Sons of JBL:Part 1:18" Version of JBL 4520

Hurry up then, weathers changing, I'll knock one up.
Make it XB/186 friendly.
I could bring it up to London for a test, but then nobody would turn up
Gets coat

nickyburnell wrote: Hurry up then, weathers changing, I'll knock one up.
Make it XB/186 friendly.
I could bring it up to London for a test, but then nobody would turn up
Gets coat

funny you should say that......

so...no other suggestion about remodel for 18" ?

bitzo wrote: so...no other suggestion about remodel for 18" ?

IMHO, scoop should be tuned for max spl to match ASS+PD1850.

Otherwise Eminence/SteveB will walk all over it.

come one lev.... I hoped something more than "match the best scoop I ever listened"
if we are talking about using pds tome on superscooper's thread there are already some good trying. But if we playing aroud large throat concept I'm so far from good sim....

bitzo wrote: come one lev.... I hoped something more than "match the best scoop I ever listened"
if we are talking about using pds tome on superscooper's thread there are already some good trying. But if we playing aroud large throat concept I'm so far from good sim....

4" gap is fine if cab is 636-672mm wide.

Remember, PD1850 scoop will also "work" with

a)Fane 18XB
b)PD186
c)Void V18-1000
d)B&C 18TBX100
e)Wembley Bline 800

Might "also" be worth drawing up "separate" Medium chamber scoop (245mm width between front baffle and rear baffle),with looser compression & 'Saul 5" throat Gap' :lol:

If compression ratio is just right, that would would work well with PD1851, Fane 1000/1500,all Turbomax, and everything else.

Needs long horn (H1270mm ?) and big mouth (W672mm ?) though to get decent throw. smiley2

[quote="levyte357" 'Saul 5" throat Gap' :lol:
.[/quote]
smiley36

ok guys, here we are, I used the same legend here.
dpanelc is the distance between baffle and panelc.
http://www.freespeakerplans.com/forum/download/file.php?option=com_jfusion&Itemid=64&jfile=file.php&id=681&time=1301771734
I took care of braces thickness, the cross one too (1,8 cm thickness). Same external dimension, internal width 60cm height 122cm depth 68.8cm pd1850 loaded 2pi 2,83v

levy version
vtc 54 litres
throat 10.5 cm
lenght 1.78cm
baf=50.5cm
panela=37cm
dpanelc=20.2cm
panelb=38cm
panelc=40cm
anga=5°
angb=3°

saul version aka medium chamber
vtc 67 liters
throat 12 cm
lenght 1.70cm
baf=50.5cm
panela=42.5cm
dpanelc=24.5cm
panelb=38cm
panelc=39cm
anga=5°
angb=3°

bitzo version
compression chamber 54 litres
throat 3.6cm obtained with keele formula
lenght 1.88cm
baf=50.5cm
panela=33.5cm
dpanelc=20.2cm
panelb=41cm
panelc=47cm
anga=5°
angb=3°


and sim
[attachment=0:3w4unk63]<!-- ia0 -->levsim.jpg<!-- ia0 -->[/attachment:3w4unk63]

so let's discuss smiley1

bitzo wrote: ok guys, here we are, I used the same legend here.
dpanelc is the distance between baffle and panelc.
http://www.freespeakerplans.com/forum/download/file.php?option=com_jfusion&Itemid=64&jfile=file.php&id=681&time=1301771734
I took care of baces thickness, the cross one too (1,8 cm thickness). Same external dimension, internal width 60cm height 122cm depth 68.8cm pd1850 loaded 2pi 2,83v

<snip>

bitzo version

throat 3.6cm obtained with keele formula

so let's discuss smiley1

Despite sims, can assure you, if you build scoop, with only 3.6cm gap below rear baffle, you'll be very dissappointed. smiley11

so the throat limit I guess...would be around half of SD?