12" J-bin....

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Hi !

I know there's been some talking about this but I
cannot seem to find any workable conclusions...

So my question is;
Can a J-bin / Scoop as used in PA, be made with a 12" driver ?

Off coarse it can, but will it work ?

Now I'm posting this in the Fullrange-forum, as I intend to make
a hifi-sorta scoop using the ol' Philips AD12202.
A terrific fullrange 12" although I'm a little worried of the high-ish
total Q (being somewhere in the range of 1.2 I guess)

My thoughts are as follows;
If I were to scale down the original J-bin, I'd alter the hornlength,
pushing the lower horn cut off frequency up.
But isn't it smarter to just narrow the design,
so keeping the hornlength the same ?

And if this is a way to go, how much would it be narrower ?

Maybe some of you backloaded-horn-masters can help me with
this please ? :confused:




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Joined 2003

Well, it would depend on the rest of the driver specs and what the performance goals are, but as a general rule a ~0.707 Qts is the upper limit.

If the Qts is this high, then either OB or a max flat impedance TL, but the latter requires specs to calculate it.


found in another thread:

edlye said:
I just found a spec sheet, but it is in German: http://www.rahaso.de/foren/msg.php?f=audiotreff_fullrange&idx=18657&

Here's a translation with the help of babel fish:

nominal impedance 8ohms
d.c. resistance of the moving coil 6.6ohms
load rating 100W
max load 150W
output 0.5W
resonant frequency 45Hz
through howling tension (lost in translation?) 9V
transmission range 50Hz - 19kHz
magnet material FXD
magnet diameter 124.6mm
magnet mass 990g
energy in the air gap 498mWs
magn. flow density 1110mT
air gap height 8mm
height of the moving coil 9.7mm
minor diameter 35mm
basket diameter 313.3mm
sound opening/free space 278/5mm
depth 135mm
mass of the loudspeaker 1650g

Unfortunatly, no Qts....

Can it be derived from other numbers ?


Hi !

hmmm, ok, I get your point :(

Seems there is no alternative then to try to measure Qts myself
Do you have any methods you'd like to recommend ?

I got some more speakers I'd like to measure so it would make
a nice session. Next weekend I'll have the time to do this...

By the way;
the "recomended enclosure" by Philips is "bassreflex or hornloading",
so I guess Qts isn't that high afterall...


It opens in a new window, larger sized when I click on ti as well but the trouble is it is a portrait on a landscape format screen and still not large enough to make out the words. I suspect it would be visible if stored and displayed on a picture viewer with expand mode.
Huh?! I see it as a white background with large enough, high contrast black characters in Mozzilla Firefox.

Anyway, no, I don't believe it will perform well in a BVR, at least not by my standards, so as always YMMV.

I'll have to get back to you later with a design if no one else helps in the meantime.

Empee said:

how would a max flat imp TL look like ?
what size am I looking at ?

thanks for your help!


You're welcome!

Well, after looking at the specs I'm not sure how much help I can be due to the way they spec'd Qes, Qms, Qts since I don't know how to convert them to free air measurements.

For sure if I use the 80 L (presumed) sealed box measured specs, the TL will be fairly large at ~10.514 ft^3, but I assume the free air specs will be less, though I don't have a clue how much less, so FWIW (all dims i.d.):

L = 66.5"
CSA = ~324"^2 (recommend 22.875" W x 14.125" D)
zdriver = 26.56"
port = CSA at bottom
stuffing density = 0.6 lbs/ft^3 simmed



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Hi GM !

as always, thank you very much for your reply and sims !

I decided to store these drivers until I got the room for a
pure open baffle, like all people I ask advise me.

I think the BIG Jalabert baffle will be the way to go, like

They are actually smaller than the Hemp BiB's I got now :)

I guess I'll take on another speaker-project to keep me buissy...

I got some Philips AD1065's but these also show a high Qts.

Last week I also obtained two 8" fullrangers by a German
brand called EAL (Electro Acoustic Leipzig), but I do not have
their specs yet...

They sound pretty good in a cardboard box (quick testbox) so
maybe they can be impemented in a BVR/horn like these

Cheers !

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