Findings with regard to repair of Monolith M300 planar canalphones
Mar 2, 2021 at 11:10 PM Thread Starter Post #1 of 2


Headphoneus Supremus
Aug 2, 2005
Those of you who recognize my avatar know i have a bad habit of buying broken headphones.

So i pulled the trigger on a "right side not working" M300, pretty complete set, $40ish shipped.

These really are a half-baked design, if that. But anyway.

Construction method is glue. Cyanoacrylate (superglue) for the shell and silicone for the driver.

Separating the halves of the shell is heat and wiggling a sharp blade, like a brand new utility knife blade.

The terrible part is that the driver will separate with the shell. At least mine did. The spacer between the front of the driver and the nozzle separated from the rest of the driver and remained siliconed to the front half of the shell.

This does not necessarily destroy the driver. But the diaphragm is pretty fragile.

Maybe more heat and patience would do the job. Who knows.

The diaphragm has a spiral on both sides and the connection between them is made at the center. It looks like they perforated it 5 times and slathered on some conductive paint.

The failure on mine was at the center. I perforated it again and applied some CaiKote-44 to both sides and have a working circuit again.

I have not fully reassembled and cannot say for sure that my repair is a complete success. The diaphragm is slightly delaminated for a few mm and i don't have the right silicone handy at the moment. I could use E6000 but that might be effectively permanent so i would rather pick up another tube of permatex flowable silicone. Some time this week.

It might turn out that i have damaged the right-side driver enough that i will be in the market for a working replacement. My ears are big enough that after replacing the "nice" but entirely inappropriate fabric jacketed cable with a thinner mmcx cable with formed ear loops i actually get a pretty good seal on the left driver so i am interested in having a working set.

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