Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => SR Forum Archives => LAB Subwoofer FUD Forum Archive => Topic started by: leon douven on June 21, 2006, 02:55:28 PM
Title: 4 driver LAB ??
Post by: leon douven on June 21, 2006, 02:55:28 PM
I've built 2 Lab subs, and i'm in the process of painting right now. Last night I was proudly sitting next to my labs (they still have 1 side open, and was looking at the horn layout (the snail shape).
I was wondering if the following could work based on the lab12 driver:
If one would increase the overall depth of the LAB cabinet by as much as 7,5" and the height by 7,5" it should be possible to fold the snail shell around 4 lab drivers.
A lab12 driver with its housing could be constructed to te rear of the compression chamber (firing right into the horn) and another one with housing firing in the bottom of the compression chamber.
The compression chamber is not as wide as a lab 12 driver, so the width of the cab has to grow a bit also.
Apart from the increased overall cabinet size all basic design parameters could pretty much stay the same... at least.. in may simple way of seeing it, with the (advantage????) of having 4 drivers pumping in the horn...
could this work, an what could be gained???.. spl???
I know this (increased cabinet size) was not the design goal of the LABsub project, but if it is possible to add 2 more drivers this way (with minor changes to the overall design) it looks like one could end up with a serious spl gain per (bigger) cabinet??
just some thoughts...
Leon Douven the Netherlands
Title: Re: 4 driver LAB ??
Post by: Elliot Thompson on June 22, 2006, 07:37:01 AM
Hello Leon.
The first downfall I see in such a design is requiring more amplifiers for each box, designed around four drivers.
The second downfall I see is throwing away the whole concept (Using multiple boxes to create one big horn), and trying to get the most SPL out of a single box.
The third downfall is size. The box is praticulary 4 feet deep already. Adding more size increases more truck space which is not "A Good Thing" when you have amp racks, and boards not fitting due to an over extended box.
Your project sounds better suited for possibly, the home audio guy, whose limited space, can't house two labs.
For moving about, from venue to venue, I can't see what I would be gaining going this route. I'll still need the minimum of 4 boxes to achieve stellar results.
Maybe you can explain what I am missing here?
Best Regards,
Title: Re: 4 driver LAB ??
Post by: leon douven on June 26, 2006, 02:53:48 PM
Hi there,
Yes more watts... jes bigger cab... no the concept stays the same...
What you are missing is SPL improvement IF?!? a 4 driver concept could seriously improve on the existing LABsub...
I was at the Pinkpop festival this year 65.000 visitors, I was at Parkpop last weekend 350.000 visitors... PA-system by AMPCO (considered one of the best in Europe)..... the low-end sucked!!!
... probably becouse they weep about truckpacksize... economics...
truckpacksize my ass...
L.
Title: Re: 4 driver LAB ??
Post by: Elliot Thompson on June 28, 2006, 09:31:53 AM
I would guess if you drew a picture (Not Dimensions) on what your idea would look like, you may get a response.
A picture is worth a thousand words, and, will bring forth more questions (And possibly answers) on housing four drivers on a single horn.
Best Regards,
Title: Re: 4 driver LAB ??
Post by: leon douven on June 28, 2006, 06:02:42 PM
Hi Elliot,
You are absolutley right,
I'm not a digital meister, so I have to figure out a way to upload some scanned drawings.
give me a few day's...
Does anybody know what a convenient filetype would be to upload some scanned drawings.
Regards,
Leon
Title: drawing 4 driver LAB
Post by: leon douven on June 30, 2006, 01:23:34 PM
this was the idea... I hope the attachement clears things up.
Its 7 inches deeper than the regular LAB. Needs to be 4 to 5 inches wider. Height remained the same.
I dont have the theoretical knowledge to re-calculate the horn, compression chamber, transition from compression chamber to horn, chambers behind the speakers, maby even some speaker parameters have to change?
But if this could be done it seems that one could house a more horsepower in a slightly bigger cab.
as I mentioned in my firs post... just some thoughts that could be discussed.
Regards Leon
Title: Re: 4 driver LAB ??
Post by: leon douven on July 03, 2006, 02:21:25 PM
Yooow!
my fella labsubbers... I find it deadly quiet...
700 vieuwers 29 downloads... and not a word???
What about the pro's out there?
How about this thing, can it work?
Regards,
Leon
Title: Re: 4 driver LAB ??
Post by: Al Limberg on July 03, 2006, 02:39:55 PM
I think the silence is a pretty good indicator of the general opinion of the pros toward your idea. First off, even ASSuming it might have potential, it would take some serious modeling and probably actual construction to see if there was any substantial gain to be made. Secondly, since the overall length and mouth dimensions of the horn remain basically constant, the additional drivers and cabinet size wouldn't affect the low frequency performance of a single cabinet in any significant amount. Thirdly you seem to pass off truck pack as meaningless in the business. With the cost of owning and operating a typical semi truck and trailer combo easily exceeding $3000 per day, additional trucks are a major concern in any operation. As an operator of a typical cube van (non-standard in all dimensions!!) I assure you, I have earned a half a dozen master's degrees in packaging over the past several years and it ain't much fun. Considering the fact that even if your plan worked, you would still require blocks of 4 to 6 of them to reach the desird low frequency performance, the additional drivers are suspect as to their value. Simply stuffing two quarts of s*it into a one quart jar doesn't change the fact that its stil s*it.
?;o) Al
Title: Re: drawing 4 driver LAB
Post by: Johan Rademakers on July 03, 2006, 05:04:08 PM
Quote:
I dont have the theoretical knowledge to re-calculate the horn, compression chamber, transition from compression chamber to horn, chambers behind the speakers
Perhaps this is the main problem, I think horns work in a different way than you might aspect, making you logic reasonable to you but not to the people that have more knowledge on the subject. Just some thoughts:
By adding two more drivers you have just doubled the Sd, assuming the compression ratio is as good as it gets that would obviously mean doubling the throat area as well. The horn is bigger at the beginning so you can get less horn in the same space. This would result in a shorter horn and/or different flare, actually downsizing the performance.
You would still need 4 to 6 cabinets to get the desired mouth area to make the horn efficient in the low-frequency region.
By doubling the drivers you have doubled the powerhandling, resulting in just 3 dB increase in SPL. This at the cost of doubling the price on drivers and amplifiers. And an even bigger hassle to handle the Lab as it is.
Afaik the labhorn is made to complement standard truck-sizes. Making the cab bigger would then result in less efficient usage of valuable space.
Just some reasons I can think of why this would be a bad idea. I'm sure there are more.
With kind regards Johan
Title: Re: 4 driver LAB ??
Post by: leon douven on July 04, 2006, 04:37:08 PM
Hmmm. I don't get it...
Mr. Limberg I know the packaging isn't fun... Shure it take's modeling... I already assumed the low-end would'nt improve... I have this masters degree also... Jes one would still need block's of 4 / 6...
but if 4 / 6 could make as much spl as 8 /12... isn't that worth the 10% extra packaging, and isn't it than even more efficient trukpacksize-wise?
what about this "truckpacksize" anyway?? are you assuming all of you are using interstate long-haul trucks with ocean going standard 20ft or 40ft ocean-going containers to move around 4 /6 LAB-subs???
Mr. Rademakers the throat area gets automatically bigger since the cabinet grows a bit in width (but it shure won't double) This could be a pain ass problem, unless you mean the volume of the compression chamber??
Aint it so that it normally take's an extra LAB to reach a 3 db gain? than this thing would be damn efficient truckpacksize-wise.
Don't get me wrong guys, if I seem a little persistent. I love this forum and you're comments are highly respected.
If this idea can't work, it can't work... no prob... but if it could.. I would like to explore it... There are worse things in life than discussing an alternative sub...
Regards Leon
Title: Re: 4 driver LAB ??
Post by: Walt de Jong on July 04, 2006, 05:12:04 PM
Hello Leon,
If you go from 4 to 8 cabs or from 6 tot 12 cabs this gives you 6dB more output. You get 3dB from the extra power and 3dB from the coupling of the cabinets.
Putting 4 drivers in a single LAB-horn only gets you 3dB. I think a better alternative would be to develop a new stronger driver for the LAB-horn (with same T/S) but with even more x-max and of course more powerhandling. Such a thing can be done but will be very expensive. The LAB as it is, is fairly optimal. I would not change to much of it.
Best regards,
Walt
Title: Re: 4 driver LAB ??
Post by: Johan Rademakers on July 05, 2006, 09:00:16 PM
I was assuming you let the horn parameters define the cabinet size, not the other way around. You want the throat area to double to keep the compression ratio the same. Unless you're certain a higher compression ratio won't damage the drivers on the long term.
Not only will two Labsubs give 3 dB more output with the same power, it will double the mouth area as well making the sub more efficient at low frequencies.
With kind regards Johan
Title: Re: 4 driver LAB ??-Truck pack?
Post by: Ivan Beaver on July 05, 2006, 09:25:28 PM
So what would you haul around 4-6 (per side) lab subs? Not a van or a 5x8 trailer. If you have a rig that size you are going to be using a truck. A truck does not have to be a tractor trailer type rig. Even a 14' truck has to be packed right, and having cabinets that fit those dimensions easily without wasted space is a big advantage.
You also have to consider the weight of the cabinets when moving them around. There have been numerous products that have failed in the audio industry, not because of their performance, but because of their size and the ability to move them around.