F120A Horn design?

[jaencer]

There is a serious lack of enclosure designs online for the F120A. It is a crying shame, because this speaker sounds fantastic. I have mine in some Double Bass Reflex enclosures made for the FX120 but using F120A, but I want to experiment with other options.

The Madisound store lists the F120A driver as 'Suitable for folded horn' enclosures. My question is WHAT 'folded horn'. How would I design such a horn? How do you tune a horn? What if I built the horn for the fe126e and used F120A?
http://www.madisound.com/catalog/PDF...ers/fe126e.pdf

If someone could help, I would build it and let the world know my findings.

[hm]

Hello,
the TUBA would be a solution

[rutcho]

FX120A is an excellent driver, but I am afraid it is not the best choise for back-loaded horn. The typical BL horn driver like FE-126E has low Qts and the SPL graph start to rise after 1-2 Khz up to the highest reproducted frequency.
FX120A has relatively high Qts=.44 and flat SPL in the 2-10Khz range. Its low Vas and relatively long Xmax (1.5 mm compared to 0.35mm for FE-126E) make this driver suitable for bassreflex, sealed box and TL applications. I think in properly designed TL this driver will show its best.

[Scottmoose]

I'm afraid I beg to differ with you there. IMO the F120a is actually quite well adapted to a BLH. As back horns can only practically operate over a limited bandwidth, a driver with a low[ish] mass corner is preferable, so you're not either running the horn up too high (and encountering lobing etc. issues), or cutting it low enough to prevent that, but ending up with a big hole in the response because the driver still needs some support above that frequency. A decent amount of linear displacement is also nice to have in hand from my POV -all other things being equal, you've more headroom available (although sensitivity naturally plays a part in that too), and most BLHs can only go so far in controlling the driver.

Agreed re the top end -the very high damping of the horn can bring that down a bit, so a rising response may be of help in compensating; depends which compromise you're willing to accept TBH. It's rarely a major issue until you get to the larger BLHs though.

[hm]

the Tuba supports the driver only below 150 Hz,
therefore it will work, very dence damping in
the press chamber.

[jaencer]

Originally Posted by hm

the Tuba supports the driver only below 150 Hz,
therefore it will work, very dence damping in
the press chamber.

Thank you all for your advise. The Tuba horn you mentioned... this can be built *** is with no modification for the F120A? Also english would help...

[jaencer]

I think i just might build the tuba.. I have enough wood already. Did you use acoustic absorbent material on the inside (lining or stuffing) anywhere?

[chrisb]

a couple of notes:

After building a pair several years ago, I would recommend against wasting the time and material on the Fostex "factory" hybrid design for the FE126E, or attempting to modify for other drivers. This is not one of their better efforts, and there are any number of DIY / public domain designs for the FE126E that substantially outperform it.

For fullrange use, the F120A can work quite well in a moderate sized vented enclosure (a la Fonken), although with it's lower sensitivity and limited excursion, system performance may benefit from the use of stereo woofers.

As for BLH, the simplest build would be a BIB

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

with the following dimensions, courtesy of Jeff

Fostex FX120 and F120a
L = (Line length) 120"
Zdriver = Driver 24" down from sealed end of cabinet
Sm = 50"^2

and finally, with minor fine tuning, no doubt one of Scottmoose's BVR family would "suffice" (as in, [much] more than )

[hm]

Hello jaencer,

look inside, softfibre is my material,
http://www.hm-moreart.de/11.htm in the middle,

the plan is in english available, as you see.
http://www.hm-moreart.de/72.htm

some people take 300 gr damping material
in only ~7 L volume !!,
not directly at the horn throat.

if you glue 4 mm mirror on the side walls,
the seen size gets smaller and the bass more tight.

Today, Tuba is constructed ~1982, i would prefer the
KORNETT in size and sound and WAF but not for your driver.