Lab12 - Tapped Horn

I left out "a. thru j. down the left side. Here's the fix.
 

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TH_v._BR

Hi joqi59,

After reading through the Visaton Forum threads I tried simulating the enclosures in question, and Hornresp will give responses similar to the responses shown in the anechoic chamber graphs. As noted before, it looks like the tapped horn used as a comparison standard is sub-optimum.

I'll attach a TH_v._BR comparison with a different tapped horn model. I believe this puts the tapped horn in a more appropriate light, even if the TIW 300 is not the ideal TH driver. To me the TH clearly outperforms the BR in a subwoofer application.

Regards,

P.S.: I hope that layertone will have more information on his LAB12 build.
 

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Last night while listening to the Fostex 168Sigma's, I felt the need for a sub to cover the most bottom end of the spectrum. I pulled out my 2 unused Lab12 drivers and began contemplating on a TH vs ELF sub. I have a intuitive notion that the TH would sound more 'natural' requiring little or no EQing, thus matching the tonal characteristics of the Fostex.

However, looking at Don's TH fold for the Lab12, a footprint of 30"x13" would have low SAF. Hence, I was wondering if I could ask here for help to increase the height and reduce the depth of the TH. Someone might have already done it and I may not know. Can someone please point out to such a fold, if it exists?

Thanks,
 
What a busy weekend! didn't get a chance to revisit this until now & wow, lots of replies, thank you all

Sabbelbacke said:
Wow, love the pictures and the build quality, very nice!! Although this is build very rugged, you might consider some bracings at large areas, Since I´m in Pro-Sound, I use similar plywood as you do and I´ve always had to add some bracings and it always improved the sound (and made rumble from the enclosure walls less).

This is my first tapped horn build & also first build using the 3/4" Appleply (15 Ply's!!) Next one will have some braces for sure


tb46 said:
Hi layertone,

Nice work! Please, keep us informed as to the placement of damping materials, and other progress.

Also, would you mind sharing name and number of the driver and CNC panel (elegant) mounting hardware?

Regards,

Details of this plan was posted by Don
http://www.diyaudio.com/forums/showthread.php?postid=1586512#post1586512

No damping materials used yet.

Hardware, i used "Self-Tapping, Threaded inserts" I like this better than t-nuts, much more stable & doesn't pop out like T-nuts.

http://www.mcmaster.com/#threaded-inserts/=1twnvs


steve71 said:
Really nice work and great pics! I like that the driver is visible. My tapped horn is very similar in layout to yours and I get slick of putting on the hearing protection and sticking on my head in the mouth with a flashlight to monitor driver excursion.

I added a ton of bracing to mine, here's a pic if you're looking for some inspiration.

http://www.diyaudio.com/forums/attachment.php?s=&postid=1625614&stamp=1223240677

BTW how to you intend to finish it - i.e. paint, stain etc.

That extra Cat5 cable, i plan on mounting a set of RGB LEDs inside to light it up.

If suitable, i will take it to a truck store & have them spray truck bed liner on it.


Don Snyder said:
It's great when a plan comes together ...

MaVo did the simulation, Chris8sirhC decided to build the first one, and I did the fold
for Chris. Now, Layertone has built one of the nicest Tapped Horns of this series.

Great job & pics,
Don

Thanks for your help Don!


ashok said:
Great construction !
How does it perform compared to regular boxed sub's with the same driver ( sealed box ? ) ?
Horn's are great for high efficiency but how does this implementation compare ?
I'm asking because the chance of me coming across a similar setup is 'very' remote .
Cheers.

Not sure yet; maybe in the future i will build a regular ported box for this driver. So far it is SCARY awesome!! :bigeyes: never experienced anything like it


Chris8sirhC said:
Those pictures look very familiar...

I did some corner braces (piece of wood 2''x2''x12'' on each of the inside fold corners. I also filled in that gap with expanding spray foam after it was completed. That space would be perfect though, for putting in a resonator or two, once you had figured out the correct length/tuning/etc.

I am thinking of having mine in a corner firing into the room through an opening in the door, and I would need to put on a small mouth extension to the horn. I am wondering if this would lower the tuning much.

Will certianly think about braces in the next build, thank you Chris

Still fiddling around with it so not sure about the extension.
 
jogi59 said:

In a 300 liters box is enough space for big enough ports

No
the tapped horn runs out of Xmax first

Visaton in germany measured a tapped horn and a vented box of the same size in their anechoic room. The surprising result was: the vented box went louder
Will the tapped horn gain more from boundary loading? I imagine that there isn't any in a truly anechoic chamber.
 
Re: TH_v._BR

tb46 said:
Hi joqi59,

I'll attach a TH_v._BR comparison with a different tapped horn model. I believe this puts the tapped horn in a more appropriate light, even if the TIW 300 is not the ideal TH driver. To me the TH clearly outperforms the BR in a subwoofer application.

Regards,

P.S.: I hope that layertone will have more information on his LAB12 build.

There was alot of rambling about tapped horns, I wanted to give it a try so a prototype test "teaser" i tried was the Tang Band 6", very surprisingly impressive for a 6"

The build, any specifics you would like to know?

the entire 2 sheet cutout was CNC routed...

By the way, any recommendations for amps? I'm currently using an under-powered Bash 300

**** correction for the link about the threaded inserts:

http://www.mcmaster.com/#92105a100/=1tx8c0
 
Hi layertone,

Thanks for the threaded insert information, have you done any comparison to the hurricane nuts (Parts Express)?

When you where building the prototype 6" (W6-1139SI?) did you have a chance to do some comparison between TH and other enclosure types, measurements or listening?

The Bash 500 is now on sale for $185.-- @ Parts Express, but excursion does become a problem for anything above 100W/6-Ohm into the LAB12 according to Hornresp. Probably not a big problem with music though.

Regards,
 
Depends on your needs, but for $270 this is pretty hard to beat for home theater/audio use:

EP 2500 @ B&H

If you believe the ratings, it comes in at about 11.2 cents a watt, delivered. I've got one, it really does weigh in at nearly 40 pounds (same heft as my old QSC). While it is not a high-end brand name pro amp, it is still some pretty serious hardware.

If you're going to be in the same room, you'll probably want a quieter fan, which is easy to do, inexpensive, and well documented on the net.

Couple it with a DSP1124P, measure and dial in your response with RoomEQ Wizard, and you're set to go.
 
BASH 500

The BASH 500 plate amp is not flat to 20 Hz as delivered.

It can be modified to be flat though, PE even provides some basic instructions. The modifications are not too hard (I've done two amps so far), but require some disassembly, desoldering, and soldering, as well as plenty of patience. The modification requires you to change two resistors on the preamp board to change the frequency and Q of the low-pass filter and remove the factory bass boost.
 
tb46 said:
Hi layertone,

Thanks for the threaded insert information, have you done any comparison to the hurricane nuts (Parts Express)?

When you where building the prototype 6" (W6-1139SI?) did you have a chance to do some comparison between TH and other enclosure types, measurements or listening?

The Bash 500 is now on sale for $185.-- @ Parts Express, but excursion does become a problem for anything above 100W/6-Ohm into the LAB12 according to Hornresp. Probably not a big problem with music though.

Regards,

I do have a bag of those hurricane nuts somewhere.

These inserts are the best by far from my experience. Drill / Route out a hole .36" diameter, use a hex to screw in & you're set.

I don't have many subs to compare to...

I did see that EP2500 @ BH, but was thinking about this Mackie FRS 2800 alternative (somewhere around 22 pounds)

http://www.amazon.com/Mackie-FRS-2800-2800-watt-2-Channel/dp/B0013OBUEW

it's not available yet??
 
tb46 said:
... excursion does become a problem for anything above 100W/6-Ohm into the LAB12 according to Hornresp. Probably not a big problem with music though.

Not "anything," only 25Hz pure sine waves. This is not unique to the Lab12, it will happen with every speaker, each at their own
critical frequency.

Fortunately, music does not contain high power single frequency sine waves, mainly because they sound like crap. No speaker
manufacturer specs this because it never happens.
 
Don Snyder said:
Fortunately, music does not contain high power single frequency sine waves, mainly because they sound like crap.

This isnt exactly true. As a matter of fact, every musical signal can be described as a certain amount sine waves, added together. Every harmonic and base tone of every instrument is simply a sine wave. Only their combination of frequency, amplitudes and phase values make them unique sounding.

As for high power, quite some music has its loudest signal in the 20-80hz area, maybe except chamber and some girl/guitar type music.

On a sidenote, single sine waves dont sound like crap, as it all comes down to the context they sit it, or else everything must sound like crap, since it is made out of single sine waves.
 
One could add that single Sine waves rarely are present in acoustical recordings (even a large pipe has a lot of harmonics) and that the duration of "mean" sounds comparable to the energy hunger and crest factor of a sine wave is a not often used stylistic device in many genres....
But there are lots of music-genres out there where you have very loooong lasting sine-waves used (Last weekend I was on an industrial/noise event.... 10 minutes 30 Hz Sine wave plus one beat... people there love it, speakers and amps get scared) and crest factors of some signals used in modern synthetical productions often tend towards 3..... (sine wave).

That´s one of the reasons why "old standards" of stated power with speakers and amps often don´t apply today, it´s a totaly different thing if one has a "normal rock concert" with a overal crest of let´s say 13 or an industrial event....
 
Agree with the general tenor of that too. That's why I believe that you should not exceed the maximum rated (or tested) mechanical excursion in your speaker/amplifier/application combination. And it does make a difference if you are designing for the home or an industrial event. :)

Regards,
 
The Lab12 has a x-max of 12mm and an x-lim of 22mm. Using this box, at 26 Hz,
Hornresp sims the x-max limited power at 90 Watts, and the x-lim limited power
at 290 Watts.

Tapped horns need DSP. They need it for the HP filter that sets the subs floor and
they need it for the x-over that sets the subs ceiling. The main suppliers are BBE,
Behringer & DBX.

One would think that DSP holds the answer to the "High Power Sine Wave" problem ...

How about it? Do you have the answer?

Don
 
One would think that DSP holds the answer to the "High Power Sine Wave" problem ...
Don´t know if I get your point, but one comment to this comes in mind:

DSPs in a Controller are quite usefull, I agree and use them a lot. Sometimes with small setups, I simply use analog high- and lowpasses in my analog x-over, which doesn´t give me the amount of control a DSP-Solution with all the limiters, compressors, phase shifts etc.. does.. But with speakers that have a fairly goo response it still sums up to a good sounding and working system.

The thing I think is much more important than DSP or not: When dealing with signals near the crest factor of a sine wave and having very long durations in these signals, raw Amp Power and keeping your speakers within xmax(lin) is a necessity. While most amps are quite able to boost more power for a short period of time (single basedrum) into your speakers and many transducers cope quite good when xmax(lin) is exceeded for a few percent with a single short impuls, these "stress-situations" realy show the limits of your system. And if these limits are exceeded, failure will occur very quick and the lifespan of yout system is reduced very quick.

So everytime I set up a system stationary in a club or disco, I always choose the outmost save condition when thinking about how big I have to go for it... Using a sine wave generator, the system is fed with sweeps and using the data from simulation and measurement, limiters are set to the point where xmax(lin) is not exceeded. A DSP System allows me to do this in regard to frequency because xmax-is different at various frequencies... Of course, this is "worst case" failure proof and most of the times, a skilled technician could squeeze out much more SPL for certain musik-genres... But you never know when the next DJ has his "selfmade hard-core-techno song" in the CD-Player and thinks it´s funny to play a song with a continous sine-wave at 40 Hz.... I rather choose a bigger amp or add two more subs than risk having one system failure, especialy with unattended systems in a club. A sinewave being the maximum you can throw at a system (except square waves, which would be crest of 1.... but well... we all know what happens with these...) it´s a simple and good way to simulate worst case and setup my systems.


Of course most "normal" music never puts that much stress on speakers and amps. That´s why RMS Ratings are often so useless (RMS being sine) when predicting the "power" of your system. If you know what you are doing and know your gear very well, you can easily squeeze more max-power out of a system than with my above method when having a rock event or simple top40 songs...
 
I´m using all kinds, it depends on what people bring up to me or what is already in a club. For my self, I've got two Behringer DCX2496 combined with different EQs (the DEQ 2496 works nicely in combo via digital link) and a few different OEM ones from digisynthetic (many DSP Solutions come from digisynthetic but are labeled differently). @Home and in my lab I am playing around with a Brute-FIR based system, which sadly I can´t take on the road so far.