db drag today
 

well, my first compitition in car audio today and I am convinced you cannot pull high numbers in this car. I have a soundstream tarantula t4-15 pushed by a soundstream PCA1500D. My car was measured at 135.6 db. i should be getting higher numbers with that setup. everything with the sub box is exactly soundstream specs, but it just seems that it just cant pull enough air to feed the sub. I am so frustrated right now that i just wanna take everything out and say screw sound comps. what is the highest number anyone has pushed in their 8?

-Steakboy

no idea how to check
how would I go about doing that other than competing and making a fool of her :)

I would like to see a pic of this box and woofer in your car.... Because if it is built to specs (4.25 cu/ft vented) I can't think of too many ways you can have it in there with still having enough airspace to feed that woofer...

do you have a pic?
have you done anything with "the big 3"
have you done anything with the HU?

what exactly is your setup?

Hey guys whats up im still installing my setup right now but soon it will all be in and ill get some numbers. I have a JL audio cleansweep running to a PG 500.4 ti for my highs then two JL audio 500/1's pushing two JL Audio 10" W7s. I also have a shit ton of Dynamat. I noticed something when installing the dyanamat. In the trunk behind the left and right carpet side panels there are two vents, fuck that I covered em up with dynamat. I'm convinced that the key to spl in this vehicle is to keep the space open where air can flow through the rear between the seats. I'll get you some pics asap. Peace

The key to SPL is tuning the box to the loudest resonant frequency. If you build a box to exact Soundstream specs, it is going to be a box designed to give some good tonal response and good output levels. It is however definitely not going to be something that is going to do well against a pure SPL type box. If your box is tuned to deliver output to 32 hz or so, and the SPL box is tuned for max output at 67hz, that is going to make a huge difference in the lanes at a SPL competition. The downfall here is that a pure SPL system is going to sound like shat for you to listen to on a daily basis. Decide what it is you are after, good sound that can play to a respectable level (which you have) or pure SPL (which you do not have).

The two rear vents are so that the pressure can escape from the vehicle when the air conditioning or heating system is used. If you value your fan, you will be unblocking those vents that you sealed. Go turn the heater fan on and wait a bit, see if it sounds different or laboured to operate. This is what happens when the cabin cannot release the pressure it is being fed by the climate control system. End result is a blown climate control fan.

^^They also relieve pressure to aid in door closing.

here's the thread that i showed my box for the first time, it has a few pics

https://www.rx8club.com/series-i-interior-audio-electronics-24/soundstream-t4-15-8-a-75494/

thanks for the help guys

-steakboy

I actually had an idea, please tell me what you think. the back of the box sticks up past the pass through a bit. If I put a port into that area, do you think it would be able to draw enough air from inside the cabin to help the sub? sorry, no pics at this time of the particular area in which im referring.

-Steakboy

I must not be getting the picture. I am assuming you have tried it w/ the passthrough door removed. If it what I am picturing, this would give you your answer.

Subs dont draw air at all. In fact the less air space you have is usally better. A port is only to delay the sound from the backside of the woofer so that you hear it at the same time as the front side. Im going to meter my car tonight with a single 10" w7 i let you guys know what happens. Oh yea my fan does suck with the vents closed but if i put it on recirculate it seems to be fine. And my ears pop a little when i close my doors.

Spl
 

My car hit a 134.6 witch is about what i expected to hit. Agian thats with a single 10w7 sealed powered w/a 500/1 in a sealed box tuned to the spec hz. level for sound quality my sub is in the recessed part of the trunk right now facing the drivers side. Once i get both subs and amps put in it should be much louder.

Steakboy, the reason i want my passthrough open is to let pressure from the sub into the cabin rather than to feed air to the sub. Idealy you would want your subs to face the rear of the trunk and sound waves would bounce off of that twards the front then off the windshield to give you peak spl.

This is misleading. Depending on what you mean by "less air space". If you are referring to "air space" inside the box, smaller is NOT better if you go below what the woofer is designed for. This is definitely not correct if you are refering to "air space" outside the box (i.e. inside the trunk). If a small area is totally sealed and there is no where for the pressure to go, it will find the path w/ least resistance. In the case of our small trunks.....probably going to be the speakers in the rear deck. If it does not directly blow the speakers, it will definitely degrade the sound quality.

Yes, I have my passthrough open to allow the pressure from the sub through. As you can see from the pictures I linked to, the sub is facing directly up against the trunklid. Unfortunately that is about all you can do with a 15 in sub that requires a 4.25 Cu. Ft. box. But here's the problem with the passthrough I doubt yopu have; my box is so large, that the passthrough opening is about half of the size it normally is. soon I'll be taking to the guys who designed the box to have a look at it and possibly redesign it. I don't want that to be the solution because I love the look of the box (As does many people). Maybe I'll try the other spec (high fidelity instead of high output) box because it is smaller. I dunno, I'm kinda dumbfounded and frustrated and even almost ready to just remove it all for now and concentrate on other parts of the car.

-Steakboy

i was referring to air space in the car. And i agree on the rear speakers to help that im enclosing the back side of the speakers and i remove the passthrough cover when i plan on turning it up alot.

steakboy i wonder if a sealed smaller box facing the rear with the passthrough fully opened would by louder tough to say i wanted to do ported but it was just to tough to make it all fit. Im still wondering how you got all that in your trunk?

From what I was told, it was pieced in. It was the only way.

-Steakboy

Well man your system is the best i think ive seen on the forum so far keep me updated!

Finally
 

Got both of my dub 7s in just in time for a bass comp. now i need to take them back out and do some fiberglassing. Well let me know if any of you are louder but my best yesterday was a 142.0

thats an awesome push. with a little tuning and letting the subs break in, you should be able to bump a few dbs

-Steakboy

hopefully I may go to a single sub ported due to voltage issues

what company sub are you gunna use? what size?

I wanna change mine up, but I love it soo much. It gets alot of attention too, so I'm torn.

-Steakboy

that's a big enclosure. my best official yet 146,7 on termlab using a vented enclosure 120L. Autotek MX5000 amp. 2 X 12'' C.V vmax subs. @ 1 ohm. ''when 8's get abused'' damn i miss db drags....

Please tell me that when you're driving around in your car you are not getting even remotely near those volume levels. Aside from the fact that some of you are getting past the threshold of pain you are doing incredible amounts of damage to your ears.