High Efficiency Speaker Asylum Need speakers that can rock with just one watt? You found da place.

---

[ Follow Ups ] Thread: [ Display  All  Email ] [ High Efficiency Speaker Asylum ]

---

[ Alert Moderator ] [ Edit ] [ Delete ]

---

Scoop design: choosing drivers & how to sim? (longer)

58.107.201.177

Posted by rick57 on March 31, 2007 at 09:10:24

Hi,

I’ve only learnt of scoop bins (BLHs) in the last few days . .

GM posting at diyaudio tipped me on these, and kindly gave me further good advice, some construction tips and a design for one of my drivers. However I’m starting a thread here as I think there’s more knowledge on scoops here

In trying a scoop, I’m looking for speakers to switch in for fun (with Lambdas in dipoles for lowest distortion with natural well recoded minimal percussive music, non-rock).
I’d probably prefer to have front midbass horns, but need to pick something easier to build.

I searched quite a bit on scoops, and an obvious thing that didn’t dawn on me, has wet my appetite further, compared to eg folded horns:
Above about ‘100 Hz’ - the scoop is a direct radiator.

I would think that beginning at say 150 –200 Hz(?) when the curve in the sound path begins to attenuate the signal, it’s probably a gradual transition. And that the upper limit of smooth response is suggested a little by driver mass rolloff Fmh, but more by piston range.

Anyhow, I read that the drivers work that best for BLHs are:
fs 33 – 50 Hz
Qts 0.2 - 0.3
A BL of 24 – 34 (high!)

I’ve three drivers that might be used, mostly optimized for small pro cabs, but close to the above suggested parameters (so one pair will be used in a vented box, and the ‘runt’ of the litter for midbass fun, probably sold):

JBL Kappa PHL
2035HPL/ Pro-12/ 5320
size: 15/ 12/ 15
fs Hz: 43/ 37/ 45
Qts: .34/ .24/ .28
BL: 16.5/ 18.2/ 23.4
Xmax mm: 7/ 4.8/ 7
Piston range: 330/ 427/ 330
Fmh: 239/ 296/ 290

Some midbass hump aside, I’d prefer to have them as flat as possible up to 350-500 Hz, to be able to use and cross them, actively, more easily to the Le’Cleach horns I’ve heard recently and really like (will likely get them when budget permits).

If I were after *bottom end, the highest BL PHL 5320 seems the best, but I’ll use subs . .
For the most extended *top end, the Eminence Pro-12 seems to me the best for the situation.

To compensate for baffle step loss (only got a handle on this yesterday!) rather than use the rolloff in midbass hump, and try blend the separate factors in, I’m inclined to measure woofer response in situ in the best placement option, then use line-level BS compensation for the rest. (To physically time align with Le’Cleach horns that are about 3.5 foot, 1.2 m deep . .)

Simming:

of Upper range/ limits, as they’re behaving like a direct radiator, for the effect of baffle size – the Edge http://www.tolvan.com/edge or MJK's MathCad worksheets (which I believe have more flexibility, so I downloaded today)

The bass end
- does Hornresp do BLHs, as a conical?? ~ with some parameters approximated, therefore not so accurate?
- Or are there formulas, that with a calculator or a spreadsheet work as well as Hornresp?

in this graph, what is a C40?
https://gallery.audioasylum.com/cgi/view.mpl?u=21168&f=upward1.gif&v=f&UserImages=21168&session=&&moniker=RCA-fan&invite=&w=800&h=500

and how could that *extra big midbass hump be scaled back/ tuned?

Thanks for your guidance in advance

This post is made possible by the generous support of people like you and our sponsors:

Amplified Parts

---

[ Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2024, Audio Asylum, all rights reserved ]

---

[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]

---