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Experiments

Valve ear speaker teardown

Ever wondered what was inside those neat off-ear speakers on the Valve Index?

“Balanced Mode Radiator” (BMR) ear speakers use custom drivers made by Tectonic for Valve. Valve list their audio solution as having these characteristics:-

Built-in: 37.5mm off-ear Balanced Mode Radiators (BMR), Frequency Response: 40Hz – 24KHz, Impedance: 6 Ohm, SPL: 98.96 dBSPL at 1cm.

In use onboard the Valve Index headset, the BMR ear speakers are unrivalled in terms of sound quality and sense of spatial soundstage for VR headsets, Emily Ridgway and her team at Valve certainly worked some magic here!

After experimenting with the BMR ear speakers and different audio headphones, I kept using the ear speakers as their excellent audio combined with quality of life (off-ear, on-board) was a great combination.

During the past year I did need to RMA a number of ear speakers, Steam support were very supportive and shipped them all as advanced replacement, and didn’t ask for the defective ones back. So I obtained some spares…

2 problem developed:-

1. Unwanted speaker movement. This seemed to worsen after lots of active gaming in Pistol Whip and Best Saber. Over time the ear speakers stopped holding the set position, drooping during a session or sudden movement. It appeared that the mechanism spring force degraded over time/use.

2. Vibrating. A slow developer but eventually the speaker pods started to vibrate at higher volumes or on bass hits. Not a malfunction of the driver but the physical connection between the speaker pod and speaker arm. This is felt as a looseness (slop) with light finger pressure, it’s easy to wobble the speakers pods.

Despite these problems I continued using the BMR ear speakers and gave Valve some feedback to help with further iterations.

How do they attach?

These attach to the Valve Index headset using a circular ‘pogo pin’ mounting system retained by a single torx T6 bolt through the headstrap.

Pogo pin mounting socket on Index headstrap

I decided to teardown one of my faulty BMR ear speakers to have a good look inside.

BMR Ear Speaker removed from Index, ‘Pogo Pin’ mounting system on the right
Carefully removed plastic cover (glued), I pushed it open using a flatblade screwdriver through the open slot for the height adjuster
Sliding height adjuster at minimum, power cable routing accommodates movement of height adjuster
Sliding height adjuster at maximum
Pogo pin mechanism taken apart showing pogo pin springs, bolts, sliding plate and circular pogo mounting

Looking closely at the “pogo pin” system, it’s cleverly designed using the springs to apply pressure to the pogo pins (to ensure contact with headstrap audio pads) and also allow vertical adjustment of the speaker with enough resistance to prevent unwanted movement.

Perhaps these springs are stretching over time/use, as springs do tend to stretch, to a reduced clamping force allowing the speaker pod to droop. It may be possible to tighten the small bolts to increase spring pressure, or pad the spring with steel washers to achieve the same.

The Circlip in the image above locks the speaker pod axle to the speaker arm.

This axle socket has gone sloppy (flogged out) on several of my ear speakers allowing the speaker pod to vibrate at higher volumes or during bass heavy audio. I’m unsure how this can be resolved without a different type of fitting, or perhaps a polymer bushing.

Circlip removed from axle
Speaker pod removed from arm, at this point I cut the power cables
Carefully working blade around speaker basket to break glue seal
Finally! Speaker assembly coming apart…
Wire basket removed, showing foam damper covering rear of driver unit
Wire basket removed from ear speaker pod
Thick foam damper from rear of ear speaker
Inside face of foam damper with moulding detail
BMR Ear Speaker pod stripped as far as possible, the plastic moulding was heavily glued to the front ring and resisted considerable force
Power wires to driver hanging inside speaker assembly
Detail showing driver and some type of baffling
Carefully cutting away the plastic moulding to access the driver
Driver core and baffling
Outside wire basket and diaphragm of driver
Cut apart driver showing magnet, copper coil, power leads
Close-up of coil

More information on the Valve Index audio is found in this blog article

https://immersivecomputing.org/2020/02/25/valve-index-ear-ergonomics/

Thanks for reading! Rob Cole.

By immersivecomputing.org

Human exploration of the immersive computing interface

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