is this a form of rear load horn scoop?

Short piece on deflectors before the big one. I give credit to the idea and implementation of this and the SupraBaffle to Ron Clarke. [img]smileys/smiley32.gif[/img]. The picture may make the deflectors actually look distant from the speakers, but they aren't. Ron bases his ideas on measurement, then forms theory, that should get some credit with you lot. (He uses a very advanced system of sensors placed in and around the horn, developed from his work programs).

1. They increase mouth size, as Jake cleverly saw. These designs are actually designed with a deflector in mind, they form the final mouth. Think of the Klipschorn and it's corner. Actually, some deflectors are designed with extra panels (cross section is like a w) that make the mouth even larger.

2. Ron himself:


The deflector is a necessary as it prevents the wave front from being
sent back to the mouth as well as providing the final wave expansion
which allows a more spherical front to develop.

The SB will allow a lower diffraction wave launch as well as providing frequency support from the roll off of the horn action.


Combing both will give a flatter FR curve with a lower Fc.


So this has everything to do with mouth termination, and ron's specialty, wavefront control.

The second part actually ties in with our talk about baffles (note the SB)
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Another short piece on cabinet material because my BSC thing jeeps getting deleted [img]smileys/smiley36.gif[/img].

NOTE: SENSITIVE TOPIC THIS IS SUBJECT OF A LOT OF DEBATE...

Resources: diyaudio.com and some personal experimentation in the past, Ron Clake for my sentence or two on damping.

Well, the object of a speaker cabinet material is to not affect the sound of the cabinet.

Sound travels faster in solids. The issue with panel resonances and all of the other talk around that factor is to do with energy storage, and release. You want to control this so it achieves the objective, as it is impossible to stop any resonances happening. What you do is stick the panel resonance up or down relative to the cabinet passband. Option one- using MDF, HDF, hewn <strike>granite,</strike> (whoops) is to whack the resonance down low. Whack one of these and it is a low ring you hear. You do this by choosing the material and making it as thick as possible. If I went with this method, I would use 1.5 inches of HDF just to be sure. Now for the opposite approach, using ply, aged woods, laminate, fibreglass, metal etc. What you have now is the situation of attempting to push resonance high above the upper cutoff of your cabinet. This works just as easily, but you don't need all the material as stated. By the way, there are other lesser known materials that work apart from BB ply and the other staples, I also favour aged woods, metal honeycomb, and bamboo ply for the latter effect. I had a subwoofer a while back made of aeronautical grade metal honeycomb.

Now for more detail:

MDF breathes. You car audio guys should know this, it breathes, and you have to paint both sides to stop it.

Energy loss in laminated enclosures. Ron Clarke:
One of the good reasons for the application of ply in enclosure
applications is the fact is thats its a laminated medium. Any energy
has to encounter several interfaces, everytime an energy encounteres an
interface of different values it gives up greater energy than a
monocramatic singular medium due to the loss at an interface.
Simply put, the more interfaces an energy has to encounter the greater the loss of energy, thus the more damping.

My final point. Stiffness. Stiffness can be checked by Young's Modulus.
MDF and chipboard aren't stiff at all.
Fir ply is stiff. BB is even stiffer. You can google for average Young's Modulus values of whatever material.

Edited by: Deadbeat

Mostly some good points, but...

Deadbeat wrote: Option one- using MDF, HDF, hewn granite, is to whack the resonance down low. Whack one of these and it is a low ring you hear.

Normally when I go whacking my rocks, I hear a high resonance - sometimes verging on supersonic.

But rock is so stiff that very little acoustic energy can couple into it from air. As I was trying to explain to another persona few days ago, you're not done understanding physical phenomena until you know where the energy is going.

Deadbeat wrote: You do this by choosing the material and making it as thick as possible. If I went with this method, I would use 1.5 inches of HDF just to be sure.

I'm pretty sure panels get stiffer rapidly with thickness. So rapidly, in fact, that the increase in mass is more than cancelled out- so the resonant frequency goes up with thickness.

Deadbeat wrote: Energy loss in laminated enclosures. Ron Clarke:
One of the good reasons for the application of ply in enclosure applications is the fact is thats its a laminated medium. Any energy has to encounter several interfaces, everytime an energy encounteres an interface of different values it gives up greater energy than a monocramatic singular medium due to the loss at an interface.

Different values of what? If he's talking about different values of specific acoustic impedance (which might be related to stiffness), then the result of a discontinuity is reflected energy, which could be said to be part of the problem not the solution. If he's talking about different values of resistive absorbtion, then you'd get the best results from the greatest value, not from changes in value.

Is he perhaps talking intuitively, and then abusing "math words" to add credibility?

You can bring up last one up that with Ron, he can be found on diyaudio or the fullrangedriver forum. BTW, I find that accusing people of abusing 'math words' is something to be done after finding out the context. Just a small thing.[img]smileys/smiley1.gif[/img]

jsg, about increasing thickness. I found that increasing thickness and bracing actually makes resonant frequency go down. This was done by comparing MDF and whacking it with a hammer. Not scientific to say the least, but it told me a few things. I thought it would do one thing but it did the other. A friend who built his subwoofer redid this experiment, and built his subwoofer (a simple Linkwitz transform box) out of 2 inch MDF painted inside out with bracing all over and stuffing galore. Maybe I did something wrong and the results are bogus, who knows? Try it. I'll believe current results.

About rocks, in retrospect that should NOT have been there. I'm not trying to cover up anything, but you pointed it out fair and square. I was meant to mention that in an introductory paragraph referring to an almost perfect building material, but alas, it morphed into that monster. [img]smileys/smiley36.gif[/img]

Thanks for the criticism. It helps.

Omar,can those corner deflector thingys be used in the corner of any room?Has he added the cutaway room walls because it's outside?
Also when does a rearloaded horn become a scoop?When you add a curve..come on aint that nitpicking.Who says a "scoop" has to be curved?theres a lot of diggers etc out there with square "scoops"...
I put it to you that they are allone and the same.As Rog says a scoop is just a reflex with a flared port....

Finally my girlfriend wants to know who's the buff guy in the pics with the circus style silver barbells and the fake tan ?...

JUST KIDDING MYKEY!

ArkSystems wrote:
Omar,can those corner deflector thingys be used in the corner of any room?Has he added the cutaway room walls because it's outside?
<div>Also when does a rearloaded horn become a scoop?When you add a curve..come on aint that nitpicking.Who says a "scoop" has to be curved?theres a lot of diggers etc out there with square "scoops"...</div>
<div>I put it to you that they are allone and the same.As Rog says a scoop is just a reflex with a flared port....</div>
<div></div>
<div>Finally my girlfriend wants to know who's the buff guy in the pics with the circus style silver barbells and the fake tan ?...</div>
<div></div>
<div>JUST KIDDING MYKEY!

</div>

I hold that a scoop is curved because that's how it got it's name. You can recognize a scoop when you see one, sectional curves and reflextors count as long as it looks like a scoop.

The corner deflectors were actually designed to replace corners. Though you could design one to fit in the corner to make the flare a bit better.

They are all one and the same? Funnily enough, my philosophy is that a cab is a cab, you can't ignore physics, it works as it individually works. You can try to classify it but there are no definite transitions. In fact a lot of the work shown earlier (as well as the sketchup) is on BVRs. Big Vent Reflex. Sound familiar? Big reflex boxes with massively flared vents. Same way you can think of anything as having reflex/quarter-wave/true horn (velocity controlled at physical mouth)/etc qualities all at the same time. A cab with a horn, a port, whatever, it's still a driver with a damn thing on one/both sides.

BTW, where's that Rog quote from?
Edited by: Deadbeat

Respect,I was feeling a bit argumentative then ..no offence ment ...hadn't had my herbal medication. I do like those lowther rear loaded tranmission line scoop reflex hornsthough ,saw some go locally for 100 odd squids.If only I had the cash at the time..guess I'll have to put them on my things tobuild list....
"a scoop is just a reflex with a flared port"

Pretty sure it was Rog who said that...(does anyone know who said that)I'll try and find it on the other side...BTW why are we talking to each other on two different forums about the same stuff..?Parallel universe I guess.

It's OK.[img]smileys/smiley1.gif[/img] None taken at all. Maybe my wording on the last bit conveyed something I didn't mean.

Dunno who said that one, i feel their sentiment though.

Are we talking about the same stuff on two different forums. It's weird, sometimes I go on this and still think I'm on SP.

DIVERSION
If you're interested in cheap fullrange goodness and have the time, I'd recommend one of the many many Fostex/CSS designs. Check out:
www.frugal-horn.com/
www.planet10-hifi.com/
www.t-linespeakers.org/
for info and plans and advice. Bit of a long shot anyway, but nice links to post.
Stay away from the Lowther Acousta and their older jobs (which appear from time to time), they can't compare to the newer (cheaper) fostex imo, the term 'shout' comes into play, though that's hardly scientific, it's what it sounds like (think 'honk' with an edge). I'll always be here.
/DIVERSION

When I bother with my next piece, it has been reworked into two parts. A short explanation of baffle step loss, and then how to compensate it, engineered specifically for pro sounders. remember, the solution is active!
Edited by: Deadbeat

Me wants the "Dalek"...might have replace my B&W DM7s ,BTW i'm Fuzzylogic over there! Edited by: ArkSystems

Deadbeat wrote: You can bring up last one up that with Ron, he can be found on diyaudio or the fullrangedriver forum. BTW, I find that accusing people of abusing 'math words' is something to be done after finding out the context. Just a small thing.[img]smileys/smiley1.gif[/img]

But I responded to what you posted here. The quote just said "an interface of different values", but the reader doesn't know what the values are of, at least from the text available in the comment. Hence the word "value" lacks meaning in any physical or mathematical sense,leaving only the association the word itself has with thescientific/rationalist paradigm.

Feel free to supply the vindicating "context" here in this thread. It was nice of you to invite me onto those "audiophile" forums, but I'll decline this time.

Deadbeat wrote: jsg, about increasing thickness. I found that increasing thickness and bracing actually makes resonant frequency go down. This was done by comparing MDF and whacking it with a hammer. Not scientific to say the least,

You're being honest, which is good, butmy experiences of tapping pieces of wood has always shown the thicker piece has a higher resonant frequency. So our anecdotal wisdom is at odds.

Deadbeat wrote: About rocks, in retrospect that should NOT have been there. I'm not trying to cover up anything, but you pointed it out fair and square. I was meant to mention that in an introductory paragraph referring to an almost perfect building material, but alas, it morphed into that monster. [img]smileys/smiley36.gif[/img]

Thanks for the criticism. It helps.

Nothing wrong with mentioning rocks. I just don't see a granite cabinet as someing that resonates at a low frequency, so I disagree with that claim.