hey all, i have two alpine type s 10s in a sealed box in my 84 camaro with an alpine mrd-m300 mono amp, and in that car it was one of the loudest systems in my town(louder than most 12s)but i changed my system over to my honda accord 2door coupe for the winter and now i have about ¼ of the bass, ive tried facing the subs different ways and it just doesnt help, and ive messed with the eq on the amp and nothin has made it louder, when lookin at the subs they seem to be movin just as much as they did in my camaro. any help would be appreciated, thank you

 

start with the basics. Double check that your wiring is done right. Disconnect one sub and see if your bass gets louder. If so, you probably have them wired out of phase.

The shape of your honda will not provide quite as much SPL as a thirdgen, but you're only talking about a few dB difference. It's got to be related to the installation, not the car.

Well... that is if the new car is capable of supplying sufficient current to the amp.

 

Definitely sounds like you accidentally wired one sub out of phase. Take Jim's advice and disconnect one of the subs, I'd bet money that your system gets louder. If it does just reconnect the second sub the opposite way it was before. I've done this so many times it's not even funny.

 

yeah the subs are probably out of phase but also an accord is a trunk as to where a camaro is a hatch that makes a big difference

 

Not a "dropping to only 1/4 of the previous bass level" difference though.

 

- double post -

 

okay one question , what is out of phase?

 

It's when you wire one of your subwoofers backwards. When one moves in, the other moves out, which effectively cancels all of the low frequency sound.

 

couldnt it be that the hatchback glass in the camaro helped the bass sound louder in the smaller space, and now that you have more air space in the honda and the bass insnt reflecting off of the glass and pounding right at the back of your head. I know when I pop open my hatch and open the subs up to the more air space it takes a decrease in the pounding of the bass. Im prolly jus shootin at nothin but I thought I'd put in my 2 cents.

 

A hatchback will result in added output compared to a trunk car, but we're talking about a couple dBs, not "1/4 as loud" as he put it. If there's a drastic loss of output, there's a problem.

Opening your hatch causes a loss of bass because the inside of the car is so small that it actually behaves as a 2nd chamber of the sub enclosure, and when you open it up, it ruins the effect. Popping the trunk on a car will have a similar effect, but because your hatch is substantially larger than your trunk, it is more pronounced.

 

Thats why I run outlaw when I compete. Crack a window, or open a door, in an SPL system, and watch the numbers jump.

My 2 cents on the problem, if its not wiring, is to check the box seals. I had a seal blow out on one of my old systems, and I got virtually no noise from that sub. Just a thought.

 

And that's why IASCA won't allow it. If everybody's car isn't set up in an identical fashion, you really can't compare results. A properly tuned system will play just as loudly with the windows up as down... and when you get to the level that some IASCA cars compete at, you damn well have a properly tuned system to be competitive. When you get to ultra-high SPLs, you need the interior to be 100% airtight, otherwise the air won't be able to sufficiently pressurize.

 

That too. I actually seem to be having a lot of problems getting my system tuned right.... At one point, when I closed all the doors and windows, my sound levels dropped to about half. I'm still baffled by that. I adjusted my crossover frequency and it's not anywhere near as bad now, but there's still a noticable difference.

 

I don't remember exactly what the culprit is for that problem, but it's usually solved by a different box design. I think it has to do with making sure that the box design compliments the transfer function of the vehicle. An spl vehicle will be most efficient when the box is tuned so that its maximum output is at the same frequency as the vehicle's transfer function. With the windows down, the transfer function frequency changes and will cause diminished output with a system that's tuned properly.

I think.

If you're tuning for sound quality, I believe this whole theory goes out the window, because when you tune for sound quality, you aim for a flat response, which will of course be severely altered when a window is open.

 

Jim's right. The box isn't the right design for the car. Most cars boost 3db @ 50hz, but others wont. The ways to change that is:
1)redesign the box to have a higher Qtc (~1.1 may be ideal for your car).
2) create an obstruction to change the path of the waves. the waves are converging too far forward in the car, and the tunnel (interior)'s resonant frequency changes with the windows open. Basically - your waves from the subs aren't bouncing off enough surfaces, or the surfaces they are bouncing off of are absorbing more than reflecting.
3)position the box differently.
4)buy a different car