Contour Enthusiasts Group Archives Forums Modifications Audio Finally Decided

Ok, after reading the forum for a couple months and finally getting the mods done on my car I decided to hit the most lacking thing I think I have ever heard of, the stock system in my car.. So after much research here it goes, what do ya'll think?
HU - Sony ESCDX - M670
2 pr Boston Acoustic RC820 - 5x7s with tweet
3 JL W6 10's
MTX Thunder 6500D (subs)
MTX RT4340 for the seps

Now the question is I want to install this myself, and after reading many many months of the forum I pretty much got a very good idea on how to set it all up, I just want to know the MTX Thunder 6500D is rated I believe at 250 x 1 at 4 ohms. It is rated at 500 x 1 at 2 ohms.. Question is how do I lower the ohm rating down to 2 ohms?

1998 Black SVT
no res
Borla exhaust
K & N Filter
Eibach springs
20% tint all around
new engine at 42,000 w/ 12,000 on the new 00 motor

If I am right, I believe you would have to bridge the amp parrallel with 2 4 ohm speakers in order to get it to 2 ohms.

To run the amp at 2ohms, here are the easiest and most common choices:

(1) Use 2ohm speakers and hook them up in stereo (normal). If your amp is rated at 500x1 @2ohms, each speaker will be receiving approximately 250w (rated).

(2) Bridge a 4ohm circuit (hook up the speakers parallel, series, whatever you want so that the total impedence of the circuit is 4ohms) to the amp. In essence, you're combining the amps 2 channels into 1 channel. Each channel will "see" half of the ohm load, 2ohms in this case. You divide the total watts by number of speakers in the circuit to get the approximate power each will see. If you've got 2 speaks, each one will get ~250w.

I prefer bridging the amp to a 4ohm circuit (method #2).

Alright, now that we've got through that, here's a little warning. NEVER EVER EVER bridge a 2ohm load (such as two 4ohm speaks in parallel) to an amp that is not rated to run at 2ohm mono (same as 1ohm in stereo).

You will fry your amp. It might not be today or tomorrow (or maybe ever if the mfgr REALLY underrates their amps), but there is a great chance that it will damage your system.

I'm pretty sure that MTX amp won't like a 2ohm mono/1ohm stereo load. They are small in size and run hot, which really increase the chance of burning something up.


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'99 SVT
Silver Frost/Midnight Blue

About as stock as they come these days.

"Drop a gear and disappear..."

Well, I think your 6500D is a monoblock amp, correct? If so it can't be "bridged". It will effectively see the total speaker impedence wired to it instead of half of it as when a two channel amp is "bridged mono".
The W6 speakers are dual 6ohm voice coil subs. If you want to show a monoblock amp 2ohms with these your best bet is to use ONE voice coil per sub, and wire all three in parallel.

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blk.99svt
n.e.Ohio

Scooby757 -
Yes the amp is a monoblock amp, and I will wire the subs in parallel using one voice coil. Building the box and amp rack throughout the week, will keep you updated. I do appreciate it, thanks again.

P.S. Dynomated the hell out of the trunk and used the dynomat door kits, thanks all for the how-tos on it. Now to figure out how to stop that damn 3rd brake light from rattling like everyone seems to have.. Remove it maybe??

You're welcome. I haven't really taken a close look at the brake light housing, but if you can take it apart without too much hassel then you might try pressing some non- hardening modeling clay into the underside of it to add mass and stop the rattle. Just a thought, I'll have to check mine out.

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blk.99svt
n.e.Ohio

WHOOO STOP RIGHT THERE! USING JUST ONE COIL IS NOT AN OPTION!!!

Now that I have your attention, wiring up only one coil will ruin the JL woofers, check the manuals it also voids your warranty (most manufacture say that). You will be over working the coil with power, it will be trying to move the whole woofer and the other coil/winding (the second coil is now dead weight) It was not designed for this. Not only is it bad but you will be chaging the woofer's specs.

Just looked up JL's site, take a lookie
http://www.jlaudio.com/tutorials/dvc/howWired.html

You may just have to sereis parrallel (sp?) the woofers and leave it at 4ohm mono. Or you can run two woofers at 1.5 ohm, that amp may handle that.

I'm curious why JL would void a warranty for only using one coil? I don't doubt that their literature states something like that but why? While it is not common practice, using one coil is an perfectly acceptable method, as long as you realize that you are halving the power handling and some other parameters.

If I were you, I would either get the JL10W3 (that is if you want brand name subs, if name recognition is not important as sound quality let me know) which i believe comes in more voice coil arrangements.

Actually, if you decide to get the 10W6, attach them so the amp sees the 4 ohm load. You will have 250watts to three subs. This should be more than enough, unless you are trying to make interior parts fall off from the vibration. You would probably get away with two W6s with all VC wired in parallel for a 1.5 ohm, but as mentioned earlier, anytime you dip below the amps ratings you are looking for trouble. Plus, you would not hear the difference between 2 subs with 250 watts to each, or 3 subs with 250 watts total.

On there site (JL's ) I did not see them stating it voiding your warranty, but it may be i the manual. I do know that Rocdford Fosgate did this. Only using one coil (if you guys didnt check out JL's site) Will over work the coil you are powering. As it tries to move the woofer the second coil is dead weight, this is added mass that the manuacture did not intend this woofer to receive causes it to strain (it will also have less xmax, since the magnetical field wil be greater than expected thus changing parameters of the woofer too.)

Here is a whole FAQ on DVC's

http://www.jlaudio.com/tutorials/dvc/index.html

Check out the one "What is a dual voice coil speaker"
Maybe you will see what I mean by one coil now being dead weight.

Somewhat interesting read. I still contend that when using them in the correct manner, only using one coil will not harm the woofer. It'll drop the effeciency of the woofer obviously. Let me try to find some more info on the subject.