IB Sub power

[Paniller]

I finally got my Kicker CVR's installed, and all the soundproofing/isolating done. Still though, they start flopping/bottoming out pretty easily. How does the power work for an IB setup?

They're supposed to be 200watts RMS. I have a 350w Alpine amp on them, which is slightly underrated and was measured to put out ~400watts. The gain is all the way down, crossover set to 100Hz.

They put out decent SPL with certain sustained low notes, but I can't get about +3 for the bass without distortion issues. It seems strange that only the lower sustained frequencies hit hard, and the higher sub frequencies and quick hits are sloppy. Thought it'd be the opposite with 8's.

So, what do you guys think?

[jkayner]

because the trunk/enclosure is so large, it's hard for the 8's to produce an accurate higher note. If you want accurate midbass from them you are going to have to make a real enclosure to put them in. 8's typically use about .5 - .6 cuft, so the enslosure needs to measure about 12x12x6-8.

[GeoffA]

Hoe are you running them, 2ohm single or 4ohm dual vc?

If your at 4 I would change it to 2 and try that.

[Paniller]

Hoe are you running them, 2ohm single or 4ohm dual vc?

If your at 4 I would change it to 2 and try that.
I got the dual 4-ohm models. The voice coils are in series for 4 ohms. Then, they're in parallel at the amp for a 2-ohm load.


because the trunk/enclosure is so large, it's hard for the 8's to produce an accurate higher note. If you want accurate midbass from them you are going to have to make a real enclosure to put them in. 8's typically use about .5 - .6 cuft, so the enslosure needs to measure about 12x12x6-8.
I'm highly considering it. It'd only be like...5 extra pounds of mdf? But totally worth it. I could even carpet it, and blend it in with the 10's below, and use that box to secure the 10s' boxes better.

[steined]

So how would you create the enclosure? Would you use the stock mounts in front and then somehow seal the MDF to the rear deck creating the enclosure? I'm having a hard time picturing it.

[fourthmeal]

These subs are not IB design. Model them in a sealed box in WinISD pro and see what you're supposed to get.

I would build a box under the deck, as shallow as possible.

Or, take advantage of your spacious trunk and build off the rear seatback area there.

Either way, try to optimize your box size to .707 Qtc and don't forget to take the displacement of the sub itself into account.

[Paniller]

These subs are not IB design. Model them in a sealed box in WinISD pro and see what you're supposed to get.

I would build a box under the deck, as shallow as possible.

Or, take advantage of your spacious trunk and build off the rear seatback area there.

Either way, try to optimize your box size to .707 Qtc and don't forget to take the displacement of the sub itself into account.
They're not designed for IB, but everyone's saying to use them, because of the high Qts rating of like .850 or whatever. If you browse the other threads, you'll see everyone using them.

I have two 10's in boxes underneath, so spacing is limited. I think I'll have to fiberglass something for them. Fiberglassing in an enclosed space upside down....urgh.

[fourthmeal]

The only way I know to fiberglass upside down is to get some modeling foam (the green craft foam will work) and make a mold of what you want. Then, take that out, and lay your glass upside down (gravity's preferred direction.) Just make sure to cover the green foam w/ foil and tape because resin eats the foam!

[fourthmeal]

Oh, btw I completely missed something here...WTF are you doing with 8" IB's AND a pair of 10" subs?

LOL.


Bro, you are on the wrong path entirely. What the heck is the point of the IB'd Kicker 8's if you have a pair of 10's? Simpler is better in audio. In fact, if you could get a single speaker (per side) to play ALL the frequency range, you would! Of course we can't do that thanks to material limitations. But your design is a nightmare of potential phase-lobing and other acoustic hell. I think we need to rework your entire concept of a system before you move one step further.

[Paniller]

Oh, btw I completely missed something here...WTF are you doing with 8" IB's AND a pair of 10" subs?

LOL.


Bro, you are on the wrong path entirely. What the heck is the point of the IB'd Kicker 8's if you have a pair of 10's? Simpler is better in audio. In fact, if you could get a single speaker (per side) to play ALL the frequency range, you would! Of course we can't do that thanks to material limitations. But your design is a nightmare of potential phase-lobing and other acoustic hell. I think we need to rework your entire concept of a system before you move one step further.
That was my next question....will cancellation and phasing ruin it all? Especially with the 10's essentially in the box of the IB's, being in the trunk.

I just basically had 2 extra empty holes and felt like something had to go in them, lol. My subs are all cheapos, and I'm honestly just fucking around playing. I have too much free time and thought it'd be fun trying to play and learn about all this stuff.

The 10's and the 8's are pretty good individually, if I can get them to work together, I'll be thrilled. I'm just playing with IB now, but if I can get them working well with the 10's, it'd be a great alternative to adding another box. Plus, I could take the boxes out for trips/track, and still have something.

[fourthmeal]

Here's the deal:

Anytime you mix and mingle speaker sizes, you must pay attention to what frequencies they play. An 8" IB sub and a 10" sealed sub are basically playing the same thing. Now, think about this for a second... When your pair of 10" subs play "out", the pair of 8's above them are also playing "out." Instant cancellation. Worse, you could end up getting some wicked phasing issues from this. Because the 10" subs are in a totally different location compared with the 8" subs, AND they are in different types of boxes, you've got the potential for some horrendously difficult frequency response issues.

A few things about audio you need to know.

We're working with atmospheric pressure waves here. Waves behave just like you learned in physics...they will cancel each other if a crest meets a trough, they will amplify if they combine, and they will create all sorts of interference patterns as well. If you haven't yet studied wave physics, I encourage you to do so.

Anyway, what you generally DON'T want are different size of speakers playing the same frequencies, if you can help it. You also don't want to play the same frequencies all over the place in different locations, either. Both of these cause issues.


So, at this point I'll ask the million dollar question. Do you want seriously excellent sound in this car? Because if you do, we can stop fooling around w/ things and plan a system that puts you in the front row of a live stage of your favorite band (acoustically speaking.) And honestly...that's what we're all here for in the the game of audio?

You mentioned you want to learn about all this stuff. I am more than happy to teach if you want to learn. I can also point you to places to learn on your own if you prefer that method. The biggest suggestion in teaching that I would like to share with you is to only spend your money on sure things, but research the living hell out of possibilities. That way, should you actually wish to have a killer knockout system (and thus be able to really enjoy your music as it was intended), you'll be able to take all the money that you would have otherwise wasted away and project that towards a solid budget for upgrading.

Once I know what path you want to take, I'll try to provide help to get you where you want to be. Alternately, if you want to put it in my hands fully I accept the responsibility. By that I don't mean I'll come do the project for you, but I can make a plan that you can follow very carefully and get results.

[Vertical]

Very valid and helpful info there.

Paniller, I'm going to avoid thread hijacking in regards to my own system build and just follow this thread to see where you're going with this. I'm going to use you're boredom and experimentation to my advantage :nah:. In the meantime, good luck with your decision.


Fourthmeal, it's always good to see a memeber contribute in a positive and constructive manner.:urock:

[fourthmeal]

Well I try to think of Karma as my direct next-door neighbor. Doing good for the community invariably leads to a more fulfilling and happy life for myself. Even something small I do seems to be rewarded nearly instantly.

Besides the whole Karma bit, I find it utterly exhilarating to help design and build (when possible) systems for my friends and family. Watching their face light up every time they get in their car makes me feel warm and fuzzy.

[Paniller]

The best system I ever heard, actually had mixed sizes. I had two of the Kenwood "tornado" 2 for $100 10" specials. Then I had a 12" JBL power in the center. That setup hit so damn clean and hard. Even the guys I knew that were into competition level stuff loved it. I was literally setting off car alarms with the tight beats of Static X (metal band if you're unfamiliar). Rap music was crazy for SPL, most people couldn't breathe in the car, and refused to stay inside. So that was...$250 worth of speakers, in homemade boxes, on a cheap-ass 700w Soundstorm amplifier.

I really wish I brought that thing to a competition. Surely I'd get some kind of budget system award. I really just winged it. All the stars must have aligned, and all the peaks in the sine waves must have matched perfectly. Perfect phasing by pure luck? I agree with the basic simpler is better theory, but if designed right...or luck intervenes again, I could get great results with this setup as well. If not, I only lost like $100 and countless hours. Which probably saves me money, as I'm not at the bar.

Now, assuming I get some cancellation/phasing issues, what kind of tools are there to overcome this? I'm sure I could take measurements, add some delay to one of the sets, and get some great results. Are there tools to compare the amp's input signal to the resulting wave, to synchronize timing of the waves?

I have an elecitrical engineering degree, so I was pretty versed in sound/signal related physics. But, I've forgotten a lot over time, and there's still much sound stuff I never knew.

[Paniller]

Here's a quick sketch so you can provide some some input if you're still interested. While your concerns are definitely justified and you know more than I do, I'd still like to follow this through as a learning experience. A little challenge never hurt anyone.

Old "dream" setup vs new. You can see my 10's are directly below the 8's. The 10's alone hit beautifully, so I don't think there's much cancellation concern between the two of them. The 8's as well, once I get them secured.
Now, based upon location, if I chose to leave the 8's as IB drivers, would it make sense to run them reversed and push in the same general direction as the 10's, or is it pretty much just a crapshoot anyway?
http://i24.photobucket.com/albums/c2/paniller/Old-New.jpg

Here's the left side amp, and left side 10" installed in case you're curious. I couldn't find the right carpet, but that carpet actually matches pretty decently in dim lighting without a camera flash.
http://i24.photobucket.com/albums/c2/paniller/0411092155a.jpg
http://i24.photobucket.com/albums/c2/paniller/0412090020.jpg

[fourthmeal]

There are no tools to overcome phasing issues, other than to redo the system correctly.

Here's why:

Phasing (and what I'm talking about here is comb-filtering) will change in response rate depending on where your ears are. If you move a few inches left or right, the comb-filtering effect will change the sound you hear dramatically. You can never solve it completely.

I would encourage you to come listen to my truck, but I'm sure along the way there are better cars to listen to. My focus in building systems is to maintain as much trunk space as possible (or reasonable given the system goals) while not compromising on sound quality one bit. I always try to get a realistic front stage image and I try to match tonality with my Sennheiser HD555 test earphones, which I consider to be "ideal". I also try out a few songs on my home theater speakers (a pair of 1979 Mission Audio floorstanders with an Elite receiver) and try to find my "center" for tonality as well. What I try to get once I have proper tonality and image is solid impact from the front stage speakers blending w/ the subs. Ideally you shouldn't even know you have subs...they should blend seamlessly with the front speakers and time-align as well. Lastly, I don't care what brands are used if they are good. Sure I have certain favorites and I also have a few brands that are "10 foot pole" options, but overall if it works to my standards then I'll consider using it.

So again, it comes down to what you want to do. I'll help you in whichever way you want to learn, or I can help design a solid setup for you if you prefer.

The first thing I would do is completely ditch your front Infinity's. The next thing I would do is source a proper processor.

[Paniller]

Having spent a few minutes on the throne(toilet) thinking about this...you're absolutely right. Multiple sources will always create destructive interference/cancellation. Even if I use tools and synchronize the phasing on one frequency, the other frequencies will not match up, because by definition of frequency, the peak to peak spacing will be different. So, I can only pick and choose which frequencies to cancel, and which to amplify. If I choose to keep two different setups, I should definitely have different LPF/HPF ranges for each.

I'll still check it out. Maybe I'll get lucky and the results will be desireable for the common frequencies in my music. But, I'll be prepared for the worst.

I think the reason my old setup worked so well, was that all the subs were very very close to each other. The wavelengths in the sub 120Hz range are larger, like 2.5+ meters, so they did not cancel. Also, the cones were close to the trunk lid, so the waves reflected off the trunk lid did not have enough distance to cancel either. With my new setup, there could be issues.

[Paniller]

The first thing I would do is completely ditch your front Infinity's. The next thing I would do is source a proper processor.
I know the "less is better" approach, but why ditche the fronts? I've heard most people prefer to ditch the back.

I'm definitely keeping them, though. I just bought them, lol. I'm not sure if a single set alone will be loud enough for me. I'd have to get some better ones, with an external amplifier to run a single pair.

I definitely want a 4-channel amplifier though. My last car was crystal clear with all alpine type R's and an external amp. I know those were better speakers as well, but I attribute most of the sound to clean external amplfication. Though, how good will that be, still using the stock HU?

[fourthmeal]

I don't mean ditch front speakers. I mean ditch THOSE front speakers. The frequency response is ear-twitchingly bad and hopeless w/ them. I've TRIED hard to get Infinity car speakers to sound "right" but without a massive EQ job it is useless.

And yes, ditch the rears. Or at least ditch the concept of changing them out. Stock will do for rear passengers typically. My front speakers can get loud enough to deafen someone, so multiple drivers are unnecessary in most cases. It all has to do with excursion vs. spl and what the driver can take. Cross over at the right point and you get what you need.

Consider going active as a true solution as well. That is really the right path if you are after perfection. This will let you actively control each speaker with time alignment, crossover, EQ, etc.

[fourthmeal]

Here's the short synopsis of an "ideal" basic setup for beginners who really want to rock:

Head unit (this one must remain stock as you know in these G8's)
Processor (takes the head unit output and converts it in the digital domain, allowing for control of time alignment, crossover point and slope, intricate volume adjustment, EQ per channel, etc. Then it sends a strong RCA signal to your amps actively.)
Main amp (a 4ch amp, two channels for your tweeters, two channels for your woofers. Alternately you can use a 6ch, or possibly a pair of amps instead.)
Sub amp (mono or 2ch, power exclusively to your sub stage.)
Front separates or components, woofers and tweeters. This makes a 2-way system. We'll skip 3-ways for now for the sake of simplicity. As one of my favorite DIYMA posters says in his signature, "If you can't get a 2-way system to sound good, a 3-way system will rape your mother."

Subs.


There are many ways to combine these features, such as 5ch amps or amps w/ processors already onboard, but the basic concept is the same.

That's it.

[Paniller]

I don't mean ditch front speakers. I mean ditch THOSE front speakers. The frequency response is ear-twitchingly bad and hopeless w/ them. I've TRIED hard to get Infinity car speakers to sound "right" but without a massive EQ job it is useless.

And yes, ditch the rears. Or at least ditch the concept of changing them out. Stock will do for rear passengers typically. My front speakers can get loud enough to deafen someone, so multiple drivers are unnecessary in most cases. It all has to do with excursion vs. spl and what the driver can take. Cross over at the right point and you get what you need.

Consider going active as a true solution as well. That is really the right path if you are after perfection. This will let you actively control each speaker with time alignment, crossover, EQ, etc.
I think you may be right. I could have sworn I loved Infinity in the past, so got this as a budget system. While they can get louder than stock without distorting, I can't honestly say the response is better. They sound almost identical, maybe a hair better.

I gotta stop spending money on the car, as I need to save for a house pronto, so I'll keep these for now. But I'd definitely rethink buying them, and would like to upgrade again in the future.

The rears sound like they may be decent, but the front components leave much to be desired. The door speakers have no bass response at all, the stockers were more responsive. I almost thought I crossed the tweeters/woofers on the crossover for a second. At least this means I can turn up the bass higher without the door speakers distorting like on the stock setup. I miss sub outputs.

[fourthmeal]

When you talk about sound proofing, do you have pics of what you did in the doors? A lot of bass can be lost by missing the boat on door prep. It is fixable however. You should expect an amplified front set of components to play cleanly down to about 60hz at a fair volume, if you pick your gear right. You don't HAVE to have speakers that can play that low, but if they can then it makes staging a little easier. In my particular setup, I have a pair of subs that are designed from the beginning to play much higher than a typical sub, without distortion. That's what the DIYMA R12's do though. Anyway even with those set at ~90Hz, I cross over right at that number on my fronts, at 12dB/oct. I can play lower, but I don't have to because the sub can. And, because my car is dead, the system still sounds properly staged because there are no acoustic rattles or other cues that would drag my attention backward.

I imagine if you sold or returned some of your gear you'd have exactly what you desire. That's the whole point of course...doing it on the cheap, right?

[Paniller]

No pictures, but for the doors, I pretty much painted on a layer of the liquid stuff anywhere I could reach with the brush. So, about 60% coverage on the outside door, and very little on the inside door. The inside door was mostly open/cut out. there were only a few pieces of metal exposed, so only maybe 1/2 ft of coverage there. It's mostly open and only covered by the moisture seal, which there's no point in painting up. I know where you're going with the bass response by sealing up the door to work as a box, but it'd need a lot of work for that. Probably something to fiberglass the openings shut. I did the same work for the front/rear, so they should sound similar, and at least as good as stock. I'm thinking maybe the crossover has a higher HPF than the rears? It's not like they're not hitting right, it's that they're...not really doing anything. I've been riding my bike a lot lately, haven't have a chance to look into it. It may be obvious like open wiring. Maybe they're NOT playing. lol.

Basically, I just did minimum soundproofing to eliminate rattles/drone, I haven't done much to improve the audio yet.

I don't think I'm going to be returning/reselling anything. Everything was so damn cheap it's not worth it. We're talking under $50 per speaker set, and $50 per subwoofer. Not worth my time right now, though maybe down the road if I upgrade.

[fourthmeal]

Ok well one way to seal the doors is by using scrap roofing tin or even by grabbing "Vote for Me" corrugated plastic signs. That stuff is pretty strong. You can use just about anything, like siding panel for instance. Just adhere it to the door so it seals up and creates a true infinite baffle door setup. The idea is if the rear wave contacts the front at any point you're canceling, so stop that from happening. The next thing is to amplify the fronts. You have not said you are doing that, so I have assume you aren't.

[Paniller]

Ok well one way to seal the doors is by using scrap roofing tin or even by grabbing "Vote for Me" corrugated plastic signs. That stuff is pretty strong. You can use just about anything, like siding panel for instance. Just adhere it to the door so it seals up and creates a true infinite baffle door setup. The idea is if the rear wave contacts the front at any point you're canceling, so stop that from happening. The next thing is to amplify the fronts. You have not said you are doing that, so I have assume you aren't.
That sounds like a good idea. I played with it this morning, and it's fine. It was just the music I was listening to. But, your suggestion sounds like a nice way to improve it, so I'll try that out.

Though, you refer to it as infinite baffle. Is that really infinite baffle? It sounds more like a sealed box. Or are you talking about just sealing one side of the speaker from the other?

[fourthmeal]

Once the sealed box size is 3X the VAS of the woofer spec it is considered IB.

[NDM]

Ok well one way to seal the doors is by using scrap roofing tin or even by grabbing "Vote for Me" corrugated plastic signs. That stuff is pretty strong. You can use just about anything, like siding panel for instance. Just adhere it to the door so it seals up and creates a true infinite baffle door setup. The idea is if the rear wave contacts the front at any point you're canceling, so stop that from happening. The next thing is to amplify the fronts. You have not said you are doing that, so I have assume you aren't.
Perforated metal is also very good to seal up doors....


Another very good material is plexiglass. Cutout a piece and seal the edges with silicone...That way if you need to get into the doors simply pry the plexi out and reapply the silicone when you put the plexi back in...1/8 inch should work fine....Here are some other tips....

You can get non-hardening clay called roma plastilina from dick blick art supply and apply around the mounting baffle as a de-coupler...then put some deadening over it to seal the clay in. I use the number 2 stuff because it is not too hard to mold.

You can also put closed cell foam behind the driver to kill the back wave of the driver

[dandragonrage]

Plexi is good for short pieces or well-braced pieces. Use one big piece supported only around the edges and it turns into FLEXiglass.

BTW, Lexan is my recommendation, because it's much easier to work with. It costs more, but the price isn't bad anyway.

[NDM]

Plexi is good for short pieces or well-braced pieces. Use one big piece supported only around the edges and it turns into FLEXiglass.

BTW, Lexan is my recommendation, because it's much easier to work with. It costs more, but the price isn't bad anyway.

The holes in the door are not that big....

Plexi is easy to work with with the correct tools...

and Lexan is actually more flexible than plexi..Which is why it works as Bullet proof windows. It flexes and absorbs the blow instead of shattering like plexi would. But plexi is in fact more rigid. In a door it will not be subjected to this kind of force so it is not that big of a deal.

If you have a router, plexi is a breeze to work with....

But either will work just fine.

[steined]

Why can't sound deadener be used to seal the doors? I thought that was the concept of using it on the inside panel. Is it because it isn't rigid and absorbs waves instead of reflecting them back into the sealed space?

[fourthmeal]

Why can't sound deadener be used to seal the doors? I thought that was the concept of using it on the inside panel. Is it because it isn't rigid and absorbs waves instead of reflecting them back into the sealed space?



The part we're covering here is the open expanses of space in the inner metal panel. Ideally a door that is completely sealed is best. Covering those expanses requires a stiff material. Once those parts are covered w/ a replacement material (plexi or whatever), then you can deaden that more with mat.

[dandragonrage]

Honestly, you can use the door panel to seal the doors if you just make a seal between the door panel and the front of the speaker. I won't say it's a bad idea to seal the door metal yourself, but it's not really as necessary as some people make it out to be. The pressure isn't going to be enough for there to be an air leak around the door panel. The main problem is when the speaker does not seal to the door panel which causes an open air effect, which brings efficiency down.

[NDM]

Why can't sound deadener be used to seal the doors? I thought that was the concept of using it on the inside panel. Is it because it isn't rigid and absorbs waves instead of reflecting them back into the sealed space?

For years I used just deadener....But when I found this trick..I realized how much performance is to gain from doing this simple mod...

Look at it this way...lets say you took a sub and put it in a sealed enclosure.....now drill some smaller holes in the enclosure....yes the performance is decreased....now drill bigger holes in it....the performance decreases even more....

This example is assuming that the sealed enclosure was not too small to begin with.

The whole point is to get the door as rigid and as sealed up as possible...the more sealed up it is, the more control there will be over the woofer.

I could here and debate this all day long but the information I am giving is from years of testing and my own experiences....

Also the more rigid the mounting baffle is....the better. You can make a simple set of components sound like there are subs in the door if you go all out with sealing....

Is this extreme needed?, Not at all, but it will improve things. I am all about extracting the maximum from what you have...always have been and always will be. Besides many of the methods I and many others use are very cheap and simple methods and if you are already taking the time to deaden the door, why not go one step further....