Terry Cain's BIB -why does it work and does anyone have those Fostex Craft Handbooks? - Page 17 - diyAudio
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Old 13th March 2006, 07:58 PM   #161
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I have some 127e's... Is that what you meant up there?


GM said I'd need an Fs of 45-50.


I checked out the FX125 which I considered purchasing but the


Fs on that is 70.


.... doing a quick search on the 127e....


nope 70.4 Fs


















f
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Old 13th March 2006, 08:24 PM   #162
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Quote:
Originally posted by Scottmoose
They'll work in Terry's original fairly well, being the predecessor to the FE17E. Could do with being larger though...

When I get home from work I'll run some numbers

Best
Scott

Thanks Scott for your prompt reply, looking forward to see those numbers
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Old 13th March 2006, 09:42 PM   #163
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Hi Scott!
The Monacor SP200MX8 must be a TVM ARZ 6608 which sells for about 9 euro here in Cz Rep.
Check out the Monacor SP155X with a 91.5 db efficiency. Looks like a candidate for BIB.
Regarding the SPH60x being a bit polite in the highs, there is a version SPH68X/AD which sports a rise around 8 k.
Also a whizzer free version added below. Albeit a low efficiency.
All these under 25 euro/pcs
Cheers



http://www.tvm-valmez.cz/index.php?i...86&l=1&catg=27

http://www.spectrumaudio.de/breit/mo...orSPW1168.html
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Old 13th March 2006, 09:44 PM   #164
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http://www.spectrumaudio.de/breit/mo...corSP155X.html
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Old 13th March 2006, 10:21 PM   #165
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Quote:
Originally posted by loninappleton
I have some 127e's... Is that what you meant up there?
GM said I'd need an Fs of 45-50. I checked out the FX125 which I considered purchasing but the Fs on that is 70. .... doing a quick search on the 127e.... nope 70.4 Fs f
Typo: I meant the FE167E. Once I've had my usual 3 hours of sleep I'll get some dimensions for the 164 up. The other Monacors look interesting...
BTW: the original enclosure was intended to house the FF125K, Fs 72Hz. But MathCad says that Fostex claimed response limits are spot on. Wouldn't be my first choice, but it doesn't look too bad either.

Best
Scott
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Old 14th March 2006, 01:07 AM   #166
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Default Re: Output Impedance

Quote:
Originally posted by jimmyd53
GM,

Good Morning. I am currently running an Antique Sound Lab Orchid 3.5 wx2 2A3 integrated amp. It has output taps for 4, 8 or 16 ohms. I have not measured the actual output impedance. Hope that answers your question.

James
Greets!

Not really, so I assumed 4 ohms and you can try the different taps to see what sounds best. Unfortunately, I couldn't come close to meeting your dims in a triangular cab and still get down to Fs with any authority, so at this point I suggest making the tallest triangular sealed cabs you can tilt into place (at least 88") and position the driver at whatever height you want. For a nominal ~18" wide baffle, using 3/4" material means the sides will need to be ~11.66" i.d..

GM
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Old 14th March 2006, 01:16 AM   #167
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Quote:
Originally posted by Scottmoose
BTW: the original enclosure was intended to house the FF125K, Fs 72Hz.
Greets!

Without compression loading, running a driver much below 0.707*Fs isn't a good idea, especially a low Xmax one, rising rate suspension system or not. It must have been designed with tiny apt. or Japanese paper house construction in mind.

GM
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Old 14th March 2006, 02:15 AM   #168
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Default my BIB!

Ok, so I dropped by home depot yesterday and cut some wood. they will be 14 3/4 deep, 7 in wide, and 70 in tall. the interior panel i will space equidistant from back wall and bottom and attach the other end to the top of the baffle. I am throwing around numbers here, but i am pretty sure i will go with 7 inch clearance between the interior panel and back and bottom.

I did not taper the rear of the horn. it is a rectangle.

the drivers I will be using will be the fx120.

any opinions on the horn dimensions?

Clark
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Old 14th March 2006, 03:02 AM   #169
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rather i might make that interior panel at 7 and 7 and use a small peice of plywood near the back corner placed at an angle to the bottom to get the 5.5 and another small peice angled against the baffle and bottom to get 5.5 inches there.

or i might just use the back peice (most likely). who knows?

i will no doubt use a few small peices here and there where there are large openings (like the mouth) in the direction of air flow to get a little more laminer (spelling?) flow and to stiffin these little guy up.

I probably won't get to the horn tonight, but advice, experiences are appreciated.

as far as the horn discussion goes,
I have found that most of terry's designs strategically use the room in some way or another to make the bass flat and real. his own listening room in the shop is purpose built for bass reinforcement, as the one shown in the photo of the BIB on mellhuish has wooden ceilings, floors, and walls (though there is some hallway induced weirdness here and there). when building this design, terry mentioned to experiment with the dimentions. in light of many of us having dry wall (or god forbid the #$#%#%@!!$^%^%& freakin acoustic ceilin tiles in my place) the horn angle ought to be considered. I would imagine it would be best in general to point the wave slightly towards the most reflective object, either wall or ceiling? I kindof like it being angled outwards towards the listener as in the original. eh who knows?

clark
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Old 14th March 2006, 08:59 AM   #170
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Quote:
Originally posted by GM
Greets!
Without compression loading, running a driver much below 0.707*Fs isn't a good idea, especially a low Xmax one, rising rate suspension system or not. It must have been designed with tiny apt. or Japanese paper house construction in mind.
GM

Oh I agree 100% -I remember you observing this to me before Greg, and I took your comments to heart -that's why I was so surprised that it was the original unit, and why I say it's not exactly my first choice. The model figures match their stated response curves, but I wouldn't care to try it in practice. The poor little thing must be screaming for mercy.

Tony, two ideas you could try this for the FE164, a 'small' and a 'large'.

Small version:
65.75" tall
Driver 26.25" down from top
14.75" deep
8.5" wide
Terminate baffle 6.25" above floor and centred between front and rear baffle walls

Larger version:
65.75" tall (131.5" total line length)
Driver 26.25" down from top
17.75" deep
10" wide
Terminate baffle 7.75" from base and centred between front & rear baffle walls. These both assume 3/4" material as usual and W & D are external.

There's a bit of suck-out in the midbass, but it's not huge; 4-5db or so, and with luck the room should help out there with them pushed into corners. Better to go with the increased Vb if you've the room, but both should do pretty well.

Clark -that box is too tall IMO. You're just looking for trouble tuning it that low. I know Fostex did with the FF125K, but as Greg notes, that's not the greatest idea (unless you're in very specific circumstances). Chop it down to 50" tall, with the driver centre 20" from the top. You'll stand a better chance of it working. I wouldn't worry about the interior strike-plates, unless you have them handy and they're not costing you anything: it's very unlikely to make a difference. Try angling the horn mouth toward the rear wall / corner.

Regards
Scott
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