Subwoofer remote/sense signal sources

[1S2A1B]

I'm installing a little 6" Bazooka powered sub in my 01 9-3. A decade ago I installed it, along with an aftermarket head unit, which included an accessory line, providing 12V to the sub when the head unit was powered on. More recently I put the original stereo back in to work with BlueSaab.

The sub is located in the corner where the CD changer goes, so I was hoping to snag the switched power from the CD changer harness, or the antenna power (not in use since I got my Viggen spoiler from the junkyard ). I learned that both devices have a constant 12v source, even when the car is off. The antenna ground is an open circuit unless it's meant to be running, and I understand the BlueSaab is activated by canbus messages.

Next I spliced into the Antenna Trigger line right from the back of the head unit, as suggested by this guy's SAAB audio site. Unforunately I found that it only has power when on radio.
There is an amplifier trigger line that controls the external amp for the front door speakers. I was recently able to add this amp to my car after another lucky day at the junkyard, but I'm not looking forward to cutting apart the proprietary cable trying to find the wire that goes with the pin.

I'm curious if it would be possible to source the 12v signal from the BlueSaab module. Is there a spot on the board that's got 12v only when the stereo is on, or only when the CD changer is selected?

[Seth]

No, there is no such signal on BlueSaab.

Your best bet is to just take the front door speaker amp apart, I believe the pins are labeled as to which is which so you can find the activate signal.

On Mon, Dec 7, 2020 at 08:11 1S2A1B [via BlueSaab Forum] <[hidden email]> wrote:

I'm installing a little 6" Bazooka powered sub in my 01 9-3. A decade ago I installed it, along with an aftermarket head unit, which included an accessory line, providing 12V to the sub when the head unit was powered on. More recently I put the original stereo back in to work with BlueSaab.

The sub is located in the corner where the CD changer goes, so I was hoping to snag the switched power from the CD changer harness, or the antenna power (not in use since I got my Viggen spoiler from the junkyard ). I learned that both devices have a constant 12v source, even when the car is off. The antenna ground is an open circuit unless it's meant to be running, and I understand the BlueSaab is activated by canbus messages.

Next I spliced into the Antenna Trigger line right from the back of the head unit, as suggested by this guy's SAAB audio site. Unforunately I found that it only has power when on radio.
There is an amplifier trigger line that controls the external amp for the front door speakers. I was recently able to add this amp to my car after another lucky day at the junkyard, but I'm not looking forward to cutting apart the proprietary cable trying to find the wire that goes with the pin.

I'm curious if it would be possible to source the 12v signal from the BlueSaab module. Is there a spot on the board that's got 12v only when the stereo is on, or only when the CD changer is selected?

2001 9-3 base

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NAML

[1S2A1B]

Thanks Seth! Here's a shot of the goods. Per the page linked above, the trigger is supposed to be the center pin of the connector. Seems it's connected to the transistor just in front of the connector. I suppose I'll take it further apart so I can solder a wire to the back side of the board.

[1S2A1B]

Ok, didn't manage to get the board out. This is a nicely built unit, I like the method of thermal contact, and the aluminum body is very thick. I bet these things last a long time if you don't try prying them apart :)
General view of the damage so far:

The nut on the center stud was loctite'd. Nut came off, but the stud is solidly adhered to the board. After more probing, I think the first place the trigger voltage goes is this resistor leg, rather than that transistor. Current plan is to add a wire to that resistor leg, put the amp half way back together, and test it in the car to see if I get 12v when I want it, and that the amp behaves normally. Perhaps tomorrow.

[1S2A1B]

I added a wire to that resistor leg. It's ugly, but it makes good contact. Reassembled and reinstalled. Turned on the stereo, checked voltage on my wire. 6.8V . Unplugged and tested the center pin on the cable to the head unit, 12V. Maybe I should have just peeled open the cable in the first place.

On my way home I decided to try wiring it up anyway, and the sub powers on just fine. Hooray! I suppose 7V is enough for the relay in the Bazooka. I'll do some testing and some crimping and I should be all set. I'll report back if anything interesting happens.

[1S2A1B]

In case someone finds this when doing something similar, here's an update on what happened after my last post. I celebrated prematurely. The lower voltage signal was not actually triggering the sub, at least not consistently.

Figuring that I did something wrong with the wiring inside of the amp, I ended up peeling open the wire between the stereo and the front door amp to splice into the 12V signal wire there. I used a needle tip on the multimeter to find the correct wire. It was the red one. I stripped some insulation, soldered on some nice silicone wire, and taped everything back together nicely. I did get 12V, until the wire was connected to the amp. Then I got the same reading as before, under 7V. I guess the trigger circuit has only enough current to trigger the front door amp, with major voltage drop.

I did have success using a cheap 12v relay wired to the Bazooka 12v power, which I believe is intended to trigger on 3.3 or 5v. That worked well, but the way it was wired, the relay was energized when the car was off, it drained the battery, and I ditched it.

I believe I could do the same thing with a transistor in place of the extra relay without hogging energy. I could probably open the amp again and grab power from the other side of the triggered relay, which can be heard clicking on with the stereo. I could also move the power for the sub to a circuit in the fuse panel which is off when the car is off.
I haven't tried these things yet because the sub hasn't been in the car. After adding the front door amp and speakers, nice new woofers, sound deadening and treatment inside the doors, there is enough bass for me. If I do wire it back up in a way that works I'll come back and update.