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'94 Grand Prix SE sedan, installing subwoofer (stock 4-speaker radio)


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I've got a little 300w 6" Pioneer subwoofer kicking around, and a few compatible amps that should still work. It's all stuff that I got for free, currently just collecting dust.

My nephew recently got a '94 Grand Prix 4-door, 3.1 with a standard 4-speaker Delco radio.

The entire set-up will fit perfectly between the driver and passenger. I've actually done it this way before on a Regal, and it fills the cabin pretty nicely with better bass on a shoestring budget.

My plan is to tap into the rear speaker wires for line-in to the amp.

Couple of questions:
-Is there a separate factory amp that I should be aware of on this model? If so, do I tap into the wiring from the radio output side, or the amplifier output side? Is there any cross-over filtering that I need to know about?

-What is the low-end range limitation for factory Delco 6x9 speakers?

-What is the low-end range limitation for the stock radio unit?

-Do stock radio units like this have an antenna trigger wire, even if there is no power antenna present?

-Is the automatic transmission clutch-master-delete rubber grommet present on this year and model?

Any and all of your input will save me a boatload of time; I might only have a few hours to get it done this/next weekend. Only ever worked on early 90's Regals for this, and I'd like to minimize the propensity for encountering potentially-tedious surprises.

Gotta know where best to set the low freq and high freq cut-off in the low hertz range, where to tap-into speaker signal line-out, where to watch out for potential signal interference, in a nutshell.

He will be using an FM transmitter on the cig lighter circuit, as well.

I'm gonna have to figure out this $h1t on my own, unless one of you can save me some hassle.

Thank you for anything and everything you can tell me before I have to dive-in solo.


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On 3/6/2024 at 11:26 PM, Robbie said:

My plan is to tap into the rear speaker wires for line-in to the amp.



For speaker level input on any car amp tapping into (or paralleling) the existing circuit is not the proper way to do this.

The head unit's amp section is designed to drive four 4 ohm channels, if you upset that impedance to the rears by adding another load in parallel into the circuit you'll cause issues for the head unit amplifier possibly causing the head unit to fail.

The proper method would be to open the circuit to the rear channels & plumb in the amplifier using the left & right speaker level inputs to the amp, then reapply the left & right rear channels using 2 of the amps four channels to the parcel shelf speakers & the 2nd set of amp outputs in a bridged mode circuit to the *new* sub.

To do this one needs a 4/1 or a 4 channel amp, 2 of the 4 channels out go to the rear parcel shelf speakers & the other 2 channels are bridged into 1 that go to the sub... ASSUMING the sub is a single voice coil driver, if the sub has dual voice coils then no bridging is required.

Edited by 55trucker
spelling error
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