TAD TL-1102 question

[amo]

Hi-

Would any one care to make an EDUCATED guess as to how much power (in watts) will be required to bring the TAD TL-1102 driver to full excursion (or at least to about 85 dB) at 35 Hz in a sealed box with a volume of 30 Liters or so? Following are some T/S params for this driver. My calculations are probably correct above Fb, but below Fb they are too good to be true. I am getting to full excursion with under 2 Watts! Can this really be???




Z-8
Sd (Sq M)-0.0366
Sd (Sq In)-56.8
Re (ohms)-7.2
1kHz (mH)-1.1
Flux Density (BL)-13.5
Vas(Liter)-121
VAs(cu Ft.)-4.27
(Cms) 6.382
(Mms) 41.3
MMS (Mmd) 34.1
(Fs) 31
(Qms) 4.35
(Qes) 0.32
(Qts) 0.3
(O-P) (Xmax) (mm) 6.2
" " (In) 0.24
RMS (Pmax) 500
Relative Efficiency 1.10%
" " (cu Cm) 227
" " (cu In) 13.9
XmaxP (P-P) (mm) 32
XmaxP (In) 1.26

[roddyama]

According to bass Box Pro, it's actually a little over 3W for full excursion at 35Hz. It also shows an F3 of ~89Hz in a 35l closed box with a Q of just over 0.5. Not bad at all.

[sreten]

Punching the numbers into WinISD Pro alpha I
don't get anything like the above numbers at all.

6.2mm (one-way) Xmax needs ~ 55w at 35Hz, produces 96dB.

I also get a Q of 0.63 for a 35L box.

RY's maximum power curve looks nothing like the maximum power
curve shape I usually see but I note its Watts/Hz, not Watts.
Well 35Hz x 2 watts is at least in the same ballpark as my results.

RY's max SPL at 35Hz is identical at 96dB, which implies
sensistivity need to be 90dB at 35Hz, which is not the case.

sreten.

[amo]

Originally posted by sreten


RY's max SPL at 35Hz is identical at 96dB, which implies
sensistivity need to be 90dB at 35Hz, which is not the case.

sreten.

Does this mean that trying to estimate power requirements for this driver below Fb will not produce reliable results? I guess I will have to wait until I get a pair and measure them. I will need a pair one way or another, for mid-bass, which I think this driver will be perfect for (it should have no problems going up to 1 KHz gracefully). I was hoping to get two pairs and running them as far down as possible, but I would not do that until I was sure they are suitable for the job. I know TAD uses them in a two way system, but I really do not want to go ported. Thank you for your input!

[roddyama]

Originally posted by sreten
Punching the numbers into WinISD Pro alpha I
don't get anything like the above numbers at all.

6.2mm (one-way) Xmax needs ~ 55w at 35Hz, produces 96dB.

The 1102 has a mechanical X-Max of more than 16mm. BBP must have some sort of function for driving the speaker past X-Max (assuming it gets non-linear after X-Max). I'm actually getting an excursion of 10.4mm to obtain the 96db @ 35Hz.

Originally posted by sreten
I also get a Q of 0.63 for a 35L box.

My model has heavy stuffing in the box. If I remove the stuffing, the Q jumps up to 0.61.

Originally posted by sreten
RY's maximum power curve looks nothing like the maximum power
curve shape I usually see but I note its Watts/Hz, not Watts.
Well 35Hz x 2 watts is at least in the same ballpark as my results.

That graph does show the power required for an excursion of X-Max (6.2mm). The acoustic power graph show the SPL output at, in this case, 500watts.

Originally posted by sreten
RY's max SPL at 35Hz is identical at 96dB, which implies
sensistivity need to be 90dB at 35Hz, which is not the case.

sreten.

[sreten]

Originally posted by roddyama

That graph does show the power required for an excursion of X-Max (6.2mm).

Well what's strange to me is it doesn't show the sealed box
alignment increasing low frequency power handling, what its
showing I'm not sure, but I'm positive the single figure watt
bass power handling quoted as 2 to 3 watts is wrong.

I've checked again and low frequency power handling in a
sealed box for 6mm Xmax in a 35L box is around 40W in the
low bass climbing rapidly above 70Hz.

If I input 10mm Xmax I get 100dB at 35Hz and power handling
of 120W at 35Hz and around 100W handling in the low bass.

sreten.

[sreten]

Originally posted by amo
Does this mean that trying to estimate power requirements for this driver below Fb will not produce reliable results? I

Not at all in my opinion for ball park figures.

Download WinISD Pro alpha and play with it yourself.

sreten.

[amo]

I will have to do that. So far I have been using JBL speaker shop (just the enclosure module) which reminds me of an enhanced version of WinISD beta. It has a few more very useful functions. Unfortunately the two mentioned applications do not agree on some numbers, such as box size at a given Q. Besides that, I have built a spread sheet based on "power requirement calculations for sealed enclosures" from S. Linkwitz's site. He has some very detailed instructions and formulas, and on an occasion or two I emailed him for clarification. Unfortunately this spread sheet has failed for low bass calculations for this driver... I think this is the trickiest part to calculate, because the numbers above Fb (Fs after the driver is placed in a box of a specified volume), are simply a function MMS and BL, as long as Xmax and power dissipation constraints are employed. Below Fb this model fails and you have to look at things like CMS, acceleration, mechanical loss.....

[dB at Hz] is simply a function of Sd and Xmax, and is easily calculated, and in fact confirms that the driver will produce at most 91 dB at 6.1 mm Xmax at 35 Hz, which is ok I guess. If that takes 40 Watts, then that is fine also. More then that, and I will have to switch over to Gainclones instead of Alephs, due to heat management issues.... I am wandering if this driver will play below Fs when used in a sealed enclosure. I am also wandering if my calculation of 12 Watt power handling to achieve 100 dB above 70 Hz is wrong as well..... If not, then this driver is a winner for mid-bass duties for sure! Thanks!

[amo]

Wow - winisd pro is COOL! I did not realize it was so comprehensive. I punched in all the params, and looked at the "SPL" graph, after changing "power" from 1 watt to 25 watts. I think this is really the answer that I was looking for and is the most meaningful information - What can I squeeze out of this driver when giving it 25 watts, at all frequencies. (I left the box size at the recommended 26 liters). If this graph is accurate, then I am in business! Thanks for the suggestion.