glassing MDF enclosure

[Lee Carter 150]

 

I plan to  resin my box- purely to put automotive grade paint in the port.  And since I am doing the port- may as well do it all.  i also want to keep the wood smell down.  The box I built for my Suzuki still make the truck smell like wood(after you pound on it for a bit) after 6 months. 

haha what? resin it so that you don't get the smell of wood? the smell of resin stays in the car a very very long time, and I think wood is a little more pleasant of an aroma.

That being said either way you can get a very smooth nice looking enclosure. I prefer resin on all my enclosures though to seal everything up tight.

 

 

Don't wanna get off subject- But I figured after it cured it wouldn't smell at all.  Though Q has already pointed me to the fact that auto primer will work the same.

[ncc74656 2]

resin's smell lasts a very long time... im glassing pods for some new speakers on my door panel now and the smell stays for a couple days in the shop after we clean up and thats in a vented shop with a lot of air space.

[Lee Carter 150]

Thanks for the info on that.  learn something new every day.

[///M5 2,833]

my boss had a circle jig for his router so yes, we do have one. i had gone searching to find one but no hardware store i went to had ever heard of such a thing so i was just going to try and use a jig saw. the box is nearly complete... crazy long build as i had to run to the store to buy tools neither i nor the shop had, yesterday the shop ran out of glue, today the shop ran out of screws... just lots of hickups. in either case i have the box with in 1/16 of an inch of error on the cuts so its coming together very nicely.

i am using some 45's striped across the inside of hte bottom of hte port and then silicone on the rest of the seams. not using any resin. here is a pic of the design:

http://i.imgur.com/XXKM1iq.jpg

You didn't go to seven corners then. They have everything.

Either way, homemade circle jigs are awesome and simple.

[ramteid 17]

Correct me if im wrong, but on the whole vacuum thing, is that not completely irrelevant? A vacuum sucks in air, so it is able to move air through the pores of the mdf. With a subwoofer however, it does not move air at all, it is exciting the air molecules and basically there is a transfer of energy from one molecule to the next. So, since it is not actually moving air like a vacuum, then it is not anywhere near capable of producing the same results, making the argument of using resin in the whole enclosure invalid? Or is my extremely basic understanding of physics incorrect?

[Impious 1,476]

Your understanding is wrong. If a speaker doesn't move air, how does it create sound ?

A heating element would be an example of an item that excites air molecules, but doesn't "push" the air. A speaker creates sound by compression and rarefaction (decompression) of the air. This cycle creates pressure waves that travel through the air creating sound waves. The frequency is determined by the number of cycles per second, the amplitude is determined by the volume of air displaced by the speaker (or literally the amount of air that the speaker moves with each cycle). The speaker is also compressing and decompressing the air inside of the enclosure with each cycle...which is why things like leaks in the enclosure's seams (which according to your logic would likewise not matter) and the porosity of the wood matter to a certain extent. You don't want giant leaks in the seams and you don't want to use an excessively porous enclosure material.

[ramteid 17]

That explains some, but at the same time i still dont think it moves air, as in pushing the air, if it did, would it not create a vacuum? My understanding is that it vibrates the air, not necessarily move it.

Edited April 16, 2014 by ramteid

[altoncustomtech 773]

It does. When the driver plays the positive half of the waveform and moves outward (assuming standard polarity) it causes rarefaction (vacuum) and when it plays the negative half of the wave form it pressurizes the air behind it. The vibration you're seeing in your mind is simply due to the frequency. The pressurization and rarefaction are happening very quickly. Think of TV, with a frame rate of 24fps you can't tell it's one picture after another and not a continuous movement. If you slow down the frame rate you can begin to see each picture. If you played a 1hz sine wave the pressurization and rarefaction are much easier to notice. Also the amount of air the driver is pressurizing/depressurizing is directly associated to the size of the cone and the drivers XMAX. that's typically not a great volume of air compared to something that creates constant air moving pressure like a air nozzle on an air hose, or the depressurization from a vacuum. Frequency again, because the speed the air is trying to move is directly related to it, changes how the air and therefore the driver pushing it reacts through openings. That's why a port works in the first place. The air inside a given enclosure volume, and a given port size, can only be moved so fast because the air has mass (albeit very small). Change the volume of air in the enclosure or port, you change the mass, you change how fast or slow it can move, that changes it's resonant frequency and voila it tunes the enclosure.

More or less.

[ncc74656 2]

i finished the box yesterday, a 3 day build in total. it sounded very nice and was very accurate with those phoenix gold's in it. the elite.1 was total over kill for those 2 subs though, gains next to zero had them maxed out. its rated at 3200W but its gotta be pushing way over that...

[jcarter1885 995]

[ncc74656 2]

I wish I had them... my battery was dead on my camera   I can call the customer and see if he can send me some. my co worker also wants to see it.

[ramteid 17]

It does. When the driver plays the positive half of the waveform and moves outward (assuming standard polarity) it causes rarefaction (vacuum) and when it plays the negative half of the wave form it pressurizes the air behind it. The vibration you're seeing in your mind is simply due to the frequency. The pressurization and rarefaction are happening very quickly. Think of TV, with a frame rate of 24fps you can't tell it's one picture after another and not a continuous movement. If you slow down the frame rate you can begin to see each picture. If you played a 1hz sine wave the pressurization and rarefaction are much easier to notice. Also the amount of air the driver is pressurizing/depressurizing is directly associated to the size of the cone and the drivers XMAX. that's typically not a great volume of air compared to something that creates constant air moving pressure like a air nozzle on an air hose, or the depressurization from a vacuum. Frequency again, because the speed the air is trying to move is directly related to it, changes how the air and therefore the driver pushing it reacts through openings. That's why a port works in the first place. The air inside a given enclosure volume, and a given port size, can only be moved so fast because the air has mass (albeit very small). Change the volume of air in the enclosure or port, you change the mass, you change how fast or slow it can move, that changes it's resonant frequency and voila it tunes the enclosure.

More or less.

Im pretty sure that is incorrect. In order for it to create a vacuum it has to literally move the air, but it only does to a certain extent. The air near the subwoofer wont end up near the operator of the vehicle; its just a transfer of energy. Rareification is just the dip in between each wave, or form of energy. There is still air molecules there, they just are not as compacted because the wave of enerfy has either passed by there or the next wave has not reached that point yet. Im pretty sure im correct on this point.

Btw, sorry OP, not meaning to thread jack.

[///M5 2,833]

That explains some, but at the same time i still dont think it moves air, as in pushing the air, if it did, would it not create a vacuum? My understanding is that it vibrates the air, not necessarily move it.

If put a piece of tape on the end of a bound up slinky and then let it go does the tape move?

Can you move in a sine wave without any velocity?

Can you do a hair trick if the air isn't moving?

Does water move when you push your hand through it?

Do you need me to go on?

[ramteid 17]

That explains some, but at the same time i still dont think it moves air, as in pushing the air, if it did, would it not create a vacuum? My understanding is that it vibrates the air, not necessarily move it.

If put a piece of tape on the end of a bound up slinky and then let it go does the tape move?

Can you move in a sine wave without any velocity?

Can you do a hair trick if the air isn't moving?

Does water move when you push your hand through it?

Do you need me to go on?

The examples you have given arent that great. A better example would be putting a piece of tape on a part of a slinky and move one hand side to side. The energy transfers throug the slinky, making the slinky move to a certain extent, but once the energy dissipates the slinky will be in the same exact resting place as it was before the energy transfer, thus the tape would also be in the same place. Or, you could see it as a rope that is held on both ends, when someone moves one side up and down quickly you will see the rope form a wave of energy that is transfered from one end to the other, the rope itself will go back to the same resting place it was previously. That is how sound waves are transfered through mediums such as air.

[Impious 1,476]

Do you seal the seams of the enclosure ? Do you recommend people seal the seams of the enclosure ?

The porosity of the wood, and leaks at the seams of an enclosure ARE THE SAME THING. Using your logic, air leaks at the seams don't matter. Don't caulk, don't use wood glue. They don't matter. This is what you are suggesting. The ONLY difference is that seams that leak can cause rather large losses if severe enough whereas the porosity of the wood is rather low loss. But they are otherwise the same thing. So, stop sealing the seams of your enclosure.

The cone moves inward on the negative half of the wave. There is the same amount of air molecules in the enclosure, but less volume for that air to occupy. What is the air going to do ? During this compression phase, if there is somewhere for the air to escape it will try to escape. It doesn't matter if it's a poorly sealed seam or the wood itself.

[///M5 2,833]

That explains some, but at the same time i still dont think it moves air, as in pushing the air, if it did, would it not create a vacuum? My understanding is that it vibrates the air, not necessarily move it.

If put a piece of tape on the end of a bound up slinky and then let it go does the tape move?

Can you move in a sine wave without any velocity?

Can you do a hair trick if the air isn't moving?

Does water move when you push your hand through it?

Do you need me to go on?

The examples you have given arent that great. A better example would be putting a piece of tape on a part of a slinky and move one hand side to side. The energy transfers throug the slinky, making the slinky move to a certain extent, but once the energy dissipates the slinky will be in the same exact resting place as it was before the energy transfer, thus the tape would also be in the same place. Or, you could see it as a rope that is held on both ends, when someone moves one side up and down quickly you will see the rope form a wave of energy that is transfered from one end to the other, the rope itself will go back to the same resting place it was previously. That is how sound waves are transfered through mediums such as air.

Maybe you should stop trying to read what isn't there.

If you constrain the slinky in the stretch/compress direction it is akin to holding your speaker cone completely still.

Perhaps when you move your hand through the water in a lake/bathtub/pool the water doesn't move in your mind, but I bet it is moving.

And btw, sound is only transferred when it moves energy. Same with any wave. They are all kinetic.

Curious in your example, did your hand 'move' the slinky?

[ramteid 17]

That explains some, but at the same time i still dont think it moves air, as in pushing the air, if it did, would it not create a vacuum? My understanding is that it vibrates the air, not necessarily move it.

If put a piece of tape on the end of a bound up slinky and then let it go does the tape move?

Can you move in a sine wave without any velocity?

Can you do a hair trick if the air isn't moving?

Does water move when you push your hand through it?

Do you need me to go on?

The examples you have given arent that great. A better example would be putting a piece of tape on a part of a slinky and move one hand side to side. The energy transfers throug the slinky, making the slinky move to a certain extent, but once the energy dissipates the slinky will be in the same exact resting place as it was before the energy transfer, thus the tape would also be in the same place. Or, you could see it as a rope that is held on both ends, when someone moves one side up and down quickly you will see the rope form a wave of energy that is transfered from one end to the other, the rope itself will go back to the same resting place it was previously. That is how sound waves are transfered through mediums such as air.

Maybe you should stop trying to read what isn't there.

If you constrain the slinky in the stretch/compress direction it is akin to holding your speaker cone completely still.

Perhaps when you move your hand through the water in a lake/bathtub/pool the water doesn't move in your mind, but I bet it is moving.

And btw, sound is only transferred when it moves energy. Same with any wave. They are all kinetic.

Curious in your example, did your hand 'move' the slinky?

Han transfer energy to it, just as with the rope example. But if a sub moved air would it not create a vacuum? If so then how would the sound wave continue to travel past the vacuum? Apparently phsyics is completely incorrect about how sound travels.

[ramteid 17]

Do you seal the seams of the enclosure ? Do you recommend people seal the seams of the enclosure ?

The porosity of the wood, and leaks at the seams of an enclosure ARE THE SAME THING. Using your logic, air leaks at the seams don't matter. Don't caulk, don't use wood glue. They don't matter. This is what you are suggesting. The ONLY difference is that seams that leak can cause rather large losses if severe enough whereas the porosity of the wood is rather low loss. But they are otherwise the same thing. So, stop sealing the seams of your enclosure.

The cone moves inward on the negative half of the wave. There is the same amount of air molecules in the enclosure, but less volume for that air to occupy. What is the air going to do ? During this compression phase, if there is somewhere for the air to escape it will try to escape. It doesn't matter if it's a poorly sealed seam or the wood itself.

A loss of energy is a loss of energy. I would think there would be much less loss with a good seam compared to a terrible seam and more loss compared to the wave traveling through the tiny pores of the wood, which is why the gain of glassing the inside is minimal? Edited April 18, 2014 by ramteid

[lithium 358]

 

 

 

 

That explains some, but at the same time i still dont think it moves air, as in pushing the air, if it did, would it not create a vacuum? My understanding is that it vibrates the air, not necessarily move it.

If put a piece of tape on the end of a bound up slinky and then let it go does the tape move?

Can you move in a sine wave without any velocity?

Can you do a hair trick if the air isn't moving?

Does water move when you push your hand through it?

Do you need me to go on?

The examples you have given arent that great. A better example would be putting a piece of tape on a part of a slinky and move one hand side to side. The energy transfers throug the slinky, making the slinky move to a certain extent, but once the energy dissipates the slinky will be in the same exact resting place as it was before the energy transfer, thus the tape would also be in the same place. Or, you could see it as a rope that is held on both ends, when someone moves one side up and down quickly you will see the rope form a wave of energy that is transfered from one end to the other, the rope itself will go back to the same resting place it was previously. That is how sound waves are transfered through mediums such as air.

Maybe you should stop trying to read what isn't there.

If you constrain the slinky in the stretch/compress direction it is akin to holding your speaker cone completely still.

Perhaps when you move your hand through the water in a lake/bathtub/pool the water doesn't move in your mind, but I bet it is moving.

And btw, sound is only transferred when it moves energy. Same with any wave. They are all kinetic.

Curious in your example, did your hand 'move' the slinky?

Han transfer energy to it, just as with the rope example. But if a sub moved air would it not create a vacuum? If so then how would the sound wave continue to travel past the vacuum? Apparently phsyics is completely incorrect about how sound travels.

 

http://www.physicsclassroom.com/class/sound/u11l1c.cfm

[ramteid 17]

That explains some, but at the same time i still dont think it moves air, as in pushing the air, if it did, would it not create a vacuum? My understanding is that it vibrates the air, not necessarily move it.

If put a piece of tape on the end of a bound up slinky and then let it go does the tape move?

Can you move in a sine wave without any velocity?

Can you do a hair trick if the air isn't moving?

Does water move when you push your hand through it?

Do you need me to go on?

The examples you have given arent that great. A better example would be putting a piece of tape on a part of a slinky and move one hand side to side. The energy transfers throug the slinky, making the slinky move to a certain extent, but once the energy dissipates the slinky will be in the same exact resting place as it was before the energy transfer, thus the tape would also be in the same place. Or, you could see it as a rope that is held on both ends, when someone moves one side up and down quickly you will see the rope form a wave of energy that is transfered from one end to the other, the rope itself will go back to the same resting place it was previously. That is how sound waves are transfered through mediums such as air.

Maybe you should stop trying to read what isn't there.

If you constrain the slinky in the stretch/compress direction it is akin to holding your speaker cone completely still.

Perhaps when you move your hand through the water in a lake/bathtub/pool the water doesn't move in your mind, but I bet it is moving.

And btw, sound is only transferred when it moves energy. Same with any wave. They are all kinetic.

Curious in your example, did your hand 'move' the slinky?

Han transfer energy to it, just as with the rope example. But if a sub moved air would it not create a vacuum? If so then how would the sound wave continue to travel past the vacuum? Apparently phsyics is completely incorrect about how sound travels.

http://www.physicsclassroom.com/class/sound/u11l1c.cfm

I already know that. All im trying to say is that air is the medium with which the sound travels and basically, the medium does not move. All the medium does is transfer the energy.

[kirill007 52]

 

 

 

 

 

 

That explains some, but at the same time i still dont think it moves air, as in pushing the air, if it did, would it not create a vacuum? My understanding is that it vibrates the air, not necessarily move it.

If put a piece of tape on the end of a bound up slinky and then let it go does the tape move?

Can you move in a sine wave without any velocity?

Can you do a hair trick if the air isn't moving?

Does water move when you push your hand through it?

Do you need me to go on?

The examples you have given arent that great. A better example would be putting a piece of tape on a part of a slinky and move one hand side to side. The energy transfers throug the slinky, making the slinky move to a certain extent, but once the energy dissipates the slinky will be in the same exact resting place as it was before the energy transfer, thus the tape would also be in the same place. Or, you could see it as a rope that is held on both ends, when someone moves one side up and down quickly you will see the rope form a wave of energy that is transfered from one end to the other, the rope itself will go back to the same resting place it was previously. That is how sound waves are transfered through mediums such as air.

Maybe you should stop trying to read what isn't there.

If you constrain the slinky in the stretch/compress direction it is akin to holding your speaker cone completely still.

Perhaps when you move your hand through the water in a lake/bathtub/pool the water doesn't move in your mind, but I bet it is moving.

And btw, sound is only transferred when it moves energy. Same with any wave. They are all kinetic.

Curious in your example, did your hand 'move' the slinky?

Han transfer energy to it, just as with the rope example. But if a sub moved air would it not create a vacuum? If so then how would the sound wave continue to travel past the vacuum? Apparently phsyics is completely incorrect about how sound travels.

http://www.physicsclassroom.com/class/sound/u11l1c.cfm

I already know that. All im trying to say is that air is the medium with which the sound travels and basically, the medium does not move. All the medium does is transfer the energy.

 

Put a speaker in water and you'll see the water move.

The medium does move, every molecule moves "forward" and "backwards".

Don't you see in the animations that the air moves?

And there is no complete vacuum, as in no air at all. We can't create a complete vacuum, the speaker creates a positive and negative pressure.

[///M5 2,833]

That explains some, but at the same time i still dont think it moves air, as in pushing the air, if it did, would it not create a vacuum? My understanding is that it vibrates the air, not necessarily move it.

If put a piece of tape on the end of a bound up slinky and then let it go does the tape move?

Can you move in a sine wave without any velocity?

Can you do a hair trick if the air isn't moving?

Does water move when you push your hand through it?

Do you need me to go on?

The examples you have given arent that great. A better example would be putting a piece of tape on a part of a slinky and move one hand side to side. The energy transfers throug the slinky, making the slinky move to a certain extent, but once the energy dissipates the slinky will be in the same exact resting place as it was before the energy transfer, thus the tape would also be in the same place. Or, you could see it as a rope that is held on both ends, when someone moves one side up and down quickly you will see the rope form a wave of energy that is transfered from one end to the other, the rope itself will go back to the same resting place it was previously. That is how sound waves are transfered through mediums such as air.

Maybe you should stop trying to read what isn't there.

If you constrain the slinky in the stretch/compress direction it is akin to holding your speaker cone completely still.

Perhaps when you move your hand through the water in a lake/bathtub/pool the water doesn't move in your mind, but I bet it is moving.

And btw, sound is only transferred when it moves energy. Same with any wave. They are all kinetic.

Curious in your example, did your hand 'move' the slinky?

Han transfer energy to it, just as with the rope example. But if a sub moved air would it not create a vacuum? If so then how would the sound wave continue to travel past the vacuum? Apparently phsyics is completely incorrect about how sound travels.

http://www.physicsclassroom.com/class/sound/u11l1c.cfm

I already know that. All im trying to say is that air is the medium with which the sound travels and basically, the medium does not move. All the medium does is transfer the energy.

If you knew that you wouldn't have posted that speakers don't move air.

Do waves in the ocean not move water? If the waves move water how are they different than acoustic waves?

[ramteid 17]

That explains some, but at the same time i still dont think it moves air, as in pushing the air, if it did, would it not create a vacuum? My understanding is that it vibrates the air, not necessarily move it.

If put a piece of tape on the end of a bound up slinky and then let it go does the tape move?

Can you move in a sine wave without any velocity?

Can you do a hair trick if the air isn't moving?

Does water move when you push your hand through it?

Do you need me to go on?

The examples you have given arent that great. A better example would be putting a piece of tape on a part of a slinky and move one hand side to side. The energy transfers throug the slinky, making the slinky move to a certain extent, but once the energy dissipates the slinky will be in the same exact resting place as it was before the energy transfer, thus the tape would also be in the same place. Or, you could see it as a rope that is held on both ends, when someone moves one side up and down quickly you will see the rope form a wave of energy that is transfered from one end to the other, the rope itself will go back to the same resting place it was previously. That is how sound waves are transfered through mediums such as air.

Maybe you should stop trying to read what isn't there.

If you constrain the slinky in the stretch/compress direction it is akin to holding your speaker cone completely still.

Perhaps when you move your hand through the water in a lake/bathtub/pool the water doesn't move in your mind, but I bet it is moving.

And btw, sound is only transferred when it moves energy. Same with any wave. They are all kinetic.

Curious in your example, did your hand 'move' the slinky?

Han transfer energy to it, just as with the rope example. But if a sub moved air would it not create a vacuum? If so then how would the sound wave continue to travel past the vacuum? Apparently phsyics is completely incorrect about how sound travels.

http://www.physicsclassroom.com/class/sound/u11l1c.cfm

I already know that. All im trying to say is that air is the medium with which the sound travels and basically, the medium does not move. All the medium does is transfer the energy.

If you knew that you wouldn't have posted that speakers don't move air.

Do waves in the ocean not move water? If the waves move water how are they different than acoustic waves?

That is what i meant by they do not move air, they vibrate it. Moving air would be more like wind, vibrations are more back and forth movements. Maybe i should have tried to convey that in another manor.

[///M5 2,833]

That is what i meant by they do not move air, they vibrate it. Moving air would be more like wind, vibrations are more back and forth movements. Maybe i should have tried to convey that in another manor.

Move = move btw.

Motion = change of position of something with respect to time and a reference point

Speaker definitely moves air. As to what you are trying to convey I don't think anyone is following as it seems contrary to the above.

[Tirefryr 1,742]

I think what he trying to convey is they excite the air rather than move it from one place to another like a pump. The pump could/would create vacuum. It is still movement, I just think that's how he's envisioning it.