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Question help - 5.1 > 2.1 soundbar (via tv passthrough)


Active Member
Hi all,

I've a problem with my setup I'm trying to get to the bottom of and I've realised that half of my issue is that I don't fully understand what "should" be happening.

I previously had an Amazon Fire TV (1st gen) connected to my Hisense 55M3300 TV via HDMI. I then have a rather cheap Sharp soundbar connected to my TV via the tv's optical out. This all worked fine - by fine I mean I got sound through the soundbar.

I've recently purchased a Xiaomi Mi Box. I've upgraded the firmware to Nougat (Beta) - I did this before anything else (I mention this as I've no idea if this is a potential cause of my problem).

I now get zero sound through my soundbar.

I've tried changing all of the settings on both the Mi Box and the TV. I've also tried connecting the Mi Box directly to the soundbar (the Mi Box also has optical out) - still nothing.

I can see the led lights on the soundbar twitching at various times so it looks as though some kind of signal is being received but I have no idea what the lights represent as I no longer have the manual.

So, this leads me to my question.

If my device (any device for the purpose of my question) outputs some kind of signal (5.1 etc) at what point is that signal decoded into something that comes out of the soundbar. Obviously the Fire TV sent a signal out to the TV...the TV sent a signal out to the soundbar...the soundbar made noise!

Is the device responsible for decoding the signal, or the tv, or the soundbar???

If the setup previously worked with the Fire TV - does this indicate that the Mi Box has a fault, or that the Fire TV was able to decode the signal before it sent it to the TV and that the Mi Box is not doing this...perhaps it's sending a signal it's expecting will be decoded downstream?

I'm happy to buy another soundbar if the issue is that my soundbar isn't capable of decoding the signal - but I'd just like to understand how it managed to work with the Fire TV.

Equally, I'm not sure I want a full 5.1 system - apart from anything else, the arrangement of my lounge really wouldn't benefit from having rear speakers (my sofa is against the rear wall).

Any help or pointers towards some literature explaining things would be really, really appreciated!



Joe Fernand

Distinguished Member
AVForums Sponsor
With your optical cable connected to the TV have a look and see if it is emitting red light at the other end of the cable.

Many TV's only support 2.0 audio via HDMI so try setting the Source to 2.0 (PCM).



Active Member
Hi Joe,

Thanks for replying.

There's a red light from the optical cable when connected to the TV or the mi box.

My TV has options for passthrough of PCM or raw... I've tried both. My mi box also has the PCM option... No configuration seems to produce sound though.

When I had my fire tv connected, the TV was set to PCM passthrough.

I bit the bullet and purchased a new soundbar (Samsung HW-K450) which will arrive tomorrow. If that doesn't work then I'll assume the mi box is faulty.


Active Member
Fixed: turned out to be the soundbar being temperamental - I unplugged everything from the soundbar and plugged it back in and it worked...typical...by this time though I'd ordered the new soundbar > ordered the logitech Z906 system > cancelled the new soundbar order...now got everything hooked up to the Z906 and it's sounding niiiiiiice ! :)

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