midbass horns - is there a difference on how these throats behave ?

[freddi]

besides giving a desired flare by rotating the chamber to do so, is there an
advantage to the Classic's way ?


A "C" horn

vs the University Classic with its throat ramps

 

[Bern Wansen]

What we usually refer to mid for me, well at leadt for me, is so damn high pitched... treble is like omg such a penetrating whistle. I would put the mid-bass denomination around the 60 - 80Hz range? The folded horn will dissipate any sound waves at these frequencies but I don't know what you planing to play so perhaps you should give some further details of your project.

 

[GM]

How it's folded sets its HF gain BW, so if still available, read Danley's LABhorn docs on how to extract as much HF as practical in a folded horn.

GM

 

[freddi]

(thanks GM - will look for the Danley article) hi Bern - here's what the upper horn drawn in red does with a 12" Community brand speaker (blue trace and in-room)

RCA-Fan indicated that it would not go higher with a 12pe32, but rather tilt the curve upwards

Resonant Frequency (Fs)51.81 Hz
DC Resistance (Re)4.73 ohms
Voice Coil Inductance (Le)1.65 mH
Mechanical Q (Qms)7.34
Electromagnetic Q (Qes)0.27
Total Q (Qts)0.26
Compliance Equivalent Volume (Vas)3.19 ft.³
Mechanical Compliance of Suspension (Cms)0.21 mm/N
Diaphragm Mass Inc. Airload (Mms)45.97g
Maximum Linear Excursion (Xmax) 3.5mm

could the University Classic's throat ramps be simplified without
penalty in its response?

its a sturdy little box being well braced 5/8" Baltic birch - hope mice
have not eaten the Community 12. I would have bought an extra but
they sold out

 

[Bern Wansen]

Hum. Here in Brazil we never use such boxes for midbasses. For a 12 speaker you can cut off the frequency at 80hz 24dB octave and again lopass at 200Hz 500hz max. Otherwise, considering the speaker parameters it will waste energy and that kick drum you aimed so far in the range you want wont sound any better if you go high in sound volume. You can cut at 63Hz for a perfect kick drum but that will blow your cone sooner or later. Well that IS midbass. In Brazil we use bass reflex boxes for midbass with just the necessary size to avoid noise in the ports. It has only one ripple at freq. response near 200Hz where you should cut off to avoid cone damage. Since your box in sealed on the back of the speaker, ripples wont go too far, but spl will be compromised. Spl × quality is s very fair trade if even a trade at all. Is that your aim or you plan to trust box characteristics to tell what they are purposed?

 

[Brian Steele]

Interesting. Can you provide a link to one of these designs, or perhaps a few pictures?

 

[freddi]

I'd like to hear more too Bern. Do you suggest a woofer with qts higher than 0.38 for midbass? FWIW, it may be illusionary and due to balance . but a Karlson enclosure subjectively hits lots harder for its size range than horns I have. (at some point larger, a horn may win) The original K15 goes to around 60Hz outdoors before dropping off. With a light cone, excursion is small for output.

 

[GM]

It should since you're comparing a 6th or higher order depending on the K type to a 4th order alignment. Over a narrow BW even the simplest Karlson is a viable option and don't understand why it's not more common in small prosound rigs.

GM

 

[Bern Wansen]

The difference is mostly timbre. You should put rockwool linings on the sealed enclosure but not too much just on the walls. This way you get rid of timbre. There is a major drawback when using the band pass 80 - 300Hz. The woofer will sound dumpy. But thats where knowledge gets around the problem. Extracting the full power of the woofer without blowing it. Again, the bigger the horn the best. But the secret is: you must boost 80Hz signal by around 6dB with a -6dB octave slope, and only then, only, crossover at 80 - 200Hz, in a manner the high impedance attributed to the higher freq wont steal too much power from your amplifier. Boosting 80 - 160Hz provides this part of the spectrum to reach maximum tolerable signal volume before the rest, leaving some headroom. Also, for any visibly excursionating woofer (althoungh you cant see it doing so inside the box) you must use a professional amplifier or a one with double the rated rms power of the woofer, because doing so the amp wont lose target power beside providing cone control and fidelity.