Pontiac G6 Forum banner

Constant hiss after aftermarket radio install

2304 Views 4 Replies 3 Participants Last post by  pucho777
After researching and getting together several things together for my aftermarket radio (Pioneer AVH-4200NEX, in case it matters), I'm left a little disappointed from a constant hiss regardless of volume (including off/muted), and actual crackling when switching inputs, like activating Siri.

I asked the installer before I left, and they said it was because the head unit was overpowering the low-voltage(?) input of the amp, and that there may be an amp interface.

For reference, I used the PAC C2R-GM11B Replacement Interface to retain the chimes and other features, following the Speedo-Swap tutorial and subsequent discussion. This is also what Crutchfield recommended, and explicitly said that I could use this to retain my stock amp.

Could he be correct, or is there something wrong with their installation?

2007 Pontiac G6 Convertible
1 - 5 of 5 Posts
In my experience the stock monsoon amp has always hissed and the level of hiss is constant no matter the volume setting on the receiver. It is there any time the amp is powered on. Annoys the hell out of me if the engine is off, but I barely hear it on the move which is why I have not bothered to change it. Sorry if that is not what you hoped to hear (pun possibly intended)
In my experience the stock monsoon amp has always hissed and the level of hiss is constant no matter the volume setting on the receiver. It is there any time the amp is powered on. Annoys the hell out of me if the engine is off, but I barely hear it on the move which is why I have not bothered to change it. Sorry if that is not what you hoped to hear (pun possibly intended)
Yes it did (with my stock HU), but definitely not this bad. Reading around, it may be due to being double-amped (the Pioneer unit providing 14W internally)...? This is simply my own conjecture.

Since the installer said it was due to the high-level output going to the Monsoon expected low-level, I'm guessing he didn't bypass using the RCA outs.

Again, conjecture; I'm just hoping someone can fact-check me. I have precisely zero experience here, and hoping someone will "Just Know" (TM) what's going on. :)
Whilst I have no direct experience, you conjecture make sense to me. If you are driving a power amp that is designed for line level inputs with speaker level output you will be over-driving the amp and amplifying any hiss from the head unit. You may be able to try one theory by disconnecting the monsoon amp molex connectors. if there is some bi-wiring from the HU and you still get sound the hiss may reduce (nothing from the monsoon amp). If you get no sound then you know the monsoon amp is still in play.

Perhaps take it back to the installer to see what they can do. Does not sound like they did the best of jobs and from what you mention they seem to know why.
I had the same prb also have the same head unit, it’s because the power the radio sends and the amp so it’s true u dble amping that’s why it hisses, I just yanked everything out and upgraded the whole sound system. Upgraded speakers to components and and put 2 12 sound ordance subs with kicker 1200w amp and Rockford Fosgate punch for the doors and deck
1 - 5 of 5 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top