Rear Speakers on 490 Amp

[Baconaire]

I have a 98 Box with the stock 'premium' 490 Nokia amp. I just replaced the Becker 210 head with a nice but cheap Pioneer unit and the sound is immediately better having the Ipod and Xm direct wired. Now I'd like to add rear speakers to fill out the good sound a bit.

On the stock system the fader 'front' would drive the dash and door speakers; all the stock speakers. 'Rear' gave nothing. Same is true with the new head which I sent to the stock amp. Wiring the new head I was able to see the 4 channel/common ground system. And my assumption is that all the stock speakers run on only two of the 4 channels(front left and right). All I want to do is add some rear cheap pioner 4x6inch 4ohm speakers(which should tuck nicely under the roll bar) off the Nokia amp. I've read a lot here and the best I can gather is I should be able to connect to the amp's harness at terminals 4/13(ground) and 12/3(ground) to power the rear speakers.

I tried a little test, admittedly the molex connectors I got were not the right size but I though they'd be good enough to test my assumptions before running all the speaker wire for real. No joy. Nothing. I did fiddle with the fader but not a peep.

My next step is to pull the head and check my wiring and that the stock rear out was wired, as I think it was. And if that fails just run the rears off the head. But I'd rather run them from the amp, if that's possible. So i guess the question I have is-can the 'premium' stock system 1998 Nokia amp, which seems like its 4 channels, power rear speakers from the amp? If I recall it R/L rear signal from head to amp was wired to the amp, but never left the amp. So what am I missing? As you can tell I'm looking to go cheap and not looking for top notch sound.

Thanks for your help.

Edited November 3, 2006 by Baconaire

[Tool Pants]

I am not the stereo guy, but I have a 1997 with the same factory amp you do, and the same 210 Becker you use to have.

But your year Box is 4 channel. But it looks like it should be a 6 channel amp, as this amp with modifications was used on the 996, and a 996 has a 6 channel amp for 996 rear seat speakers.

This is why in the Box oem configuration you need to run the additional rear speakers off the head unit, unless you have put in a 6 channel amp.

Then, this all changed in 2003-2004 with the MOST system, as that amp has 2 unused channels.

[Cassiebox]

Tool Pants is correct, you will need a 6 ch amp in order to power the rears. The stock amp is 4x40. 2 channels for the front, 2 for the doors (which have a filtered signal and only produce lows).

You also are correct about the rear pre-amp outputs going to the amp. The door speakers (again only produce lows) are driven off a combination of the front and rear channels from head unit. Thus when you fade all the way to the front, you'll get almost nothing from the doors. Since you don't have rears yet, if you faded all the way to rear, again you'd get almost nothing.

So your choices to power rear speakers are:

1 - find a 6x40 from a 996 (check fleabay or classifieds on various boards)

2 - power from head unit (but impact will be minimal unless h/u has 40W output to balance w/ OEM amp)

3 - an aftermarket 2 ch amp (jump feed from existing OEM amp)

In order of ease of installation (2, 1, 3), order for effectiveness (1,3, 2), cleanliness of install (1,2,3)

Now, the real issue w/ the boxster's sound system is the clarity which is a direct result of the crappy OEM paper cone speakers that were installed. If you've taken a look at any of them, you'll see. Check out this guide to modifying the boxster's sound system:

http://www.renntech.org/forums/index.php?a...ost&id=5022

It is a GREAT too but here are my 2 cents:

1 - just go ahead and modify the stock basket on the dash speakers. Don't waste the $50 on the adapter - you'll NEVER go back to the stock speakers once you change them out w/ good coaxials

2 - don't even waste the time trying to find a better 5.25" speaker for door to install in the OEM 'tuned port'. For the amount of bass a 5.25" can produce (I don't care who makes them), the OEMs are as good as any. You won't find any 5.25" speakers to make it better b/c 5.25"s aren't designed for low end - plain and simple. I tried 3 different sets and none was any better - regardless of rated freq range. Spend the time (2-3 extra hours) to make baffles and mount 6.5"s in the door. Find a good 6.5" or 6.75" speaker that:

- produces lows of at least 45 Hz

- has a RMS range of 2-50W (any higher on the low end of range and you'll have to really crank up volume to hear any bass realtive to all the other speakers)

- is 2 Ohm rated (OEMs are 2 as well)

- has a sensitivity rating of 91 dB or higher

I used Infinity Kappa 6.75" (Infinity Kappa 652.7i) and they are absolutely awesome. So much so, I actually had to turn off the loudness setting on my H/U and adjust my bass setting down to 0 (treble at 5 or 6 and faded to the rear 1-2) to balance everything out (I have rear speakers). Definitely worth the $129 I paid for them from crutchfield (plus the $30 in materials from Lowe's and Pep Boys to make baffles).

On another note, someone on ppbb.com is selling a rear 'pizza box' w/ PNP speakers and a 6x40 amp. Might save you a ton of time instead trying to make a custom enclosure and find a good amp, etc. for other speakers. Here is a link: http://www.ppbb.com/boards/ppbbphp/showfla...;o=&fpart=1

Good luck and definitely use the guide that Andy M put together. It is priceless.

Edited November 4, 2006 by Cassiebox

[Baconaire]

Thanks. That makes sense given what I'm experienceing. The only thing I don't get is that when I fade rear I get nothing, zero,nada. It was that way with the Becker and that way with the new head. I'll confirm it on the way home this eve. I do have door speakers.

The PNP kit instruction say that if you have the 490 to wire the rears to the new pins on the amp instead of the head.

But I'll try running them from the head. Its a 50wx4 plus subs. I don't know if Mosfet means anything. I think it will be fine . Was not expensive, but probably plenty powerful to give me good sound on small speakers. Not looking for audiophile quality. Just want to fill out the sound a bit.

[Cassiebox]

You'll get 0 from the rears if you hooked into your 4x40 amp as there aren't and channels in the amp w/ power to the rear. On the 4x40, 2 Chs are for the dash and the other 2 are for the doors - none for rear. I understand the PNP instructions say to wire to amp instead of head. However, and here's the caveat missing, it depends on MY of Boxster. The '03-04 came w/ a 6x40 amp standard (along w/ the MOST system) regardless of having rear speakers in the pizza box or not. So if you added the rears, all you have to do is power them from the amp using the open pin spots. But, '02 and prior only came w/ a 4x40 amp unless they also came from factory w/ rear speakers. Then they also got the 6x40 amp.

In that case, w/ your '98, you only have a 4x40 amp. Although the harness at the amp has the open pin locations for the rear, even if you put your wires in there, there aren't any channels w/in the amp to power them.

Hope that makes it clearer for you. Good luck.

Edited November 4, 2006 by Cassiebox

[Baconaire]

Thanks. It started to sink in the more I thought about it. I'll try wiring the rears from the head and see how that sounds.

Thanks for the clarification. It helped a lot.

[Baconaire]

Reporting back. I wired the rear speakers to the head and they sound great. I had two options:

-4x6 pioneer speakers 4ohm

-KLH indoor 3 way speakers-8ohm

The pioneers sounded crummy so I'm bringing them back. I got the pair of KLH's for $20 (yes I said $20) at the BestBuy clearance table! They tucked perfectly under the rollbar and really wake the system up. I highly recommend them as a cheap alternative($50 retail @ BB). Wired directly to my new head. Keep in mind I got rid of my soft pizza box long ago.

http://www.bestbuy.com/site/olspage.jsp?sk...d=1140393393470