doug928

I have an Alpine CDA-7875 head unit with an 3510 amp (4 channel probably only reated at 40w/channel). This work was installed by the PO and the system is OK but it definitely needs a subwoofer (and probably more power) the speakers were upgraded to alpine's also. So my question - should I by a new 5 channel amp and rewire the system - or - by a mono amp (if possible?) and try to wire into the existing system? The existing amp is mounted next to the passenger seat under the removable compartment. I want to make the installation as painless as possible without removing too much carpet. Any suggestions as to how to proceed?

Kaz

I toyed with the idea of a 5 channel amp but in the end went with a four channel for my Alpine speakers and another 2 channel for my subwoofer. Both amps are mounted on the wood behind the rear seats with enough wire give so that the seats can be raised and lowered. The amps are AudioVox amps by the way.

Wouldn't say it was painless but it was done right so I wouldnt have to go back in for anything silly.

Mark

The 'existing amp' you describe is likely the OEM. It has VERY LITTLE power. I would guess that it has been bypassed for the Alpine!

You could go with a powered sub, or a sub & amp. You would be surprised how good things sound when the head unit is NOT having to drive the bass! Bass is what takes up the majority of the power!

EDIT - I found very little info on the 3510 - except that it is a 1998 model! There has been MUCH improvement in car audio since then!. I would consider scrapping it if it doesn't sound good when you have added a sub.

doug928

Kaz - why a two channel for the sub?

Mark - I guessed as much since it was installed with the head unit. If I go with a sub amp only I believe I should only have to tap into the head unit for the bass frequencies. I believe there is a bass connection for this unit. Does this make sense?

ew928

Doug,
Why not run a mono dedicated amp?
If the Alpine 4-channel is working fine with no alternator whine or clipping,
keep it.
Dave Lomas recently introduced their spare tire wheel sub-box. That'll be stealth
and give some decent low frequency fill.

But can you hear the stereo with X-pipe and RMB.

Currently running sub amp in the rear storage compartment (rear AC delete)
and 10" sub in the spare tire well.
Ernest (NYC) Near stock mouse quiet S4 exhaust.

Kaz

I went with a two channel in the event I add another subwoofer.

Bill 86.5 928s

Most amps are two channel with bridging capabilities to connect mono to a subwoofer. In my system I chose to make my own enclosure and run two ten inch subs off of a stereo or two channel 400 watt amp. I'm using an Alpine AM/FM/CD player with 4x45 watts per channel into the Porsche stock speakers and that seems to sound OK. My first sub amp was only 200 watts and it did not perform as well or have the punch that the 400 watt sub has. I also found that the preamp out connections on the Alpine deck was the way to go when driving the 400 watt sub amp. When using the preamp out, the Alpine deck has a separate control for volume of the boom box( sub). I run the sub amp in true stereo mode with no filters therefore being two channels of audio with great mid range and excellent bottom end. This seems to run ok for me, granted, I'm not an audiophile or professional stereo wiz but I am content with my sound and pleased with the results. Good-luck with your system..............Bill

Tom. M

I had a similar setup...an alpine amp/pioneer unit added when factory system was removed. I took out the aftermarket pioneer head unit and cd changer...added a blaupunkt Toronto receiver for the stock look....put in a three piece MB Quart setup in the front doors (custom work by Thurston (goldknight))...powered those by two channels of the amp, power the three rear seat speakers by the Toronto head unit, and kept two channels (to be bridged) for a sub when I put one in the back...

The sound is awesome now...(esp have 6 1/2 inchers up front with 4's and tweets). and when the sub goes in ..it'll be even better....

The amp itself is mounted on the back of the passenger rear seat back...unobtrusive and doesn't get in the way of storage..

later,
Tom
midlman@rennlist.net
89GT

doug928

Thanks for the input guys but here's another question - Can you use a mono amp say it's rated for 1000w RMS @ 2 ohms to drive a speaker with a dual coil rated at 6 ohms? I am trying to piece a sub woofer set together and I haven't done this in a looong while. Thanks.

Ketchmi

If you run the DVC in parallel, you end up with 3 ohms and the amp will provide 750 watts into that load. (a whole hell of a lot of bass)

https://rennlist.com/forums/showthre...ight=subwoofer

This post has some good info for you. The "Baby Belle" amp by Memphis will fit on our sub box and power the whole system. It has 4 channels at 55watts per and one at 400.

http://www.memphiscaraudio.com/produ...ails.asp?id=28

doug928

Dave - by the DVC do you mean the dual voice coil? and run it in parallel with each connection off of the one mono amp?

Ketchmi

Yup, exactly.

doug928

Thanks.

cobalt

If you don't mind going with the large sub woofer in the spare tire well you have many options. If you are trying to stick with a stock looking stereo there aren't many options.

Nothing is made today that has power and fits in the stock location along side the passanger seat. I did however find a series of older amps dating back to the 90's that do fit and are available on Ebay from time to time, used. Soundstream made a nice sub amp called the Rubicon Angina. You need to make sure it is the early generation to fit. Dimesions are something like 5.3 x 7 x 2.3. It is a mono amp delivering 100 watts x 1 at 4 ohms and 200 watts x 1 at 2 ohms. Carefull there are 2 versions since then that will not fit. There is also the soundstream D100 II amp that is a full stereo amp at 50 watts by 2. This will not give you as much bass but allows you to power the 6.5's seperately and you could replace them with a coaxial speaker and add additional sound and volume. The last amp is a tight fit but is excellent for low deep bass out of the 6.5 mid/subs. You will need to replace the speakers with a premium quality speaker to make it work otherwise they distort. I recommend the MB quart Pro series or better. This is the Directed Audio 250 D Mono amp. It has stereo inputs with 2 speaker output but is mono rated at 125 w x 2 at 4 ohms. With a shoe horn it fits and I must admit using the sub out on my Nackamichi CD 500 head unit along with the 47w x 4 it delivers full clean sound with great low frequencies that sound almost as good as the 12" seperate sub woofer. I can drive down the road at 80 mph windows open and stereo at half power and still have good clean sound with back kicking bass. BTW Directed audi also makes amps for Orion, A/D/S and Precision Power.

Good Luck

doug928

Here's what I'm going to do - Based on Dave's recommendation I'm ordering an Audiobahn 10" sub and also ordering an Alpine 1000W mono subwoofer. I think I'll make an enclosure to mount in the spare well and probably mount the amp somewhere near in the hatch. I'm going to keep the older alpine amp and see how things sound after the install.