Alan

Yes the 130A Bosch were on the GTS as stock. For what you propose you probably don't need to upgrade - esp if you will not be running it at hign volume very much. The time you need more power than the alternator can provide is mainly at idle - where you may suck from the battery if you have it cranked up high... Before a new alternator - I'd recommend a higher capacity battery and a audio cap (prob 0.5 - 1.0 farads) - these will help with that situation (1: in having enough power and 2: in not hearing clipping - esp for a sub woofer bass)

Even the 130A alternator may struggle under idle conditions - but in cases where you are driving with lots of other electricals on it will be a bit better... Prob not needed

You can take a wait and see attitude here on all these and decide later on upgrades.

Alan

RyanPerrella

GAZ,

Apparently (now i dont know i dont have one in front of me) the RF come with a card showing what each amp makes. They have rated and what i guess is the tested power or "dynamic power" in RF speak.

Take a look at the specs, http://www.rockfordfosgate.com/produ...n_US&p_status=

Now my front channels are 30-80 watt RMS, so i hope they dont produce the 86 RMS thats rated "dynamic" whatever that means. I dont know why they would misrate their amps low, but have a look.

RyanPerrella

Yeah i will be coming up and would love to see it. Will you have you car, or is it still in the shop?

I would also love to run a hammer or spanner on my car, i have a PSD fault, i want to get the codes off it to see what needs to be done to get it out of the "not active" mode its in.

Bill Ball

I had no trouble with 75W RMS x 4 plus a sub amp of some wattage and a center channel amp running off the stock alternator. Sure, when idling, the lights would pulse with the music. The idle output of the alternator is something that a higher amperage alternator output won't fix. You can try adding a big capacitor. That really doesn't help. Others have fussed with the voltage regulator - bad idea. I've thought about using a smaller pulley on the alternator to increase its RPMs, as the alternator output kicks in just barely above the 675 engine idle speed. I even have a smaller pulley, but haven't installed it. Again, the only problem I ever see is at idle, and the amp loads are not actually the problem. The alternator output at idle at night is not completely adequate even with the sound system turned off.

RyanPerrella

So i guess i will stick with the stock unit, if and when it goes, i will get a rebuilt 130amp GTS alternator and leave it at that. Thanks for the input on this adventure.

RicerSchnitzzle

for the system you're describing you should be fine. A cap is not needed either. If you encounter issues at idle, raising it a tad can help a lot. An overdrive pulley is also an option for better idle performance but you sacrifice higher heat and less alternator life in the long run. A larger alternator will generally put out more juice at lower rpms but takes a higher thresh hold rpm for self excitment leading to poor idle performane. I had my Bosche rebuilt to 195a with an overdrive pully. Puts out 163a at 2000rpm.

VehiGAZ

Ryan,

I read through the website and the manual. The "Dynamic Power" rating is RF's own system which is another way of measuring power output (in their favor ;-). It may be a more meaningful way to measure power output than W rms, but it's theirs only, and so not very useful for comparison to other brands.

Anyway, you can see at the top of the specs page that they rate it at 50W rms per channel at a 4 ohm load (< 0.05% THD) and 100W per channel at a 2 ohm load (< 0.1% THD). Pretty good rating, and it would be conservative compared to amps rated at 50W rms into 4 ohm at 0.5% THD or higher, so yes, it may be considered "under-rated" compared to others in the industry. Btw, I could not find a minimum load rating, so I'm guessing that they still do not handle less than 2 ohm safely anymore, as I brought up previously.

With MB Quart separates, each channel will see a total load of around 3.2 ohm IIRC, so each set will be getting around 62.5W rms. Speaker ratings by contrast are always conservative, because the manufacturers don't want to replace them when you blow them out. Don't worry about it - they'll be able to take it.

Seriously, if you're not looking to out boom-boom the Civic next to you at the stop light, then you will be fine with the stock power supply.

VehiGAZ

I just heard from my installer - he could not fit the 6.5" speakers in the rear without cutting the panels, so he's going to do 5.25's all around. There were 6.5" grills over them, which is what threw us both off. Anyway, strange - it might be just those particular speakers that won't fit, but I wonder if all 6.5" speakers would need cutting.

Bill Ball

The problem is there is an interior panel recessed behind the quarter panel liner. The opening in the quarter panel liner is large enough for 6.5s, but that recessed panel has a hole in it only large enough to accomodate the stock 6.5s relatively small and shallow magnet. I enlarged that hole just a bit - no biggie as it is completely hidden - so it could accomodate 6.5s with much larger and deeper magnets.

RyanPerrella

Gaz,

My car had already been modified to fit 6.5" speakers. Thanks for the heads up though. I pulled a pair of Polk 6.5's. The MB Quarts are the same depth if not shallower so i am pretty sure they will fit.

dr bob

Gaz--

It took some grinding/sqawing/fitting on the frame to get 6.5's to fit in the B-pillar buckets and get the original covers on. I put Infinity 2-ways there. Sound is nothing to brag about that's for sure! I'll probably end up with something bigger in the spare well someday, so those 6.5's will be mid fills or disconnected. I have the rear deck speakers disconnected now to move the soundstage forward a bit.

There's plenty to think about, and no place to execute much in the 928!

VehiGAZ

Thanks for the info, guys!

Yeah, the installer had me thinking he'd have to cut up the interior trim panel, but I just talked to him again after reading these posts, and he confirmed it's the metal plate behind the trim panel that has to get cut, so I told him to go for it. Of course, they had mounted the 5.25's in there at that point, so he's got to take it all apart again and put the bigger speakers in and move the 5.25's to the front tomorrow.

Kevin in Atlanta

<Stupid thoughts/> I wonder if you could mount MBQuartz tweeters on the a pillars using gauge pods? I just don't think the tweeters and mids in the door panels achieve much. I wonder if you could build a couple of tiny enclosures for the mids on each end of the dash? That would get the sound to the same height as your ears and the direct the sound to you rather than in front of you.</Stupid thoughts>

RyanPerrella

Ok, I had to bring this thread up again because i just read about what I consider the ideal amp for the 928.

Alpine will have this new 5 channel PDX amp "PDX 5" that is a 10 x 8 x 2 sized amp with 4 x 75 W RMS and 1 x 300 W RMS. Supposed to be out sometime next month with an MSRP of $599.99 but I expect it to have a street price around $400 if not less. If your still considering upping your car audio, i would definitely check out this amp in our space limited 928's

Bill Ball

That does look like real nice amp. Where do you plan to put it?