I understand that MY2001 has rear speaker outputs on the stock head unit, but of course they go unused. Here's my question.

I leased my S, so I'd prefer to do as few permanent modifications as I can. Can the front and rear channels be bridged on the head unit as a simple way to increase power to the front speakers? I realize this creates impedance problems, as well as possibly destroying the unit if it's not built to handle it. Has anyone tried this yet? Will it work? Is the unit even bridgeable?

Thanks.

 

You don't want to do that...

Just add rear speakers, its completely reversible to stock. You could probably even return the car without any issue at the end of the lease even if you left them in.

 

Never never never bridge amp outputs unless they were designed for it. At best you'll heat up the amp significantly...at worst, you'll blow a stage (if not both). The stock head (as well as just about every other cheap stock head out there) is not designed for this. Go with Lucid's rear speakers, make your own, use line-level converters and go with an amp, or just plain replace the stock head, but don't bridge it.

 

OK, so I'm two weeks late in responding. But, hey, I get to log one more post, and sound like I know what I'm talking about at the same time.

The amps in the stock head unit are already a bridge configuration. That's how they get (supposed) 20 or 22 watts out of a single sided 13 volt supply. Neither side of the speaker output is at ground potential (talking about the amplifier power supply ground, which in this case is chassis ground), which is a dead give-away it's a bridge configuration.

Aftermarket amps that are designed for bridging use a dual power supply, like +40 volts and -40 volts, with the center being ground (amplifier power supply ground) . One side of each speaker output is the same as this ground. When you go into bridge mode, the 'grounded" side of one speaker is instead connected to the other amp output, thus giving you twice the voltage swing.

This works with "bridge designed" amps because they invert one of the audio channels before it goes into the amp. Then, they mark one of the speaker outputs "backwards". They mark the positive negative and the negative positive. (is that confusing?) so the end result puts the audio signal back in phase.

If you have an after-market amp that was not designed for bridging, often you can bridge it anyway if you add an inverter to the input of one amp channel. I ran a non-bridge-able amp in bridge mode about 20 years ago, long before it became popular, by doing just that.

Not recommended for the electronically challenged.

 

Thanks guys,

I hung out with a lot of sparkies (EE's) in college, but I preferred mechanical, so my knowledge isn't all that acute. I read enough to find out how bridging actually works (i.e. what you said actually made sense modifry ). I was just curious if there was "wasted potential" sitting in those rear speaker outputs from the main head unit.

- Honer

 

I think you'll find most S2000 owner would agree that the only 'wasted potential' of the stock head unit is the valuable space it's taking up preventing you from having a decent head unit.

I actually still have mine, the rear output is a convenient way to adjust the bass shakers, but not much else.