Andy Tang

iTrader: (3)

I think the simple rule of thumb, is that 12" for depth, and 10" for punchy, quick bass!

I use to have two 10" which gave me a bit of both worlds! In my current install I'm looking at a 12" sub, but only because my musical tastes have changed slightly! Less dancey, dancey stuff and more Garage/Rap type stuff. I want the depth, that my old stereo use to struggle with!

Use the Sub out as that will allow you to control the bass from the head unit. I know that my Kenwood MD headunit can control the crossover point, the phase and the amount of bass!!

If you get the 10", you may think that it's not quite enough! At least with the 12", you can calm it down and still get the low bass that the 10" only dreams about!!

Just my personal opinions!
Andy

AndyHolmes

Hello all,

I have a Sony MD (MDX8500R), and I have just bought, but not picked up, an entry level ICE setup.

JBL 6.0c MKII front 6.5" + 1" component speakers.
JBL DA1002 Amp 2x150W / 1x300W RMS amp
JBL 12" Sub in a ported wedge box (comes as 1 unit).

I am not bothering with rear speakers as I rarely have rear passengers and I shall run the fronts from the headunit which is 4x50W rms.
The head unit has 2 pre-outs, a sub-out and a changer controller.

My music tastes are very wide, from Classical, Pink Floyd through to acid house and even a bit of rap/D&B.

I am now thinking I should have bought a 10" sub, any advice ?

Also, would I cable the amp from the sub-out or from the rear pre-out, the head unit has built in HPF and LPF on the outputs.

Thanks boys, this is my first attempt at a semi-decent setup so any help would be appreciated.

Andy Holmes

chiark

I'm running 2 10s, and there's loads of bass should you want it. I did run 2 twelves in a Fiesta, and that hurt. I was very, very young, so plead mitigating circumstances.

Nick.

ian/555

Is there any reason that you couldn't run one 12" and one 10" Sub in the same box, or even seperate boxes?

rockin'Ru

Yes there is.Say you're listening to a really kickin' cd and you punch up the bass;chances are,you like the combo of punch and thump of the 12".The 10" won't keep up and bottom out trying,adding a nasty distortion to the music.Unless you have individual control [xover and level control wise]it's not a good idea.
As for the 10 or 12" debate,imo,go with the 12".JBL's need lots of space,that's why you have a JBL in a small box that's PORTED.I almost bought a pair of 1800gt's until I ran the t/s through a program and each 18" woofer needed 11 cubes to be right.
Take that JBL and put it in a 2.0 sealed box and give it a try.If you're not happy,put some styrafoam in it and try again.
I have 4 MTX 12" 6000's,each in a 1.25 cube sealed,and listening to Bad Company or Kid rock makes no diff,as long as you have the control over them.They'll adjust to anything.
Just a crazy american's two cents.

chiark

I'm with rockin on this one.

Having two sub systems doesn't work, even if using the same size drivers. Subs reproduce frequencies in a different manner, and it sounds pants.

A friend didn't believe this, and went for two 12s and two 10s. It sounded, erm, not good. Even he grudgingly agreed.

Shame really, as it's the obvious answer to use a 10 and a 12 (or 15)...

pat

chiark,

I'm not convinced about multi-sub systems not working. I've played with more combinations than I care to remember. One of the most convincing I've had to date (in a house) was a combo of 18s, 12s and 8s... it took a long time to warm up, about 30 minutes to 1 hour at a moderate level (about 100dB), then it was as sweet as anything. The 18s are earth-shattering, I measured over 120dB at 20Hz, at 35Hz it was off the scale (over 130 dB). Once warm it was run about 110dB which meant it wasn't twiddling its thumbs but there was still plenty of dynamic headroom. Damn I miss that house :-) It was there that I messed about with negative impedance output stages, got my damping factor close to infinity, the control was scary, the cones just would not move if "tapped", it was like punching a brick wall

Anyway, back to cars, I think that a pair (or more) of differently sized subs should work OK, as long as there is a sufficiently decent crossover (active, of course!) network. I would go with sealed enclosures, although ultimately they won't go as deep they should help reduce any intermodulation distortion resulting from running two subs. I've used a pair of 10s and a 15 in a Scoob and it does work quite well, but it does take a bit of setting up!

As for embarassing stories, I did once run an 18 in a Pug 205. But I was young and foolish. Now I'm not so young but still very foolish

Cheers,

Pat.

kryten

In a car (as opposed to the house), you've got more far problems to deal with.

The speakers are almost never on-axis, so its the reflected sounds you hear, some of which are delayed due to the reflection's longer path length.

The biggest problem with multi sub installs is cancellation at certain frequencies. Even two subs the same can cause problems if not installed with this in mind.

Saying that, a combination that I have heard working was using 8" as a midbass/sub up front and then 12" for sub from the boot, though the amount of time setting the system up and tweaking the EQ was frightening!

Most people's reasoning for wanting to use multiple sizes is low end extension, but a properly designed 12" system with plenty of amp power will go as low as needed. Pair of 10s is also a good solution - I just prefer the single sub.

The problem with most 15/18" drivers is they need _so_ much space, which they don't normally get as they are just shoved into whatever box the shop had - hence they often have _less_ low end extension that the smaller subs.....

Andy, you could try blocking up the port on the box - this will change the sound slightly and will probably cost you a couple of dB at the lowest end of the scale but may give you a better overall sound.

Oh and chipping in on the embarrasing front, I ran a pair of JBL 15" in a ported isobarik box from a pair of Kenwood 1021 modified amps - VERY loud but not that musical.....

rockin'Ru

These gents are right.You can get the same sound from a 10" in a large box as a 12" in a small/medium box.But the extra cone area of the 12" gives it a slight advantage in spl,and in some cases sq.The 12 is a great all around sub with many possabilities depending on the box.
I myself am a drum freak and run 4 12" subs in my hatchback.I've given them a year and two different boxes and am now going to experiment a little.

AndyHolmes

Well thanks for ALL your replies,

I am confused by most of them but what the hell !

My system is now in place and sounds ~OK. The 12" sub was awesome (all the my rear number plate rattled too much), but I much prefer a punchier bass and have therefore swapped the 12 for a 10 and I am much happier. I shall try covering the port to see what difference it makes.

My problem is now the impreza, EVERYTHING rattles especially the boot. What can be done about this. I believe that dynamat (?) is the way to go for the door panels. The boot, I doubt anything could stopp the rattles in there.

Cheers

Andy Holmes
ps I dont really rate the front JBL GT6.0c's I can't seem to find any mid bass in them at all?

chiark

Andy

It's damn difficult to stop the rattles. I've given up and admitted that it will just sound poo from the outside. I daresay lots of time with expanding foam, dynamat and experimentation would get you "deader".

Regarding the JBLs, here's a stupid question. Have you checked the phases of all the connections? If not, you may want to deliberately try putting one of the midbass drivers out of phase. It works in some cases, and not at all in others.

My Astra sounded better with one midbass out of phase with respect to the rest of the system.

Nick.

classicrs

Hi
I would recommend amping up your front speakers and also use a high-pass filter to take away the low bass. this will improve the sound, as for the rattling trim problem(the bane of all car audio installs) i have heard about the sound deadening foam but have never used it but it sounds like a good idea, dynamat works great as well.
I have the same problem with my 18" sub rattling everything including my eyeballs
cheers
duncan

herky

Try some sound deadening material like Dynamat or Fosgate Roadkill, not only will these tone down resonances but if you have a modded subie exhaust help with cabin noise. I myself like a well powered 12", it is better to be able to deliver more power to a speaker than to underpower it.