Car power amp problem

[daviddd]

I have fitted a power amp to drive a sub-woofer in the campervan but am getting no output to the speaker. I have double checked all the wiring and switch settings; the speaker measures 4 ohms OK, but there isn't a squeak out of it when I power up and play a CD. I'm running the audio signal from the spare RSA output terminals on the head unit and have wired the speaker in bridged mode as per instructions. It's an old Alpine twin-channel amp that I used to run on a former car and was working fine 2 years ago when last used. Any ideas anyone? I have downloaded the instruction manuals and all seems OK.

I have and know how to use, a DVM, and would like to test the speaker output terminals - what should I be reading from the amp output with speakers disconnected? I know the output trannies can blow but they seem to measure OK.

[octane]

Has the headunit got options of turning the sub on or is there any settings for controlling the pre-outs on the head unit?

[daviddd]

there is a remote power switch-on lead but I have connecetd a permanent 12v to the amp whilst testing - it is lit up. As far as controlling the sub-woofer is concerned I can't see anything specific to control it at the head unit end - I presume that the normal bass control does that. There is a gain control on the amp which I have tried all settings of.

[cemmts]

Think you will find the amp needs all 3 connections Ground, Live and remote "normally blue wire" to operate.

If your head unit doesn't have a remote but does have a powered ariel feed this can be used as a amp remote feed.

Basically a feed to tell the amp yes the head unit / ignition is on.

[cemmts]

http://a248.e.akamai.net/pix.crutchfield.com/ca/learningcenter/car/amp_wiring_diagram.gif

[daviddd]

thanks for that. Any idea what I should be measuring across the amp speaker terminals (with speaker disconnected) on the ohms range?

[octane]

think it depends on what ohms the amp kicks out. If its 4ohms then thats what you get in 2 channel mode but if your bridging then it will be 2ohms.

Something like that anyway....lol

[dx100uk]

na that sadly will not be true.
its 4ohms impeadance, which cannot be measured, just calculated.


whatever you do/do not get on ohms will be meaning less.

dx