Eminence 18 Scoop

on the original plan there was another negative expansion....on section 56

bitzo wrote: from here

levyte357 wrote: I estimate internal chamber depth to be: 245 - (30+18) = 197mm, is this what you're using to estimate chamber volume ?

20 cm

levyte357 wrote: Would leave the duct out of sim for now, and just model scoop in 3 segments,

throat to first corner
first corner to start of horn mouth
mouth start to end of horn mouth
......

I don't get it what do you mean however here's how I model this scoop.
http://www.freespeakerplans.com/forum/download/file.php?id=697
section 12 horn
section 23 horn
section 34 duct,
section 45 horn
section 67 horn
then horn till mouth
in section 34 there's the negative expansion I modeled it like a duct with these dimensions s3*s4/2 in akabak hd={h3} wd={width} len={h4/2}

Bitzo, what happens if,

1. cab is 73mm deeper,
2. first corner brace is 45° 180mm long
3. Opposing corner brace is 45° 254 mm long
4. large upright is reduced in length by 30mm

?

nothing.
if I sim section 56 like an horn or like duct is the same. That's why in bracing style A or B there's not a real "akabakian" difference.
May be if h6 more littler than h5 would be some difference, I guess a larger dip. But probably a 186 like more this layout.

edit: ops you edit your post after mine ;P however I'll try to. Now I simmed only the point 2

However.....60cm internal width right? and what do you mean for depth? to me is the distance of rear panel from baffle, just watch the legend in super scooper and jbl thread. Large upright means panelb?

edit: ok too much sims too fast with too many drivers.... smiley29
however....
enlarging the volume of section 34 give more lowend and more bumpier with driver like pd1850, bph effect I guess. Make this cab deeper means give more low end but more horny taste. So you'll have a similar effect like enlarging compression chamber without doing it. So may be these last mods make this cab loveable by low qms driver.

bitzo wrote: Make this cab deeper means give more low end but more horny taste.

I meant extend rear of cab from 725mm to 798mm.

Also shifting last corner brace.

levyte357 wrote:

mykey- wrote: that's exactly what I drew up a month ago

I wonder if the 12 and 15 draw up the same? if not I was right about it being a typo mistake

The original Eminence illustration is not to scale, so incorrectly depicts panel placement.

Here's scale drawing Saul did last year showing this,

[attachment=0:qrjorhq8]<!-- ia0 -->original_emmy_scoop.jpg<!-- ia0 -->[/attachment:qrjorhq8]

:lol: you're repeating stuff I told you ages via PM :lol: I know it's not to scale

who cares


can someone just build one, and see how it works

levyte357 wrote:

bitzo wrote: Make this cab deeper means give more low end but more horny taste.

I meant extend rear of cab from 725mm to 798mm.

Also shifting last corner brace.

done.
levy 1 neg it's your first proposal
levy 1 neg dep with last mod
levy 1 neg dep 18n840 last mod with bms driver
[attachment=0:1q1a14lz]<!-- ia0 -->eminence3.jpg<!-- ia0 -->[/attachment:1q1a14lz]

I changed a bit the way to model negative expansion. I parametrized the corner brace lenght, so the duct lenght is calculated in this way ((h4*h3)-sin(rad(45))*cos(rad(45))*bracea^2/2)*width/(h3*h4). If the corner brace isn't at 45° I can parametrize also the angle. Now the second negative expansion is a proper horn section.

saul wrote: who cares


can someone just build one, and see how it works

Yes I will.

1st though agree on plan, don't say well I meant...
2nd. Post the plan exactly as you want.

Curved section will be as simple as possible for this prototye, so probably in three bits.

It will be tested with an XB.
It will be in Devon.

mykey- wrote: :lol: you're repeating stuff I told you ages via PM :lol: I know it's not to scale

But I meant with 2nd corner brace staying as 45° smiley2

bitzo wrote:
done.
levy 1 neg it's your first proposal
levy 1 neg dep with last mod
levy 1 neg dep 18n840 last mod with bms driver
http://www.freespeakerplans.com/forum/download/file.php?id=701&mode=view

IMHO, the Eminence plan with 45° 180mm long braces of same length, seems least complicated way to go, and is proven to work.

should be really nice to face scoop sim and spl measurement. But...IMHO should be quite pointless prototype another eminence original scoop. Just a personal opinion but I'm more interested into the son of jbl.