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Author Topic: History of the LABhorn!  (Read 20014 times)

Don Snyder

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History of the LABhorn!
« on: May 03, 2005, 02:18:11 pm »

Since the LABhorn is a DYI project, it’s no surprise that there are at least 5 versions of  Tom Danley’s baby. The earliest version dated 2/17/02 was drawn by Tom himself, and is now posted on the documents page as “labhorn1a.jpeg” and “labhorn2b.jpg” under the word HORN. While the drawings are rough, there is enough info to get the job done, but it is doubtful that anyone built a LABhorn from them.

The second version was done by Brian Fehrman, and approved by Tom. It is very professionally done, and much more complete. It is dated 4/4/02, and was used to build the first LABhorns on record. While there are several changes from Tom’s original design, none of the changes altered the horn flare enough to make any difference (IMHO). You can find Brian’s version on the documents page

At this time, we were all in “horn learning” stage, and several people noticed inconsistancys between the two versions and the table of the “perfect” horn. Some even thought that the difference between 3/4” plywood and 18mm plywood had to be reconsiled. During this stage, Peter Sylvester created a third version of the LABhorn with dados and biscuits that “corrected” both Brian’s and Tom’s versions. Peter built one LABhorn, then made more “corrections” and made a second one. Peter reported that he could measure no real difference between his cabinets and the results as reported by Al Limberg, “Too Tall” and others. While he may not have “fixed” anything that mattered acoustically, Peter’s version is the most rugged box you could build. His website has been an inspiration to many, with his pictures, drawings and explanations…Good work, Peter!

There are two other versions, and since I don’t know which one came first, I flipped a coin and Jeremy Bridge’s version is the winner. I’m afraid that the coin toss is the only thing that Jeremy wins, since his drawing has too many errors to be used by someone who doesn't have the experience to find them. It purports to be a “metric” version, but has the English dimensions as primary dimensions (but sometimes rounded to the nearest inch). While the drawing is mostly done in the U.S. standard third-angle projection, Jeremy detailed one part of the nose flare in “Dutch” projection (first-angle). There are a few lines that should be dotted that aren't (horizontal flare #1).

That brings us to our fifth version, a major revision by Brad Litz that he calls version 3. His version is for home theater sound. More like fine furniture than a “roadie proof” speaker, the compromises he made may make his version useless for pro sound. For instance, he raised the compression ratio to 3, which stresses the speaker cone. Until someone builds this version and takes it on the road, we can’t be sure the LAB-12 can handle the stress. He has posted 3-D cad files plus some detail part drawings on his website, which means you must have 3-D cad to get the info. He used Hornresp to model the changes, and seems very happy with the results… Good job, Brad!

In the end, Tom’s design is a complete success.  “Improvements” by all the builders did little to damage this rugged horn. One or two piece baffle, 3/4” or 18mm plywood, 5 1/2” or 8” corner brace, different access covers … all the horns worked fine.


Tom’s Drawings @ prosoundweb
http://web1.prosoundweb.com/lsp/labhorn1a.jpeg
http://web1.prosoundweb.com/lsp/labhorn2b.jpg

Brian’s Drawings @ prosoundweb
http://web1.prosoundweb.com/lsp/horn_asm_1.dxf
http://web1.prosoundweb.com/lsp/horn_asm_2.dxf
http://web1.prosoundweb.com/lsp/horn_asm_3.dxf
http://web1.prosoundweb.com/lsp/horn_asm_4.dxf

Peter’s Website
http://home.comcast.net/~labhorn/

Jeremy’s Drawings @ prosoundweb
http://web1.prosoundweb.com/lsp/LAB_18mm_drawing_1.dwg
http://web1.prosoundweb.com/lsp/LAB_18mm_drawing_2.dwg
http://web1.prosoundweb.com/lsp/LAB_18mm_drawing_3.dwg
http://web1.prosoundweb.com/lsp/LAB_18mm_drawing_4.dwg

Brad’s Website
http://www.geocities.com/hulkss/index
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Timmahh

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Re: History of the LABhorn!
« Reply #1 on: May 03, 2005, 06:08:00 pm »

Don, To add to your history, my partner and i HAVE produced 4 v3 Labs.  Now they havent been in weekly use, but are getting used more and more as summer approaches, and to date are proving to be good, no failures to date. they had a very aggressive work out a few weeks ago, 2 per side under 2 Viking X215 cabs and were running aprox 125 db.  solid clean and clear. it was a REAL releif to make that slp level without hearing major amount of Crap ( other wise known as harmonic distortion or a DJs Dream. heh) .  WE are going to finish building the other 4 v3s we started last yr. just need to start adding the already finished modules to the rest of the parts...  To date, the 1st four are performing quite well. understand that to date we are still useing them at the standard xover points of 80 give or take a bit. we have yet to cross them over 90, but plan on doing some heavy testing soon.  We are in the same 30 mile area as Al L and Too Tall, so we will also be able to get a good x vs x comparison of our four stacked up against four of Als Originals.   We only did a few changes of Brads design, 1 we set and used the Aluminum Covers. and 2 added routed in, rear top handles and 45 degree the back bottom to add casters for mobility.  these boxes are solid and just pound.  We will go and see Too Tall as soon as timeings permit, and get some readings with praxis and smaart and put up the two readouts and see whats what. im sure Too Tall will post results when ready or i will.  I d like to also at that time, if time permits, to start crossing over higher than 90 up to the 200 range as suggessted by Brads design, and see what changes occur, as well as see if the drivers are rigorous enough to handle the higher compression ratio. but so far so good.  just wanted to add a touch more info, and let you and others know so far, V3 is a quality design, and is taking road use well.  more as soon as its available.
Timmahh
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I had to do it cuz I'm Just like that!!!!!
Timmahh!!!

Brad Litz

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Re: History of the LABhorn!
« Reply #2 on: May 04, 2005, 12:33:49 am »

Just a few comments

His version is for home theater sound.

Not really, it is for anyone who wants to benefit from a higher crossover point and flatter frequency response.

More like fine furniture than a “roadie proof” speaker

Not so. It is all 3/4 plywood and fully screwed together with pocket screws. You can add "roadie" stuff like handles, metal corners, metal access covers, and use epoxy glue if you want to. You could rabbit the bottom panel if you expect to drop them down hard often (they are heavy).

The compromises he made may make his version useless for pro sound.

This is absolutely not true. V3.0 is not compromised. It is a refinement of the earlier cabinet designs that have a slightly undersized rear chamber, oversized front chamber, and a deviation in the horn expansion near the throat. The only real major change I made was an increase in the compression ratio to extend the upper frequency response.

For instance, he raised the compression ratio to 3, which stresses the speaker cone.

The Lab12 driver can easily handle the 3.0 ratio. The cone is only 10 inches in diameter, and extremely stiff. Many horns with much less cone strength and stiffness have been made by others with similar compression ratios. I have never heard of a Lab12 cone failure. The driver surrounds fail from too much excursion and the voice coils burn out on occasion.

Until someone builds this version and takes it on the road, we can’t be sure the LAB12 can handle the stress.

True, assuming the build quality is good.

He has posted 3-D cad files plus some detail part drawings on his website, which means you must have 3-D cad to get the info.

There is a link included with the 3D model files to a free viewer that will show the dimensions and how it all fits together very easily.

He used Hornresp to model the changes

The design changes were analyzed and made only after the computer model accurately matched the measured response of the early cabinet designs.

seems very happy with the results

The results speak for themselves. The measurement details are posted on my web site. They sound sweet with three TD2's on top.

index.php/fa/1588/0/
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Brad Litz

Don Snyder

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Compression got you down?
« Reply #3 on: May 04, 2005, 01:45:06 pm »

Hi Brad & Timmahh -- In an early post, Tom explained that his first servodrive horn (with 2-15's) had problems at a compression ratio of 3. He reinforced the cone and got it stiff enough to work. I believe that he wanted to avoid any possible problem with the LABhorn, and was being cautious. Remember, details like compression were worked out before anyone had even seen the LAB-12. Brad's right about the LAB-12 being tough. With that big inverted cap and stiff material, I'd bet that the cone would hold up.

While it may be an advantage to hipass at 150-200Hz for recorded music, it isn't so clear that Subs for live music need to go that hi. Many live sound people who are pushing LABhorns, are using them from 32 to 80Hz because they can run the low end of the bass, kick drum & floor tom Aux Fed, and run every thing else thru an 80Hz hi pass. Why 80Hz? 'Cause that's the bottom note on a guitar, and is well below voice. This keeps much of the "mud" out of the vocals and seems to fix more problems than it creates. In the end, it's all subjective and your mileage may vary!

Question for Brad: What change flattened out the 50Hz dip?

~Don Snyder
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Brad Litz

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LABsub v3.0
« Reply #4 on: May 04, 2005, 09:03:10 pm »

Hi Don,

Sorry, I got a little defensive in that last post of mine.

What change flattened out the 50Hz dip?

An increase in rear chamber volume helped fill in that 50 Hz dip.

I'm using a 24 dB/Oct crossover at 120 hz. It works very well as the v3.0 cabinet is good for nearly an octave beyond the crossover point.

Here is the result with TD2's. I aimed the measurement mic perpendicular to the speakers so it rolled off the high end a bit.

index.php/fa/1598/0/

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Brad Litz

Don Snyder

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Just the facts, mam !
« Reply #5 on: May 05, 2005, 02:52:31 pm »

Hi Brad -- Thanks for the info. You have every right to correct what I said. After all, you designed & built the v3.0 and you did a great job.

No offense,
~Don
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