FE206E BIB short version (140 inches)

[e_fortier]

Hi,

I'm looking for the frequency response of the shortest verion of the 206e bib, has it been publish yet ?

The longer one is impressive with a -3db at 30Hz but the shorter one would be more WAF

Thanks in advance,
Eric

 

[freddi]

here's a simulation in AJ-Horn - for spl vs xmax limits I had xmax listed as 1mm instead of 1.5mm. It would reach 1mm by ~1.2 watts or so around 40Hz

http://img220.imageshack.us/img220/93/shortbib206eya8.gif

 

[freddi]

and here's the sim again with wider view of response plus I corrected the max spl to 1.5mm xmax

http://img220.imageshack.us/img220/7058/shortbib206e15mmak4.gif

Z-out 0-2-4 & 12 ohms

An externally hosted image should be here but it was not working when we last tested it.

 

[Vix]

I was looking at the data about Fe206E Bib, and there's something confusing:

If you look here:

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

you'll see that Sm=133.875

On the other hand, if you look at the vaules at the Bib calculator, here: http://www.zillaaudio.com/bib-calculator.htm

for Fe206E, Sm=90.606

Which one is correct?

Thanks

Vix

 

[Scottmoose]

Neither. As has been pointed out in the past, many (most) of the dimensions listed on Jeff's site pre-date the T/S alignment used in the Excel sheets. They'll still work happily enough, but the LF alignment may be slightly different.

 

[Vix]

Thanks Scottmoose,

Then, which one (BIB calculator) should we take? Sorry for a dumb question, maybe I missed something...

Regards,

Vix

 

[Scottmoose]

Whichever you like. There is no right or wrong (within reason). The BIB calculators provide a specific alignment, but you don't have to use it.

 

[Vix]

Thanks!

 

[Godzilla]

I know someone that built both the short and longer BIB for the 207e and loves them both. I guess it depends on your room/ceilings but either one should be great. Even if you built one with a line somewhere in between the short and long you would have a great sounding speaker IMO. The BIB is forgiving and the charts will reflect that. The longer line will have deeper bass, otherwise you get the other BIB advantages like large imaging, dynamic sound, efficiency, easy corner placement, etc...

OT... This week i cut holes for 15 inch Eminence Alpha's... will glue up the H frames and connect over the weekend maybe... can't wait to see how they enhance my BIBs using 6.5 inch Fostex drivers... Amazing how i need two 15" pro drivers to enhance the bottom octaves of my BIBs... I can't wait!

 

[e_fortier]

Hi,

Thanks to all for the answer.

I just checked and the ceiling in the basement (where my HT is located) is 80.5 inches (205cm) high.

How much distance do you need from the top of the BIB to the ceiling so the coupling of the horn's mouth has a nice transition to the ceiling.

I just want to make sure I get the maximum from this BIB based on the dimensions I have.

Is it worthed to make it lets say 150 inches instead of 140 to get a little more bass or is this irrelevant.

Thanks for the help

Eric

 

[e_fortier]

I forgot to mention that these BIB won't be located in corners but instead up againt a wall on each side of the TV.

Eric

 

[GM]

Well, the standard minimum distance of a port to a parallel surface is its end correction, but backed up against the wall will create a mirror image that doubles the BIB's mouth (Sm) effective area, so find the effective radius (R) of this 2x larger Sm, then the minimum distance (Dm) = ~0.613*R, so 80.5" - Dm = BIB height.

GM

 

[e_fortier]

Thanks for the answer.

I'm not sure I'm following you since the Sm is calculated using Vb and the height (L) so I wold first need to find the required L to get Sm so it looks like a vicious circle

Lets say I choose Sm of 90.6 square inches based on a height of 86 inches (too high) then 2 x Sm is 181.2 woule be the new surface and is equal to (4 x pi x Rsquare) so
R = square root of ; (181.2/(4 x pi)) = 3.8 inches

Dm = 2.3 inches

Even by finding these number I'm still stuck since the above is based on a L of 86 inches.

How do I solve this...

Thanks for the help.

Eric

 

[Scottmoose]

By trying a few options?

Note that GM pointed out that's a minimum distance, not an automatic requirement. It's really not that hard.

1/ Assuming factory specs. for the 206, select a reasonable tuning frequency -say, 48Hz, for a 140in line or 70in tall box with a CSA of 111in^2.
2/ Double that to account for the virtual doubling of the terminus size caused by the rear wall, = 222in^2.
3/ 222/pi^0.5 gives 8.4in.
4/ 8.4*0.613 = 5.1492in.
5/ 80.5in - 70in = 10.5in
6/ 10.5in - 5.1492in = 5.3508in.

So, room & to spare.

 

[e_fortier]

Thanks Scottmoose,

It looks like it would be a trial and error exercice to get the maximum height BIB based on ;

1. The height of the ceiling.
2. Try to account for the required minimal spacing from top of BIB to ceiling.
3. Use the back wall to load into the ceiling.

Can I ask you where you got the CSA of 111 inches square.

I wish I could put these in the living room but it could be pricey in laywer's fee

It looks like I will built the 70 inches high BIB

My brother in law hates FR speaker because the lack of bass, can't wait to see his face when he's gonna hear these.

Thanks,
Eric

 

[Scottmoose]

Are you really that bothered about a couple of Hz?

The CSA is just from the standard T/S alignment for that driver / tuning frequency, rounded to the nearest sensible figure.

 

[e_fortier]

I just find that 48Hz is high, my floorstander are tuned to 37Hz so I was hoping to go even deeper with the BIB.

 

[Scottmoose]

That's 48Hz at the 1/4 wavelength. F10 will be an octave lower (i.e. 24Hz) & useable down to 30.

 

[e_fortier]

Amazing...

Thanks, now we're talking

My sub also has a F10 of 24Hz and F6 of 30Hz so this is quite amazing for a 8 inches vs my 12 inches sub...

Thanks a lot for the answers.

One more thing; Regarding the internal and external speaker wire I was thinking of using small gauge instead of inserting a 3-4 ohm resistor, would 22 or 24 AWG be OK. Distance will be about 3m from the amplifier (solid state Yamaha)

Thanks,
Eric

 

[Scottmoose]

Should be fine, although you won't get much voltage drop over that distance. If you wish to take that approach, go for the 24ga.