fe87e Superbowls - diyAudio
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Old 28th January 2009, 04:45 PM   #1
Juspur is offline Juspur  Denmark
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Join Date: Feb 2005
Location: Near Copenhagen
Default fe87e Superbowls

Hi there
Here's my new creation: the (fostex) fe87e Superbowls.


Click the image to open in full size.

The wooden bowls are from IKEA (link to danish IKEA-bowls here:
http://www.ikea.com/dk/da/catalog/products/60057258

It's simply a 9 liter closed box with no parallel sides. The bowls are 28 cm (about 11 inches).

I made holes for the fe87e and the speaker wires, attached the wires and screwed the fe87e's into one of the bowls, then glued two bowls together with superglue/istant glue (with a 5 minute long, light pressure).

No stuffing at all (tried half and quarter-full - none at all was absolutely best (the other solutions more or less dull and undynamic).

One hour later I used transparent silicone for airtightening.

A total of two hours work at all.

The fe87e is modified with a thin layer of Dammar (Dammar is a sort of painters' varnish), which made a night-and-day difference in sound reproduction: It's going deeper and is clear in sound, but absolutely non-fatiguing.

The Dammar had to dry out for 3-4 days in a warm environment.

I chose the fe87e ahead of the fe83e, because it has a falling frequency response (which I prefer). Fe83e is rular-flat according to fostex.

Now, another detail:

Click the image to open in full size.

The speakerwires are just pressed towards the drivers wires: in that way, the signal isn't lead into the "big, bulky speakerterminals of unknown quality", but lead wire-to-wire. I feel this gives a little more presence than traditional "speakerwires-into-bulky-terminals-solution").

The speakers are placed on two heavy bags, which I bougt in a diving shop. The purpose is eliminating resonances - and it seems to work.

This little speaker has a fs of 140 hz before dammar-treatment, so a bass-solution could be fine.

But I'm perfectly happy - uses foobar with a 4th order Chebychev rolloff at 180 Hz to avoid too big xmax. I can hear the bass-notes (but not feel the physical presence) - and the bass is fast and enjoyable (so is the speaker overall).

Final note
Tried building the same Chebychev-filter - and it rolled off as expected, but also took some of the dynamics - and subjectively 25% of the sound level (I guess it's about 3-4 db sensitivity I lost).

Conclusion: Steep x-overs at low frequencies eats sensitivity and dynamics. Cannot be recommended.
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Old 28th January 2009, 06:17 PM   #2
lejaybo is offline lejaybo  United Kingdom
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hello

loving this build,

can you suggest a separate sub that would match nicely with these speakers?
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Old 28th January 2009, 06:27 PM   #3
Juspur is offline Juspur  Denmark
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Join Date: Feb 2005
Location: Near Copenhagen
Hi Lejaybo

Well, I tried with a AudioPro Ace Bass 2, which is considered a very fast and good sounding sub (new price around 1000 us $ in EU, 500 us$ used in EU) - but it wasn't fast enough in the lower notes.

Be aware that you have to get some kind of filter on the Superbowls - or they'll blow out on the lower notes.

Most subs only have a 6 db/octave roll-off for the satellite speakers - and that's not enough in this case.

So you either have to make a steep crossover at a low frequency, or a not-so-steep crossover at higher frequencies - and the last solution demands a bass-system with output longer up (and not an ordinary sub, which usually crosses over at maximum 100-120 Hz).

regards,
jesper
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Old 28th January 2009, 06:29 PM   #4
kazoo is offline kazoo  United States
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They look great. You have to love salad bowls. They make the enclosure that much faster to make. I am still enjoying mine.

John
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Old 28th January 2009, 06:31 PM   #5
Hugo82 is offline Hugo82  Netherlands
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Looks good.
My dad has one of those woodturning machines (old 1, hoping it still works) and was planning to make some small spherical fullrange satelites in the future, but this is a much less hassle then creating the sphere yourself.... wish i thought of using Ikea or any other bowls

Very Nice.
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Old 28th January 2009, 06:41 PM   #6
Juspur is offline Juspur  Denmark
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Join Date: Feb 2005
Location: Near Copenhagen
Hi Everybody
Kazoo-John's bowls can be seen at :

latest project TB 3" bamboo

They are absolutely stunning.

I guess there are several advantages, using fullrange speakers in round, closed enclosures:

1) No standing waves, since no parallel sides
2) No need for baffle step compensation, since ALL sound can travel behind the speaker
3) Closed enclosure gives best impulse treatment
4) No xover = no degradation

... If it also could play sub-20 Hz-notes, then
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Old 28th January 2009, 06:43 PM   #7
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I actually considered this build too but time makes fools of us all. Very nice work I must say.

The subs I originally planned for was/is to made of a cardboard tube with the outer diameter as the balls, ie 28 cm, and then strengthen it with several layers of carbonfiber cloths around the outside. And in the bottom placing 2 10" drivers in coupled cavity configuration in a closed box, ie the tube.

Using the right drivers, I was thinking Peerless XXXLS's it could go all the way to sub-20 Hz.

Putting the ball on top of that would make the speaker appear from all sides like a lower case "i". I even have come up with a cool name for it, The i-ball.
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Old 28th January 2009, 06:43 PM   #8
Juspur is offline Juspur  Denmark
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Join Date: Feb 2005
Location: Near Copenhagen
Hi Hugo82

As far as I remember, IKEA has those bowls in 12, 20 or 28 cm (equals 4, 8 or 11 inches). Good hunting
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Old 28th January 2009, 06:51 PM   #9
Juspur is offline Juspur  Denmark
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Join Date: Feb 2005
Location: Near Copenhagen
Hi, Saturnus

I go t an Idea - A 10" driver in each end of a long tube. One firing down, the other firing up.

You can buy tubes at:


http://www.joma-pack.dk/

or

http://www.greif.dk/g_deko_design.asp
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Old 28th January 2009, 06:53 PM   #10
lejaybo is offline lejaybo  United Kingdom
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these look beautiful

definatley gonna build a pair of these now, been searching for a perfect build

could a sub be built in a round enclouser ?
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