Build your own 2x12" TH (The Kraken 212 TH) - Page 11 - diyAudio
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Old 6th November 2011, 04:55 PM   #101
tb46 is offline tb46  United States
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Hi 18Hurts,

Post #100: "...I want the lower tuning for pipe organs and the like--the LAB 12 won't do that....".

The above mentioned version of the Eminence LAB12 in a tapped horn may not go as low as the single version of the Kraken using the JBL GTO1214, but that does not mean that a similar sized TH with the Eminence LAB12 does not go just as deep, or maybe deeper.

Maybe you could put Hornresp to use and let us know.

Regards,
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Old 6th November 2011, 06:47 PM   #102
18Hurts is offline 18Hurts  United States
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Quote:
Originally Posted by tb46 View Post
Hi 18Hurts,

The above mentioned version of the Eminence LAB12 in a tapped horn may not go as low as the single version of the Kraken using the JBL GTO1214, but that does not mean that a similar sized TH with the Eminence LAB12 does not go just as deep, or maybe deeper.

Maybe you could put Hornresp to use and let us know.

Regards,
I like the LAB 12 driver and always wondered why the designs for it never really included 16Hz types considering it has such a low Fs of 22Hz. The single JBL as a 18Hz sub fits my size and weight requirements and if I blow the $96 driver into the recycle bin--less painful.

I know Vas has an effect on the size of a horn to some degree, not sure how much though. The LAB 12 is 4.4 cubic feet with the JBL 1214 a much smaller 2.05 cubic feet. The LAB 12 is larger than the Kraken and not tuned as low, is the Vas being half with the JBL the major contributor?

I have 6 weeks to learn Horn Response and model various drivers and use the Kraken as a template. I need to take my plate subwoofer out that is going to drive the Kraken and see if it is a 4 or 8 ohm amplifier--if it is 8 ohms I can use the dual VC version of the JBL and run it at 8 ohms. The Vas on the dual voice coil is 66 liters VS 58.2 liters of the single VC so it must be verified with Horn Response to modify the design if required. Since the dual has a Vas 13.4% higher than the single--do I make the path 13.4% wider to compensate? That would lower the compression ratio a bit and the dominoes start to fall. If so, that is fine as it will still work with two sheets of plywood.

Looking forward to getting better with Horn Response, my initial foray using my 10" TB sub I have laying around was close but showed I need to get more fluid in my understanding of all the parameters before taking blade to wood.
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Old 6th November 2011, 07:50 PM   #103
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Quote:
Originally Posted by m R g S r View Post
How does the 1x12 Kraken compare to the Lab 12 horn? (20-25hz tuning or so...) Kraken is a few inches taller, but not as deep...
Lab12 - Tapped Horn -
According to tuning and maxSPL, they are almost identical. The Kraken 112 is
about 0.5 dB louder due to the larger Xmax and T&S-parameters that better
suits a horn tuned to slightly below 20 Hz.

In a TH, VAS should be low and fs about 1.4 octaves above the tuning point
of the horn. In that case, the JBL-driver excels the LAB 12. The LAB 12
would like a lower tuned horn in my point of view. That is seen in the round
bump in the simulated (the measured response shows otherwise) freq.
response of the LAB-TH compared to the Kraken. Seeing them together in
the 2pi-plot also makes me want to comment the drop in low freq. (20 Hz)
for Kraken. The horns are designed this way to better fit the room gain,
making the bass less boomy and more tight.

To sum up, after seeing the measured response of the LAB 12 and have done
some simulations I would say for practical use, the horns have very similar
performance, both in SPL and low freq. The difference as I see it the driver
cost and the additional inductor needed for the LAB 12 horn, also to mention
the dimensions, high and thin or low and wide. Pick your choise I am sure
both horns will satisfy your needs.



An other thing not mentioned in the drawings. Please use some foam in the
folds, as in the LAB 12-horn. It will make the horn sound more dynamic and
cleen.
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Old 6th November 2011, 07:51 PM   #104
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Quote:
The Vas on the dual voice coil is 66 liters VS 58.2 liters of the single VC so it must be verified with Horn Response to modify the design if required. Since the dual has a Vas 13.4% higher than the single--do I make the path 13.4% wider to compensate? That would lower the compression ratio a bit and the dominoes start to fall. If so, that is fine as it will still work with two sheets of plywood.
Let's simulate first and see what will happen
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Old 6th November 2011, 07:54 PM   #105
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Quote:
Originally Posted by 18Hurts View Post
I took a look at the very sparse spec sheets on the DD woofers,

The JBLs have a lower resonant frequency at 28Hz VS the DD 30.3Hz which can cause issues. Also the sensitivity is 5dB lower at 85dB VS 90dB of the JBL (at 2.83 volts) Since DD did not put the sensitivity spec at one watt, I am assuming it is 2.83V. It won't go as low or be as loud as the JBL at the same power input levels.

The Kraken is tuned at 18Hz which is very low for a DD to be tuned, I'm sure it can withstand being pushed that far down but the cone travel will be used up trying to get the same SPL as the JBLs.

Another option to entertain is what would a JBL GTO 1514 do with the design as a single woofer. It has the same output as two 1214's and the 15 incher has a Fs of 25.1 Hz. Could the design of the Kraken be modified to run a 16 Hz tuning with a single 15" JBL? It would have to be wider which would help with stability but I'm worried about compression on the cone. The 15" version looks spec wise about the same as the 12" with the same voice coil diameter so the compression ratio might need to be dropped down.

One of my games with Horn Response is to play with the Kraken design--if I'm going to modify something, knowing that it works at a very high level is a great place to start. Model a single 12" and a single 15" and calculate size/weight and see if the 15" could handle a 17 or 16 Hz tuning. I was not smart enough to cut wood before the cold weather came so it's a good excuse to become proficient with Horn Response while the cold winds blow and freeze my wood working area.
The sensitivity of the driver is not directly translatable to the horn
sensitivity. It rather depends on the compression ratio and BL factor.


The JBL 15" has too low BL for a 15"-driver to work well in a TH. Your better
of with the Kraken 212 then instead.
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Old 6th November 2011, 08:00 PM   #106
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I already have the Lab TH and enjoy it for Home Theater use. Was just curious how the Kraken stacks up...as you and the sims confirmed. They are pretty darn similar.

One nice thing about the Lab TH is the mouth exit location. I have mine lying on its side, and it acts as a stand for my TV. If you do that with the Kraken the mouth would be pointing up towards the ceiling. Unless you change it's exit location
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Old 6th November 2011, 08:04 PM   #107
tb46 is offline tb46  United States
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Hi Petter,

I agree that main difference is the driver cost, that's why I'm happy that Spuddy has made the leap, and build your initial design. The LAB12 may also be the more rugged driver, but I'm in no position to more than guess at that. The JBL's are more than adequate for home use.

Thanks to you and Spuddy for all the additional inspiration.

Regards,
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Old 7th November 2011, 06:38 PM   #108
18Hurts is offline 18Hurts  United States
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For my first tapped horn, it will be the Kraken 1x12

My family voted for the Kraken 1x12 over the LAB 12 due to portability to move it around for cookouts etc. A 16Hz LAB 12 TH would be great but it very large in comparison and I can always build a second Kraken 1x12 if needed. By nature I have to know what I'm building so learning HR is the top priority at this point. The dual voice coil version of the JBL interests me so at least I get to add something to the design. You can bet I'll be modeling the LAB 12 for 16Hz through Horn Response as a mental exercise--I don't "need" it but my wife might get into pipe organ music some day.

Now back to the tutorials on Horn Response and reading through all the post on DIY audio so I can get to 100%.
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Old 7th November 2011, 06:44 PM   #109
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Personally I don't think this sub would suit music playback very well.
Look how things get above 70hz or so in the sim. You're not really getting a clean flat 2 octaves out of this horn...And unless you have some large mains, the subwoofer will be trying to play higher than that 70hz...
I know you said you wanted it for pipe organ playback, but that's probably one of the few types of music which has content under 30hz...
Also with a horn of this size (path length) you need a good deal of delay set up via DSP for your mAins to keep things from sounding muddy
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Old 7th November 2011, 09:07 PM   #110
18Hurts is offline 18Hurts  United States
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Quote:
Originally Posted by m R g S r View Post
Personally I don't think this sub would suit music playback very well.
Look how things get above 70hz or so in the sim. You're not really getting a clean flat 2 octaves out of this horn...And unless you have some large mains, the subwoofer will be trying to play higher than that 70hz...
I know you said you wanted it for pipe organ playback, but that's probably one of the few types of music which has content under 30hz...
Also with a horn of this size (path length) you need a good deal of delay set up via DSP for your mAins to keep things from sounding muddy
My requirements are rather odd,

A pair of very efficient (96dB 1w/1m) vertical line arrays with 12 five inch woofers and 48 10mm tweeters per speaker is the "garage" system. An old 45 watt Pioneer receiver with 15Hz highpass filter switch drives the arrays to loudness levels I require for inside the garage AND outside for cookouts. The poor 120 watt sub amp pushing a ported 12 at 30 to 80Hz struggles during classical music and gives up outside.

Figure the Kraken 1x12 used by itself inside the garage will give me the 65Hz and below hit the arrays won't do and be efficient enough at 120 watts corner loaded for musical peaks. Two of them outside for the monthly cookout will use a much more powerful amp so easy to match up to the arrays. The sound guy at the local church wants to hear vertical line arrays as an experiment in sound and load up organ music to hear what a tapped horn can do. The church stuff will use their amps, DSP, EQ etc so I'll get to play with solutions in real time to see how smooth I can make the system play.

The 1812 Overture, pipe organs and the like got those discs banned from the house HT system--the garage is my last stop since I'm not into headphones.
My wife likes the garage system since it allows me to play my "crazy" music out in the garage and keep her world in peace (and quiet)
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