So here's the deal: the VMK20 and Sennheiser BT T100 find each other, shake hands politely, and announce they're connected – but no sound comes through. Like two Finns at a bar: connection established, but nobody's talking.
This problem is annoyingly common with this combo, and the cause is usually pretty simple.
Why isn't the audio coming through?
The T100 is a bit of a fussy transmitter. It supports multiple Bluetooth codecs, and if it negotiates the wrong codec with the VMK20, the connection looks like it's working – but the audio gets lost along the way.
The VMK20 supports the aptX Low Latency codec, and that's probably exactly why you bought this combo in the first place. It works great, as long as the T100 knows what's expected of it. With default settings, it might try to use some other codec, and then the audio vanishes like dad's beers at a midsummer party.
How to fix it
- Reset the VMK20 – Plug a 3.5mm AUX cable into the headphones and unplug it. This resets the Bluetooth circuit. Simple but effective trick.
- Set the T100 to the right mode – Check Sennheiser's instructions on how to force the transmitter into aptX LL mode. Usually this is done by holding the pairing button for a specific time or switching modes with a short press. The T100 has different modes for different codecs, and you need to pick aptX LL specifically.
- Clear old pairings from both devices – Turn off the VMK20, restart it in pairing mode (hold the MFB button until you hear a tone and the light flashes). Put the T100 in pairing mode too.
- Reconnect – Let the devices find each other with a clean slate. Don't keep other Bluetooth devices nearby to cause interference.
- Check your audio source – Sounds obvious, but make sure the device connected to the T100 (TV, computer, whatever) is actually outputting audio. Sometimes the problem is on that end.
Multipoint can mess things up
The VMK20 supports multipoint, meaning it can be connected to two devices at the same time. If the headphones are already connected to your phone or computer, they might prioritise the other connection. Try turning off Bluetooth on your other devices first and connect solely to the T100.
If nothing helps
If audio still won't come through after all these tricks, the issue might be with the T100's firmware version or some other setting on Sennheiser's end. Check Sennheiser's website to see if there's an update available for the transmitter.
If you suspect the VMK20 is at fault, drop us a message at info@valco.fi. Include your order number and describe the situation, and we'll sort it out. We fix things here – we don't chuck them in the bin.
And if all else fails, an AUX cable will at least get the audio flowing. It's not as elegant, but it always works – a wired connection doesn't need to negotiate codecs with anyone.
