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Discussion Starter #1
Hi there. Been around a bit, but have never done an Infinite Baffle setup.

I have two 12" Alpine Type X's (1000/3000) with a Q value of 0.64 and a F value of 29 HRZ.

My manual/spec sheet doesn't have an IB setup as the "recommended styles" for an enclosure, but after doing research, the Q and F values are all that's really important. (Correct?)

This set up will be going into a 96 Honda Accord. I understand the front wave and rear wave must be completely separated. I know a downside is loss of SPL, but at 1000 watts per, I can give away some power... and after that... I'm clueless.

Any tips or ideas? Does this sound like a crazy or stupid project?

Any input would be great, thanks!
 

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my experience with ib in car is that the rear deck will need some deadening and reinforcement. make sure your baffle is quite thick, mine is 1.5" (.75 mdf x2).

as far as Q and fs values (although the values you listed look decent), i didnt get into that too much for my install because i used a sub that is typically used IB (mach 5 mj18). what you can do is just graph the type X's in a huge sealed box in winisd. that will give you an approximate idea of what to expect.

im sure there might be some other things.. either way, have fun with it!
 

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They should work fairly good, sure just model them in the volume of your trunk plus a little since trunks are not tight like a box. Expect them to roll off at/under Fs, expect them to roll off more with a lower qts and not much with a high qts of ~.7, so those should be ok. I try to run double the sub for IB as I would a box. If you take the RMS rating of your subs and half that, you should only need about that to hit xmax, more power than that will just beat the subs and not gain you much output. You need to visually look at the subs in action to determine this.

You can push more power to them if you run a subsonic filter but as you raise it for more power handling you will lose bottom end, depends on what you want I primarily like IB because I can get lots of bottom (<35Hz) if I go large enough. I would tell you to put 15s in if you want more lows. I've run IB for a long time when I could. Check my build thread on the pyle 15s I have now and the infinity quad 12s I had before that, just search pyle they will come up as nobody uses pyle on here lol.

I primarily use 3/4 ply for my IB setups but I've never run over 500rms to them I have now, and doubt I am using it anyway. I reinforce any span over a few inches and tend to fill the baffle with sub. But the wood is great at dampening and strengthening panels, so do try to make it large as you can. With my current 15s the opening for the seats is quite strong so the baffle is mounted to that and I covered the rear deck to seal the holes and stiffen it. The whole rear window still vibrates at high output, so does the trunk lid and roof, but I can't hear any noises at that point lol. What I am saying is it is pointless to make a baffle that will hold up the car if the car shakes anyway. It is nice to make it thick enough you don't have the cone hitting anything if you hang them, if they have that kind of xmax. More baffle is not going to hurt anything. My problem is I just took the 12s out because they were so heavy they made the car drive differently, so I have an issue with unnecessary weight.

A lot of subs will do IB, the manufacturer may not be interested in that because some people will put them in and apply max power and beat them to death. You might do that with a JBL GTi, but not such a good idea with a typical sub it will break sooner or later. They are not thermally power limited, they are physically xmax limited when used IB. You will blow the suspension or break the former if it bottoms hard/etc. On top of that when you get to xmax (or xmech usually) you are getting distortion from the high xmax. If you need more output, get more xmax and/or more cone area. I went the cone area route; these pyle 15s barely move in normal SQ listening levels they only start to bounce when I dial them up for fun. And they can hit 25Hz all the time. Last point is if you have a PEQ handy, they can wring about any type of sound you want out of IB subs....until you run out of xmax of course and the lower you go the more you will need.
 

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John Myers won a world championship, or two with them in his rear deck running them IB. I heard the install... they sounded great, better than most subs.
 

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Discussion Starter #6
@ Oliver - Thanks for posting. This question/thread was posted only after at least 10 hours of research, and this site, among several other has been really great. Also, IB is too short to search (haven't tried IB install thought....)
@Lithium - Thanks for that idea, I've read it being done but hadn't thought about it in this situation. Is it tough to select specifically my sub/box sq. ft. in the program? Seems like it could get complicated fast. I've used the program for simpler things... well, maybe not (port designs, etc) so maybe it won't be too bad.
@sqshoestring - So, right now I have each Type X on an MRD-M1005 (1000 RMS) so each sub is getting a full RMS rating... should I maybe only run 500 to each? That almost doesn't make sense... but the sub-sonic filter part totally does. So, with a F value of 29 Hrz, don't expect much output below that? And it's at this point that the sub will start to cook itself because of the xmax, right?

So, all in all, I'm running them in a nice 2 cubic foot custom built fiberglass box... and I'm sure there will be some glassing involved in this project to keep things nice. How much power will I lose? I love the way things pound now... but would like more space in the trunk, a bit better SQ, and well, just trying something new, but will I half my output? That's what it's sounding like.

(thanks all for the comments/tips!!!)
 

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.............
@sqshoestring - So, right now I have each Type X on an MRD-M1005 (1000 RMS) so each sub is getting a full RMS rating... should I maybe only run 500 to each? That almost doesn't make sense... but the sub-sonic filter part totally does. So, with a F value of 29 Hrz, don't expect much output below that? And it's at this point that the sub will start to cook itself because of the xmax, right?

So, all in all, I'm running them in a nice 2 cubic foot custom built fiberglass box... and I'm sure there will be some glassing involved in this project to keep things nice. How much power will I lose? I love the way things pound now... but would like more space in the trunk, a bit better SQ, and well, just trying something new, but will I half my output? That's what it's sounding like.

(thanks all for the comments/tips!!!)
Try searching 'infinite baffle' and possibly use google and "IB" with quotes on this site. Can also scroll the builds most say IB in title.

Those are 1K rms, so yes around 500rms should be about right each its hard to say exactly. It all depends on what you do, to get lower you need more xmax in the same size sub, to get louder you need more xmax if you are playing bass....that is what I mean; the lower you want them to play the faster you will use up the xmax. The lower you let them play the less power you can lay on them. Those are stout subs, but I still would not recommend powering them up harder once you hit xmax it is pointless. With a tone you can see they will not get more xmax as you go louder....only applies to maybe 40Hz and below. IB is not ideal for SPL, but it can do ok if you SS them. It is really the same as a huge sealed. What you really lose is the peak you get from the smaller box, you can EQ and SS it to the same response IB and you will be close but not quite.

Far as Fs and qts, that is what it will sound like with no EQ, just like if you tuned a box. In the end you can EQ it any way you want and they will put out until they have no more xmax. So a sub with huge xmax will go louder IB and take more power, but if the T/S is way off it will sound like crap until you EQ the hell out of it. That is all that means. For example a mega watt 15 with 2" xmax and qts .3 will roll off and have no bass, but if you EQ the bass back up and lay the power to it it will hammer because it can move lots of air to make low bass. If you want high bass like SPL all of this is not as large an issue, as it does not take near the xmax to make 50hz as it does 30hz.

I you have fold down seats, just hack a piece of CDX ply up and make a temp baffle to see what you get. It will give you an idea even with leaks. The one nice thing about IB, is you can get full xmax on less power, and you are getting full xmax you are moving that much air.....when it comes to low bass. For SPL a box can peak spl up higher by pushing the Q up. If you model it, you will see it. In winISD just drag on the sealed box size, you will see the peak go up at rec box size and flatten back out as you get to your large trunk volume.
 

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Discussion Starter #9
Does "SS" mean sub-sonic"?

And so, after around 40 Hrz, I'll just be wasting power on them basically? Hmm... that's tricky, because I do listen to a good bit of rap/hip-hop. Obviously I would have to filter the subsonic up to... well, it sounds like at least to the F (29 Hrz).
So will I lose, so far as listening ability, half of my power? I understand about the xmax, etc, and how the sub will reach it's xmax much quicker, but does this mean less output? OR does it just mean less power to achieve the same output, so far as what I can hear? If I am cutting my output by half... it might not be worth it, in some ways I really like what I have now.

How does your Pyle do, so far as output? (I know db is hard to tell, but does it hit pretty good, and still clean?)

Crazy question, but what if I built my baffle right behind the rear seats, sealed it all up just like an IB, but had a sealed enclosure behind the subs, would this increase output? I've faced boxes into the cabin before, but it never sounded that great. Just a thought...
 

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You gain lowend notes and some clarity , plus you get your trunk space in the deal.;)

This ain't about tub thump

If you want some output , think Xmax and displacement

A couple of pistons and some long ass stroke:cool:
 

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Just because you are giving the HALF the power does NOT mean you will then get HALF the OUTPUT, All he is saying is that in a IB install it only TAKES half of the power to make the subs reach there physical limits,whereas a sealed enclosure needs the FULL power to reach is physical limits because the box helps to stiffen the sub's suspension but in a IB install you have NOTHING helping the subs suspension which is why you only need HALF the power to reach full excusrion as opposed to full power to reach full excursion in a sealed box...
 

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Just because you are giving the HALF the power does NOT mean you will then get HALF the OUTPUT, All he is saying is that in a IB install it only TAKES half of the power to make the subs reach there physical limits,whereas a sealed enclosure needs the FULL power to reach is physical limits because the box helps to stiffen the sub's suspension but in a IB install you have NOTHING helping the subs suspension which is why you only need HALF the power to reach full excusrion as opposed to full power to reach full excursion in a sealed box...
I've got a problem with what you wrote here. Your first sentence in this example is wrong.

The fact is, you will be getting half the out put with half the power. You're assuming that because your speakers are reaching their 'physical limits' that they are playing at there max output.

That's not true.

The lack of a box means the speakesr have a softer suspension and will reach max excursion with less power than the same set-up in a properly sized 'sealed enclosure'. But the output will DEFINITELY be LESS.

...you can't 'give something up' but get the same (or better) results.
 

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I've got a problem with what you wrote here. Your first sentence in this example is wrong.

The fact is, you will be getting half the out put with half the power. You're assuming that because your speakers are reaching their 'physical limits' that they are playing at there max output.

That's not true.

The lack of a box means the speakesr have a softer suspension and will reach max excursion with less power than the same set-up in a properly sized 'sealed enclosure'. But the output will DEFINITELY be LESS.

...you can't 'give something up' but get the same (or better) results.
What is the difference??
If going IB means it takes half the power to make FULL excursion than how is it NOT giving you the same output at half the power??
 

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I've got a problem with what you wrote here. Your first sentence in this example is wrong.

The fact is, you will be getting half the out put with half the power. You're assuming that because your speakers are reaching their 'physical limits' that they are playing at there max output.

That's not true.

The lack of a box means the speakesr have a softer suspension and will reach max excursion with less power than the same set-up in a properly sized 'sealed enclosure'. But the output will DEFINITELY be LESS.

...you can't 'give something up' but get the same (or better) results.
My sub needs 150w to reach Xmax at 20Hz. What do I have to gain if I give it 300w at the same 20Hz?

It's maxed at 18mm of excursion. The sub can't increase in displacement (its Sd is constant), it can't go any further with excursion...so what happens with the extra power? This is not a rhetorical question :laugh:

Ever had an IB setup? Ever played with WinISD? I'm guessing not. We're violating Hoffman's Iron Law a bit because I don't actually have a 14 cubic foot box...but hey, my trunk happens to be 14 cubic feet, I'll use that as the enclosure. Power handling goes down, of course. If you think I'm mad about using a 9 x 6" amp with a 30A fuse for my sub... :laugh:

For gits and shiggles, I took 30 seconds to model something up in WinISD of drivers I already had entered. My IB15 with 150w in 14 cubes vs a CSS SDX15 with 350w in ~3.5 cubes...yeah, they reach the same SPL level.

Sure, the CSS would take more power in a sealed box...but...one of the other 3 parts of HIL is lessened in exchange ;) I could add another sub, 150 more watts, in still less space lost in the trunk than one CSS and just destroy it, even with tons of power :laugh:

Oh, let's have some more fun. From this thread http://www.diymobileaudio.com/forum/klippel-reviews-driver-specs/91158-acoustic-elegance-ib12-8-a-2.html#post1151152 this post http://www.diymobileaudio.com/forum/1151610-post39.html

Straight from the guy who designed/built my driver...emphasis is mine:
stryke23x said:
From a simple standpoint with no shorting rings and no fancy materials being used, there are a few steps to lower flux modulation. One is to use a coil with less wire. Less wire, less current, means there is a weaker electromagnet moving through the gap. More efficiency and lighter mass is key because you need less power to get a given SPL. That's why I cringe at all the larger 3" or 4" or even larger coils that are being used in so many drivers.
 

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My sub needs 150w to reach Xmax at 20Hz. What do I have to gain if I give it 300w at the same 20Hz?

It's maxed at 18mm of excursion. The sub can't increase in displacement (its Sd is constant), it can't go any further with excursion...so what happens with the extra power? This is not a rhetorical question :laugh:

Ever had an IB setup? Ever played with WinISD? I'm guessing not. We're violating Hoffman's Iron Law a bit because I don't actually have a 14 cubic foot box...but hey, my trunk happens to be 14 cubic feet, I'll use that as the enclosure. Power handling goes down, of course. If you think I'm mad about using a 9 x 6" amp with a 30A fuse for my sub... :laugh:

For gits and shiggles, I took 30 seconds to model something up in WinISD of drivers I already had entered. My IB15 with 150w in 14 cubes vs a CSS SDX15 with 350w in ~3.5 cubes...yeah, they reach the same SPL level.

Sure, the CSS would take more power in a sealed box...but...one of the other 3 parts of HIL is lessened in exchange ;) I could add another sub, 150 more watts, in still less space lost in the trunk than one CSS and just destroy it, even with tons of power :laugh:

Oh, let's have some more fun. From this thread http://www.diymobileaudio.com/forum/klippel-reviews-driver-specs/91158-acoustic-elegance-ib12-8-a-2.html#post1151152 this post http://www.diymobileaudio.com/forum/1151610-post39.html

Straight from the guy who designed/built my driver...emphasis is mine:
...?...wtf r u talking about?
 

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What is the difference??
If going IB means it takes half the power to make FULL excursion than how is it NOT giving you the same output at half the power??
Yeah...it takes less power to get the subs to reach max. excursion in an IB set-up as it would to get the SAME subs to reach max. excursion in a sealed enclosure.

You think these two set-ups would yield the same 'output' in loudness and bass responce just because they happen to be reaching full excursion??

I don't think so...

I could be misreading what you're writing...but you can't get the same output with less power by going to IB from sealed. This can't possibly be what you're saying....right??

Oh, and to ryan s.;

seriously man...you babble, so yes...i'm glad you kept the last post simple.

: )


For what it's worth...I agree with what you said about your subs hitting max excursion at 150watts. You're right...going to 300watts will do nothing for you.

But that's got little to do with the post i was replying to....so...I feel kinda justified in my original responce of 'wtf'....
 

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You think these two set-ups would yield the same 'output' in loudness and bass responce just because they happen to be reaching full excursion??
They do.

I'd throw in some graphs but I have a feeling they'd sail right past :laugh:
 
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