sub firing discussion

[KARLEON 10+ year member]

Well today wasnt hectic at all on the shipping docks at work and i was just thinking about sub firing directions. I was wondering if any of you had any links that explain sound, soundwaves, bass waves, acoustics, what ever..

I have searched the topic. But i guess i generally see people quoting other people and have no proof or facts to back up their reasoning. Like how a certain tone needs x amount of room to fully develop.

Note, this isnt a topic of which way to fire subs....but more like facts and articles explaining WHY and how those things work. I hope im making sense.

Click to read more...

 

[squeak9798 5,000+ posts]

If bass needed X amount of room to develop, we'd all be driving around in buses because a full length bass wave won't fit in our car.

Here is one article: http://www.installer.com/tech/aiming.html

Don't know how much to believe from this guy. Sometimes he sounds smart (like in that article), but sometimes he just totally misses the boat (like in the gain setting article)

 

[KARLEON 10+ year member]

ha, yea i came across that article too. When i was reading the gain setting article and he was referring to it as a volume, im like yea right... And that article is what made me start wondering how sound waves really work. Like for a certain tone, does it really take x amount of length for it to fully develop. Or after the wave fully develops (after that certain length), at the point thats when it starts to decrease and loose volume? Or does sound waves loose it intenseness period as it travels.

Hmmmm, i need to find all the myths and rumors about how sound travels and work and post them and people can see all the things im talking about. Because i have yet to try it out, but i still believe (just from my readings, not from actual testing) that an enclosure firing forward and properly completely sealed off from the trunk can sound and be just as loud as one firing towards the rear... But i have no idea thus my reasoning for wanting to reveal these rumors and myths to see if indeed they are actually true.

 

[KARLEON 10+ year member]

Plus, if im not mistaken, in his testings he flipped the box around and fired the forward without sealing them off from the trunk. Now i have done that with my dual magnum D2s. and no it wasnt as loud as rear firing. Which i believe is what alot of people go by. I still didnt have a meter at hand, but by ear, it was definately not as loud as firing towards the rear. But im starting to wonder if it was completely sealed off what kind of difference it would have made.

 

[InhumanAcura 5,000+ posts]

Every frequency has a certain legnth. Brad found a calculator off google that you just plug in the frequency and someother variable and it gives you the legnth of the wave.

If your just interested in learning thats cool, but its not something you need to worry about unless your trying to tune a wall. The concept is to get that frequency to fully develop right at the sensor location.

On top of that you have to play with the volume and port to get the impendance rise as low as possible and still peak at the vehicle/installs resonant frequency...

Its a good topic, hopefully someone will shed some light on it...

 

[Damaso87 10+ year member]

Hmm...so basically the spl will vary with each different frequency, since the waves are a different lenth. Trying to create a box and positioning combo that will give you a perfect sounds is practically impossible, because of these different wavelengths. One can only make a box so accurate for a certain range of frequencies, anything other than that doesnt really matter.

(Just my opinion, i dont really know for sure, but putting 2 and 2 together...)

 

[InhumanAcura 5,000+ posts]

From what I understand (a very minute amount), you tune the box to the 1/4 or 3/4 wavelegnth (this obviously meaning 1/4 or 3/4's of the waves legnth) from the sensor loaction.

The vehicle we use peaks at 51hz, the legnth of a 51hz wave is ~25-30ft IIRC, so obviously 1/4 or 3/4's legnth of that from the port to the kickpanel is not going to happen...

Like I was trying to say, it doesnt really matter unless you have a wall.

 

[Damaso87 10+ year member]

Furthermore, what if youre playing at 32hz? The wavelength is going to be significantly different, and the 1/4 or 3/4 of a 51hz wave may not match up.

Bass isnt a constant 51hz wave all the time, every time (lets hope not) so you would have to factor in the variety of wavelengths that re being played.

 

[squeak9798 5,000+ posts]

Furthermore, what if youre playing at 32hz? The wavelength is going to be significantly different, and the 1/4 or 3/4 of a 51hz wave may not match up.
Bass isnt a constant 51hz wave all the time, every time (lets hope not) so you would have to factor in the variety of wavelengths that re being played.

Inhuman is talking about comp setups only. So yes, they would be playing 51hz all the time.

1/4 wave sounds nice....but in 3D reality with reflections and such, it hardly ever works out right (in comp vehicles). Back when I was into SPL, many of the competitors had stopped even worrying about the 1/4 wave theory.

 

[Damaso87 10+ year member]

Ohh, i see...i must have missed that. I thought he was referring to daily listening.

 

[InhumanAcura 5,000+ posts]

Inhuman is talking about comp setups only. So yes, they would be playing 51hz all the time.

1/4 wave sounds nice....but in 3D reality with reflections and such, it hardly ever works out right (in comp vehicles). Back when I was into SPL, many of the competitors had stopped even worrying about the 1/4 wave theory.

The competitor who informed me on what I do know has done very well with the 1/4wl theory //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif