JBL extreme sub mod.

Not a bad idea about disconnecting the rear door woofers and connecting that to the sub. The rear door lower woofers (6.5") don't really make much bass anyways. You are leaving the upper door midtweets alone, right? You need those midtweets for rear passenger sound stage.

 

You don't need to disconnect the rear speakers to get the signal for the sub amp. You do need to make sure that the rear speakers are getting a full signal instead of one with a high pass filter (or otherwise modified signal) which sometimes happens with premium factory systems.

Yes, i've ran two 12s (JL Audio, Diamond Audio, Orion) with a 1500w Diamond Audio amp and a Diamond D9 amp (400 w) for the front mids/highs. You definitely need to use Dynamat and other rattle fix techniques.

I fried the big amp and have since dropped down to a 600w Arc Audio mini amp and single Orion 12 in a vented enclosure.

 

I'm adding a 12 inch sub this weekend - and I'm going to put the amp in the trunk compartment. Any ideas for a good ground? Can I hook it to the battery ground? I herd that's not a good idea. There are several bolts holding the HV battery in place I could ground to - but I'm not sure if that's the best idea.

 

Use the negative battery terminal or where the negative cable grounds to the chassis.

 

The MS-8 will totally sum & de-eq the signal coming from the factory JBL amp. It will also then act as an 8-channel active electronic cross-over, time-aligner, and auto-eq....if you don't like the result of the auto-tuning, it will allow you to shape the sound any way you like. You really only need to use one of the 8 channels of output for input to your sub amp...you would then have 7 channels left to feed to separate amp channels for your mids & highs. What do you plan on doing for mids & highs? You should easily be able to keep using the rear speakers, either off of the MS-8 directly or the factory amp or an aftermarket amp.
Can you tell I'm jealous that you're getting an MS-8? I've had my eye on one for months.

 

I believe that you are mostly correct. You would take all eight channels of output from the factory amp and feed them as input to the MS-8 (although a lengthy thread on DIYMA.com suggests that you really only need front left, front right, & sub as inputs and the MS-8 does the rest). You probably wouldn't want to run both the MS-8 and output from the factory amp to speakers simultaneously...the MS-8 would likely get very confused as to why it was unable to adjust the channels not coming from its outputs.

The reason I asked about what aftermarket speaker setup you were planning to run was in case it used passive crossovers, in which case you wouldn't need to run all eight channels. My suggestion would be to run the front stage as two way active (using 4 channels of output off the MS-8) then use one channel for output to a sub amp. If you absolutely have to have rear speakers playing, you could either replace the factory drivers with a simple coaxial 6.5" in the lower door or run components using a passive crossover.

 

Yeah, i would have the rear midtweets operational too...for the rear passenger's soundstage. Otherwise, the soundstage is too far in front...and the rear passengers will mostly just hear bass (from the rear massive subs) more than actual music.

But, i think that GeoGeek has a good point about upgrading your front speakers. Since you're doing all this, it might be a good idea to go all out! Get a good component speaker...and connect the tweeter to one channel of MS8 and midrange to the another channel.

 

Rear speakers make it harder to get a solid center image. With a good set of front speakers and power you really don't need rear speakers unless you just need extra volume.

 

Stick with 2-channel system...don't try to make it a surround sound system. The way JBL did it is right. This is why the rear speakers (midtweets) are low in volume/output. It is mainly for staging for the rear passengers...they are not there to provide much of ambience (or rear fill) for the front passengers, nor do they provide surround sound effects.

Does MS8 know that the rear 2 channels are sending signal to the subs? Or will MS8 just think that the rear 2 channels are for rear fill?? Is there a mode to make the MS8 know that 2 channels (of 8) are for bass only? I need to read up on MS8!

 

The MS-8 treats all 8 channels the same way; they can be configured to output whatever you'd like. There is no predetermined output type for each of the channels.
In a typical example: Channels 1 & 2 can be set up to run the dash speakers, 3 & 4 to the mid-bass in the front doors, 5 & 6 to run the rears (or "sides"), and then 7 & 8 to run subs.

 

The new high end decks and processors have built-in digital time alignment. This allows you to set a time delay on each speaker as needed. I found that with my eXcelon KDC-X993 I only needed to set a 1.2-1.4sec time delay on my left front speaker to produce a decent center image. I had to reset the battery last weekend and the deck went back to default settings and the result was dramatic. I had forgotten how much the time delay helps. My tweeters are not in the stock location so your delay time will likely be different.

 

How did you wire in the amp? Straight to the battery? Are you concerned about a huge load like that amp on a little battery? Will the battery be drained quickly? Ive had several large systems and its always a concern. My current system {not in my Prius}has 2 JL Audio 1000/1 amps wired to a large battery with a large alternator and I can drain it very fast. How can the Prius keep up? I too have a 2010 Prius and am hesitant about a future install because of this. Am I missing something?