Finished my BIB horns with FE168 sigmas - Page 2 - diyAudio
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Old 11th March 2008, 08:57 AM   #11
aroS3 is offline aroS3  Greece
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Could you share your actual BIB 168EZ dimensions ?
If so, please mention also material thickness.
Thanks...
George
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Old 11th March 2008, 04:28 PM   #12
gnugear is offline gnugear  United States
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I used 3/4" baltic birch for the enclosure and followed these dimensions http://www.zillaspeak.com/bib-fostex.asp

I actually built the shorter one but will probably do the larger one next.

Height was 64", width was 7.5" and the depth was 10" (internal dimensions) and the space at the bottome of the fold was 5". The face is a just a solid piece of poplar from home depot. You need the extra thickness to keep the back of the driver from touching angled panel on the inside .... and it covers mistakes.

Hey Godzilla, I felt my cab last night and did feel a lot of vibrations on the back. Is it best to double it up or do some kind of bracing pattern?
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Old 11th March 2008, 06:31 PM   #13
chrisb is offline chrisb  Canada
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Quote:
Originally posted by gnugear
I used 3/4" baltic birch for the enclosure and followed these dimensions http://www.zillaspeak.com/bib-fostex.asp

I actually built the shorter one but will probably do the larger one next.

Height was 64", width was 7.5" and the depth was 10" (internal dimensions) and the space at the bottome of the fold was 5". The face is a just a solid piece of poplar from home depot. You need the extra thickness to keep the back of the driver from touching angled panel on the inside .... and it covers mistakes.

Hey Godzilla, I felt my cab last night and did feel a lot of vibrations on the back. Is it best to double it up or do some kind of bracing pattern?

FWIW, some of the Fostex/Nagaoka designs incorporate interesting combinations of double layers of material / standing rib* bracing, particularly on back panels of larger horn cabinets.

* several strips of material (usually plywood) laminated to form something like an approx 2x4" rib, attached edgewise to the rear panel

They also do some curious things with enclosure side walls - overlapping layers of uneven sized pieces to achieve a thicker compound panels.

It would be interesting to see measurements of the difference in resonance distribution / attenuation for such fabrications, compared to more conventional construction.
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Old 11th March 2008, 06:59 PM   #14
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Hi all,

I have done some measurements for you (and me) at the inside of my FE168EZ BIB, using Room Eq Wizard and MCE2000 electret.
My BIB is made of 3/4" plywood, dimensions as per Godzilla site (long version) and full lined with a 2mm cork.

Click the image to open in full size.

The first measurement is the usual setting, a small layer on the base. At the 2nd one, I added a large volume of pillow material on the base.

Click the image to open in full size.

As you can see, no effect (small differences due to the electret position) on the "accident" in the 300/500 area...

I tried also to line the internal bafle (visible side), again it changed nothing but the LF... so the phenomena seems to be not so simple to explain.

Perhaps that is all about harmonics, or just vibrations transmitted thru the plywood (internal bafle ?) as you can hear medium frequencies when you put your ear in contact to the panels...

I dont know but I really don't care as soundstage and imaging are good enough and I don't have the "cupped hands" sound... only big LF resonances due to a bad room, another story...
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Old 11th March 2008, 07:50 PM   #15
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Default flush mounted?

I can't see if the Fe167 above is flush mounted.

I've just been learning how to handle my small router gizmo and wonder if I should do the procedure on the BIB.

Working free hand, the flush cut I did on an MLTL came out kinda ragged. I haven't got any bearing bits.

procedure made my workspace smell liek a camp fire.

I have to find that jig in my old audioXpress/Speakerbuilder mags.

There's a way to make a template and use a bearing bit to get a nice smooth job done.
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Old 11th March 2008, 08:02 PM   #16
chrisb is offline chrisb  Canada
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Default Re: flush mounted?

Quote:
Originally posted by loninappleton
I can't see if the Fe167 above is flush mounted.

I've just been learning how to handle my small router gizmo and wonder if I should do the procedure on the BIB.

Working free hand, the flush cut I did on an MLTL came out kinda ragged. I haven't got any bearing bits.

procedure made my workspace smell liek a camp fire.

I have to find that jig in my old audioXpress/Speakerbuilder mags.

There's a way to make a template and use a bearing bit to get a nice smooth job done.
If you're talking about flush mounting a round driver like the Sigma series, it would likely be even easier to just make 2 concentric passes with a simple circle jig (i.e. Jasper jig, or shop made compass style).


With a shop made jig in MDF (the best use for this material yet!), and a router with plunge base or accurate depth of cut gauge, you can use a wide mortise bit and make a single pass for the outer rebate, and then follow with the inner cut for the driver opening.

10 minutes and you're done.
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Old 11th March 2008, 09:15 PM   #17
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Default Re: Re: flush mounted?

Quote:
Originally posted by chrisb


If you're talking about flush mounting a round driver like the Sigma series, it would likely be even easier to just make 2 concentric passes with a simple circle jig (i.e. Jasper jig, or shop made compass style).


With a shop made jig in MDF (the best use for this material yet!), and a router with plunge base or accurate depth of cut gauge, you can use a wide mortise bit and make a single pass for the outer rebate, and then follow with the inner cut for the driver opening.

10 minutes and you're done.

I did use a rabbet bit on some small round speaks. But Fostex are all square flange.


After about an hour of looking through old Speakerbuilder mags, I found the article for any interested:

It's called Easy Driver Flush Mounting by Rodney Buike Volume 32 Number 6 June 2001 page 62.

Buike may have put this up on the web someplace. If I had good tools, I would have done this already. To get the shape (that is not exactly sharp cornered, you need a router stand and shaper bit to get that fine snug fit.

I just followed an outline. Bit even with only about an 1/8 bite I was getting a lot of smoke on my particle board baffles.


Every now and again, it's fun to go throught he old mags and look at the designs.

For example I saw some 'wings' like GM described for my MLTL.

But it still looks like a stretch to accomplish for who knows what sound difference.

For the free hand work, I guess I'll just have to get a fresh bit for $6
and take an even shallower pass first.
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Old 11th March 2008, 09:31 PM   #18
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Fast forward a few years... "they aren't finished yet because i couldn't bear to be without them"

It's only been 7-8 months in my case... so far.
...But Honey, If I build another set of speakers, I can finish THESE!


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Old 11th March 2008, 09:42 PM   #19
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Quote:
Originally posted by chrisb
standing rib* bracing
Akthough not as pretty perhaps as doubling the back wall, the "exoskeleton" approach should be much more effective.

dave
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Old 11th March 2008, 09:50 PM   #20
chrisb is offline chrisb  Canada
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Default Re: Re: Re: flush mounted?

Quote:
Originally posted by loninappleton



I did use a rabbet bit on some small round speaks. But Fostex are all square flange.

I did refer to the Sigma series (as shown) - so far all examples I've seen are round.

Quote:

......

For the free hand work, I guess I'll just have to get a fresh bit for $6
and take an even shallower pass first.
Don't waste your money on anything less than a cabinet grade carbide bit, and as large a cutting diameter as your template collar or jig will allow. For the smaller diameter bits (i.e. 1/4" or less), try the spiral upcutting bits.
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