is this a form of rear load horn scoop?

Lev, I'm not writing this because I have an interest in Hi Fi, but I think that some sort of influence can be taken from designs in the Hi Fi world. The designers are much more adventurous than in PA and can produce a sound that is way out in front of anything that comes out of black boxes. With electronics way out in front of acoustics I think more adventurous projects are needed to try and step up a gear or two in sound.
Since the start of these forums (this one and the other one) do you think that sound has progressed. There has been a lot of talk and writing and simulating. There are people still using and wanting to use cabs that were designed 30 years ago.
Perhaps we should dedicate a section called 'where do we go from here', and try to come up with a few solutions
Sorry to be off topic, but when I read what people write, it can start me thinking along unrelated lines sometimes.

Here here

Well said tony. While there are some concepts that might not be so useful round here (Linkwitz transform, etc), there are those that are. Like my mentioning of aperiodic rear chambers, if that could ever be done, among other things. I posted a new post because I had said something that was partially wrong, and editing it would be sneaky.

Now, rethinking the classic scoop shape into different foldings...anybody up for an 18" double 'scoop' scoop? or a rear firing one with deflector to increase mouth size greatly?

Edited by: Deadbeat

Tony.A.S.S. wrote: Lev, I'm not writing this because I have an interest in Hi Fi, but I think that some sort of influence can be taken from designs in the Hi Fi world.

Completely agree, and if someone had put forward discussion of a PA scoop, which is a version of a "hifi" scoop, no problem; I just found it objectionable to see all this "hifi" discussion in the scoop forum.

I would have preferred to see and hear, how rig owner A got his 4x scoops to sound better and louder than rig owner B's 8x scoops.

levyte357 wrote:

Tony.A.S.S. wrote: Lev, I'm not writing this because I have an interest in Hi Fi, but I think that some sort of influence can be taken from designs in the Hi Fi world.

Completely agree, and if someone had put forward discussion of a PA scoop, which is a version of a "hifi" scoop, no problem; I just found it objectionable to see all this "hifi" discussion in the scoop forum. I would have preferred to see and hear, how rig owner A got his 4x scoops to sound better and louder  than rig owner B's 8x scoops.

Referring to the last part.

---

Probably knowledge and experience. There's a lot of wasted boxes out there, waiting to be driven properly. It also may take a bit of money because it cant always be done on the cheap.

just to get back to the tl / horn debate, i was under the impression that tl enclosures had a line behind the driver which reduced in cross section along its lengh. thats how mine are built anyhow
the line is in place to absorb all but the lowest frequency engery from the back of the driver, hence the reduction in cross sectional area
as i understand it, the best transmission line should be ever decreasing in cross section, and as long as possible.

levyte357 wrote: Shouldnt all this be in an "Obscure Hifi" sort of forum?

No one here is gonna build these for use in a rig, so to me, it seems a bit pointless having it here.


Edited asalwaysby levyte357 - 2 mins after posting

What a ridiculous thing to say!

Starta new site called " www.Lev'sSpeakerPlans.com "where only you are alowed to post, you would only need a "heavy amp" topic and a "scoop" topic. Job done.

Jake_Fielder wrote: <div>What a ridiculous thing to say!</div>

You're right, I guess many of the above "scoops" are used by PA rigs. [img]smileys/smiley2.gif[/img]

I also guess the Newest scoop on the block is very similiar to the above, especially with timber prices the way they are.[img]smileys/smiley36.gif[/img]

Jake_Fielder wrote:

levyte357 wrote: Shouldnt all this be in an "Obscure Hifi" sort of forum?

No one here is gonna build these for use in a rig, so to me, it seems a bit pointless having it here.


Edited asalwaysby levyte357 - 2 mins after posting

What a ridiculous thing to say!

Starta new site called " www.Lev'sSpeakerPlans.com "where only you are alowed to post, you would only need a "heavy amp" topic and a "scoop" topic. Job done.

levyte357 wrote: You're right, I guess many of the above "scoops" are used by PA rigs.

I also guess the Newest scoop on the block is very similiar to the above, especially with timber prices the way they are.

I never said the above "scoop" is used by PA rigs, so your sarcasic comment is pointless. There is no need to be so protective.

Infact, after looking at the"scoop" and reading a comment Tony made i have added a couple of pieces of wood to my design. So if nothing else; it has helped one person.

I realise that you won'tbe aware ofthis but general chit chat like this threadcan really help when designing, prototyping and buildinga speaker cabinet.

this design is far more "scoop" than some of the "scoops" you talk about anyway.

Scoop scoop scoop scoop

Scoop

scoop

Not editedby Jake_Fielder - 19 August 2008
becauseI mean whatI say

I am not posting this in another forum because there isn't one for back loaded horns. Oh wait...[img]smileys/smiley24.gif[/img]


csg, I'll answer your Q from the other thread soon. BTW, tlines can be defined by taper, they are quarter wave resonators, and can have tapers (as opposed to expansions) which can narrow, stay the same, or expand.

Now back to what we could take away from these enclosures.

NOTE: most of these enclosures don't fall into specific categories (they are under MJK's theory, though), eg hybrid tline blh.

This is probably going to be a multi post monster.

1. How do they design these enclosures?

Notice that they don't use hornresp down those parts to calculate the response, and some measurements have been reasonably true as I have seen. Ron Clarke designs his enclosures using heavily modified software from the petrochemical industry:


When i first got into Single Driver Full Range Back Loaded Horns (SD FR BLHs) i built
around 10 different horns all based on the figures established by the greybeards,
and even some from GM, and later i borrowed some of the math from Martin for the
TL action. During these builds i went thru extensive testing using pressure sensors
mounted inside the horns and established a great deal of data. Later i incorporated
a basic program which was established to measure pressure surges in petro chemical
vessels. This program was extensively modified to act with the data i had accumulated
and the different medium that the wave travelled thru. The program is still being
changed and if it will ever reach an end, i have no idea. The last major change came
about when Dave (planet 10) and Chris remarked on the compressed sound effect of
the A126. I thought the programming was correct, but when i investigated further
i realized there was an error in the BW of the horn vrs the baffle step. The answer
is an increased CC and the supra baffle.



All went to show me that i wasn't as smart as my boss thinks (if ya cant stun them
with brilliance, bufflo them with BS is my motto). Now i really have poor programming
skills, but a fair handle on math and some physics, so i have a young kid who is
an exceptional programmer actually do the work and all i do is say " incorporate
this or change that" and he really does the work, not me.

</font>
The 'Martin' mentioned is Martin J King who (along with Ausperger, though on a completely different approach yet having the same result) has created lots of the modern math used in designing a variety of quarter wave enclosures. Now his software (actually a suite of simple to use MathCad worksheets, he has lots and lots of them for all sorts) is what everybody else uses. It used to be available for free, but too many commercial designs have been made without credit. The results are quite accurate (look at measured plots on Bob Brines' audio site for examples).

All of Martin's work regarding quarter-wave enclosures can be found on:
www.quarter-wave.com/
'Front and Back loaded horn' theory is most likely going to be the point of interest.

EDIT:
The next few posts will focus on more practical aspects such as 'what concepts' can we take away from this?
Also, ron recommends 18mm 13ply BB for all of his projects over MDF, this will be explained in the next installment hopefully.
Edited by: Deadbeat