enclosure thickness

[ibanender 2]

You might as well just brace a single layer to get the box resonance out of the sub's passband.

Because then you deal with the complications of internal bracing? Yes, there are adverse affects. I NEVER use internal bracing.

Why?

I'm sure bracing in an acoustic suspension enclosure, a 4th order, or a 4th order bandpass wouldn't hurt.

Wherever there is air flow, it causes problems. Perfect example (and not the only case), in my S10 I did no internal bracing and made the box 5.25" thick except for the baffle which was 6" thick. If you put ANYTHING in that box, score dropped. I left a drill in the box once and lost over 1 dB. In other smaller box applications, I've heard turbulence from bracing as well. Depending how your brace is, I could see it causing a problem with phase or standing waves. The only bracing I'd deem usable is thick threaded rod.

Don't assume everyone is concerned about a "score". Acoustic reproduction might just hit the list as important...

While they may not be concerned with a specific number, if they want "loud", that's a "score". Loud is loud, whether it be an ear or a meter. The same way you make a daily system loud, you make it loud for a meter. Your acoustic reproduction won't be accurate if you have turbulence and audible noise from it. Standing waves will give dips or spikes in response, a direct relationship to accurate reproduction.

[ibanender 2]

It also depends on how your internal bracing is structured. Some may actually help with flow.

Care to explain? I can't think of any way a flow helping structure would act as a brace, and vice versa.

[irie kid 0]

3/4 in. fiberboard would do you good.

[///M5 2,833]

You might as well just brace a single layer to get the box resonance out of the sub's passband.

Because then you deal with the complications of internal bracing? Yes, there are adverse affects. I NEVER use internal bracing.

Why?

I'm sure bracing in an acoustic suspension enclosure, a 4th order, or a 4th order bandpass wouldn't hurt.

Wherever there is air flow, it causes problems. Perfect example (and not the only case), in my S10 I did no internal bracing and made the box 5.25" thick except for the baffle which was 6" thick. If you put ANYTHING in that box, score dropped. I left a drill in the box once and lost over 1 dB. In other smaller box applications, I've heard turbulence from bracing as well. Depending how your brace is, I could see it causing a problem with phase or standing waves. The only bracing I'd deem usable is thick threaded rod.

Don't assume everyone is concerned about a "score". Acoustic reproduction might just hit the list as important...

While they may not be concerned with a specific number, if they want "loud", that's a "score". Loud is loud, whether it be an ear or a meter. The same way you make a daily system loud, you make it loud for a meter. Your acoustic reproduction won't be accurate if you have turbulence and audible noise from it. Standing waves will give dips or spikes in response, a direct relationship to accurate reproduction.

The OP asked about good enclosures not loud ones. There are a ton of people that don't care about loud at all, reference levels perhaps, but loud has connotations that are all negative IMO. If you said linear, flat, capability to blend or something sure, but loud not so much.

As for your acoustic reproduction comments, true if you have audible noises it will take away from it but flexing panels will cause way worse distortion than any bracing techniques. Bracing will also help to stop standing waves and alter the inner shape of the box to a less symmetric rectangle which is also of benefit but of course we are discussing subs here which play sounds with LONG wavelengths.

[ibanender 2]

3/4 in. fiberboard would do you good.

All the 3/4 MDF I've seen lately is TERRIBLE. It's very soft, flexes very easily, and costs more than a high grade plywood. The 2 grades of MDF can be identified if it's light or dark. Dark MDF = bad.

[ibanender 2]

You might as well just brace a single layer to get the box resonance out of the sub's passband.

Because then you deal with the complications of internal bracing? Yes, there are adverse affects. I NEVER use internal bracing.

Why?

I'm sure bracing in an acoustic suspension enclosure, a 4th order, or a 4th order bandpass wouldn't hurt.

Wherever there is air flow, it causes problems. Perfect example (and not the only case), in my S10 I did no internal bracing and made the box 5.25" thick except for the baffle which was 6" thick. If you put ANYTHING in that box, score dropped. I left a drill in the box once and lost over 1 dB. In other smaller box applications, I've heard turbulence from bracing as well. Depending how your brace is, I could see it causing a problem with phase or standing waves. The only bracing I'd deem usable is thick threaded rod.

Don't assume everyone is concerned about a "score". Acoustic reproduction might just hit the list as important...

While they may not be concerned with a specific number, if they want "loud", that's a "score". Loud is loud, whether it be an ear or a meter. The same way you make a daily system loud, you make it loud for a meter. Your acoustic reproduction won't be accurate if you have turbulence and audible noise from it. Standing waves will give dips or spikes in response, a direct relationship to accurate reproduction.

The OP asked about good enclosures not loud ones. There are a ton of people that don't care about loud at all, reference levels perhaps, but loud has connotations that are all negative IMO. If you said linear, flat, capability to blend or something sure, but loud not so much.

As for your acoustic reproduction comments, true if you have audible noises it will take away from it but flexing panels will cause way worse distortion than any bracing techniques. Bracing will also help to stop standing waves and alter the inner shape of the box to a less symmetric rectangle which is also of benefit but of course we are discussing subs here which play sounds with LONG wavelengths.

A solid built enclosure IS a good one. "Loud" is what you make it. Why do SQ guys have 600 watt front stages, then don't go over 90 dB? "Overhead" isn't THAT much.

Having an extra thick box solves the flexing problem and won't induce any other noises. Will bracing help stopping standing waves? Sure, but so will changing the box shape. Don't make your box a cube, problem solved. There is such a thing called a "golden ratio", which should pretty well guarantee no standing waves. Besides, even if you had as standing wave of some variety, you're assuming response is linear in a lab or simulation. What about the vehicle's effect? You shouldn't have a problem with standing waves with long wavelengths anyway, unless your box is huge.

[Tirefryr 1,742]

Wait! No one here uses steel enclosures??? Why the F did I let that guy talk me into that $240 enclosure from steel that is on order???

Once you do a 100% steel box, you'll go back to wood. Having to tap holes and bolting in the sub is a PITA. Ask me how I know. Now if you're talking all steel except where the speaker mounts, I can show you an Explorer done that way. It's 1/2" steel.

Drilling and tapping steel is quite easy. I don't see the issue here. As for bolting drivers in, doesn't everyone? Threaded inserts have been available for ever.

[Tirefryr 1,742]

MDF grades are distinguished by the lines on the board, not the color.

And how does air "flow" through an enclosure? It is excited, it does not flow.

[Julian 641]

All tread is best for bracing IMO.. Bracing raises scores. No doubt.

[ibanender 2]

MDF grades are distinguished by the lines on the board, not the color.

And how does air "flow" through an enclosure? It is excited, it does not flow.

I guarantee, if it's the dark MDF, it shares the same lines. You may not have a bundle available to see the markings, or know what the markings mean, so going by color has proven accurate.

The port is excited, the box has flow. Throw some packing peanuts in there and you'll see what I'm talking about. Or better yet, stick something in the box anywhere near the port and see/hear what happens.

All tread is best for bracing IMO.. Bracing raises scores. No doubt.

Rigid raises scores, not necessarily bracing.

[Tirefryr 1,742]

ALL the air is excited. There is NO flow, it is not a pump. If there were flow, it would have an intake and exhaust.

As for the MDF colors, I know what you are talking about, but they are the same grade. I had this conversation twice with two different supplies for work. The color variation comes from the different wood species and binding agent mixtures.

[Julian 641]

RIGIDITY comes from bracing! Without having to have the box 2-3x the thickness!

The definition of rigid is Stiff, rather than flexible; Fixed, rather than moving; Rigorous and unbending.

[ssh 924]

No your wrong! Mud slinging yay

[///M5 2,833]

A solid built enclosure IS a good one. "Loud" is what you make it. Why do SQ guys have 600 watt front stages, then don't go over 90 dB? "Overhead" isn't THAT much.

Who said anything about 90dB? Why don't you understand that midbass is the challenge and adding sub bass is ultra easy in comparison.

Having an extra thick box solves the flexing problem and won't induce any other noises.

No it doesn't. Again you have to address not only the frequency but the damping as well. Adding thickness surely has benefit as you note I even recommended it earlier, but it isn't the end all solution. Sort of like using damper as a blocker.

Will bracing help stopping standing waves? Sure, but so will changing the box shape. Don't make your box a cube, problem solved. There is such a thing called a "golden ratio", which should pretty well guarantee no standing waves. Besides, even if you had as standing wave of some variety, you're assuming response is linear in a lab or simulation. What about the vehicle's effect? You shouldn't have a problem with standing waves with long wavelengths anyway, unless your box is huge.

The golden ratio doesn't guarantee squat and is another rule of thumb that is generically not so useful. You also have to do a lot more than not make your box a cube. Symmetry is your enemy. The vehicles "effect" is independent of the box. The only thing you aren't confused by in this post is the long wavelength comment, but inconveniently for you that counteracts your whole accurate reproduction post from before.

Standing waves will give dips or spikes in response, a direct relationship to accurate reproduction.

[///M5 2,833]

Why do SQ guys have 600 watt front stages, then don't go over 90 dB? "Overhead" isn't THAT much.

Better question for you. Why do some people have ONE box that does something and without thinking about the math or reasons then apply all the things they did in that box to every other situation?

[Sencheezy 689]

ibanender, your not gonna win this one

[Julian 641]

[ibanender 2]

ALL the air is excited. There is NO flow, it is not a pump. If there were flow, it would have an intake and exhaust.

As for the MDF colors, I know what you are talking about, but they are the same grade. I had this conversation twice with two different supplies for work. The color variation comes from the different wood species and binding agent mixtures.

Yes, all air is excited, and there is flow. Air moves, it is exchanged. Do you think pole vents and basket vents are there because air is stagnant? No, it gets moved around, that's what cools a voice coil. Even outside of the sub itself, it's not circulating the same dead air. If air moves, there is flow. It can change directions in a short area, but that's still flow. Get inside ANY seriously loud SPL vehicle, look at the box, and tell me there's no flow. We go to great extremes to make sure things are very smooth and gradual.

To me, that says different wood species are harder or softer, which coincides with my findings.

RIGIDITY comes from bracing! Without having to have the box 2-3x the thickness!

The definition of rigid is Stiff, rather than flexible; Fixed, rather than moving; Rigorous and unbending.

While your definition is accurate, there are side effects to bracing. What happens when you stiffen a bridge by putting a brace across the lanes a foot off the pavement?

A solid built enclosure IS a good one. "Loud" is what you make it. Why do SQ guys have 600 watt front stages, then don't go over 90 dB? "Overhead" isn't THAT much.

Who said anything about 90dB? Why don't you understand that midbass is the challenge and adding sub bass is ultra easy in comparison.

Having an extra thick box solves the flexing problem and won't induce any other noises.

No it doesn't. Again you have to address not only the frequency but the damping as well. Adding thickness surely has benefit as you note I even recommended it earlier, but it isn't the end all solution. Sort of like using damper as a blocker.

Will bracing help stopping standing waves? Sure, but so will changing the box shape. Don't make your box a cube, problem solved. There is such a thing called a "golden ratio", which should pretty well guarantee no standing waves. Besides, even if you had as standing wave of some variety, you're assuming response is linear in a lab or simulation. What about the vehicle's effect? You shouldn't have a problem with standing waves with long wavelengths anyway, unless your box is huge.

The golden ratio doesn't guarantee squat and is another rule of thumb that is generically not so useful. You also have to do a lot more than not make your box a cube. Symmetry is your enemy. The vehicles "effect" is independent of the box. The only thing you aren't confused by in this post is the long wavelength comment, but inconveniently for you that counteracts your whole accurate reproduction post from before.

Standing waves will give dips or spikes in response, a direct relationship to accurate reproduction.

Why do SQ guys have 600 watt front stages, then don't go over 90 dB? "Overhead" isn't THAT much.

Better question for you. Why do some people have ONE box that does something and without thinking about the math or reasons then apply all the things they did in that box to every other situation?

SQ people get judged at 90 dB, and often listen at that level too. Midbass is easy if you know how to install, or don't have limitations like stock speaker location only.

I guess you're talk about dampening factors on amps now too right? Are you suggesting having a rock solid box isn't acoustically good? I'm not confused by anything. Scientifically speaking, the golden ratio has the least possibility of creating a standing wave, on axial, tangential, or oblique modes. Even if you were concerned about a standing wave at say, 35 hz, the wavelength is 32 ft. You'd have to be SEVERAL octaves below that before you hit the standing wave in any box that would fit in a car, so the effects would be minimal. Yes, vehicle reaction does change things as we both agree, so why are you so concerned about having this magically perfect box when the vehicle will change that anyway?

And lastly for your condescending remark, those are the people that copy others designs and listen to the first person that will spit information at them. After building 250+ boxes, I can honestly say I know why boxes do what they do most of the time. There are some cases that are freaks of nature and that's when I set out to figure out why. I'm working on that right now actually, and my next test box will likely confirm my findings. It's the anti-music box and you'd hate to apply it to a daily application, but knowing the how and why is what drives improvement.

ibanender, your not gonna win this one

"Winning" on a forum isn't even a real thing. Everybody wins in their own eyes and you can't tell anybody they're wrong if they don't want to learn or assume they know everything. I know what I've done, I know what works and what doesn't, and you can build what you wanna build (what do I care, not my car), but at the end of the day I have something to show from my experience.

[///M5 2,833]

ALL the air is excited. There is NO flow, it is not a pump. If there were flow, it would have an intake and exhaust.

As for the MDF colors, I know what you are talking about, but they are the same grade. I had this conversation twice with two different supplies for work. The color variation comes from the different wood species and binding agent mixtures.

Yes, all air is excited, and there is flow. Air moves, it is exchanged. Do you think pole vents and basket vents are there because air is stagnant? No, it gets moved around, that's what cools a voice coil. Even outside of the sub itself, it's not circulating the same dead air. If air moves, there is flow. It can change directions in a short area, but that's still flow. Get inside ANY seriously loud SPL vehicle, look at the box, and tell me there's no flow. We go to great extremes to make sure things are very smooth and gradual.

Flow has direction. Which direction is this flow? Movement does not equal flow. Does the speaker cone flow?

As for the great extremes you allude to, that is not for flow but to reduce laminar resistance.

 

RIGIDITY comes from bracing! Without having to have the box 2-3x the thickness!

The definition of rigid is Stiff, rather than flexible; Fixed, rather than moving; Rigorous and unbending.

While your definition is accurate, there are side effects to bracing. What happens when you stiffen a bridge by putting a brace across the lanes a foot off the pavement?

Then you would be an idiot of an engineer. The Tacoma Narrows bridge was sufficiently stiff, but had the wrong resonance and not critical enough damping at resonance. It failed miserably.

Why do SQ guys have 600 watt front stages, then don't go over 90 dB? "Overhead" isn't THAT much.

Better question for you. Why do some people have ONE box that does something and without thinking about the math or reasons then apply all the things they did in that box to every other situation?

SQ people get judged at 90 dB, and often listen at that level too.

I guess you're talk about dampening factors on amps now too right?

Just like there are more people who want an SPL setup than compete the same holds true for SQ. To me it is all about the music.

Are you suggesting having a rock solid box isn't acoustically good? I'm not confused by anything. Scientifically speaking, the golden ratio has the least possibility of creating a standing wave, on axial, tangential, or oblique modes.

Look up Modal Analysis and damping. This discussion is about resonances, not amplifiers.

Yes, vehicle reaction does change things as we both agree, so why are you so concerned about having this magically perfect box when the vehicle will change that anyway?

I wasn’t suggesting a rock solid box wasn’t good, but that your idea of an ideal box isn’t rock solid. Bracing is an integral part of designing a good enclosure. The golden ratio is far from golden and again another rule of thumb that gives people the wrong information. Sure if you are limited to an empty box with no bracing and it has to have 90 corners it is better than a square, but it is FAR from ideal.

This discussion wasn’t about the vehicle, but about correct box building techniques. Either way though since the environment is jacked the question then becomes do you want to start with a box with a crappy response and try to fix it in a crappy environment or do you want to start with the most ideal box for the installation and then try to fix the crap the environment creates? Real simple if you ask me, I’ll take the least amount of electronic compensation as possible.

[Duran 387]

Reducing laminar resistance...

[///M5 2,833]

Reducing laminar resistance...

Your right, I probably should have just stated surface resistance to the moving air but in this case it is exactly one of the confusing things to Ibanender so I did that on purpose. Just because you are dealing with the requirements to reduce resistance for laminar flow does not describe flow in itself. The point in excessive treatment is just that, to reduce resistance.

[ibanender 2]

Flow has direction. Which direction is this flow? Movement does not equal flow. Does the speaker cone flow?

Yes, flow has direction, and if it moves in 1 direction, then quickly changes direction, that's still flow. Flow is not uni-directional, but can only be in 1 direction at a time. Let's say for instance I put something in my port, and I played it for 2 seconds, according to you, whatever I put in my port would be in the same position I placed it, yes? If it's agitated it should be equal movement according to what you're saying.

As for the great extremes you allude to, that is not for flow but to reduce laminar resistance.

Then you would be an idiot of an engineer. The Tacoma Narrows bridge was sufficiently stiff, but had the wrong resonance and not critical enough damping at resonance. It failed miserably.

laminar flow

 

–noun Hydraulics, Mechanics .

the flow of a viscous fluid in which particles of the fluid move in parallel layers, each of which has a constant velocity but is in motion relative to its neighboring layers.

So now SPL boxes are liquid cooled? Smoothing it makes it louder because of liquids in the box? So you're a bridge engineer now? Yes there was a resonance problem, maybe they should have added more bracing... I bet if they had thicker material, the resonance would have been lower and wind wouldn't have matched that.

Look up Modal Analysis and damping. This discussion is about resonances, not amplifiers.

My comments had nothing to do with amplifiers, which would be apparent if you know what axial, tangential, and oblique modes are.

I wasn’t suggesting a rock solid box wasn’t good, but that your idea of an ideal box isn’t rock solid. Bracing is an integral part of designing a good enclosure. The golden ratio is far from golden and again another rule of thumb that gives people the wrong information. Sure if you are limited to an empty box with no bracing and it has to have 90 corners it is better than a square, but it is FAR from ideal.

This discussion wasn’t about the vehicle, but about correct box building techniques. Either way though since the environment is jacked the question then becomes do you want to start with a box with a crappy response and try to fix it in a crappy environment or do you want to start with the most ideal box for the installation and then try to fix the crap the environment creates? Real simple if you ask me, I’ll take the least amount of electronic compensation as possible.

Who's to say you're gonna have crappy response from the enclosure period? You're making the assumption if you don't make the most epic box ever, it won't sound good. What if you have a 50 hz dip, but your vehicle has a 50 hz peak, now all the sudden it's perfect! Bottom line, your quest for perfection is stupid because no matter how much you try to get it perfect, something will screw with it, or it will be so minute it will be inaudible.

[ibanender 2]

Reducing laminar resistance...

Your right, I probably should have just stated surface resistance to the moving air but in this case it is exactly one of the confusing things to Ibanender so I did that on purpose. Just because you are dealing with the requirements to reduce resistance for laminar flow does not describe flow in itself. The point in excessive treatment is just that, to reduce resistance.

Why does reducing resistance matter if there isn't flow?

[///M5 2,833]

Flow has direction. Which direction is this flow? Movement does not equal flow. Does the speaker cone flow?

Yes, flow has direction, and if it moves in 1 direction, then quickly changes direction, that's still flow. Flow is not uni-directional, but can only be in 1 direction at a time. Let's say for instance I put something in my port, and I played it for 2 seconds, according to you, whatever I put in my port would be in the same position I placed it, yes? If it's agitated it should be equal movement according to what you're saying.

You can't make up definitions.

http://dictionary.reference.com/browse/flow

What you are trying to coin would be instantaneous flow which is also only a term ever used when you add rate to the end of it describing flow. It is directional and has a source. What happens in a box is not flow.

As for the great extremes you allude to, that is not for flow but to reduce laminar resistance.

Then you would be an idiot of an engineer. The Tacoma Narrows bridge was sufficiently stiff, but had the wrong resonance and not critical enough damping at resonance. It failed miserably.

laminar flow

 

–noun Hydraulics, Mechanics .

the flow of a viscous fluid in which particles of the fluid move in parallel layers, each of which has a constant velocity but is in motion relative to its neighboring layers.

So now SPL boxes are liquid cooled? Smoothing it makes it louder because of liquids in the box? So you're a bridge engineer now? Yes there was a resonance problem, maybe they should have added more bracing... I bet if they had thicker material, the resonance would have been lower and wind wouldn't have matched that.

Viscous fluids are regularly gases, not restricted to but usually.

My comments had nothing to do with amplifiers, which would be apparent if you know what axial, tangential, and oblique modes are.

You specifically brought up amplifiers not me and unrelated to the modal comments.

I guess you're talk about dampening factors on amps now too right?

I wasn’t suggesting a rock solid box wasn’t good, but that your idea of an ideal box isn’t rock solid. Bracing is an integral part of designing a good enclosure. The golden ratio is far from golden and again another rule of thumb that gives people the wrong information. Sure if you are limited to an empty box with no bracing and it has to have 90 corners it is better than a square, but it is FAR from ideal.

This discussion wasn’t about the vehicle, but about correct box building techniques. Either way though since the environment is jacked the question then becomes do you want to start with a box with a crappy response and try to fix it in a crappy environment or do you want to start with the most ideal box for the installation and then try to fix the crap the environment creates? Real simple if you ask me, I’ll take the least amount of electronic compensation as possible.

Who's to say you're gonna have crappy response from the enclosure period? You're making the assumption if you don't make the most epic box ever, it won't sound good. What if you have a 50 hz dip, but your vehicle has a 50 hz peak, now all the sudden it's perfect! Bottom line, your quest for perfection is stupid because no matter how much you try to get it perfect, something will screw with it, or it will be so minute it will be inaudible.

I've never stated if you don't make the most epic box ever it won't sound good. Just applying simple science to maximize the goal at hand. "What ifs" are only valuable if you know about them and plan ahead of time. Dumb luck is not science and in answer to the OP's question makes no sense.

[///M5 2,833]

Reducing laminar resistance...

Your right, I probably should have just stated surface resistance to the moving air but in this case it is exactly one of the confusing things to Ibanender so I did that on purpose. Just because you are dealing with the requirements to reduce resistance for laminar flow does not describe flow in itself. The point in excessive treatment is just that, to reduce resistance.

Why does reducing resistance matter if there isn't flow?

Seriously you don't get it? I never said there wasn't air moving, just no flow.