   #471
Aengus is offline Aengus  Canada
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Nice. Is that a double layer of 18mm plywood?

Regards.

Aengus
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Old 4th February 2009, 09:04 PM   #472
wixy is offline wixy  Australia
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Quote:
Nice. Is that a double layer of 18mm plywood?
Yep.
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Old 8th February 2009, 02:54 PM   #473
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Martin, thank's for sharing.

Took about 4 hours from start to finish.
Top and bottom piece from a bed.(a bit smaller : 19x36 inch ....made all the x-over parts 10% smaller also)
Cut holes .............place speakers.
Look for x-over parts in the box.......
start listening...............and be surprised!!
Total cost:
woofers 2x 40 euro (Qtc ; 0,78 was the best I could find around here)
foster 085 2x 1 euro
x-over , was in the box ??
wooden stand at the back 2x 2,5 euro
small parts , about 2 euro
anyway less then 50 euro !!!
Sound like thousend euro each !!

Great work Martin!!
Never build anything with so much ease and so satisfying result!!
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File Type: jpg alles optio 6-5-09 104 [640x480].jpg (60.0 KB, 1277 views)
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Old 8th February 2009, 06:12 PM   #474
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Quote:
Originally posted by Leonidas
Martin, thank's for sharing.

Took about 4 hours from start to finish.
Top and bottom piece from a bed.(a bit smaller : 19x36 inch ....made all the x-over parts 10% smaller also)
Cut holes .............place speakers.
Look for x-over parts in the box.......
start listening...............and be surprised!!
Total cost:
woofers 2x 40 euro (Qtc ; 0,78 was the best I could find around here)
foster 085 2x 1 euro
x-over , was in the box ??
wooden stand at the back 2x 2,5 euro
small parts , about 2 euro
anyway less then 50 euro !!!
Sound like thousend euro each !!

Great work Martin!!
Never build anything with so much ease and so satisfying result!!


Those are some slick looking panels!
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Old 12th February 2009, 11:38 AM   #475
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to tea-bag,

Thank's for the compliment.
All the work was already done in the bed factory.
Was the only proper way for me to re-use the bed-components.
I'm at work at this moment, will post another pic of the back-side this evening.
They have 100+ hours on them and start sounding more smooth.
Very positif reactions from the others who hear them.
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Old 5th April 2009, 12:01 PM   #476
wixy is offline wixy  Australia
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Getting close to finishing!

Click the image to open in full size.

Click the image to open in full size.
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Old 5th April 2009, 01:49 PM   #477
Rudolf is offline Rudolf  Germany
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Sorry wixy,

from what I can see on your picture, the inner taper of the FE108 back opening looks quite narrow. Any chance to get it any wider, like chamfering a bit at the outer end?

Look, what a difference different mounting of a driver can make for the front (black) and back (red) wave on-axis:

Click the image to open in full size.
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Old 5th April 2009, 02:03 PM   #478
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You may also get a pleasant surprise if you mount the Fostex from the rear, rather than in front - (try a couple of clamps and a length of board)
Nice work on that big slab and the support bracket. EnABL next?
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Old 24th September 2009, 03:21 PM   #479
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The Back Story
I bought a pair of Fostex FF85k drivers to build a pair of micro-Fonkens. Since I was in the middle of another build (Metronome with F120A,) I built a pair of cabinets (using the term very loosely) from 2 liter soda bottles and scrap wood which I dubbed The Sprites.

I was so taken with the FF85k that I decided to build an OB with it. I figured Id build an H-baffle with Eminence Alpha 15, per Martin J King. So I bought the Alphas and another pair of FF85ks.

Now Im going crazy seeing the drivers just sitting in my office. Cant wait. Must build something NOW! Maybe Ill buy a piece of OSB and make a simple passive OB like MJKs project. But Ive got half a sheet of birch veneered ply sitting in the garage. Maybe I should use that. Cant stand to make a hack job with decent ply...

OK, fire up MJKs MathCAD worksheets and look at how the FF85k might work. And while Im at it, how about making the baffle more attractive? Consult wife...

Sidebar
My wife has been VERY tolerant of my stereo systems. From the rather large RTR 280DRs I bought back in 74 to the Visonik sat/sub second system added in the late 70s. The key is consultation. If she is part of the process, then she is invested in the program. So the ugly little Sprites were fine in the living room before the micro-Fonkens were finished. And now theyre fine in the family room preparing for the OBs. She chuckles every time she looks at them.

An MJK OB (mostly)
Large black rectangles wont cut it. (Too much like the monoliths from 2001A Space Odyssey.) A key stone shape (22 wide at the bottom and 14 wide at the top) with a veneered, beveled edge and finished with clear polyurethane gets the nod of approval. The MathCAD model looks essentially identical to the rectangular baffle.

Perfectly vertical isnt good; a 5 degree tilt should do it. How to support the baffle? start with a base 15 deep X 22 wide made from 2 layers of 0.5 BB ply leftover from the micro-Fonkens. Triangular side pieces 28 tall made from demolition scrape (kitchen remodel a couple years ago.) That doesnt sound like enough to brace a 15 woofer... OK, lets add 2x4s up the sides and another between those supports above the woofer. Photo below shows a back view--one before and one after the flat black paint.

Second photo is a front view.

I am adding small furniture glides with 1/4-20 shafts for now. If I dont like them, I can replace them with spikes.

By the end of this weekend I hope to have the paint and polyurethane done and enough hours on the FF85ks for me to install the drivers. More then...
Attached Images
File Type: jpg OB-02.jpg (55.3 KB, 321 views)
File Type: jpg OB-01.jpg (65.8 KB, 344 views)
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Old 24th September 2009, 04:33 PM   #480
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Those look great!.
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