Shawn Stanford

I was looking at this spec from Crutchfield. I think the amp can handle 2 ohms to the sub:

• 80 watts RMS x 4 at at 2 ohms + 350 watts RMS x 1 at 2 ohms

Michael Benno

Here is the installation of the Alpine amps. Both of these fit under the stock cover. You can see the aluminum bar stock used (from home depot) to mount the amps to and mount to the factory holes in the chassis.

Zirconocene

Dang, that is really tidy. I might have to follow your lead on this (also) to clean up what's in my car right now. As you know, there are some issues that need to be addressed anyway.

Cheers

Hilton

The Bose woofer from a Nissan Rogue also fits in an S4 spare, and has a built-in mono amplifier. Part JM20A.
The amp (part 297171-003P) is 70W into 1ohm load and works with the 1-ohm rated woofer.

The easiest option is to buy one of the subs with the wiring cut off, so you have both sides of the harness at the connector, to wire into. If you look at the connector from the harness side (clip facing up as shown), the pin numbers are marked as follows:

2 | 4 | 6
----------
1 | 3 | 5

1 = Brn = Audio signal - (line level)
2 = Yel = Audio Signal + (line level)
3 = Braided (thin black) = Shield for audio signal
4 = thin Grn = Amp ON Signal (12V switched)
5 = thick Black = Ground
6 = Thick grey (some reported black with silver stripe? mine is bluey-grey) = Battery +12V (fuse here)

The amp side of the harness has different colours (of course) - using the same numbering above..

1 = yellow, 2 = purple,3 = white, 4 = blue, 5 = black, 6 = orange

Lastly, in case you're tempted to experiment with other models.. I also previously bought a late Murano Sub, 1BM0A, which has two woofers and an amp built in, but it does not fit into the S4 spare wheel.

Hilton

Oh - also thank you George ( @19psi ) for the info on using a Bose subwoofer.. it was his original post on the Bird site in 2013 which led me on the journey: http://forums.pelicanparts.com/porsc...tock-look.html

Brent A.

Thank you. I came across a 1BM0A from an FX35 and was intrigued by the dual woofer aspect. It looks like I should remove it from from my list.

gazfish

I was looking into a drop-in solution but already had an amp I wanted to use and I was in the mood for a woodwork project. Using every inch of the space in the spare wheel area and 13mm thick MDF was enough air volume for a 10” sub. Used it for the first time just now and a massive improvement over the speakers I’ve been trying in the B pillar.
Once the protecting grill arrives I’ll put the cover and carpet back over it.

Michael Benno

thanks for adding this option to the thread. I was wondering what the part number was for the powered version.

this is a really great option and allows for a lot more flexibility to choose a 6-channel amp for the cabin 10-speaker system in 90+ cars or a 4 channel amp in the 8 speaker system in early cars

dukenukemx

Tried copying Michael Benno idea and I'm having some trouble. The first problem is that it isn't very loud. I wired it up to both left and right speakers in the rear trunk area and I can barely hear the subwoofer. It does work, but not very loudly. It might as well not even be there. powering all the speakers in the car, mainly because it's small and fits the stock location. The stereo still sounds loud, just not the subwoofer. Not sure if I need to put an AMP just for the sub or maybe my wiring wasn't done correctly. I didn't take the time to figure out which set of wires go to left or right, assuming the set of wires are associated with left and right. I also didn't take the time to pay attention to which wire is hot and ground. There's also the mounting of the subwoofer which as you can see is off center. Not sure if I need some adapter to get it to bolt center? I have a 1985 Porsche 928.

Michael Benno

Hi there and thanks for referencing this post. Let's see if we can figure this out so you are happy with the solution. We should be able to get the sub loud enough that you can tell a difference and even need to turn it down. With Stereo wiring it is critical that you pay careful attention to correct wiring, don't mix positive and negative leads otherwise, it could damage the components or they will not work properly.

The first issue that I see is that you are trying to power the sub-woofer off of the 2-channel amp you have. Subwoofers operate on separate frequencies and require a dedicated channel where you can isolate the frequencies being sent to it in order for it to work correctly.

The second issue is that the impedance of that subwoofer is 2-Ohms and the rest of the OEM speakers in your 1985 model year car are 4-Ohm. Unless you changed the factory speakers to 2 Ohm, you cannot have different impedance level speakers driven from the same channel.

You will need to find a power source to drive the sub. The sub will require about 45-90 watts to drive it properly. Also, you need to limit the frequencies being sent to the sub to between 20–200 Hz. Most Mono amps have both of these capabilities. Some multichannel amps have subwoofer outputs as well. You just need to make sure the amp supports 2ohms. If your head unit has a dedicated subwoofer output then it can send the frequencies to any amp as well.

Some additional questions:
1. What is the head unit in this car?
2. Are you running the 8 original OEM speakers or aftermarket speakers? If the latter please provide the impedance and number of drivers and locations.
3. can you confirm if this sub woofer is not the powered version, meaning there is no amp inside (remove the cover). If you have the powered version then you need less stuff.

Bales

Hi, not a reply to dukenukemx question, rather a new one. I've been trying to find a good 5 channel amp for this that fits in the original space, loved the Picasso that Shaun suggested but it's just a little big. Reading Michael's reply above, realised that my SQR46 has a sub out. So if I'm happy with the volume for my front and rear speakers powered directly from the head unit (which I am), am I correct in thinking I can just place a mono 2 ohm amp in the orginal amp location to power the sub? I have the unpowered Bose from a wrecked Nissan. Feeling like I should have clocked on this before, so asking just in case I have been around this path and forgotten something!

dukenukemx

So you mean I gotta take either the left or right channel and wire it twice to the same channel? Like take the left channel and wire it twice to the sub?
All the original speakers were gone as the previous owner had done some crazy stuff to it, then ripped it out and left the stereo system broken. I replaced them all.

So I need a mono amp that puts out at least 45-90 watts and works between 20-200 Hz. Would wiring it entirely to the left side temporarily make it louder?

Quote:

Some additional questions:
1. What is the head unit in this car?

A Xtrons double din head unit.

Quote:

2. Are you running the 8 original OEM speakers or aftermarket speakers? If the latter please provide the impedance and number of drivers and locations.

All Aftermarket.

Quote:

3. can you confirm if this sub woofer is not the powered version, meaning there is no amp inside (remove the cover). If you have the powered version then you need less stuff.

I have to take a look tomorrow. I doubt it since it's so light.

Bales

28170 CA10A is the unpowered.

Michael Benno

Yes, you are exactly correct, using the sub-output directly to an amp (mono or multichannel) would work. That is what I am doing. I am using the frequency and gain controls in the SQR46 DAB to drive the sub and they work great. Another thought, you may even try driving the Bose sub directly from your head unit to see what that sounds like. The head unit has 45 Watts Per Channel, which might be enough to drive the sub. You might have to turn the gain up to get the sub to perform but it;s worth a try.

BTW, I have not found a 5 or more channel amp that will fit in the factory location. This little guy came on the market recently and I wonder if it would suit your needs:

Clarion XC2510 Compact 5-channel amplifier — 50 watts RMS x 4 at 4 ohms + 300 watts RMS x 1 at 2 ohms

I am extremely happy with the dual Alpine Amps I have in my car and I see that there have been some updates to the amps. Using 2 may be a good solution. I found the factory speaker sound very good with a good amp driving them (assuming the speakers are in good condition).

Michael Benno

@dukenukemx

You absolutely cannot share that 2-channel amp between a sub and the other speakers. The frequencies are different. The sub requires very low frequencies. The door speakers and B-pillar speakers use high and mid frequencies. If you send those high/mid frequencies to the sub, you will get very low outputs (as you are hearing) and will not get any deep base. Amplifier stereo channels are paired left and right, they are not meant to be divided among unpaired speakers. You would loose "Stereo" if you do. When driving a sub from an amp shared with other speakers, you need a dedicated mono channel or a dedicated pair of channels (L&R).

Let's get back to the outputs on the head unit. Which Xtrons model do you have? can you provide a link? I can look it up and let you know if you can drive your sub from that.

Regarding the speakers, we still need some specifications on the impedance. Can you provide links to the speakers that you have installed? That way I can look them up and provide guidance.

One potential solution direction is that you power your speakers directly from the head unit and power your sub from the Boss 2-channel amp. In this scenario the left and right outputs on the amp would each power a voice coil in the sub. See the dual voice coil diagram below.