The left ear is not giving audio

Possibly this is a wire that has been snapped or disconnected under speaker membrane. Very bad design. I had the same problem (although on the right ear). If you remove the ear pad and the padding, you will see the membrane. No need for any tool to do this. Apply soft pressure with a non metallic non piercing tip on the upper portion and you should hear it play. I squeezed in a piece of paper to have the membrane apply pressure on the wire and bingo. I'm not sure though how long it will last. If it start failing again I will unscrew the piece and look for a more permanent fixture. If you search on Google, you will find a Youtube video (in Spanish with English subtitles) showing you how do it. The guy did it on QC15 earpiece but the same applies on QC25, the wire is just in a different location. Hope this help.

Just called bose they said that qc25 that were made before mid 2015 have had trouble with one ear going out they have fixed the problem and are replacing yours free if it was made before mid 2015 call tech support

Reda Bitar, either a bad driver or loose wiring. Check this guide to get to the driver. Let us know what you find.

"I will share what I have found.

After you disassemble your earcup, which ever side of malfunction, take a closer look into the plastic/vinyl cone.

There are two single copper wire going underneath the cone.

They are about or little bit thinner than human hair.

It seems like those copper wire rusted over time.

I used to wearing my QC3 while I was working out.

So, sweat and other moisture might be soaked into the earcup and eventually affected the copper wires.

The problem is not soley upon the rust, but it will be broken as the cone bouncing up and down million times and it ages.

I truly believe that BOSE intends to make this as it is.

Only two single copper wires, thinner than a human hair, connects between the circuit board and the voice coil.

2 years of life cycle... confirmed.

After 1 year of manufacturer's warranty, it will blow out anytime soon.

All the warranty/replacement items will be opened and the two copper wires will be replaced.

They will be factory sealed back, having a new ear cups, and sold as ""Factory Refurbished"".

I am not talking about the quality of BOSE products. I love BOSE

However, they should pay little more attention on those little things.

If any executive of BOSE read this, think it again.

Customers love a reliable quality product.

They will purchase it again for their loved ones.

Don't make a customer to buy the same thing twice within 2 years, or to spend more $$ for unnecessary upgrade.

After the inspection, I ended up tearing off the vinyl cone.

The copper wires were already broken before I tear off the cone.

The vinyl cone is somehow glue to the voice coil, so I broke the voice coil at the end.

Final word?

My QC3 left is gone, permanently.

I had been using this for 3 years, and stored it for another 3 years.

Now is the time to get a new gear once again.

I WILL NEVER WEAR THIS WHEN I WORKOUT OR UNDER ANY TYPE OF MOISTURE ENVIRONMENT.

Hope this ease your mind.

Don't try to fix it because this is made as the copper wires are supposed to break after a while.

Good luck.

Paul."

Take these to a Bose retail store. There is a good chance they will replace even if you are out of warranty. The sales rep looked up the serial number and some QC 25 models have been recalled. They gave me a brand new pair.

"Ok, here's a fix that we found on the internet. Check it out. We tried it and it works. I don't know if it will continue to work for a long time, but at least it works. The video is in Spanish with English subtitles. There is a good written explanation down in the string written by Chris Moler. We had to use two strips each doubled over of a business card for our solution.

https://youtu.be/_OYva0hOW0Q"