I put a subwoofer in a lawn tire and it fit

[MankDeems]

I believe this is b sort of ported. I think the hole on the bottom of the sub let's the sub breathe.

That is a vent for the coil specifically if I understand has no bearing on the airspace inside the "box"

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[mamboman777]

That is a vent for the coil specifically if I understand has no bearing on the airspace inside the "box"

That's true, but the coil is not sealed from the cone. In most subs, the back of the sub is in the same enclosure as the sides of the sub.

 

[Chrisicus]

It sounds okay

I don't believe you.

 

[Lane]

That's true, but the coil is not sealed from the cone.

I've done an 'autopsy' (heh) on dozens of dead woofers. For those that had a vented back piece, the other end was effectively sealed, or more specifically, you couldn't pass air through it to the interior of the box or to the front/cone side of the woofer. The voicecoil is on the other end of that vent which is attached to the spider.

Since that Dual woofer has a vent in the back, imagine the pole piece in the diagram wasn't there. There is a tiny tiny gap between the voicecoil and magnet since the voicecoil has to move back and forth within that space, but any air that could sneak between those which could get through the very fine wire mesh of the spider that would be enough to affect the performance of the woofer would be negligible.

In other words, you probably can't get to the air inside the tire through the vent in the back of the woofer magnet. So that magnet vent being open to the outside world probably doesn't hurt the performance of the woofer. I'd be more concerned with the air seal on the places where the woofer contacts the tire.

When a woofer with a vent in its magnet is playing and really working hard, I have felt airflow coming from the vent in the back of the magnet. But I'm pretty sure it's the compression of the air volume that is sitting in that small sealed area inside the voicecoil up to the backside of the cone itself.

 

[mav_kev]

Not a financial advisor, but don't spend any more money on this project. Not even a nickel.

 

[billbillw]

Something tells me the OP has never heard of Thiel Small parameters. This is wrong on so many levels.

 

[MankDeems]

@mamboman777 I'm still thinking about this stupid thing as a fiberglass box is a fiberglass box

what if it was an entirely sealed enclosure with a passive radiator on the bottom?...

imagine stands on the bottom to create a 1" air gap. This 8" kicker reflex PR is designed for .4cuft enclosures my Volume=πx5.5²x6=.35cu FT, with a Shallow 10" (I understand the sub occupies the inner volume) It wouldn't be optimal but I'd still be under the price of a single "custom" box with the woofer, Passive rad, fiberglass and tire

 

[Lane]

Questions this brings up:

* Ideally, you should determine the specific model of your woofer and look up the Thiele/Small parameters for it. With those, you can use any of the online enclosure calculators to compare how different enclosure sizes/designs perform with your woofer in them.
* Are there online calculators that will allow you to model this enclosure with a passive radiator and without? If not, you're just guessing on whether it will provide any benefit.
* How far away from an adjacent surface does a passive radiator need to be? One inch may be too close for it to work as designed.
* When you calculate total enclosure volume of the tire, are you subtracting the volume that the speaker's structure occupies? With a small box it matters more and you really should do that before using any of the online calculators. The volume of a speaker itself is often provided by the manufacturer in addition to the T/S parameters.

You'll likely want to research this stuff. I've probably built two dozen enclosures over 35 years and more than a few were constrained by volume and budget like yours. Personally, I wouldn't go with the passive radiator as I don't think it would provide enough of a difference to justify the cost/effort. But using one of those online calculators should tell you for sure.

 

[rallyshark]

Generally, you need a passive radiator to be double the cone area of the actual driver(I'm skipping a lot of details). In other words, you'd need two 10" passive radiators. Alternately, you could use a single 12-15" passive. The single 8" passive would blow itself apart with that 10" driver you have. All of that aside, you don't have the space for it without modifications to the under seat area.

Let me save you a lot of wasted time and effort here... You don't have enough air space, no matter what kind of enclosure you try and turn your tire into. A sub enclosure needs to be rigid(opposite of the tire). There is no way what you have is going to sound good, no matter what you do to it. You can either build an enclosure to get more air space, or buy one. Buy once, cry once. I completely get wanting to try stuff and experiment to see what the different results are, but it's an exercise in futility here. Trying to make something work with that tire is so far from the actual needs of a functional subwoofer, that there simply is no combination that will be realistically good.

Keep going if ya want, but you could have just spent a little more money and been done with a good enclosure and much better sound. Not to mention, it will look better than a lawn mower tire under your seat

 

[billbillw]

A passive radiator has to be in a sealed/non leaky box.. It is an alternative to a port. Both a port or a passive radiator are specifically designed to resonate at a frequency that is complementary to the T/S parameters of the woofer and the box design.

Your vented pole sub in a tire is just a leaky, and poorly designed sealed box. The vented pole does not hold pressure from the other side of the voice coil/spyder. Just because it makes noise, doesn't mean its good.

 

[MankDeems]

Generally, you need a passive radiator to be double the cone area of the actual driver(I'm skipping a lot of details).

Let me save you a lot of wasted time and effort here...

no matter what kind of enclosure you try and turn your tire into. A sub enclosure needs to be rigid(opposite of the tire).

Keep going if ya want, but you could have just spent a little more money

Not to mention, it will look better than a lawn mower tire under your seat

You wasted a lot of time writing that book, you clearly missed the part where I said

"I'm still thinking about this stupid thing as a fiberglass box is a fiberglass box"

It wouldn't be optimal but I'd still be under the price of a single "custom" box for the woofer, Passive rad, *fiberglass* and tire

Thanks, I see now 2x my rad size vs driver size is the rule of thumb but every single prebuilt woofer I've seen has matching driver and rad size so whilst I may not want to go down I might just match it and add/remove weight

A passive radiator has to be in a sealed/non leaky box.. It is an alternative to a port. Both a port or a passive radiator are specifically designed to resonate at a frequency that is complementary to the T/S parameters of the woofer and the box design.

Your vented pole sub in a tire is just a leaky, and poorly designed sealed box. The vented pole does not hold pressure from the other side of the voice coil/spyder. Just because it makes noise, doesn't mean its good.

Yeah yeah yeah no noise is better than poppy rattles I get it, what you missed is The passive rad and upgraded shallow sub would be in an entirely sealed fiberglass "box" meaning the pole vent is irrelevant to the passive rad question

so while you're correct my current setup isn't incredibly functional, god forbid I try to make a solution (like there aren't ultra thin all in ones that are plug and play for $300)

any hardware I buy in the future easily could end up in a different enclosure. all the "this is a lost cause, waste of money, stop" posts aren't helping because a tire and fiberglass Is less than $40

Questions this brings up:

* Ideally, you should determine the specific model of your woofer and look up the Thiele/Small parameters for it. With those, you can use any of the online enclosure calculators to compare how different enclosure sizes/designs perform with your woofer in them.
* Are there online calculators that will allow you to model this enclosure with a passive radiator and without? If not, you're just guessing on whether it will provide any benefit.
* How far away from an adjacent surface does a passive radiator need to be? One inch may be too close for it to work as designed.
* When you calculate total enclosure volume of the tire, are you subtracting the volume that the speaker's structure occupies?

You'll likely want to research this stuff. I've probably built two dozen enclosures over 35 years and more than a few were constrained by volume and budget like yours. Personally, I wouldn't go with the passive radiator as I don't think it would provide enough of a difference to justify the cost/effort. But using one of those online calculators should tell you for sure.

Unfortunately I can't find a passive rad calculator. all I want is a bass drum I can remove in seconds and retain some of my under seat storage. I might just say fuck it and go for it, if I don't like it I'll put it in a different box

 

[rallyshark]

Oh I read everything you wrote, but I was just trying to help ya man. We all are. I shall not waste anymore "books" explaining what you don't know. Carry on pissing in the wind my friend

 

[TedTX]

Wow two years in college wasted on a electronics degree learned more about sound systems here.

 

[MankDeems]

Wow two years in college wasted on a electronics degree learned more about sound systems here.

Oh I read everything you wrote, but I was just trying to help ya man. We all are. I shall not waste anymore "books" explaining what you don't know. Carry on pissing in the wind my friend

I appreciate you guys trying to save me from disappointment but I just don't understand why we'd throw this idea to the wind if there are 10" subwoofers in even smaller enclosures with amps built in

KICKER 46HS10 Compact Powered 10-inch Subwoofer, https://a.co/d/cqxIUVR seeing something like this makes me think it's not a mathematic impossibility guess I'm just frustrated because it seems attainable and rocket surgeons are telling me nah impossible

How does a woofer like this overcome being in such a small enclosure in a retail item but it's a mathematic impossibility for something with an even larger volume?

 

[Silver23]

You just need a MUCH bigger and stiff tire! ahaha

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