Spl

[FullSink18]

I have a 10"(600) and 1 12"(1100) plus 6x9 at like 100w, 6 1/2 at 40watt All audiobahn except 2 kenwood amps that run the speakers.

I am running the 12 at only like 750watt and the 10 at 600watt. I was wondering if 120db was good or what not.

Also i was wondering how sound off comps. work do they put you into class if so based on what. And what all do u have to do to get into them.

Well I have Hit 140 db (Metered) with my 2 10" W6's. I was only running about 225 Watts to each. That by todays standards is still low. In the street class there are guys hitting high 140's with a single 12", and low to mid 150's with dual 12" drivers. In the dbDRA Street 1-2.

Honestly I would say chuck the 10 and get another 12" and build a better box for the 2 12".

With two 12" SUbs in dbDRA You would be in possibly Street 1-2 class, depending on your system. In IASCA's IDBL you would be under the Stock 161 - 260 square inches (no walls) With two 12"

[FullSink18]

well my box design goes like this i have the 12 face out toward the trunk, the ten is completely concealed with the woofer pushing towards the 12. The idea was for the 10 to feed air to the 12 giveing it more power. any thoughts

[Accord Man]

120db wont get you far in SPL rounds.

About your setup do you have any pics? Getting 2 different size (even brand) subs to work together is usually a pain in the butt.
From what I understand the 10" is directly in front (and perfectly parallel) of the 12", right ? How far apart are they?

Once I was experimenting with 12" solo-barics.. And when fast to face, about 18" apart, I was able to kill sound.. Like less than 1/10 of the bass was coming out.. And the subs were working at full travel (with roughly 600w rms on each sub).. Freaky huh?!

Originally posted by FullSink18
well my box design goes like this i have the 12 face out toward the trunk, the ten is completely concealed with the woofer pushing towards the 12. The idea was for the 10 to feed air to the 12 giveing it more power. any thoughts

If you can get the 10" away from the 12". You might be getting some cancellation due to the drivers facing or even trying a gross push-push isobarak suetup. If you have a means to measure the SPL I would advise you try running one driver and see what it does.

[Racing Rice]

Wow, 120db is freakin low! Ive seen two 8s in a truckbox behind the seat of a truck hit 124db. I would definatly get the 10 away from the 12s and see what happens.

[FullSink18]

what this crappy drawing is try to show is my box. The cone of the 10 faces the magnet of the 12. It was suposed to push more air to the 12 makeing it louder. The 10 is completly hidden in the box and the just the cone of the 12 is out

[Racing Rice]

Im no expert on boxes, but that doesnt make much sense to me. :o

[FullSink18]

I am going to redesign it with 2 12s at 1000 watts each. The box will be sloped with subs pointing up and out the trunk.

Originally posted by Accord Man

Once I was experimenting with 12" solo-barics.. And when fast to face, about 18" apart, I was able to kill sound.. Like less than 1/10 of the bass was coming out.. And the subs were working at full travel (with roughly 600w rms on each sub).. Freaky huh?!

The reason the sound was killed is because the sound waves simply canceled each other out. Since they were the same brand/size subs, they were probably emmiting a near exact sound wave. If two soundwaves with the same frequencies/wavelengths hit each other head on (each moving in an opposite direction from the other), they will cancel each other out. If both waves were moving in the same direction and interesected, then the sound would be amplified.

(sorry for the long explanation, we just learned this in my highschool physics class, so it's fresh on my mind)

first of all, i dont know why you'd want to combine sub sizes. second, i'm not sure that the 10 "feeding" the 12 air is a good idea. i'm assuming that you have the 12 getting power, and the 10 getting power to. this is a good concept if you're using a passive driver though. a passive driver setup is one driver that has power going to it, sharing a common chamber with a passive driver, or one that isn't hooked up and doesn't have a magnet or terminals. since they're sharing a chamber, the air that the driver with power going to it moves also moves the other driver.


you on the other hand have two different sub sizes, moving different amounts of air. thats your first mistake. i wouldn't do that personally because since you're moving two different amounts of air, i think that sounds bad. theres cancellation.

secondly, there is no passive driver. you have both subs getting power to them. they both take strokes at the same time. so if they're both taking an outstroke, theoretically the air that the 10 is pushing behind the 12 thats already on an outstroke, could push the 12 past it's xmax taking these two enclosure concepts into consideration. hope that makes sense

[Racing Rice]

Originally posted by Prophcy0
If both waves were moving in the same direction and interesected, then the sound would be amplified.

So you mean like in an isobaric setup with the subs in 180 degree phase?

[FullSink18]

Hmmm we talked abou that in physics too. Thats why i borrowed their db meter just to see. I have also come to the conclusion that my current setup is crap. But thanks to all of you i can change this and be ready to compete this summer.

both waves were moving in the same direction and interesected, then the sound would be amplified.

going with this idea i think i will build a box with 2 12s. That have a slight angle toward each other so their sound wont hit and cancel but will travel a little ways and then intersect. plus i will angle the box to point up and out of the trunk. This will hopefully make alot more noise. Please let me know if there any problems or suggestions to this box idea.

[ShagginJet]

I'm not sure what meter you used or how you set it up, but there is usually a special setup and meter that is used when they messure all this at competitions. You might want to pay the entry fee, get tested, just to see if your meter is as accurate.

Originally posted by FullSink18
Hmmm we talked abou that in physics too. Thats why i borrowed their db meter just to see. I have also come to the conclusion that my current setup is crap. But thanks to all of you i can change this and be ready to compete this summer.



going with this idea i think i will build a box with 2 12s. That have a slight angle toward each other so their sound wont hit and cancel but will travel a little ways and then intersect. plus i will angle the box to point up and out of the trunk. This will hopefully make alot more noise. Please let me know if there any problems or suggestions to this box idea.

You don't necessarily have to angle the subs at each other, since sound waves spread out into all 3 dimenstions. just face them both straight out towards the trunk and the trunk will act as a sounding board (it vibrates at the same frequencies as the subs, which amplifies the sound). You can play around with angles if you want, but it shouldn't matter that much.

[Accord Man]

Originally posted by Prophcy0
The reason the sound was killed is because the sound waves simply canceled each other out. Since they were the same brand/size subs, they were probably emmiting a near exact sound wave. If two soundwaves with the same frequencies/wavelengths hit each other head on (each moving in an opposite direction from the other), they will cancel each other out. If both waves were moving in the same direction and interesected, then the sound would be amplified.

(sorry for the long explanation, we just learned this in my highschool physics class, so it's fresh on my mind)

After reading your post I just about fell off my chair.. But hey, this is a discussion board.. So its cool.. Lets talk a little about bass.

Sound cancellation isn’t as simple/obvious as you seem to think.. Especially when talking about bass.

High school phys has taught you right.. But that theory only applies to directional waveforms (waveforms that are directional) Is bass directional?

How would you go about canceling a bass wave? Invert the sine. And how do we do that? Reverse the phasing of the sub or reflecting the wave. I wont comment on phasing since that’s pretty obvious.. Reflecting waves are a commonly overlooked source of bass loss (in a 2+ sub setup).

i.e. : 2 subs are firing towards the trunk, both wave patterns are almost perfectly parallel. When the waveform is reflected off the trunk, the parallelism is often lost.. Then guess what happens..?




Now that that’s settled, a quick note on the direction to face the subs.. In general, for optimal performance, for a ported setup = facing front, for a sealed setup = facing rear. The trunk lid does NOT act as a sounding board. It simply reflects the bass wave. And the less it vibrates, the better it is (otherwise you are simply loosing bass).




For those giving advice, please only do so if you know what you're talking about.. No good can come when the blind lead the blind.

I apologize. I knew someone with more knowledge about sound would come along and say I was completely wrong. When I asked my physics teacher (who actually knows physics and doesn't just teach by the book) why you get more bass when you face a sub towards the trunk, he told me that the trunk acts as a sounding board. I guess he was wrong.

And about the whole cancellation thing - I should've known that it wouldn't be that simple.

[Accord Man]

Dont worry dude, its alright.. From time to time a newbie will come along thinking he's got it all figured out ( Audio wise).. I thought you were that person, but your aren't..

I obviously have great pleasure in feasting off the newbie's head.. Then the noob gets pissed and asks to continue the debate on a forum he his more familiar with (usually 1 of the big audio message boards), thinking I'm not a member there, so the people of that board will support what he says rather than what I say.. Until the noob realizes I'm one of the original members of that boards, but I simply used a screen name different from Accord Man..
Typical scenario.

There are many people who know much more than me about audio.. And thats great, but I dont like when someone thinks they'Re the shizznit.

Hey FullSink18 What subs will you be getting? Are youplanning on competeing? And would that be db draps, or Sound Quality? I may have some helpful pointers I could give ya.

[FullSink18]

Well I will be using 2 audiobahn 12s that could push 1100watts each. I want to compete really bad it would be in spl of course but maybe also in clarity. I have to audiobahn amps that push 600watts at 2ohmns, which is what im running my crappy box set up now. I want to run that amps a full bore that would be at 1ohmn CAN THAT BE DONE? Also for a new box set up I want to have two 12s on a slight angle facing up and out towards the trunk. I am definatily new to all this so i appreciate all the help from u you guys. So ACCORD MAN you will be a great help. I need more advice on this box setup. Since u may have read from the start of this form my bad box setup trial one.