Sub Build assistance.

[fuzz092888]

So here are some T/S parameters. I should have a box plan later tonight, but wanted some input from anybody on here as well as to what they think the box should be. Any help would be appreciated.

f(s) = 30.95 Hz
Q(ms) = 5.325
V(as) = 117.10 liters (4.135 cubic feet)
n(0) = 0.34%
M(ms) = 469.80 grams
R(e) = 3.26 Ohms
Q(es) = 0.961
SPL = 87.47 dB SPL 1W/1m
C(ms) = 0.06 mm/N
Piston Diameter = 393.7
Z(max) = 21.35
Q(ts) =0.814
L(e) = 1.368 mH at 10kHz
SPL = 91.36 dB SPL 2.83 Vrms
BL = 17.61

 

[fuzz092888]

So the plans for the box are pretty straight forward. The top and bottom are 22 in squares with the sub being 36-40 inches tall depending on bracing. The F3 for a 36inch tall box is 26.42 Hz with a volume of about 8.1 cubes not including bracing. I was told that if I make it down firing it will lower the F3 anywhere from 3-10 Hz depending on the room so I think I may do that to gain a little bit more output down low and I like the idea of having nice clean sides.

Oh yea, Qtc = 1.231

 

[TLS Guy]

So the plans for the box are pretty straight forward. The top and bottom are 22 in squares with the sub being 36-40 inches tall depending on bracing. The F3 for a 36inch tall box is 26.42 Hz with a volume of about 8.1 cubes not including bracing. I was told that if I make it down firing it will lower the F3 anywhere from 3-10 Hz depending on the room so I think I may do that to gain a little bit more output down low and I like the idea of having nice clean sides.

Oh yea, Qtc = 1.231

That is a sloppy high Qts driver.

You can only put that driver in a sealed box. The volume of the air in the box needs to be 5 cu.ft. This will give you an F3 of 35 Hz.

You did not specify an xmax or max RMS output, so I can't tell you what spl. you will achieve.

If you put that driver in a ported box you will damage the driver fast and it will sound awful. You will really find out what boomy bass is.

You should not make the box larger than 5 cu.ft, again to stop the driver destructing. With a suspension that loose, the volume I have modeled will give optimal total system compliance. The box will need filling with Polyfill. A good firm fill, but not tightly compressed. This gives you a Qts of 0.814 the same as the driver. You can never get a Qts of the total system lower than the Qts of the driver only higher.

The Qts of that driver is too high, and bass reproduction will not be accurate.

I think a Qts of 0.7 is max, and in fact too high for me. I like Qts around 0.5, then bass is nice and tight and non resonant.

If you have not already bought that driver, I would be looking for something else.

 

[Alex2507]

Oh yea, Qtc = 1.231

I also thought that was high.

Just in case you're unaware TLS steered me toward a particular alignment for my DIY subs and I'm exceedingly happy that I listened. At the time it wasn't so much that I understood all the ins and outs of subwoofer design as it was that I just believed him.

 

[TLS Guy]

I also thought that was high.

Just in case you're unaware TLS steered me toward a particular alignment for my DIY subs and I'm exceedingly happy that I listened. At the time it wasn't so much that I understood all the ins and outs of subwoofer design as it was that I just believed him.

I'm glad you are still happy with your subs.

I have his design, saved under Fuzz Box.

 

[fuzz092888]

So the plans for the box are pretty straight forward. The top and bottom are 22 in squares with the sub being 36-40 inches tall depending on bracing. The F3 for a 36inch tall box is 26.42 Hz with a volume of about 8.1 cubes not including bracing. I was told that if I make it down firing it will lower the F3 anywhere from 3-10 Hz depending on the room so I think I may do that to gain a little bit more output down low and I like the idea of having nice clean sides.

Oh yea, Qtc = 1.231

That is a sloppy high Qts driver.

You can only put that driver in a sealed box. The volume of the air in the box needs to be 5 cu.ft. This will give you an F3 of 35 Hz.

You did not specify an xmax or max RMS output, so I can't tell you what spl. you will achieve.

If you put that driver in a ported box you will damage the driver fast and it will sound awful. You will really find out what boomy bass is.

You should not make the box larger than 5 cu.ft, again to stop the driver destructing. With a suspension that loose, the volume I have modeled will give optimal total system compliance. The box will need filling with Polyfill. A good firm fill, but not tightly compressed. This gives you a Qts of 0.814 the same as the driver. You can never get a Qts of the total system lower than the Qts of the driver only higher.

The Qts of that driver is too high, and bass reproduction will not be accurate.

I think a Qts of 0.7 is max, and in fact too high for me. I like Qts around 0.5, then bass is nice and tight and non resonant.

If you have not already bought that driver, I would be looking for something else.

I already bought the driver awhile ago, I was just waiting on the build. I specifically asked for a driver that would do better in a sealed box. So you think the box design that I was provided with would be inadequate?

 

[fuzz092888]

 

[Send Margaritas]

Sorry for the off-topic question. Fuzz (Alex?) What software did you use for that?

 

[TLS Guy]

Trust me, that box is too big. Use the 5 cu.ft box. The bass will be much tighter, and you won't even notice the rise in f3. Any way roll off is 12 db per octave for a sealed sub.

You will really regret building that bigger box. Less will be more, much more.

 

[fuzz092888]

Sorry for the off-topic question. Fuzz (Alex?) What software did you use for that?

It's bass box pro 6, but I didn't do it. The guy who built the sub took the T/S parameters off of the sub after he finished it and then modeled the box.

 

[fuzz092888]

Trust me, that box is too big. Use the 5 cu.ft box. The bass will be much tighter, and you won't even notice the rise in f3. Any way roll off is 12 db per octave for a sealed sub.

You will really regret building that bigger box. Less will be more, much more.

Thanks for the advice, I really appreciate it. I just have another question, would downfiring vs front firing make a difference in F3?

 

[Alex2507]

I have his design, saved under Fuzz Box.

Listen, there's enough of that kind of talk in The Boring Thread, alright?

 

[fuzz092888]

Thanks for the advice, I really appreciate it. I just have another question, would downfiring vs front firing make a difference in F3?

Another question, so a 22 X 22 X 22 inch box would give me about 6.1 cubic feet, which leaves me a cubic foot for bracing. Does that sound about right, too much, too little?

 

[TLS Guy]

I already bought the driver awhile ago, I was just waiting on the build. I specifically asked for a driver that would do better in a sealed box. So you think the box design that I was provided with would be inadequate?

Yes, I do, it is too big by over 50%.

The 5 cu.box will sound much better, and I mean a lot better.

You have a huge xmax, so if you add 12 db per octave Eq, staring at 40 Hz, and an infra sonic filter at 20 Hz you will have a pretty impressive sub. Qt will be on the high side, but not totally unacceptable. The smaller box also gets rid of that nasty bass ripple around 100 HZ.

Build the small box it will be easier and be much better. The driver will thank you as excursions will be less and it will have the proper restoring force form the box, as it won't get it from the suspension, with those parameters.

 

[fuzz092888]

Thanks for the advice, I really appreciate it. I just have another question, would downfiring vs front firing make a difference in F3?

Yes, I do, it is too big by over 50%.

The 5 cu.box will sound much better, and I mean a lot better.

You have a huge xmax, so if you add 12 db per octave Eq, staring at 40 Hz, and an infra sonic filter at 20 Hz you will have a pretty impressive sub. Qt will be on the high side, but not totally unacceptable. The smaller box also gets rid of that nasty bass ripple around 100 HZ.

Build the small box it will be easier and be much better. The driver will thank you as excursions will be less and it will have the proper restoring force form the box, as it won't get it from the suspension, with those parameters.

So the 5 cubic foot box takes bracing into account? So the overall box volume will be less than 5 cubic feet? I was planning on building the box around 6 cu. feet so that after bracing the overall volume would be 5 cubic feet. Did I just misunderstand?

 

[TLS Guy]

So the 5 cubic foot box takes bracing into account? So the overall box volume will be less than 5 cubic feet? I was planning on building the box around 6 cu. feet so that after bracing the overall volume would be 5 cubic feet. Did I just misunderstand?

No, Box pro only takes the stuffing into account, you have to add everything else to Vb to get Vt.

I think front fire is better, as you need those frequencies above cut off.

 

[fuzz092888]

No, Box pro only takes the stuffing into account, you have to add everything else to Vb to get Vt.

I think front fire is better, as you need those frequencies above cut off.

I know this is beating a dead horse, and someone else can chime in to save TLS Guy the headache of describing this further to me, but I want a box with external dimensions of about of 22.5in X 22.5in X 22in so that after I add bracing the total internal volume is 5 cubic feet?

External dimensions of a 22in cube gets me internal dimensions of 20.5 X 20.5 X 20.5 giving me a volume of 4.985 cu feet. So I really want to have internal dimensions closer to 21 X 21 X 20.5 to give me an internal volume of 5.23 cu. feet which would also give me the external dimensions above. Does that sound right?

Am I finally getting it????

 

[TLS Guy]

I know this is beating a dead horse, and someone else can chime in to save TLS Guy the headache of describing this further to me, but I want a box with external dimensions of about of 22.5in X 22.5in X 22in so that after I add bracing the total internal volume is 5 cubic feet?

External dimensions of a 22in cube gets me internal dimensions of 20.5 X 20.5 X 20.5 giving me a volume of 4.985 cu feet. So I really want to have internal dimensions closer to 21 X 21 X 20.5 to give me an internal volume of 5.23 cu. feet which would also give me the external dimensions above. Does that sound right?

Am I finally getting it????

Ok. Take you internal volume 5.00 Cu.ft. Now add air displaced by the driver and the volume of the braces. If you have a plate amp, you need to add that as well. The total bill will be Vt. Now take that volume and work out the external dimensions and your cutting plan. Build it and enjoy.

 

[fuzz092888]

Ok. Take you internal volume 5.00 Cu.ft. Now add air displaced by the driver and the volume of the braces. If you have a plate amp, you need to add that as well. The total bill will be Vt. Now take that volume and work out the external dimensions and your cutting plan. Build it and enjoy.

I had another question, if you would be so kind

A friend of mine gave me this excel spreadsheet for box design. When I input the T/S parameters the bigger box gives me the lower Qtc and actually tells me that an even bigger, 11 cubic foot box would give me the lowest Qtc.

I'm not doubting or questioning your advice, I'm just curious why this would be. Thankee kindly.

 

[TLS Guy]

I had another question, if you would be so kind

A friend of mine gave me this excel spreadsheet for box design. When I input the T/S parameters the bigger box gives me the lower Qtc and actually tells me that an even bigger, 11 cubic foot box would give me the lowest Qtc.

I'm not doubting or questioning your advice, I'm just curious why this would be. Thankee kindly.

It is mathematically impossible to have any alignment with a lower Qt, than the Qts of the driver, so draw your own conclusions about that program.