# Pioneer GM-D8604 amp problems



## AdrianR (Sep 19, 2014)

Hi, 

My brother has a Pioneer GM-D8604 amp with a Pioneer TS-W304R 12" sub and Focal Ps165 V speakers in a Alfa Romeo Giulietta. It is running of the stock H/U.

The left audio has just died and only just produces hissing out of the tweeter and bass out of the woofer. I have tried different cables and rechecked all the wiring I have even swapped the audio channels over and the problem still persists, meaning it is the amp.

This is his second amp the previous was a 5 channel JBL GTO amp (although this was second hand and already had some channel issues so Im not sure if the car killed this one).

Things to note: Due to using the stock head unit the front and rear speakers bridged on the the one channel, the sub bridged across the other 2ch.

Could power fluctuations from the alternator or battery have caused this as sometimes the interior lights flicker when music is playing.

thanks for the help.


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## plushterry (Jan 22, 2015)

How have you bridged the front and rear speakers? Sounds a bit like you might have fried something by having wrong impedence? 

Try testing it with your ipod plugged straight into the amp's RCAs with a 3.5mm to RCA lead, see if it plays that channel then.


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## AdrianR (Sep 19, 2014)

Both front right and rear right are wired together and the same for the left side. They are also the same speakers front and back.

Thanks for the tip he will try it tomorrow.


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## gijoe (Mar 25, 2008)

It looks like you have it bridged to 2 ohms, which you can't do. You probably damaged the amplifier by doing that, and you'll either need to replace it, or have it repaired.


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## chucko58 (Feb 7, 2015)

That amp is supposed to be 1Ω stable per channel (2Ω bridged), according to Pioneer.


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## gijoe (Mar 25, 2008)

chucko58 said:


> That amp is supposed to be 1Ω stable per channel (2Ω bridged), according to Pioneer.


GM-D8604 - Class FD 4-Channel Bridgeable Amplifier | Pioneer Electronics USA

Where do you see that? I see 4ohms bridged, but I haven't opened the manual.


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## chucko58 (Feb 7, 2015)

gijoe said:


> GM-D8604 - Class FD 4-Channel Bridgeable Amplifier | Pioneer Electronics USA
> 
> Where do you see that? I see 4ohms bridged, but I haven't opened the manual.


It's right there in the spec. Click the Specifications tab on the lower left. The amp has a continuous power rating at 1Ω of 125 W x 4. Below that, if you click on Main Features, you'll see the Load Impedance Allowance is 1-8 Ω.

There could be some other wiring fault in the installation, but if it failed driving a 1Ω load, it should be returned under warranty.


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## plushterry (Jan 22, 2015)

I think you've probably ****ed it tbh mate. Seeing the spec sheet, it looks as if you can't run it bridged unless it's at 4 ohms.GM-D8604 Pioneer - Amplifier - Car Entertainment


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## AdrianR (Sep 19, 2014)

He has sent it back and is getting a new one. What would be the correct way to wire them?


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## gijoe (Mar 25, 2008)

I checked and the amp should have been fine at 2ohms bridged, so if you had them wired that way you shouldn't have had problems. I'm not sure what caused your problems, either you screwed something up, or you just got a bad amp. To avoid damaging the next amp make sure you follow the manual, there is a specific section on bridging two channels.


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