1998 disco rear door speakers

Hi folks, just replaced the battered old rear door speakers with a like for like pair. Have a jvc head unit up front. Problem I’m having is I’m not getting any sound what so ever from them. I’ve tested all the pins and I’m getting voltage to the amp, and I’m also getting voltage post amp to the speakers, but only 5 volts, I would expect to see the voltage changing at the speaker terminals when music is playing. Anyone know what I’m doing wrong or how to get sound coming out of them?

Hi, I can't help with your problem I'm afraid but I'd be interested to know what speakers you have found and where I could get some from? Good luck sorting your problem, I'm Sure someone will be along soon with some good advice.

DiscoRay said:

Hi, I can't help with your problem I'm afraid but I'd be interested to know what speakers you have found and where I could get some from? Good luck sorting your problem, I'm Sure someone will be along soon with some good advice.

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Hi discoray, that’s okay I’ll get to the bottom of it eventually! In the meantime, here is the link to the replacements I bought
https://www.ebay.co.uk/itm/Car-Radi...-/152263894279?_trksid=p2349624.m46890.l49292

Sound is AC and IMO too fast to see on a test meter so requires a scope. From what I remember human hearing is 20Hz to 20KHz.

BTW are you talking about the subwoofers in the rear door or the rear passenger doors?

backinblack said:

BTW are you talking about the subwoofers in the rear door or the rear passenger doors?

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Hi back in black, yes subwoofers is what I’m on about mate. And yeh that makes sense only being able to see on scope etc, but could it not be an issue with the amplifier if I am getting a 5v reading on the speaker connections do you think?

I don't know much about the (presumably D1) headunit as I got rid of mine a number of years ago but don't most head units have a separate Sub woofer output?
I can understand the 5v from the amp but if there is no input from the headunit for the amp to send to the speaker. I'm guessing the JVC isn't the original LR headunit?

This is what I scoped from my L322 door speaker and if I am reading it right the sound wave is sitting on roughly 5v DC

Yes it’s a d1 and correct, jvc head unit is not standard, just one I used to fill the hole when I bought the vehicle.I’ve played around with the audio settings but there is a phono output on the rear which I guess could mean that the head unit doesn’t support the factory amp? And that’s promising news about scoping it and seeing the voltage sitting at 5 amps. I’ve read threads in which people have cut and soldered phono connectors onto the factory wiring but I’m not sure I want to go about doing that?

Have you still got the standard headunit? is there a separate sub output on the standard HU?

Ben Haigh said:

Hi folks, just replaced the battered old rear door speakers with a like for like pair. Have a jvc head unit up front. Problem I’m having is I’m not getting any sound what so ever from them. I’ve tested all the pins and I’m getting voltage to the amp, and I’m also getting voltage post amp to the speakers, but only 5 volts, I would expect to see the voltage changing at the speaker terminals when music is playing. Anyone know what I’m doing wrong or how to get sound coming out of them?

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Ok starting at the beginning, no I don’t know what your doing wrong.
So was there sound from the previous “ battered old rear door speakers“ ?
As you say have the 12volt at the amp, (there’s two 12v supply’s, when the head unit is switched on, and ignition switched to position 2) and 5volts carrier at the loudspeaker terminal
So do you have the audio signal at the door amp? that will be from the pre-amplified outlet at the rear of the head unit to the door amp, the signal is carried on a black + white wire in a screened cable.
If your head unit has a pre amp output, in the settings menu you possibly may find the output gain adjustment to adjust, if the sound from your new loudspeakers is low or high and distorted that, the door amp doesn’t have any adjustment.

discool said:

Ok starting at the beginning, no I don’t know what your doing wrong.
So was there sound from the previous “ battered old rear door speakers“ ?
As you say have the 12volt at the amp, (there’s two 12v supply’s, when the head unit is switched on, and ignition switched to position 2) and 5volts carrier at the loudspeaker terminal
So do you have the audio signal at the door amp? that will be from the pre-amplified outlet at the rear of the head unit to the door amp, the signal is carried on a black + white wire in a screened cable.
If your head unit has a pre amp output, in the settings menu you possibly may find the output gain adjustment to adjust, if the sound from your new loudspeakers is low or high and distorted that, the door amp doesn’t have any adjustment.

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Hi discool, no there wasn’t any sound at all, I found a like for like pair on eBay, 4ohm speakers, 6.5” and 120watt I believe? Had to crimp some female spade connectors onto the existing wiring so that I could plug them into the amp. I was obviously expecting them to work straight away when I turned the radio on because the only idle plug behind the stereo was the old connector for the volume control on the dash, everything else plugged straight into the iso connectors. As I said previously, I tested the plug with a multimeter and got the two 12v live feeds, and when the radio was on, I was also seeing 5volts at the connectors on the speakers after the amplifier, but no sound what so ever.. very confusing.
I’ve played around with all the settings on my head unit but can’t get anything out of it, the only thing I can think is that the stereo doesn’t support it due to it having a red and white phono connection on the back for an aftermarket amp

backinblack said:

Have you still got the standard headunit? is there a separate sub output on the standard HU?

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No it’s a jvc head unit with seperate sub output

As @discool says, may need to put a plug on the black + white wire in a screened cable

backinblack said:

As @discool says, may need to put a plug on the black + white wire in a screened cable

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Such as a phono plug?

Ben Haigh said:

I’ve played around with all the settings on my head unit but can’t get anything out of it, the only thing I can think is that the stereo doesn’t support it due to it having a red and white phono connection on the back for an aftermarket amp

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Ok so a left and right channel, they should be bridged together to form one as the sub is a single mono channel, you may be able to change that in the head unit menu.

discool said:

Ok so a left and right channel, they should be bridged together to form one as the sub is a single mono channel, you may be able to change that in the head unit menu

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I’ll give it a try shortly and let you know the outcome

Ben Haigh said:

No it’s a jvc head unit with seperate sub output

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How have you connected the speakers to the head unit?

Marmaduke said:

How have you connected the speakers to the head unit?

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With iso lead that came with the head unit

Ben Haigh said:

With iso lead that came with the head unit

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The red and white jacks?