System design for multichannel audio playback to small speakers

[Noah Norman]

I'm trying to determine the best setup to enable me to send multichannel audio out of QLab to passive speakers (likely 5 of them, the smaller the better). I want to use small, passive speakers so I can hide them in a room for an immersive theatrical presentation and only run lamp cord to them rather than XLR and power. 

My first thought was to send multichannel audio down the HDMI out of a mac to a surround sound receiver / all-in-one system that decodes and powers some small speakers. From what I gather, though, it's not possible to encode multichannel audio to send over HDMI from QLab. Unfortunately, it seems that in order to get multichannel audio into modern receivers, your options are ADAT or HDMI.

I could certainly see using a multichannel USB interface but after that I'm stuck for a good solution to get something like (5) x1/4" cables into a home theater receiver ... or is there some other multichannel amplifier type that I'm not aware of that mitigates this problem?

Any help would be appreciated! 

Thanks very much,

N

[Paul Gotch]

On Tue, Oct 01, 2013 at 02:14:39PM -0700, Noah Norman wrote:
> some small speakers. From what I gather, though, it's not possible to
> encode multichannel audio to send over HDMI from QLab. Unfortunately, it
> seems that in order to get multichannel audio into modern receivers, your
> options are ADAT or HDMI.

Anything that has been designed recently will be able to accept
multi-channel LPCM over HDMI as it's basically required due to a bunch
of banal reasons around bluray. Therefore QLab doesn't need to encode
audio to compressed surrround sound format.

Consumer receivers will have TOSLINK not ADAT Lightpipe, same
connectors totally different, and fundamentally stereo for unencoded
audio, interface.

I'm not in a position to test this at the moment but open "Audio MIDI
Setup" and select the HDMI output. There should be a drop down with the
formats selectable. If there is one with mutiple channels then you
might get QLab to recognise multiple channels.

If there is only the option for 2 channels then QLab is never going to
play more than stereo, although other applications that can send
non-audio streams in hog mode such as VLC will be able to send multiple
channel.

> I could certainly see using a multichannel USB interface but after that I'm
> stuck for a good solution to get something like (5) x1/4" cables into a
> home theater receiver ... or is there some other multichannel amplifier
> type that I'm not aware of that mitigates this problem?

At that point you just buy a multi-channel power amp with balanced
inputs and forget about consumer level products. For example Yamaha
XM4080 provides 4 x 80W channels in 2U.

-p
--
Paul Gotch
--------------------------------------------------------------------

[Noah Norman]

Good man Paul!

The advice about commercial amps with balanced inputs was a 'duh' moment for me. That is obviously the solution.

Thanks!

[Mick Ritchie]

Hi Noah


I picked up a bargain pioneer home a/v box on ebay and when hdmi cable is plugged from mini mac to it Qlab shows up HDMI audio ouput.
I was concerned about reliabilty and turning on and off but its been installed for a couple of weeks without a problem - 6 avi neutron speakers
not as 5.1 but could do. When buying a box I bought s/h because new ones rarely have multiple line in and preamp outputs these days and
having preouts means i can use it for larger amps and speakers
My 2009 macbookpro also worked using minidisplay to hdmi audio which was a surprise. I just used multichannel wav files. I havent tried alongside
video so dont know if that would work yet.
Its worth checking the specs of a/v boxes as older ones may only have stereo hdmi - only drawback is qlab crashing if any hdmi settings are changed
and setting up a/v boxes is a challenge in itself

I did do a similar thing years ago using digital audio output from a mac to an older home cinema box using spdif and that also worked fine but meant using ac3 and playback from vlc - before qlab2 was even a twinke in the eye

any other advice dont hesitate

mick

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