Sony XS-L104P5B

[Alex2507]

Eddie's neighbors need audio help. So the story is that Eddie's neighbor Steve (not Kenny of the Spandex) bought this sub at a yard sale and plans to buy a box at Walmart for 30 bucks and put it in the trunk of his old school Grand National. Sounds simple enough. The problem is that this guy has done me a pretty big favor and now I feel compelled to do him a solid by fishing out an alignment from either TLS or Annunaki.

I got the spec's from Crutchfield.

Vas (liters) 19.3
Fs (Hz) 37.7
Qts 0.57
Xmax (millimeters) 6

I started going through one of my books to find the formula that would tell me if this sub was better suited for sealed or ported designs but I got impatient. I know TLS mentioned it in one of his posts in one of my threads and the # 0.4 seems relevant but my monkey brain needs more coffee ... with about a pound of sugar.

 

[Swerd]

Eddie's neighbors need audio help. So the story is that Eddie's neighbor Steve (not Kenny of the Spandex) bought this sub at a yard sale and plans to buy a box at Walmart for 30 bucks and put it in the trunk of his old school Grand National. Sounds simple enough. The problem is that this guy has done me a pretty big favor and now I feel compelled to do him a solid by fishing out an alignment from either TLS or Annunaki.

I got the spec's from Crutchfield.

Vas (liters) 19.3
Fs (Hz) 37.7
Qts 0.57
Xmax (millimeters) 6

I started going through one of my books to find the formula that would tell me if this sub was better suited for sealed or ported designs but I got impatient. I know TLS mentioned it in one of his posts in one of my threads and the # 0.4 seems relevant but my monkey brain needs more coffee ... with about a pound of sugar.

Efficiency Bandwidth Product: EBP = Fs/Qes
See page 15 in Ray Alden's book.

If Fs/Qes is 50 or less, use a sealed box. If Fs/Qes is more than 50, use a vented box.

We don't know Qes for this driver, but I'm guessing that the Xmax of 6 mm might be a bit small for a 10" driver in a sealed box.

That web page you linked suggests a ported box of 0.9 cubic feet with a 3" diameter port, 11.125" long.

 

[Alex2507]

That web page you linked suggests a ported box of 0.9 cubic feet with a 3" diameter port, 11.125" long.

The owner saw those recommendations and decided to go with a sealed premade box of .75ft^3 because of what he thinks he knows about sealed -vs- ported but I've seen Annunaki come up with numbers that get more out of subs than the manufacturer's recommendations.

I'll take a look at pg. 15. Thanks.

 

[Alex2507]

Okay, here we go. I am mixing my info up pretty badly but in my defense all
those numbers and little letters don't lend themselves to easy answers.

If the Qts of the driver happens to equal 0.4, the optimum vented box will resemble a B4 (4th-order Butterworth) alignment. As the value of the driver Qts drops below 0.4 the optimum vented box will begin to resemble a QB3 (quasi 3rd-order Butterworth) alignment. As the value of the driver Qts rises above 0.4, the optimum vented box will begin to resemble a C4 (4th-order Chebychev) alignment.

I found the rule in my other book:
Use a port when the box volume is greater than 2 Vof.

Vof=Vas x Qts^2
=.68 x .57 x .57
=.22

Seems like it's telling me that ported is better.

The graph my book provides seems to suggest that a ported box of 1.1 ft^3 might be okay. I haven't gotten to the port size and length yet. I have some stuff to do before I go further.

 

[Swerd]

Here are some simple to use online calculators. You can plug in those Vas, Fs, Qts values and quickly see what gets predicted. You can change Qtc, box volume, port tuning, etc to your heart's content to see what it predicts. Click on the Plot Frequency Response Curve button to see a predicted frequency response curve.

I used the T/S values you supplied, and ran them for a sealed box and a vented box. I chose a standard Qtc value of 0.707. You may wish to go as low as 0.5, but for tight bass that is not exaggerated, go no higher than 0.71. At Qtc of 1.0 or higher, it will have a strong resonance peak. It will ring on and on at that resonance freq, giving it a one-note bass sound. Most uninformed people think that is good, but you know what a properly designed bass cabinet can sound like.

Sealed Enclosure Calculator (Qtc)
The box volume (Vb) comes out as 35.84 liters or 1.26 ft³. F3 will be 47 Hz and the roll off will be a gradual 6 dB per octave.

And for a Vented Box-Calculator
With a 3" diameter port tube (7.62 cm), Vb comes out to be 57.68 liters or 2 ft³. The tube will be 11 inches long. That port will be tuned to 26 Hz.

Those smaller boxes that Sony suggested will have a higher Qtc and will be one-note bass boxes.

Edit: I just ran the numbers for that $30 0.75 ft³ sealed box. Qtc will be 0.787. Maybe that will be good enough for a car trunk. The box may be thin walled. Add some 1x1 or 1" dowel (closet pole) bracing.

 

[annunaki]

While I would like to help here, I simply do not have enough parameters to use to get a reasonably accurate model.

I generally need:

Qes
Qms
Fs
Vas
Re
Xmax
Le
Sd


In order to come up with a reliable model I need at least those parameters. Qes could be supplemented with Qts or Qts for Qms as well. Without these it will not model properly.

 

[TLS Guy]

Eddie's neighbors need audio help. So the story is that Eddie's neighbor Steve (not Kenny of the Spandex) bought this sub at a yard sale and plans to buy a box at Walmart for 30 bucks and put it in the trunk of his old school Grand National. Sounds simple enough. The problem is that this guy has done me a pretty big favor and now I feel compelled to do him a solid by fishing out an alignment from either TLS or Annunaki.

I got the spec's from Crutchfield.

Vas (liters) 19.3
Fs (Hz) 37.7
Qts 0.57
Xmax (millimeters) 6

I started going through one of my books to find the formula that would tell me if this sub was better suited for sealed or ported designs but I got impatient. I know TLS mentioned it in one of his posts in one of my threads and the # 0.4 seems relevant but my monkey brain needs more coffee ... with about a pound of sugar.

I have made a few assumptions.

This will be a car thumper.

If you port it, I think an enclosure of around 1 cu.ft, is probably about optimal. However F3 will be around 165 Hz with a thump peak at 55 Hz.

The vent velocity of the quoted port will be off the clock.

It needs about 1.5" X 10" X 35" minimum. That is a lot for a 1 cu.ft. box.

If you use the recommended sealed alignment, F3 will be in the neighborhood of 200 Hz, with a smooth second order roll off.

I think low bass output will be about the same ported as sealed, but the sealed response will be smoother.

Under either loading output will be close to zero at 40 Hz or below.

If you must use that driver, I would use the 0.78 cu.ft sealed box.

I doubt having a full set of T/S parameters will change the bad performance significantly.

 

[annunaki]

I have made a few assumptions.

This will be a car thumper.

If you port it, I think an enclosure of around 1 cu.ft, is probably about optimal. However F3 will be around 165 Hz with a thump peak at 55 Hz.

The vent velocity of the quoted port will be off the clock.

It needs about 1.5" X 10" X 35" minimum. That is a lot for a 1 cu.ft. box.

If you use the recommended sealed alignment, F3 will be in the neighborhood of 200 Hz, with a smooth second order roll off.

I think low bass output will be about the same ported as sealed, but the sealed response will be smoother.

Under either loading output will be close to zero at 40 Hz or below.

If you must use that driver, I would use the 0.78 cu.ft sealed box.

I doubt having a full set of T/S parameters will change the bad performance significantly.

While I have no doubts this driver is a 'sub-par' performer, having a full set of T/S parameters to develop an accurate model will let one know just how poorly it may perform.

 

[Alex2507]

I want to thank you three guys for #1 helping out and #2 keeping me entertained.

I'll let the owner have a peak at the thread so he knows something about his driver.