I purchased a used AVIC-Z110BT and wired it up to my 2010 VW Jetta. After turning it on, I was annoyed to hear a baseline level of hiss and a bit of whine around the level 12 volume mark. The noise increases with volume proportionally as I increase the output.

When music is playing, I cannot hear it except during very quiet vocal parts.

I installed the unit fully aware of pico fuse issues, so I was careful to wire the RCAs prior to applying power to the unit. To investigate, I opened the Z110BT and searched for a burned pico fuse, but found none. I checked every fuse on the PCB for continuity with my digital multimeter, and found them all intact.

The unit exhibits this hiss in my car and wired to my test bench as well. I've verified that the hiss is not coming from the amplifier, because an iPod and portable CD player are hiss-free when plugged in. The stock radio was also hiss-free even at full volume. The hiss comes through the front and rear pre-outs equally.

I tried the RCA wire grounding trick, and it makes no difference to the hissing.

Am I overlooking something? Is this a bum unit? I appreciate your help

You didn't say which inputs have the hiss. BT stereo OK? Sounds like it is only the radio. Is it both AM and FM? Did you install HD radio? Is so, does that hiss?

I admittedly hardly ever listen to AM and rarely FM, mostly BT stereo and ipod. So I can't say if my AVIC has any hiss, or if it is more than I would expect. I do remember having to adjust the EQ for BT audio for streaming talk shows, but that was to reduce the bass. You might be able to filter it out with a custom EQ setting on those few inputs, escpecially AM, which is noisier by nature.

In fact, that might be all it is. The AVIC might have a broader frequency response than your stock radio, which might have had a band-pass filter. However the Equalizer in the AVIC allows each input to be customized.

You didn't say which inputs have the hiss. BT stereo OK? Sounds like it is only the radio. Is it both AM and FM? Did you install HD radio? Is so, does that hiss?

 

I admittedly hardly ever listen to AM and rarely FM, mostly BT stereo and ipod. So I can't say if my AVIC has any hiss, or if it is more than I would expect. I do remember having to adjust the EQ for BT audio for streaming talk shows, but that was to reduce the bass. You might be able to filter it out with a custom EQ setting on those few inputs, escpecially AM, which is noisier by nature.

 

In fact, that might be all it is. The AVIC might have a broader frequency response than your stock radio, which might have had a band-pass filter. However the Equalizer in the AVIC allows each input to be customized.

Hi RonS, thanks for the reply! I only tested the unit on iPod and CD input since those are my primary sources. The FM/AM work, but those sources are so noisy anyway that I didn't bother. For an idea of the issue, listen to your unit on an iPod or CD, turn it to about 15 on the volume, and then pause the music. You'd expect to hear nothing coming from the speakers, but I hear a static hiss and a light humming from all speakers.

The very strange thing is that if I connect the subwoofer outputs instead, I hear the same hiss but with a lower frequency. If I connect multiple the front and subwoofer pre-outs and fade between them, the hiss changes tonality as I do so.

I've ordered a replacement unit and intend to see if mine is simply faulty.