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Just out curiousity.. Why would you suggest he uses one as a PR to begin with?

My first question was about isobaric.
Maybe we talk about that before a PR?
 
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But typically wouldn't you want the PR sharing the same box space? I've never used a PR before so that is a sincere question..
They work by using the "air spring" the active woofer creates so they are useless in their own air space.
 

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But typically wouldn't you want the PR sharing the same box space?
That would be correct, and I read Holmz post the same way you did ...
Or one ends u with a PR, which is where they should have started anyhow.:cool:
Sounds like he suggested that a single sub with a PR is what should be done /shrug

For what it's worth, I don't think it is necessary to worry about and plan around blowing up your gear ... unless you are that person that is constantly blowing up their gear.
 

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They work by using the "air spring" the active woofer creates so they are useless in their own air space.
That's I was I thinking. I know PR are popular in home audio towers that may have 4 x 6" cones with 2 of the 4 acting as PRs in addition to the mids, tweets, etc.. but at what point is it better to use a PR in a car audio application?

Again.. I'm just trying to learn a little more about PRs in general.
 

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Did not @Holmz suggest that if one ends up toast, he would end up with a PR which is where he should've started?

Or maybe I just misunderstood his post.

But typically wouldn't you want the PR sharing the same box space? I've never used a PR before so that is a sincere question..
Sorry, my bad. I have Holmz blocked so i don't see his responses. I saw this one from SLOVIC that i thought you were referring too.

If one woofer blows or has a loose connection it will act as a passive radiator and possibly damage the other. That's about it as far as I know.


Also, Holmes has a thing about PR's and thinks everyone should be using them. Problem is they just are not that practical in cars.
 

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That would be correct, and I read Holmz post the same way you did ...

Sounds like he suggested that a single sub with a PR is what should be done /shrug

For what it's worth, I don't think it is necessary to worry about and plan around blowing up your gear ... unless you are that person that is constantly blowing up their gear.
Usually we throw out ideas.
The shared space allows to have twin sealed, or a single PR. So it gives options.
And isobaric may also minimise spatial volume.

A port or slot locks one in, and uses more volume... And the OP was volume limited.


Sorry, my bad. I have Holmz blocked so i don't see his responses.
...
Wow, i am popular
 

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Also, Holmes has a thing about PR's and thinks everyone should be using them. Problem is they just are not that practical in cars.

That's exactly what I was thinking.. but like I said, I never used them just because it seems like a waste of woofer.. and if moving air is the goal you'd think you'd wanted that 2nd woofer powered instead of just re-flexing off the other.
 

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...
Also, Holmes has a thing about PR's and thinks everyone should be using them. Problem is they just are not that practical in cars.
That is not exactly accurate.
I think that they should be considered... not automaticlly be used.
You're possibly reading more into it, than what was intended.

Most cars are spatial volume limited... a PR solves some of that.
And many people are unsure about port tuning with cabin gain... a PR solves that.

But they also cost money.
 

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That's exactly what I was thinking.. but like I said, I never used them just because it seems like a waste of woofer.. and if moving air is the goal you'd think you'd wanted that 2nd woofer powered instead of just re-flexing off the other.
Its always been a way of being able to get the desired response of a ported box without having to have the internal volume. But the problem with that is not you can have ported boxes with much less airspace than in the past. So when dealing with say 1.5 cuft, its hard to fit a woofer, and the required 2 passive radiators in a way that makes sense with the existing baffle space. I figure in another 10 years the desired subwoofer configuration will be servo driven subs. :)
 

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That's exactly what I was thinking.. but like I said, I never used them just because it seems like a waste of woofer.. and if moving air is the goal you'd think you'd wanted that 2nd woofer powered instead of just re-flexing off the other.
That second sub would be lighter, and cause the it to unload be tuned higher.

So one either needs a PR in the hole there, or a plug and us an aero port.
or another powered woofer in the hole.

It would sound snappy for a while and the remaining subs suspension would fail.
 

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Its always been a way of being able to get the desired response of a ported box without having to have the internal volume. But the problem with that is not you can have ported boxes with much less airspace than in the past. So when dealing with say 1.5 cuft, its hard to fit a woofer, and the required 2 passive radiators in a way that makes sense with the existing baffle space. I figure in another 10 years the desired subwoofer configuration will be servo driven subs. :)

Well stated, and very helpful.. Thank you!
 

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That second sub would be lighter, and cause the it to unload be tuned higher.

So one either needs a PR in the hole there, or a plug and us an aero port.
or another powered woofer in the hole.

It would sound snappy for a while and the remaining subs suspension would fail.
Assume one of the woofers does in deed die. Unhook it from the amp of course but leave it in the box.. and so long as the coil is not just seized to death it becomes a PR. Is this correct? And if so, how does the sub that is still alive die? I've never heard of woofers straight up dying because they were in a box is 2x MFGR Recommendation. And were not talking refoaming or something, we are talking coil/motor failure due to being an too big of a box?

Or am I simply misreading/misunderstanding your reply?
 

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Assume one of the woofers does in deed die. Unhook it from the amp of course but leave it in the box.. and so long as the coil is not just seized to death it becomes a PR. Is this correct?
...
If one sub failed then that would act as a PR, but we tuned very high and be a vented box that is 2x larger than a sealed box...
So yeah...
But it would be tuned all wrong.


... And if so, how does the sub that is still alive die? I've never heard of woofers straight up dying because they were in a box is 2x MFGR Recommendation. And were not talking refoaming or something, we are talking coil/motor failure due to being an too big of a box?

Or am I simply misreading/misunderstanding your reply?
That "2 sealed in a box" is probably in the ball park of being the right volume for a single ported box(?), however the light sub would be too light for a low tuned PR, and the good sub would fail from a suspension failure or ripped up cone, or some bottoming out failure.

The main point was that a "shared volume dual sealed' allows for a dual sealed, and maybe a PR? or even a plug and a port in the second hole.
 

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If one sub failed then that would act as a PR, but we tuned very high and be a vented box that is 2x larger than a sealed box...
So yeah...
But it would be tuned all wrong.




That "2 sealed in a box" is probably in the ball park of being the right volume for a single ported box(?), however the light sub would be too light for a low tuned PR, and the good sub would fail from a suspension failure or ripped up cone, or some bottoming out failure.

The main point was that a "shared volume dual sealed' allows for a dual sealed, and maybe a PR? or even a plug and a port in the second hole.
I got you man.. Now I understand
 

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I got you man.. Now I understand
Really mniSQ generally knows this sub stuff.
(so ignore my ravings.)
 

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Any reason why those particular subs when constrained to .6 airspace? Surely there's other DVC subs that would be optimized in .6 sealed.

Sent from my SM-G986U using Tapatalk
 

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Given the option of a single 10" D4 or a pair of 8" D2 subs with the same 300W mono either way, why would you go one way or the other? The pair of 8s has about 30% more cone area and 2mm less Xmax but 4 coils running off that 300W. Image Dynamics ID are the specific subs in question. Would your answer change if we were talking about Alpine Type R?

EDIT - only considering sealed enclosure due to space.
Personally, I would go with the single 10. Reasons being that it can hit a little lower then the 8s a d given you'r amount of power, twin 8s might be a little underpowered with 300 watts. I would think the single 10 would operate better with that amount of air space then the twin 8s.
 
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