jules wrote:

I'm not an audiophile but fascinated by this thread. In the past I changed speaker capacitors on my Octavia VRS on the advice of forum members with a marked improvement.
What is the benefit in fitting the sub woofer pipe for a listener with average hearing ?

jules wrote:

I'm not an audiophile but fascinated by this thread.

I must say I concur; I have definitely "subbed" this thread

I have never felt the subwoofer enclosure while it is working hard, or even at all for that matter. To have a guess, it's probably worthwhile giving it a bit more mass. Sticking butyl sheet around it wouldn't do any harm. The more mass it has the more speaker energy will be going where it should.

I have 10mm acoustic foam (to reduce noise from the car, wasn't thinking of the actual subwoofer at the time) under the subwoofer enclosure so there is a gap there, & butyl on the car. The enclosure is pressing against the foam. So maybe in my case sticking some butyl on the remaining sides of the enclosure is enough to finish if off.

Click image to enlarge

Click image to enlarge

Huge noise protection must be done first of all (before any speaker changings). I even use a chance during taking my engine off to make a noise protection more serious.

I haven't seen somebody else who did it this way. But final result has made me so happy that even reimbursed me all expenses!

Click image to enlarge

I had a quick look at the sub enclosure & the flat area on top at the rear vibrates (under extinguisher). I didn't take the wheel out to look at the sides & I have some acoustic foam on the enclosure for the car, not thinking about the subwoofer at the time of installation. Butyl would be better than foam as it has mass. Stiffening the box would be better still, but there is not a lot of room as you need reasonable thickness.



When I put the boot floor back in, with sound track still playing, I noticed that the whole boot floor vibrates a lot. I have no idea but it could possibly be vibrating a touch more due to the butyl I have lined the wheel well with, but I never did any benchmarking. My boot floor is raised 6mm (grey spacers) to fit the 255/60R18 tyres.

Link to acoustic insulation thread, no point repeating everything https://www.freel2.com/forum/topic33026.html Procrastination, mankind's greatest labour saving device!

Acoustic insulation ARB TPMS 3xARB air compressors After cooler Air tank On-board OCD pressure air/water cleaning Additional 50L fuel Carpet in doors ABE 2x1kg Waeco 28L modified fridge Battery 4x26ah Solar 120w Victron MPPT 100/20 DC-DC 18amps 175amp jumper plug Awning 6x255/60R18

My wheels are standard so I covered whole Sub with noise-protection like the below:

Click image to enlarge

Click image to enlarge

Use 5083 alloy aluminium. There is no give in 8mm plate. Glue it onto the enclosure & run some threaded rod through to the underside of the enclosure. Tapped into some 6mm plate, as this is a smaller area. Probably M6 thread is heavy enough to hold top & bottom together in half a dozen locations. Procrastination, mankind's greatest labour saving device!

Acoustic insulation ARB TPMS 3xARB air compressors After cooler Air tank On-board OCD pressure air/water cleaning Additional 50L fuel Carpet in doors ABE 2x1kg Waeco 28L modified fridge Battery 4x26ah Solar 120w Victron MPPT 100/20 DC-DC 18amps 175amp jumper plug Awning 6x255/60R18

Good alternative for plywood!!! I have to check if 5083 alloy aluminum is available in shops.
 MY13 SD4 HSE Lux
IAM2.1 Level 3
Meridian Premium Surround Sound with Extra Upgrade

I was in the industry for 2 decades. Try to get the rolling mill grain running the length of the enclosure but you will never notice unless you put it under a press. It is a whisker stiffer than across the grain. Make a template out of ply or MDF so you get the finished product a perfect fit first time.

Tap all your holes as well in the MDF so every aspect of your template lines up.

Metal fabrication engineering places will have it. Not your hardware store. Procrastination, mankind's greatest labour saving device!

Acoustic insulation ARB TPMS 3xARB air compressors After cooler Air tank On-board OCD pressure air/water cleaning Additional 50L fuel Carpet in doors ABE 2x1kg Waeco 28L modified fridge Battery 4x26ah Solar 120w Victron MPPT 100/20 DC-DC 18amps 175amp jumper plug Awning 6x255/60R18

FL2Vano wrote:

I stumbled across this subwoofer enclosure machined out of aluminium. It has given me some ideas, but I won't be doing the same as the shape is too difficult & it's not worth getting it 3d metal printed.



Doing some tests with my subwoofer I was surprised how much the forward section of the enclosure vibrates up & down. It's probably more than others as the bottom of mine when screwed in place presses down on the acoustic foam & butyl I put around the wheel well. The whole bottom of the enclosure is firmly supported, so the top surface probably moves twice as much, or at least close to it.

My thoughts at this stage it to tie the top & bottom together with threaded rod. A few more ideas are in the pipeline.

I have ordered an enclosure to pull apart & look what can be done to cross brace it. About a month before it will turn up, hopefully!

I think I will keep the enclosure sealed as I am quite happy with the amount of base in the car. Maybe the base will get tidied up, although it probably will be pretty hard to tell, but I will be able to a side by side test but not in situ. Procrastination, mankind's greatest labour saving device!

Acoustic insulation ARB TPMS 3xARB air compressors After cooler Air tank On-board OCD pressure air/water cleaning Additional 50L fuel Carpet in doors ABE 2x1kg Waeco 28L modified fridge Battery 4x26ah Solar 120w Victron MPPT 100/20 DC-DC 18amps 175amp jumper plug Awning 6x255/60R18

Some technical reading!

https://sound-au.com/articles/boxstuff.htm

https://www.qtasystems.co.uk/articles/how-to-damping.htm

https://www.audioholics.com/loudspeaker-de...e-stuffing


Currently working out some internal bracing ideas, probably in aluminium. Will also tie this to the outside of the enclosure to hopefully clamp the enclosure in place. The speaker itself really needs to be bolted to the bottom on the enclosure.

I assume Meridian have designed the subwoofer enclosure to the correct volume. Adding bracing inside will reduce volume, but adding stuffing increases apparent volume. Procrastination, mankind's greatest labour saving device!

Acoustic insulation ARB TPMS 3xARB air compressors After cooler Air tank On-board OCD pressure air/water cleaning Additional 50L fuel Carpet in doors ABE 2x1kg Waeco 28L modified fridge Battery 4x26ah Solar 120w Victron MPPT 100/20 DC-DC 18amps 175amp jumper plug Awning 6x255/60R18

A prototype for cross bracing inside the enclosure. M6 thread in the end of 12mm rod. There is ribbing inside the enclosure but at this stage I don't know how they line up on opposite sides, but that's easy enough to work around. The cross bracing is a scaled down version of a block of wood inside a large speaker.




Edit: This is on the back burner. I normally order items directly from the supplier even from overseas. I ordered this from ebay for the first time. The order was confirmed from USA with quite a large portion being freight costs. I now looked at the order as it was now in the due period for delivery. The seller had cancelled the order & there was no email. So that was pathetic service! I was looking forward to do the modifications. Procrastination, mankind's greatest labour saving device!

Acoustic insulation ARB TPMS 3xARB air compressors After cooler Air tank On-board OCD pressure air/water cleaning Additional 50L fuel Carpet in doors ABE 2x1kg Waeco 28L modified fridge Battery 4x26ah Solar 120w Victron MPPT 100/20 DC-DC 18amps 175amp jumper plug Awning 6x255/60R18

jules wrote:

I'm not an audiophile but fascinated by this thread. In the past I changed speaker capacitors on my Octavia VRS on the advice of forum members with a marked improvement.
What is the benefit in fitting the sub woofer pipe for a listener with average hearing ?

Lightwater wrote:

A prototype for cross bracing inside the enclosure. M6 thread in the end of 12mm rod. There is ribbing inside the enclosure but at this stage I don't know how they line up on opposite sides, but that's easy enough to work around. The cross bracing is a scaled down version of a block of wood inside a large speaker.




Edit: This is on the back burner. I normally order items directly from the supplier even from overseas. I ordered this from ebay for the first time. The order was confirmed from USA with quite a large portion being freight costs. I now looked at the order as it was now in the due period for delivery. The seller had cancelled the order & there was no email. So that was pathetic service! I was looking forward to do the modifications.

It should be huge Subwoofer for it! Hope you will get it finally and test.
 MY13 SD4 HSE Lux
IAM2.1 Level 3
Meridian Premium Surround Sound with Extra Upgrade