Sub response vs efficiancy?

[sqguy 0]

I have four 12s (infinity dvc) IB into my seat, they work great and have enough output for me but weigh a ton. So I'm thinking of lighter subs that are more efficient as well. So I'm reading up on it and that kind of sub tends to make less sub bass but more mid bass....a 12 might split at 40Hz where the common HD sub makes more under that and efficient sub more over that (more db); so they have more rolloff at lowest frequency. I like 30Hz, not sure if I would lose much since the difference is not very great. But now I am thinking maybe two efficient 15s would work better; with a lower Fs they should get deeper than efficient 12s right? Maybe as deep as the 12 infinitys?

Two 15s might even weigh less than four 12s, but I'd have to make a new baffle. If it did work then I would have more amp room too. Looks like two 15s would be about 25% less cone area. I cross the subs at around 35-45Hz, of course IB tends to rise in db the higher you go so xover little lower than with a box. I can crossover higher if I use the parametric to boost 30Hz or cut 60/etc. Or should I try to stay with a more normal HD car sub not so efficient, weighs more, but go with two 15s? The current 12s put out way more than my high side on 400wrms, don't want to lose much but not needing more at this time until rest of it gets revamped (will be modding fronts soon). The efficient drivers with much smaller motors weigh a lot less, I'd really like to try to make them work IB if possible. I can feel that weight in the back of the car its too much. Could also run less amp maybe, that could save a couple pounds too and footprint. If I ever figure out the front mounting I want to go active so would need room for three amps.

My last option might be to go with four 10s of some kind, but often are near same weight as 12s anyway since efficient 10s will have a hard time with 30Hz (done that before).

[///M5 2,833]

Dropping 30lbs in the rear will NOT be something you can feel.

[sqguy 0]

I hate it when I don't get the email for a post.

I sure felt it when I put that loaded baffle in, I actually put those rubber bumpers in the springs because if I loaded some stuff in the trunk with people in the car it went way down. It was fun to get into the trunk as well. This 15" driver would weigh less than one of the current 12s. I may suffer a little output with 2 15s, but that would be ok...I'll keep the 12" baffle around. Just need to know it will not be worse SQ-wise....you know, a totally stupid idea. When I ran them before I used 10s, and they had to be crossed over low (50Hz) because they really rolled off but still were fairly nice on 2x75rms. Was thinking the 15 would not roll off so much on the bottom, but I have never used 15s before and not IB of course.

[audio-neon 34]

You want woofers with a low Fs (free air resonance). You are going to loose output the lower you go with any woofer, it's natural. I have seen IB installs with woofers from 8" to 22". The key to getting low is cone area. I have seen a camaro with 2 18"s ib that gets in the teens frequency wise. You also need more power to get lower.

My suggestion is to grab 2 15" woofers (lean towards pro-audio woofers, or as you mentioned efficient woofers) Something with a light cone and low inductance will help the woofers "transient response". I have been thinking about picking up some Mach 5 IXL's for my new infinite baffle toys. Oh and try to atleast feed them half their rated rms (at least have it available.) IB needs power to get low.

[///M5 2,833]

I hate it when I don't get the email for a post.

I sure felt it when I put that loaded baffle in, I actually put those rubber bumpers in the springs because if I loaded some stuff in the trunk with people in the car it went way down. It was fun to get into the trunk as well. This 15" driver would weigh less than one of the current 12s. I may suffer a little output with 2 15s, but that would be ok...I'll keep the 12" baffle around. Just need to know it will not be worse SQ-wise....you know, a totally stupid idea. When I ran them before I used 10s, and they had to be crossed over low (50Hz) because they really rolled off but still were fairly nice on 2x75rms. Was thinking the 15 would not roll off so much on the bottom, but I have never used 15s before and not IB of course.

30 lbs is a rather high number for the weight you'd be saving, it would be less. If 30lbs causes your car to sag, you have serious issues with your suspension you should fix. Even on the track adding 30lbs will slow you down not even tenths so why would you care about it??

[sqguy 0]

You want woofers with a low Fs (free air resonance). You are going to loose output the lower you go with any woofer, it's natural. I have seen IB installs with woofers from 8" to 22". The key to getting low is cone area. I have seen a camaro with 2 18"s ib that gets in the teens frequency wise. You also need more power to get lower.

My suggestion is to grab 2 15" woofers (lean towards pro-audio woofers, or as you mentioned efficient woofers) Something with a light cone and low inductance will help the woofers "transient response". I have been thinking about picking up some Mach 5 IXL's for my new infinite baffle toys. Oh and try to atleast feed them half their rated rms (at least have it available.) IB needs power to get low.

I agree with the cone area thing, I've been running 4 10s for a long time here and there. It was all I could fit, but I managed 4 12s in this car on about 400wrms. Not quite enough power but it does put out. Can't fit 4 15s, even thought about 8 10s but no amp room then and back to the weight issue again. These infinity sound better than I thought they would, but they really don't get moving that much either. At full tilt they are hitting maybe half of xmax...maybe why they don't sound bad. My system is gone at that point as the high side can't keep up. I don't think big xmax is the way to go IB, but hard to find info on that. That is why I always used as many drivers as I could so each would run easier. This can get fairly loud with them hardly moving at all.

30 lbs is a rather high number for the weight you'd be saving, it would be less. If 30lbs causes your car to sag, you have serious issues with your suspension you should fix. Even on the track adding 30lbs will slow you down not even tenths so why would you care about it??

I can't find a weight, but they are heavy subs. The car was even without the subs and then was a little low with them, it is just not made to carry weight I guess...typical econo car. The rubber things lift it just a hair, all I wanted to do. It only has 65K on it, and only 125hp with an auto trans. If I could halve the sub weight I'd be happy, this is heavy as a box. Weight is only one reason, I want to try efficient subs anyway unless someone says they will not work and my memory of them is all wrong.

I have plenty of amps to try, from 350 to 1kw RMS. Not sure what it will need, I assume less with more efficiency yet it may sound better overpowered (not overdriven). The subs I have looked at usually say half rms for IB, so I am around 100-200rms per sub with most I have found with better efficiency. Most of these amps are class D to help use less power. On the other hand I don't like overly dynamic IB subs a large amp can make. When pushed they seem to top out more, makes that typical IB issue worse. Trying to get an arc audio tripath to try, don't know much about them but seem to be pretty good? I tend to figure an amp has to be pretty trashy to sound bad on subs.

[todd.brust 29]

You want woofers with a low Fs (free air resonance). You are going to loose output the lower you go with any woofer, it's natural. I have seen IB installs with woofers from 8" to 22". The key to getting low is cone area. I have seen a camaro with 2 18"s ib that gets in the teens frequency wise. You also need more power to get lower.

My suggestion is to grab 2 15" woofers (lean towards pro-audio woofers, or as you mentioned efficient woofers) Something with a light cone and low inductance will help the woofers "transient response". I have been thinking about picking up some Mach 5 IXL's for my new infinite baffle toys. Oh and try to atleast feed them half their rated rms (at least have it available.) IB needs power to get low.

I agree with the cone area thing, I've been running 4 10s for a long time here and there. It was all I could fit, but I managed 4 12s in this car on about 400wrms. Not quite enough power but it does put out. Can't fit 4 15s, even thought about 8 10s but no amp room then and back to the weight issue again. These infinity sound better than I thought they would, but they really don't get moving that much either. At full tilt they are hitting maybe half of xmax...maybe why they don't sound bad. My system is gone at that point as the high side can't keep up. I don't think big xmax is the way to go IB, but hard to find info on that. That is why I always used as many drivers as I could so each would run easier. This can get fairly loud with them hardly moving at all.

30 lbs is a rather high number for the weight you'd be saving, it would be less. If 30lbs causes your car to sag, you have serious issues with your suspension you should fix. Even on the track adding 30lbs will slow you down not even tenths so why would you care about it??

I can't find a weight, but they are heavy subs. The car was even without the subs and then was a little low with them, it is just not made to carry weight I guess...typical econo car. The rubber things lift it just a hair, all I wanted to do. It only has 65K on it, and only 125hp with an auto trans. If I could halve the sub weight I'd be happy, this is heavy as a box. Weight is only one reason, I want to try efficient subs anyway unless someone says they will not work and my memory of them is all wrong.

I have plenty of amps to try, from 350 to 1kw RMS. Not sure what it will need, I assume less with more efficiency yet it may sound better overpowered (not overdriven). The subs I have looked at usually say half rms for IB, so I am around 100-200rms per sub with most I have found with better efficiency. Most of these amps are class D to help use less power. On the other hand I don't like overly dynamic IB subs a large amp can make. When pushed they seem to top out more, makes that typical IB issue worse. Trying to get an arc audio tripath to try, don't know much about them but seem to be pretty good? I tend to figure an amp has to be pretty trashy to sound bad on subs.

I'll agree with what you say about an amp has to be trash to sound bad on subs. But from what I have read on heard about Tripath or Class T topology, it isn't anything special at all. An over-glorified class D amplifier. They changed some stuff with the feedback loop and the modulator and compacted most of it into a single IC instead of having discrete component output stage. You'd be better off with a proven Class D amplifier IMHO. I'm not 100% sure, but I am pretty sure. I was told to avoid Tripath for those reasons when I was looking into building a Class D for a school project.

Not sure about you IB stuff though. Never had any experience with it. Lol

[sqguy 0]

I love IB, it is much like a large ported box with no box....but you need to have more drivers to keep your db. I had 4 10s and then put two of them in 4cf ported and it was near the same but not quite, on the same amp (at 2ohms not 4--80/60wrms x2 at 2/4ohm and they would bottom maxed out). Efficient lower wattage subs, likely not that low of Q. Some people say it is sloppy, but that is in the tuning/amp/drivers and can take time to weed out. You can't run huge power per sub, I like the great 30Hz response the most with no box.

Hmmm, I have alpine 350, 500, and maybe get a 600rms class D's. A mrv-1002 if I go class ab. A lightning audio strike 1kw rms at 1 ohm, 700 at 2 ohms. Maybe the kar1000 to try, and have some cheaper 300-800rms amps that are class ab. Had a 400rms class d alpine but someone bought it. Even have a 300 SS that might run them. Have to get going so I can drop some of these amps sitting around here.

[///M5 2,833]

I wouldn't draw the analogy to a ported box, not even close

[sqguy 0]

The crossover point and car were different, but it sounded very close to the same to me except the four 10" put out a little more. Of course the four were in the best IB car ever, a second gen F-body. The other was a horizon winter beater, the box filled the entire hatch to the shelf. The subs were out the sides at the tail lights, they seemed to horn out of that hole and up the hatch. Ports on the top. Not massive loud like today, but back then it was killer. Best yet they sounded great on all kinds of music. I've been hard pressed to duplicate the sound since with all kinds of boxes as I've had few cars I could do IB in lately.

[mrogowski 6]

Hi there,

It sounds like you've been around IB and pretty much know what it is you want. I do agree with M5 though - I doubt you would notice a weight difference by dropping from four 12's to two 15's, unless of course, other excess weight follows (amp(s), battery).

I also wouldn't be too concerned about switching from four 12's to two 15's either. If you can match the displacement-per-power ratio between four drivers verses two, there will be no compromise in output whatsoever. You mention the 12's were only working at around half excursion. Unfortunately, not knowing the design, you could very well have been reaching Xmax at that point (or past it) and not know it.

If however you do know the parameters of the 12's and can roughly judge just how much you were exerting them, this can be a baseline for choosing 15's that will work for you. The folks who tend to worry more about excursion are those who are building subs for home theater applications (e.g. this driver has 2mm more Xmax than that driver so it MUST be better - yeah right...). Since your focus is on music only, excursion by itself becomes a much less of a factor, but a factor nonetheless since you are now trying to equal the output of four 12's with only two drivers.

Can you move to two 18's instead? If not, then you are left with choosing two fifteens that can handle the throw and more power to achieve what it is you can already do.

Good luck!

Mark

[ANeonRider 3]

A single 15" has plenty of output here.

[///M5 2,833]

A single 15" has plenty of output here.

I'd say yours has more than plenty.

[ramos 2]

I wouldn't draw the analogy to a ported box, not even close

I would go as far as to say polar opposites of each other.

[sqguy 0]

I wouldn't draw the analogy to a ported box, not even close

I would go as far as to say polar opposites of each other.

Both heavy on the bottom end, how is that much different in results? I like IB because I can't fit huge boxes in my vehicles, so I use more drivers and get the same sound. I can fit 4 drivers in a flat plane space of one driver's sealed box that can't get that low, or something like that. You're not going to get spl, but my subs are too loud for the rest of the system by far right now....on a kicker 700.5 that I read a lot of praise for in that price range, and with front and rears playing. It is pitiful with just the front comps. I estimate I could run a deep ported 10" in the space I am using, how much output at 30Hz would I get with an expensive 10 compared? And building a flat box would take more effort, I just don't think it could do it. I have a 400rms 10 I have tested with inverted in a ported 1cf (1cf+), it works but I don't think it can compare. Have not had time to stuff it in my trunk and try it. I ran at least 5 different 12s in a 1.25 ported that was huge in my trunk, they were a joke compared to the IB.

[ramos 2]

I wouldn't draw the analogy to a ported box, not even close

I would go as far as to say polar opposites of each other.

Both heavy on the bottom end, how is that much different in results? I like IB because I can't fit huge boxes in my vehicles, so I use more drivers and get the same sound. I can fit 4 drivers in a flat plane space of one driver's sealed box that can't get that low, or something like that. You're not going to get spl, but my subs are too loud for the rest of the system by far right now....on a kicker 700.5 that I read a lot of praise for in that price range, and with front and rears playing. It is pitiful with just the front comps. I estimate I could run a deep ported 10" in the space I am using, how much output at 30Hz would I get with an expensive 10 compared? And building a flat box would take more effort, I just don't think it could do it. I have a 400rms 10 I have tested with inverted in a ported 1cf (1cf+), it works but I don't think it can compare. Have not had time to stuff it in my trunk and try it. I ran at least 5 different 12s in a 1.25 ported that was huge in my trunk, they were a joke compared to the IB.

The IB install I recently did is FFFFFFFFFFFFFAAAAAAAAAAAAAARRRRRRRRRRR from heavy on the bottom end, and has an extremely flat response. Requires a lot more power and surface area IB to get the same low end reinforcment that can be had from a simple ported enclosure

[///M5 2,833]

double post

[///M5 2,833]

Exactly. No one here said that the IB wasn't preferable, just hugely different from ported.

[sqguy 0]

You do have to cross them off lower due to the natural roll off, and it is worse with efficient drivers usually, but for the room taken out of my trunk I can always get a pile more 30-40Hz than a box. This alpine seems to have a less db slope, I mostly run it at 35Hz on the label. I've never run over 100rms to a driver, but never used over these 300rms drivers either (for IB). In fact this is first IB I've ran that the amp could not bottom the subs. If you get a bunch of 60Hz and no 30 then you have the wrong setup, I've been there. Unfortunately most of the systems I ran IB were before the days of listing the parameters of subs (or I can't find them or don't remember what model), so I don't know exactly what those subs were (bought late 80 to mid 90s). Really po's me. Back then only the paper subs worked well and hard to find those now, but many poly subs were junk back then. Even now the few IB built subs I have found do not seem to go that low on their charts. It would help me to compare old/new responses. The sub used is very important.

As far as my setup, I just ran a test CD to see what it was at with my weak mids. I tune it with music, have not bothered to test until I get midbass better. It has subsonic set to 15Hz on the crossover. At 10-15Hz it mostly shakes/rattles, 20 I can hear nice, 30 and 35 is peak and loudest in car, 40 cuts back some and maybe it falls slightly (roughly as this by ear) up to 60 where the mids are about the same level. 20 and 50Hz are roughly the same volume by ear. Isn't that close to ported?

I like it, but I don't have to put much in the trunk to get rid of the 20Hz I have found. Less driver might go lower if I can keep the output which is just about right, it shakes all the mirrors if needed. The subs wash out everything right now, midbass/mid/treble and I have the parametric cranked way up in a range centered around 85Hz. Can only crank the subs on music with weak bass if I want to hear all the music. I don't crank it that often, but I want to feel it once in a while and when I feel it I can't hear the rest.

Also found if I boost the 30Hz with the parametric and raise the crossover point to maybe 50, it hits tighter and still puts out the sub bass. Only one parametric on this so I can't do it with the weak mids. If I could it seems to give them a flatter response with plenty on the bottom.

[emperorjj1 2]

maybe its just my srpings (very stiff) but i didnt notice a difference putting 2 15s, 2 kintetiks and the heavy dual baffled box

im with m5 here... i can see your point and all but whats going to happen when u spend $$$ on the new setup and it does the exact same thing as before? if your springs are sagging then they will continue to do so

now if you sorta want to swap anyway but weight savings would be an added bonus then go for it but i dont see that as a good basis to swap equipment your happy with

[sqguy 0]

now if you sorta want to swap anyway but weight savings would be an added bonus then go for it but i dont see that as a good basis to swap equipment your happy with

Yes definitely. I ran this type of sub a long time ago with success, most people today say they will not work so I am hesitant plus not sure they are exactly the same....but are pretty cheap for a gamble. Also swapping from 5ch to 2 or 4 ch amps so should do the subs or I'll have to remount it all again and very time limited right now. Like I said it actually puts out more than I need, plus I don't have it maxed out with 400w. Guess I'd rather have less and be closer to maximum use, same great trunk room, less weight, and if it works have people drop jaw when they see what is in there like they did long ago.

I notice a difference in this car with one 120lb passenger. I'd rather drive a faster car but too low on my list to worry about right now. I like this no car payment thing.

This was a pic from install before I finished the wiring, was just testing amp on subs there. I put bolts in baffle between top/bottom subs and wired to those, ran wire behind and back out at top of amp. Tucked the top wiring up to deck, etc. Really all you see is the motors and amp unless you get down in the trunk with a light. I have carpet to put on it when finished with it. Thinking 15s at bottom and amps higher. Not ideal, but it is hard to get at the bottom part unless I make some kind of amp rack and don't want to lose trunk room. I keep thinking, because I don't like the amps on the baffle really but what else to I do and not take up space. Some larger items I carry fit in there good right now. Also thinking about a vanity panel that just covers the whole thing up (not sealed at all) and stick a fan in there someplace.