Infinite Baffle efficiency clarification.

[soydeedo 10+ year member]

Well I tried my best to search beforehand, but since most people just say IB it's not the easiest subject to research on here so please take it easy on me if it's hidden in some thread 13 pages back or something. =)

If you don't want to read the backstory, etc just skip to the bold question at the bottom instead of skipping the whole thread. Thanks.

Ok so the general rules of thumb that I've seen repeated over and over that pertain to my question are:

1) IB setups in trunks act somewhat like very large sealed boxes so they are more efficient and require much less power to get moving.

2) An IB setup will never get as loud as the same woofer in a regular sealed or ported box.

Alright with that out of the way let's get on with it. I have a 2002 civic with a weak 70a alternator so I'm looking for efficiency, and I'd like some more output than what I've got now. Right now I'm running 2 IDQ.v1 12's in a sealed box so I know I can throw out ~650w to my sub channel without significant voltage drop.

Now I know I can port them, but I don't want to take up 4cu ft net, probably 5cu ft gross [remember these are v1]. So I was thinking I could get some new drivers, go with a Trunk Baffle setup, save a boatload of space, and come out with some more output on the same amount of power.

My reasoning is this: a hypothetical driver can take 1000w sealed and put out x db. Ported will be x+3 db or so. IB/TB will be something like x-3 db, but only requires maybe 300w. Since that x-3 db is only a little less than that of a 1000w sealed driver it is still probably louder than one of my ~300w sealed IDQ.v1's, no? Is this reasoning correct? That's my whole question. Yes I know a lot depends on which driver I select as well, but say I went with IDMax's, Mag's, or hell even IDQ.v2 15's.

I guess a more concise question would be whether an IB/TB setup with its significantly lower power requirements would have only slightly less output than a fully powered sealed box or would the output difference be pretty large? For reference slightly would be something like going from ported to sealed and large would be like halving the power to a boxed sub. I'm pretty sure it'd be noticeable but only slightly, but I need to make sure. I can probably take it from there.

Thanks for reading. =)

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[Immacomputer 10+ year member]

The difference in output from about 40-80hz probably won't be too much but you should gain output below that. Output is very much frequency dependent and changing enclosure types is going to change your frequency response which changes output. If you really want an efficient setup, IB would be a good option and you may or may not lose output (this of course would depend over what frequencies you're talking about).

 

[soydeedo 10+ year member]

Yeah I'm interested in the 20-70hz range mainly so it sounds like this'll be spot on. And yeah better low, low frequency response was another plus behind IB. =)

 

[helotaxi 5,000+ posts]

Theoretically there should be no difference in output between IB and sealed. The difference will lie in the response curve and the power needed to get the subs to their max output.

 

[profundus-sanus 10+ year member]

Theoretically there should be no difference in output between IB and sealed. The difference will lie in the response curve and the power needed to get the subs to their max output.

exactly, since your not utilizing anything other than the forward wave of the woofer

 

[Immacomputer 10+ year member]

exactly, since your not utilizing anything other than the forward wave of the woofer

But you're changing the air spring on the sub which will change the response and then in hand change output since output is frequency dependent.

 

[profundus-sanus 10+ year member]

But you're changing the air spring on the sub which will change the response and then in hand change output since output is frequency dependent.

which was previously said in the statement I agreed with...

 

[soydeedo 10+ year member]

Thanks fellas. Now I just need some cash to fund this conversion. =P

 

[Gebrochen 10+ year member]

Whatever sub you get, ask the manufacturer how well it works in IB. I remember subs made for this application were somewhat common in the early 90's, but I don't see it in the specs these days. When you wall up the baffle, go as far as you can to separate the speaker plane front and back.