Terry Cain's BIB -why does it work and does anyone have those Fostex Craft Handbooks?

[Godzilla]

>>> I'd like to use this same system to make a bib for the
FF165 after all the raveups Godzilla has given the driver
and then compare the FE127e BIB with that.

Loninappleton – I have both the 165k and 127e. This morning I listened to the 127e in the living room. The sound was excellent. Here is a pic of the finished speaker. Pine with dark walnut stain. They are small and fit nicely on either side of the fireplace. I’ve had no complaints from the wife. She called me to watch the boys play and I shut the system off and went out for some fun.

http://www.zillaspeak.com/fostex127eSSB.asp

Later this afternoon I went downstairs and listened to the 165k BIBs. Sound was also excellent. The performance comes alive with the BIBs. Jack Johnson sounded very much alive and in the room as did all the instruments. Then Regina Spektor was right there in my room. Amazing sound from the BIBs! You can hear all the spaces in between the instruments. Vocals are very real sounding. Maybe it was the tubes too… or the new room treatments absorbing all the echo in the room. Regardless, you want to listen forever. Wife called to take a ride somewhere. I told her just one minute but instead listened another 30 minutes before my butt would leave the listening position. Pine with red mahogany stain. Very nice look for a hack like me.

http://www.zillaspeak.com/bib-godzillabib.asp

127e BIBs may have the same -glue your butt to the chair magic- but in the slotted box they don’t sound anywhere near as good as the 165k BIBs.

G.Kennedy – your BIBs look fantastic! Amazingly, BIBs don’t take up a lot of floor space. They are tall, slim and elegant IMO. Great job!

[planet10]

Originally posted by Godzilla
This morning I listened to the 127e in the living room. The sound was excellent. Here is a pic of the finished speaker. Pine with dark walnut stain. They are small and fit nicely on either side of the fireplace. I’ve had no complaints from the wife. She called me to watch the boys play and I shut the system off and went out for some fun.

http://www.zillaspeak.com/fostex127eSSB.asp

Now i know where that design came from... out of the blue someone asked me if we could do a flat-pak of those and get a set of modded drivers for them... we did and he loves them

dave

[Godzilla]

I was worried when I simmed them in WinISD that they may sound a bit bloated but I must have gotten lucky. No bloat. They are pretty small and feather light made from pine. No one ever seems to notice them at all in the living room. I suppose they look rather bland. They do fill the room with sound and recreate piano pretty darn well (we have a piano in the room). They are very clear and image great but not as great as the bigger BIBs. These, the BIBs and the Straight Pipes are speaker cabinets I’ve kept and finished over the years. They don’t have major sonic flaws. Most all my ported cabinets end up gutted in storage because they sound hollow or bloated. I am going to build a similar slotted box - but much smaller - for a 3 inch TB for the den soon. I’m hoping for similar results!

[djn]

Yes I would like the manufactures name for that wood. We don't have a manareds here. Cheers..

[resident]

Originally posted by G.Kennedy
I did say RED .....

The red is awesome, I used Transfast cardinal red.

Wow
impressed!

[copperhead]

G. Kennedy, what line length did you use for your Bibs?

[Vix]

Originally posted by Godzilla
… or the new room treatments absorbing all the echo in the room.

A bit OT...could you please make some pictures of these room treatments?

I just want to see how those bare walls look after a treatment. I will maybe need to treat my room as well, so just wanted to see how it turned out in your case-(WAF acceptable?)


Regards,

Vix

[G.Kennedy]

Originally posted by copperhead
G. Kennedy, what line length did you use for your Bibs?

138"

Here is a quote from this thread regarding the 168 Sigma, not sure if it is Scottmoose or GM. I used these parameters to build mine.


"168EZ

All dimensions are internal. WxD ratio wants to be 1:1.4142 to preserve the flare around the base. Try not to deviate from this if possible. So internally 7.25in wide x 10.25in deep (always round up to the nearest sensible figure). If you're using 0.75in material, that will make for a box 8.75in wide x 12.5in deep.

The FE168ESigma can handle a slightly longer line than I suggested originally on the Zilla pages. I keep meaning to get the revision to Jeff. Increase the line length to 138in (70in tall cabinet externally) with a Zdriver of 29.25in from the internal sealed end."

[GM]

Greets!

Out of curiosity I tried manipulating the simplified Margolis-Small max flat formula to see if I could find a simple formula to approximate a BIB 'close enough' and the few diverse ones I compared with this formula worked for me:

Vb = 20*Vas*Qts^1.25

(Vas can be either as liters or ft^3)

Note that this accounts 'close enough' IMO for the internal baffle, driver, bracing loss and when applied to T.C.'s or Scott's 'small' BIBs it's considerably bigger, with a relatively 'full' response more like all the ones I've posted. Since all I changed was the Qts exponent, you can decrease Vb, LF gain BW by increasing it.

Note too that the formula assumes a tuning of one ~octave below Fs, so for low Fs drivers where you want to tune it to ~Fs, then if you want to maintain the 'flavor' of the BIB's response you'll need to input half the driver's Vas and calc its path-length (L) based on Fs/4 in lieu of Fs/2. This way, the mouth area (Sm) remains constant and only the length, driver position changes.

Anyway, for those with the capability, please do some comparisons to a variety of existing sims and let me know if any appear to be unacceptable.

GM

[Scottmoose]

Nice one Greg -you've done it again.

Thus far, in the comparisons I've made, this appears to work very well indeed. Vb usually comes out a little larger than I often use, which I know you prefer (& I confess you've convinced me to that way of thinking too) & response seems consistantly solid. Looks like you've cracked it, or at least one way to size the box for a target alignment. This is much better than what I was trying to work with.

Cheers
Scott