Random speaker (subs) questions...now with pic

[subawhatsubawho]

If you check out my sig you will see that it says (6) JBL DVC 12 inch subs. This is only half true as I only have (3) DVC and (3) SVC subs.

I am in the process of building a box that will hold all of these subs.

My questions to the engineering gurus"

1. Should each speaker have it's own chamber. (I build them like that anyways)

2. Can sine waves cancel each other out?

3. If I cut out the plastic on the side of the rear (interior) strut tower, can I squeeze 38 inches out of it?


Here is what is left that needs to be done.

1. Cut and install (1) side panel of box

2. Cut and install (5) divider walls of box.

3. Caulk entire box with liqued nails

4. Install rear of box (bottom)

5. Install speakers with wires

6. Install Polly-fill

7. Attach to amps

8. As MAgicMike would say.....feel the bass!!

[dzx]

To answer question 1, they don't all have to have their own chamber but it will sound a lot cleaner.

If you port the box it will be a lot louder but it will also not have as clean a sound.

[Legacy777]

Sine waves can cancel each other out if they're 180 deg out of phase from each other. So if your polarity is the same for both subs, you should be fine.

[Bheinen74]

in your order of steps, you need to switch steps 5 and 6
thats all i can help with here

[Threshld1]

if your going sealed i would put them all in seperate chambers though make sure they are as close to the same volume as you can. Otherwise this will give you a slightly different response for each sub which could be avoided by one chamber. Ive done both single and shared volumes for sealed and ported boxes and ive found sealed should be seperate and ported together. but in theory if you fabricate it symetricaly it shouldnt matter.

As far as cancelation yes it happens all the time. make sure you have all of them on the same general plane and same phase wirring. it comes down to basic wave motion from physics, google.com

best of luck, 6 drivers should give you some good pounding. Im itching for it to be warm enough here to start fiberglassing and get my comp 15" 2200watts rms 300oz magnet beast in.

Post pics of process and finished

[subawhatsubawho]

DOH!!! You are right. I was soooo tired when I wrote that.

[BAC5.2]

So you are going to build a box with individual boxes inside it (one for each sub)?

I want pics!

My Forester needs a sub. A single 10 should be enough for what I am looking for though.

[magicmike]

I would not combine dvc's with svc's in one box on the same plane or even in the same car. you shouldn'r even amp the subs with different sources either. I'm at work so I dont want to elaborate further but I can go on and on if someone wants to hear...

[subawhatsubawho]

I am building a 6 chamber sub box. The three DVC subs will be ran to produce a 2.67 ohm load.

The three SVC's will be wired to produce a 1.34 ohm load.

The 3 DVC's will be powerd by a monoblock amp as will the 3 SVC's. Both different amps.

I really don't forsee a problem...Whats your say in the matter Mike?

[Threshld1]

I would not combine dvc's with svc's in one box on the same plane or even in the same car. you shouldn'r even amp the subs with different sources either. I'm at work so I dont want to elaborate further but I can go on and on if someone wants to hear...

uh what does it matter how many VC's there are on your subs if they are getting the same signal, only thing VC's do is allow you a choice when trying to impedance match your subs to your amps. futhurmore what does it matter as they will be in independent boxes aswell

also he never says different sources just multiple amps which hes not even doing any strapping across coils so there are no issues at all provided he sets his gains and eq's and x-overs correctly.

[magicmike]

you write quite eloquently for not knowing what your talking about...

I'll repost later when I have a chance to link to some sources

[subawhatsubawho]

Now behave Mike...Don't make me roll up in your driveway with my SVC's and DVC's and crank your famous speaker terror upper.

[Threshld1]

thats like saying you cant run your speakers with those DVC subs cause they are SVC... right... let me know when you find those sources for "it wont work"

[subawhatsubawho]

Now now boys.

Mike and I go back a bit. Not big bit...but a bit. I am always open to peoples thoughts but only if they know what they are talking about. I'm not sying that you (threshld1) don't what you are talking about but I know for a fact that Mike was an installer for a stereo shop as was I and the DVC/SVC was something I didn't know about.

I just wish he would hurry it up before I finish this box.

[Binford]

you write quite eloquently for not knowing what your talking about...

I'll repost later when I have a chance to link to some sources

Listen to Mike; don't mix. I'm on his side.

[Threshld1]

Alright lets look at the basics here,
lets say you have 2 amps that do say 300 watts rms x 1 chan @ 4 ohms
and then lets say you have a DVC 2 ohm sub. you wire it in series to achive a 4ohm load providing the speaker with 300 watts RMS @ 4 ohms from our amp
now lets say you have a SVC 4 ohm and you wire that up to the other amp. you get the same 300 watts rms @4 ohms
both subs are seeing the same amount of power

now lets say you take a sub output signal from your deck and split it to the 2 amps (obviously you loose half your effective pre-out power to each amp but if you run 2 amps that is what happens, and this is totaly independent of the load on the output stage of the amp). So you set your gains and x-over on the amps independly to the same output level(should be able to match them with a scope)...

how is it going to be any different between the two in output? and then as this is directly related to what subawhatsubawho is trying to do except he has more than 1 sub on each amp (lowering the amount of power to each speaker) how is there any affect on your output???

The only differances as far as i know between a SVC and DVC sub is your choice for impedance matching your amp and a minute Qts differance but when your running 6 drivers you arent going for precise sound anyways.

My point is that just because you worked in a shop doesnt mean that you can simply say it wont work. I have plenty of experiance installing/using mobile audio equipment too and i work for Bose Corp, whats your point....
Ill talk with a tech here and get some solid information either way but without any technical data what your saying makes no sense.

[subawhatsubawho]

Hmmmmm....now that you said Bose....you have my attention.

I have a Bose wave radio and that thing sounds sweeet. It set me back $400.00 but it is worth it.

[Binford]

Hmmmm......Bose........Too tinny for my taste.

[subawhatsubawho]

Small...yet powerfull. They take the sound and just make a stage out of it...If angled properly it's like being there.

There is Bose outlet store not far from my house.

[Binford]

I am building a 6 chamber sub box. The three DVC subs will be ran to produce a 2.67 ohm load.

The three SVC's will be wired to produce a 1.34 ohm load.

Running with different ohm loads to different "sets" of subs will change the amount of power to each. The "set" with a lower ohm load will have more power running to it. The "set" with a higher ohm load will run more effiecently, with less power to it. Adjusting the gains is not the way to fix this.

I'm sure you can throw all this in, and make it sound alright, or even loud, but you'd be in the category of "jerry" rigging it. It's like putting different brands of tires front to back on your AWD. Even though they SAY they're the same size, and you can put them on and drive with everything seeming to be OK, how do you think your center diff would like it being a little off?

[subawhatsubawho]

Please keep in mind I am running 2 different amps. (1) amp just for the DVC's and (1) just for the SVC's.

The only thing I am concerned about is the amps making power and the speakers making bass. I am trying to create a large sound pressure level in my car. Unless the sine waves are going to cancel each other out I don;t think there is much of an argument. I am using 3/4inch MDF with heavy duty liquid nails and not to mention plenty of bracing to prevent flexiing. Don;t think for one second that I plan on keeping those wimpy amps. I will eventually be running (1) JBL monoblock for each DVC and a (1) JBL monoblock to power all (3) SVC's.

Unless I read that running the speakers the way I am, I will most likely keep chugging along. It's not like putting a cat and a dog in the same car....is it?

From all my years experinece I know that when I face the front of the speaker to the back of the vehicle I get more bass. I know they say you should "load" the speaker for the type of music you listen too. I listen to metal and bass so I want the boom. My only concern is with a box this big, if I install it with the speakers facing up , I am basically sending all the bass to the ground. If I stand it up I will most likely get the bass I desire but then it will be there for the world to see. Here in FL you can't tinit youir windows too dark so thats out, I guees I will either live with the bad bass unber the cargo cover or invest in a good alarm.

[Binford]

Going for SPL, huh? Competing? The best I've done at a competition was 154.6 DB with four 10" Kicker L7's (the original squares) powered by a Kicker ZR1000 in a wall in a 1995 S-10 extended cab. I know a little about competing, thinking I may get back into it.

I realize your running two amps. With both amps driving different ohm loads, there will be a difference of power, and effiecency, between the two. The only way to "equalize" this difference will be to adjust the gains until you "think" they're equal. This is not the purpose of a gain adjustment. They are NOT volume knobs for your bass like so many people tend to use them for. This, also, will not truly equalize the two "sets" of subs to one another, and may cuase cancellation without you even knowing it. It may "sound" lounder, but if you are truly going for for SPL, what sounds loud is often decieving. There is no way anyone can estimate what kind of SPL levels a system will put out just by listening to it. I really have a rant about this area of SPL. If this is just for bumpin' down the boulevard, go for it. It won't be "right", but you may very well not notice that. However, remember my analogy above with the tires. You may develop a pressure difference between the subs and smoke one or two of 'em. But hey, that's what competitions are all about!

[Binford]

You must have added to your post above, or I missed that last paragraph. In a wagon, subs pointing up=loud(boom). From my experience at least.

[subawhatsubawho]

I added...

I pointed my (2) 12's up and I wasn't happy with the sound...thats why I tried facing them towards the back. I guess I will just have to do a trial and error and see what sounds best. I'm not doing it to compete, I just wantto have the level of bass in my car that I can enjoy. I think I might hook up just the DVC's then the SVC's and see how they sound by themsleves. Time will tell.

My friend Ronnie has eighteen 18's in a chevy astrovan and that bitch pounds. He stopped competing years ago but he still has the van and will take it to local car shows just to see the look on peoples faces. I used to go with him when he would compete...I was one of the guys holding the door shut.

Unlike some people I know what gain is for and I know how to use it properly. I also know how to use a decible meter and an RTA.

I also don't use those so called crossovers that are built into the amps. Those things are good if you have your subs in a best buy bandpass box. (Not in my car)

[Bheinen74]

I am pretty familiar with this type stuff too.
I currently run an old school Kicker S8L7 dual 4 ohm voice coil, wired for a 2 ohm load, facing down, into the spare tire. If you open the rear hatch of my wagon, you cant tell there is anything there. It maybe hits 121 Db SPL, with it running off a Kicker 400 watt mono sub amp. Even thogh the SPL is low, it sounds real clean, awesome in the vehicle. It doesn't produce the deep bass to hear from miles away though. Also have two sets of Polk Audio separate components 6.5 inch with separate tweets, running with a kicker KX125.2 amp.

I used to rock my CRX Si with two twelves (crunch) and cheapy Rockford 125 Wattt amp and it hit 125.7 that is an official IASCA certified competition.

moral here is, I dont know.
but...
I am going to rock with two kicker s12l7's solobaric square type in my newest ride, using my kicker kx 400.1 amp. I bet it will wake up my town when i turn some juice to it. just my intuition that it will be too loud, and I will just migrate down to a 8 inch in the spare tire again. (kicker s8l7 are awesome, it handles 1500 watts RMS easily, for an 8 inch speaker, problem is it takes about 3 months to break the woofer in, for full movement of the cone and coils.)
Oh, and i finally gave out on using a plexigalss cover for this. The woofer blew apart the plexigalss cover not just once, not twice, but three times, so I just ripped it off and put on MDF. I use white GE silicone window and door frame caulking for my joints. Dont go to Home Depot and ask for the black caulk.. lol