System not like I expected?!

[Villainstone 10+ year member]

Ok I have a 2003 Tiburon GT with Infinity sound system. I have a PPI BK 1300W Amp, 12" Gcon in a custom enclosure tuned to roughly 35Hz. No Big 3 yet that will come in July. So now here is what seem odd...

After all is set and done my gain is at about 60%, that seems high to me when my amps RMS is nearly double the RMS of the sub. The bass boost which I would rather not have to use is about 50%. Subsonic filter in in the at about 25%, LPF is about halfway. I dont have a DD, DMM, or an O-scope. I had to set my gains by ear.

Now these settings give me about the same bass as my old 400W RMS sub, and 500w RMS amp. Thats what is so mind blowing to me. Hands down this system is better in every way. Better sub and amp and better box. So why does it seem like my knobs are so high?

If I left anything out please let e know

Click to read more...

 

[TheFiverMan 10+ year member]

is the sub wired correctly?

 

[mylows10 5,000+ posts]

i'm thinking out of phase

 

[cb1000r 10+ year member]

Somethings not right, I have the same amp, does what its supposed to. That should be much louder unless your box is way off. Als setting the gain to 60% is not the correct way to do it...just sayin.

 

[jbarnesiii88]

I always start with the small things... are my connections and ground 100% clean and secure? Do I have the right wire gauge for my amp? Do I have my amp's temperature under control? Did I change anything else (besides the amp and sub) when I upgraded? (wire location, ground location, fuse location)

Sometimes getting a new system means you also need to some in-depth tweaking with the amp and HU combined. Or maybe your new enclosure isn't what you expected; material wise. It may be 35Hz but materials absorb and bend to the air movement and can effect how much "real-feel" power is coming from your sub.

 

[cb1000r 10+ year member]

What headunit do you have.

 

[Fattony911 10+ year member]

I've seen supposedly custom boxes from shops tuned in excess of 60hz...where you get the design from need somebody to check the math on you dimensions?

 

[Villainstone 10+ year member]

Ok the box is double thick 3/4" MDF so 1.5" obviously lol. I built it myself and went over the math several times. The numbers should all be accurate of course with a margin of error. I covered it with chop mat fiberglass and resin, sanded and then carpeted. Sub is wired to 1 ohm, I checked the other day at school with a DMM. The ground is bolted right to the rear strut tower, I sanded the car, and the connector. The power is ran pretty much the only way you can from the bat to the amp lol. All with 4g wire. My head unit is a Kenwood KDC-319 its dated but was free so I use it for now. I noticed the lights dimm a good amount. So I was wondering could it be poor current, combined with the sub being so tight and new?

 

[cb1000r 10+ year member]

idk man, sometimes car acoustics are a SOB. When i wen't from ported box tuned 32hz to my Tline on same woofer I lost output but gained a broader range, I could play low as hell and clean all the way to my 63hz lpf. On the ported box it would slam 35, then fall on its face everywhere else.

 

[jbarnesiii88]

That right there may be your problem. Is your enclosure ported or no? If it is not ported, then 1.5in is way too thick for an enclosure. You want some flexibility on your walls so your sub has more room to move that air. I try and make my boxes so the two side walls expand about 0.15mm, which gives me about an extra 1.25mm flexibility in my sub foam. This gives me better sounding thumps and after-tones, but slightly less return-response (not noticeable)

If it is ported, your sub may not be moving the "box air" properly. I suggest you try a different type of port. Instead of just a hole or a tube that protrudes inside the box, try a bi-force port. It is basically 2 @ .5" ported holes with J-shaped tubes stemming out from them. The two port ends are connected to a T joint with one port hole as a result. The two air ports force eachother to expel only a certain amount of air out of the resulting port, and you can adjust this. This allows for a tighter bass and more response. This method may sound ridiculous, but it is the same method used to make motorcycle racing exhaust pipes. Mechanics use backpressure and stroke pressure to make the highest-performing pipes (sound included)

 

[cb1000r 10+ year member]

That right there may be your problem. Is your enclosure ported or no? If it is not ported, then 1.5in is way too thick for an enclosure. You want some flexibility on your walls so your sub has more room to move that air. I try and make my boxes so the two side walls move about 0.5mm, which gives me about an extra 1.25mm flexibility in my sub foam. This gives me better sounding thumps and after-tones, but slightly less return-response (not noticeable)
If it is ported, your sub may not be moving the "box air" properly. I suggest you try a different type of port. Instead of just a hole or a tube that protrudes inside the box, try a bi-force port. It is basically 2 @ .5" ported holes with J-shaped tubes stemming out from them. The two port ends are connected to a T joint with one port hole as a result. The two air ports force eachother to expel only a certain amount of air out of the resulting port, and you can adjust this. This allows for a tighter bass and more response. This method may sound ridiculous, but it is the same method used to make motorcycle racing exhaust pipes. Mechanics use backpressure and stroke pressure to make the highest-performing pipes.

Umm motorcycle pipes and subwoofer output are different things entirely, on a moto pipe (i assume we are talking 4stroke) the ideal exhaust is reverse cone, and it has to be spot on to work exactly like it should, it actually uses backpressure to its advantage, not the case with your sub. Looka t GP bikes to see what I am talking about.

1.5" thick is not a problem at ALL with enclosure design, in fact less flex is better (usually), in car audio its all based on your particular vehicle, one persons gain can be your loss. On your other statements how in the hell do you design .5mm flex into your enclosure and how do you think this gives you 1.25mm extra flexibility in your foam, what ever the hell that even means. Where did you get this info...? and if flex is so good for subs why do world record holders and people who compete use fiberglass, concrete and any other method they canf or their class to eliminate flex in an enclosure or on their car?

There are other things I would go over OP, how much port area do you have? port length and net airspace? Your construction method seems sound, let us see the dimensions. Small port, too high or too low tuning could be the problem, let us see the dims.

 

[cb1000r 10+ year member]

Also try different enclosure positions if you can, sub/port forward, back, up, to the sides, in my truck sub and port up is loudest, and if I rotate to have sub and port forward it is a huge difference, never tried rear.

 

[SoCaLBaMF]

That right there may be your problem. Is your enclosure ported or no? If it is not ported, then 1.5in is way too thick for an enclosure. You want some flexibility on your walls so your sub has more room to move that air. I try and make my boxes so the two side walls expand about 0.15mm, which gives me about an extra 1.25mm flexibility in my sub foam. This gives me better sounding thumps and after-tones, but slightly less return-response (not noticeable)
If it is ported, your sub may not be moving the "box air" properly. I suggest you try a different type of port. Instead of just a hole or a tube that protrudes inside the box, try a bi-force port. It is basically 2 @ .5" ported holes with J-shaped tubes stemming out from them. The two port ends are connected to a T joint with one port hole as a result. The two air ports force eachother to expel only a certain amount of air out of the resulting port, and you can adjust this. This allows for a tighter bass and more response. This method may sound ridiculous, but it is the same method used to make motorcycle racing exhaust pipes. Mechanics use backpressure and stroke pressure to make the highest-performing pipes (sound included)

 

[Villainstone 10+ year member]

Ok so here is the box. I put the dimensions on it to save me from having to type it all out.

View attachment 26543095View attachment 26543096

 

[jbarnesiii88]

Sorry, its hard for me to explain. But, I was just giving an idea that I had tested successfully with my professor, no need to bash on me. And I had .15mm wall flex, not .5mm, mistype.

The flex method involves "the control of expanding and contracting of the walls in order to control the expanding and contracting capabilities of the sub". You are able to use the (expanded wall's) contraction force to your advantage.

For the U-port, it just has to be done to be shown. To sum it up, it tries to keep a constant air volume in the box, and moves air in and out ONLY when it needs to (like a vent). It's trial-and-error for the calculations and hands-on attempt.