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Author Topic: T-48 FAIL !  (Read 10010 times)

David López Aguilar

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T-48 FAIL !
« on: October 15, 2013, 02:52:53 pm »

Hi guys, my name is David López, iam from México City.

I have 6 t-48, but I'm not happy with them because their sound is quality and feel that they need something.

And if I'm seeing something like Scoop, as LAB12 are very difficult to do, and good for the moment I have six Titans, 4 HD215 and 6 copies of Turbosound TMS 111

BFM leave league

http://billfitzmaurice.info/forum/viewtopic.php?f=1&t=18788

PDA-The other option is that I have Twelve Eminence Kappa Lite 3015LF speakers and I've only used 6 in the T-48, just could use these 12 speakers on some other model that really sound like a Cerwin Vega L36 Yorkville LS1208 or as few as that if there is no option, guide me and tell me if it suits me better to Scoops, G-SUB, Hog Scoop or something
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Spenser Hamilton

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Re: T-48 FAIL !
« Reply #1 on: October 15, 2013, 03:07:40 pm »

Hi guys, my name is David López, iam from México City.

I have 6 t-48, but I'm not happy with them because their sound is quality and feel that they need something.

And if I'm seeing something like Scoop, as LAB12 are very difficult to do, and good for the moment I have six Titans, 4 HD215 and 6 copies of Turbosound TMS 111

BFM leave league

http://billfitzmaurice.info/forum/viewtopic.php?f=1&t=18788

PDA-The other option is that I have Twelve Eminence Kappa Lite 3015LF speakers and I've only used 6 in the T-48, just could use these 12 speakers on some other model that really sound like a Cerwin Vega L36 Yorkville LS1208 or as few as that if there is no option, guide me and tell me if it suits me better to Scoops, G-SUB, Hog Scoop or something

Your last thread was closed due to non-compliance with the Real Name Policy that is enforced on this forum. Opening another thread will not get you different results, please read the thread below and change your name as advised by Doug. After that I'm sure that some of us will be glad to help you figure out how to move forward.

http://forums.prosoundweb.com/index.php/topic,234.0.html

Regards
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Stu McDoniel

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Re: T-48 FAIL !
« Reply #2 on: October 18, 2013, 12:23:12 am »

Hi guys, my name is David López, iam from México City.

I have 6 t-48, but I'm not happy with them because their sound is quality and feel that they need something.

And if I'm seeing something like Scoop, as LAB12 are very difficult to do, and good for the moment I have six Titans, 4 HD215 and 6 copies of Turbosound TMS 111

BFM leave league

http://billfitzmaurice.info/forum/viewtopic.php?f=1&t=18788

PDA-The other option is that I have Twelve Eminence Kappa Lite 3015LF speakers and I've only used 6 in the T-48, just could use these 12 speakers on some other model that really sound like a Cerwin Vega L36 Yorkville LS1208 or as few as that if there is no option, guide me and tell me if it suits me better to Scoops, G-SUB, Hog Scoop or something
Whatever sub boxes you choose try not to MIX different cab designs in your pile of boxes.
Use all of the same sub box design with your system
http://www.eminence.com/pdf/Kappalite_3015LF_cab.pdf
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Elliot Thompson

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Re: T-48 FAIL !
« Reply #3 on: October 30, 2013, 11:05:43 am »

PDA-The other option is that I have Twelve Eminence Kappa Lite 3015LF speakers

Hi.

With 12 Eminence Kappa Lite, you can design 6 Double Fifteen Reflex bins. I am not sure how low you want to go but you should easily attain 40 Hz with one box. Of course, if you add some equalisation, you should attain around 30 Hz. 

Best Regards,
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Ivan Beaver

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Re: T-48 FAIL !
« Reply #4 on: October 30, 2013, 11:46:50 am »

Hi.

With 12 Eminence Kappa Lite, you can design 6 Double Fifteen Reflex bins. I am not sure how low you want to go but you should easily attain 40 Hz with one box. Of course, if you add some equalisation, you should attain around 30 Hz. 

Best Regards,
And when you start to eq down below the natural response of the loudspeaker (like a number of manufacturers do to "try" and extend the LF response) you are actually INCREASING the power going to the loudspeaker at those freq.

So when you turn the whole thing up-you will be at the maximum output at the lower freq  before you reach max output at higher freq (say 50-100hz).

So overall the cabinet will not get as loud as you would think.

As long as the levels are low it is fine-but just be careful at higher levels.

Not only does the power go up-but the driver excursion does also (sometimes by a greater amount than the power)-so physical damage can occur easily.
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Ivan Beaver
Danley Sound Labs

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Elliot Thompson

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Re: T-48 FAIL !
« Reply #5 on: October 30, 2013, 12:04:38 pm »

And when you start to eq down below the natural response of the loudspeaker (like a number of manufacturers do to "try" and extend the LF response) you are actually INCREASING the power going to the loudspeaker at those freq.

So when you turn the whole thing up-you will be at the maximum output at the lower freq  before you reach max output at higher freq (say 50-100hz).

So overall the cabinet will not get as loud as you would think.

As long as the levels are low it is fine-but just be careful at higher levels.

Not only does the power go up-but the driver excursion does also (sometimes by a greater amount than the power)-so physical damage can occur easily.

When I said 40 Hz, that was –3 dB. Take into consideration he would have six boxes at his disposal he can boost 31.5 Hz on his equaliser and attain the low frequency extension without stressing each driver during the process. That is the beauty about using quantity. You will never drive twelve fifteens as hard as someone using six when SPL is the motive.

Best Regards,
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George Dougherty

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Re: T-48 FAIL !
« Reply #6 on: October 30, 2013, 12:42:32 pm »

Hi guys, my name is David López, iam from México City.

I have 6 t-48, but I'm not happy with them because their sound is quality and feel that they need something.

And if I'm seeing something like Scoop, as LAB12 are very difficult to do, and good for the moment I have six Titans, 4 HD215 and 6 copies of Turbosound TMS 111

BFM leave league

http://billfitzmaurice.info/forum/viewtopic.php?f=1&t=18788

PDA-The other option is that I have Twelve Eminence Kappa Lite 3015LF speakers and I've only used 6 in the T-48, just could use these 12 speakers on some other model that really sound like a Cerwin Vega L36 Yorkville LS1208 or as few as that if there is no option, guide me and tell me if it suits me better to Scoops, G-SUB, Hog Scoop or something
I didn't get how you're processing the signals to the T48 and HD215 out of that. It sounded like you're using a pretty gentle 18db slope on the HP of the T48.  To not destroy the critical bass region with interactions between the cabs it seems you'd need to properly time align, crossover steeper and match phase response between the two cabinets. At 100Hz on your crossover, if done wrong you could be totally trashing the kick and thump response of your system.  The T48 has about a 14ft horn length which definitely needs accounting for.
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Art Welter

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Re: T-48 FAIL !
« Reply #7 on: October 30, 2013, 12:45:14 pm »

When I said 40 Hz, that was –3 dB. Take into consideration he would have six boxes at his disposal he can boost 31.5 Hz on his equaliser and attain the low frequency extension without stressing each driver during the process. That is the beauty about using quantity. You will never drive twelve fifteens as hard as someone using six when SPL is the motive.
Elliot,

Regardless of quantity, a ported cabinet with an F3 of 40 Hz will be -10 dB or more down at 31.5 Hz.
A pair of drivers in a F3 40 Hz box would exceed Xmax at 30 Hz with about 100 watts, anything approaching 900 watts at 30 Hz would just make the cones flap uselessly. 

With cones as light as the 3015LF, they can get "tenderized" very quickly,  equalization more than a few Hz below Fb won't get much of anything but ripped cones.

Art

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Elliot Thompson

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Re: T-48 FAIL !
« Reply #8 on: October 30, 2013, 02:26:22 pm »

Elliot,

Regardless of quantity, a ported cabinet with an F3 of 40 Hz will be -10 dB or more down at 31.5 Hz.
A pair of drivers in a F3 40 Hz box would exceed Xmax at 30 Hz with about 100 watts, anything approaching 900 watts at 30 Hz would just make the cones flap uselessly. 

With cones as light as the 3015LF, they can get "tenderized" very quickly,  equalization more than a few Hz below Fb won't get much of anything but ripped cones.

Art

Art,

That is not taking the impedance versus frequency into factor. The excursion is proportional to the impedance the loudspeaker sees at the given frequency at the given power.

For example,

An amplifier delivers 1000 watts @ 8 ohms from 20 – 20,000 kHz. The loudspeaker’s impedance rise to16 ohms @ 40 Hz and reverts back to 8 ohms @ 50 Hz. So the loudspeaker will get 1000 watts @ 50 Hz, & 500 watts @ 40 Hz. When this occurs the xmax will be reduced for there is less voltage passing through the speaker @ 40 Hz than 50 Hz. 

This is a quick design I’ve drawn up using two Eminence Kappalite 3015 in a reflex box. Notice where the impedance stands @ 29.6 Hz.




29.6 Hz: 29.2 ohms
39.5 Hz: 5.58 ohms
52.7 Hz: 4.00 ohms



Best Regards,
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Ivan Beaver

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Re: T-48 FAIL !
« Reply #9 on: October 30, 2013, 03:49:59 pm »

Art,



An amplifier delivers 1000 watts @ 8 ohms from 20 – 20,000 kHz. The loudspeaker’s impedance rise to16 ohms @ 40 Hz and reverts back to 8 ohms @ 50 Hz. So the loudspeaker will get 1000 watts @ 50 Hz, & 500 watts @ 40 Hz. When this occurs the xmax will be reduced for there is less voltage passing through the speaker @ 40 Hz than 50 Hz. 


NO

The "voltage passing" through the voice coil will be the same (assuming a flat response input signal).

The power that is dissapated by the voice coil will be different at different freq-due to the impedance.

But the voltage applied to get the 500 and 1000 watts would be the same.
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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

Elliot Thompson

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Re: T-48 FAIL !
« Reply #10 on: October 31, 2013, 10:24:45 am »


I would imagine it is how one interprets it for we are saying the same thing. You are looking at it from a voice coil perspective. I am looking at it from the load the amplifier sees when the impedance fluctuates from the loudspeaker at the given frequencies.


If David López Aguilar is playing Reggaeton, he will need bass bins that can reach to 40 Hz with a good amount of efficency. The graph below is the overall measured frequency response of a popular Reggaeton song.





Below is the measured result of the Titan 48. As we can see, the Titan 48 frequency response starts to decline exactly where Reggaeton’s bass is most prominent.

http://audioroundtable.com/ProSpeakers/messages/489.html

Although, David López Aguilar stated he has six Titan 48 bass horns if, six Titan 48 bass horns could not give him what he need, chances are the bass horn is not suited for his requirements.

The response offered in the measured Reggaeton track is not an issue for a reflex box (G sub) and, possibly the Hog Scoop David is eyeing. However, it is up in the air where those Eminence fifteens would stand in the Hog Scoop based on having completely different TS Parameters recommended for the Hog Scoop.

Best Regards,
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drew gandy

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Re: T-48 FAIL !
« Reply #11 on: October 31, 2013, 12:19:00 pm »

There are many box modeling programs that will show you a graph of driver excursion vs frequency.  I don't know of any program that shows this graph based on anything but a flat drive voltage signal.  In other words, when the modeling program shows that the excursion goes through the roof below the box tuning frequency, you can rest assured that the amount of power being dissipated by the speaker VC is of virtually no consequence with regard to this excursion.  My opinion jives with Art's; boost below the FB of a vented alignment offers very little payoff and a significant increase in potential damage. 
Now, an overdamped vented alignment might benefit from some boost right around FB.  But even then there is no free lunch.  I encourage anyone who wants to play around with boost on their subwoofers to first create a computer model of your speaker and take a look at the expected driver excursion and vent velocity graphs before you dive too far into it.  Understanding the differences between thermal power handling and excursion limit will go a long way towards getting the most out of your speakers. 
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Elliot Thompson

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Re: T-48 FAIL !
« Reply #12 on: October 31, 2013, 04:50:06 pm »

Loudspeaker Cabinet Simulators are only as good as the TS Parameters you enter in the software.

Literally measuring the TS Parameters of the driver to ensure the figures reflect the manufacturers specifications is the best option. Fortunately, there are programs such as ARTA, CLIO in addition to the Woofer Tester that can make such calculations.     

The next step would be to literally measure the loudspeaker’s performance in terms of frequency response in addition to the impedance curve in the box under real-world conditions. Once you have created an enclosure around a particular loudspeaker, there is a greater chance of achieving the requirements you are aiming for.

Unfortunately, many are not willing to go through the trouble of learning free loudspeaker design software more so getting acquainted with measuring TS Parameters of a loudspeaker. They rather find a design on the Internet, build the box, place speakers with TS Parameters that differ from the recommended driver assigned for that particular box, and hope for the best.

Possibly, I am a tad too old fashioned. For the only way I know to determine the thermal or mechanical limit of a loudspeaker is to literally drive the speaker until you smell something is burning, see smoke or hear the voice coil crashing against the back plate.

Best Regards,



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Re: T-48 FAIL !
« Reply #12 on: October 31, 2013, 04:50:06 pm »


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