200L Barrel Subwoofer

[kiwifi]

I've decided to build a subwoofer out of a 200L plastic barrel. I have three subs at the moment, all sealed, and I feel like l am missing some LFE punch when watching movies. This sub will focus on frequencies below 35Hz.

I happen to have a pair of Pyle PL1090BL 10" drivers and according to WinISD, they will be a good match for a 200L enclosure tuned to 15Hz. They will be mounted face to face (isobaric). Three 85cm x 80mm pieces of PVC down pipe will make up the port.



I've included a mockup of what it will look look like. Imagine the barrel and vents painted black!

 

[alex-z]

Did you actually measure the T/S parameters? I wouldn't believe Pyle's own specifications for a single second.

The biggest problem you will face is the barrel flexing a considerable amount at low frequencies. Expect your actual performance to differ significantly from the model. A much better option is a sonotube subwoofer, the circular forms used for concrete pours.

 

[kiwifi]

These barrels are designed to hold 200kg plus of liquid, so I don't think that flexing will be an issue any more than it would be for a sonotube.

 

[voodooless]

I happen to have a pair of Pyle PL1090BL 10" drivers and according to WinISD, they will be a good match for a 200L enclosure tuned to 15Hz. They will be mounted face to face (isobaric).

Pretty cool idea . Where did you find a full set of TS parameters for the driver? If I enter what is available from the data sheet, a 1 liter box would work just as well, which is ridiculous. So from that data alone would not trust the simulation.

 

[kiwifi]

I am relying on the data sheet, but I will try and measure the T/S parameters to see how close they are.

The fact is, I already have the PL1090BL's so that's what I am going to use. It's not costing me anything!

 

[voodooless]

I would definitely recommend measuring. I would also not do Isobaric. You will not get more output from it and costs you a driver. Better just use both normally in the big box.

 

[abdo123]

I would definitely recommend measuring. I would also not do Isobaric. You will not get more output from it and costs you a driver. Better just use both normally in the big box.

I agree, Isobaric here makes no sense, extension below 35Hz will always be lacking because it's a 10 inch woofer, he needs 15-18" at least for that sort of response.

 

[Blumlein 88]

The Sonotubes will flex less than these barrels. Maybe create a bandpass enclosure by segmentation of the barrel. The segmentation will help stiffen the barrel.

 

[voodooless]

bandpass enclosure

Then you will definitely need more parameters.

But adding some bracing is probably a good idea. Holding 200 liters of liquid does not mean it won’t flex. A plastic bag can also be made to hold 200 liters of water, that doesn’t mean it would work as a subwoofer enclosure .

 

[kiwifi]

I'm pretty sure that cylinders don't need bracing. Any flex will be end to end.

The barrel is about 1m tall, so the first internal resonance (1/4 wavelength) is 74Hz. There will be a low pass filter at 35Hz on the input signal to the amp, plus 15cm of wool in the bottom of the barrel. Hopefully that will help control any potential resonance issues.

 

[Chrise36]

I'm pretty sure that cylinders don't need bracing. Any flex will be end to end.

The barrel is about 1m tall, so the first internal resonance (1/4 wavelength) is 74Hz. There will be a low pass filter at 35Hz on the input signal to the amp, plus 15cm of wool in the bottom of the barrel. Hopefully that will help control any potential resonance issues.

You can try with one first in bass reflex and experiment with the isobarik if you are getting anything better. If you are not going to build a new box or change the existing one there is no need to measure the drivers.

 

[kiwifi]

Standard vs Isobaric as modeled by WinISD

 

[egellings]

The Sonotube, made of layers of paper formed into a hard board, would have a lot more internal damping than a plastic sheet tube would. So I think the Sonotube would make for a better woofer cabinet. Of course, in a cylindrical tube like that, the flexing would be minimal because the hoop stress would stretch, rather than flex (bend in & out) the material, and the plastic could be quite resistant to that, I 'spoze. For a rectangular box, then not so much; plastic might be too bendy.

 

[abdo123]

View attachment 165205

Where did you get the rest of the parameters necessary for this simulation?

 

[kiwifi]

Where did you get the rest of the parameters necessary for this simulation?

The T/S parameters came straight off the manufacturer spec sheet

 

[alex-z]

The T/S parameters came straight off the manufacturer spec sheet

Why would you trust T/S parameters from one of the least reputable audio brands in existence? Even the good brands have a 10% margin of error.

 

[abdo123]

The T/S parameters came straight off the manufacturer spec sheet

The ones in the brochure you sent are not enough for the simulation you showed.

 

[kiwifi]

The ones in the brochure you sent are not enough for the simulation you showed.

Which ones are missing?

 

[abdo123]

Which ones are missing?

DC resistance (Re) and maximum impedance (Zmax).

 

[kiwifi]

DC resistance (Re) and maximum impedance (Zmax).

DC resistance is 3.9 ohms per winding. The max impedance I would have to measure with a frequency generator.

Regardless, I am using these drivers because that is what I have to hand. I am basically building an enclosure that resonates at 15Hz and hoping that the driver behaves itself in that enclosure. With a Qts > 0.7, the driver should fine in a large "box". In fact, the bigger the better.

The proof will be in the pudding...as they say.