Choppy Audio

Hi

i have a 2010 MX5 with Bose and the original head unit.

In the last day or so, the audio has been fading in and out, like someone is fiddling with the volume and the speakers occasionally pop. I was listening to the radio at the time so switched to aux in to test it here and it did the same so wasnt the staion being funny. 

Anyone had this before? Feels like the radio is on the way out.

Has the Audiopilot setting become enabled?

Sadly it isnt. It’s really random and when it pops it sounds like when you plug a speaker in to a live socket. The audio then goes off briefly. 

Today was interesting as I turned the radio off and it was still popping which makes me think it’s the amp behind the passenger seat but I’m not sure. 

For info, audio pilot was off. 

According to the usual circuits, the amp is powered through a relay switched on by the head unit.  A bad contact inside the relay could be the problem.

Now try to find the relay…

Ha ok!

well I found the amp behind the passenger seat so that is a start! Do you know where the relays typically are? Don’t fancy stripping the car down to find it.

I have got a Haynes manual on the way so hopefully that will help…

Annoyingly, in trying to demo it last night it didn’t do it, but this morning it did. It’s a good call though as it does sound like a disconnect/reconnect noise.

I spent some time today trying to see if I could get any further with the problem of the audio dropping in and out so took it out for a drive… and not one drop in audio…

The difference with this drive is I had the roof down for the most part as sun’s out, roof down, right?

I figured this out about half way into the drive as I remembered when I closed the roof in the past and engaged the clamp, the audio would dip briefly as the lock engaged. This happened again today as I put the roof back up and from that point forward, the audio started to dip again as I drove around.

I’m now wondering if there is some play in the roof clamp which means the audio dips because of this? Or maybe a wiring issue here?

Does anyone else’s hard top roof dip the audio when the clamp is engaged? I guess the next question is, if it does, why does the audio dip when you engage the clamp?

I had a suspicion that cornering was a trigger for the audio dip/pop along with the usual British road pot-holes bumping the car about and shaking things up a bit!

With the roof down, you can push your finger into the hole in the windscreen where the clamp goes and replicate the roof going in and it does the same thing and dips the audio.

Good observation!

Bose knows about the different audio conditions roof open/closed and adjusts the sound accordingly. The clamp is a reasonable place to put a sensing switch.

From what you say it seems that the "Striker Switch"switch buried inside the clamp socket may have a problem, it might be as simple as a loose wire or even a wire being shorted to chassis if the switch itself is loose. or the plunger to the switch, or even a faulty switch (unlikely). If it is the problem then taking off that top “Front Header Trim” seems to be the only way to get at it.

It might simply be that the striker needs adjustment.

Good luck.

 

As of yet I’ve not managed to check the striker plate / switch due to being busy and then my car being under snow haha

i am curious, however, as to whether anyone else has the behaviour on their hardtop where they engage the roof clamp and the audio cuts out briefly? If no one else has this then it may indicate a bigger problem with the whole mechanism.

i thought I’d update this, simply to offer a conclusion and some info for anyone else having the same issues. 

Firstly the striker plate was a red herring, it’s supposed to do that whenever the roof opens and shuts. 

Having given my car to Mazda for a week whilst they fixed the tensioner wheel on the aux belt, I asked them to check the radio. For a week they could not identify the issue but on the last day of having the car, they managed to replicate the problem and agreed to replace the Bose amp. If you believe what the garage says, it cost the warranty about £1k to do that!

anyway, if you have issues similar to what I described here, please check your amp.