Surround challenge of the day! 4.0 downmix, source & amp at opposite ends of room, WAF.

hoverdonkey

Standard Member
Hi


I have a head-scratcher that has been bugging me for a couple of years and would be grateful for some tips. I'll start with my main question and then explain why I'm asking it:

Is there decoder (or small AV receiver with pre-outs) that can downmix to 4.0?


I want to set up an (occasional) 4.0 surround system because:
  • I can't have a centre channel as our projector screen comes down in front of a large doorway, so I would like to centre signal info to go to front stereo speakers.
  • My wife won't allow a sub, so I would also like sub channel info to go to the front stereo speakers (they are transmission line speakers with very good bass extension).
Additional constraints:
  • The front stereo pair are currently powered by a valve amp, which I want to keep in place, i.e. no switching speakers to an AV receiver, as I want an easy life (wife again). The amp use the usual two channel RCA inputs. The speakers cables are in the wall.
  • The source is an Xbox One S, which can output by Toslink or HDMI. Snag is this is at the back of the room - it currently connects to DAC at the front of the room (where the amp is) via a Toslink cable that goes from back of room, through ceiling.

So, is there decoder (or small AV receiver with pre-outs) that can downmix to 4.0? I have spare amps/speakers for the rears. If cheap enough I could consider using two decoders (one at front, one at rear), which could be fed by duplicating the Toslink output from the XBox. Alternatively, I could use one decoder and send two channels to the other end of the room by Bluetooth AptX Low Latency (but this is adding extra tech in the chain and, I have a hunch, is just asking for trouble).

Any thoughts very welcome! Thank you.
 

Isco 3

Active Member
If you tell any AV receiver there is no centre channel, no side surrounds, no wides, no sub or Atmos, it will only play through your 4 speakers by default.
 

ShanePJ

Well-known Member
AVForums Sponsor
Don't panic about the centre channel as almost any av receiver worth anything today can run in phantom mode (which basically means it doesn't have a centre speaker and the centre channel is switched off). As for not using a subwoofer, These can be tucked away out of sight (which should mean out of mind to). A Rel TZero Mk2 is one of the most compact on the market at £300 mark whereas the Kef KC62 still very small is at a different scale of the market. If you didn't want to run a woofer at all, again, its like the centre channel where your speakers need to be set to "full range" and the woofer is switched off which will send all the low frequencies to the front speakers. The only real down side to this is all speakers have a limit of what frequencies the can produce and once you have hit that limit, you will hear nothing else below that. So for exciting explosions and the likes, the system may sound a little lifeless

So, as to whether there is a small av receiver, almost any will do the job from the Yamaha RX-V4A to the something more elaborate like the Anthem MRX-740, the list is endless :)
 

hoverdonkey

Standard Member
Don't panic about the centre channel as almost any av receiver worth anything today can run in phantom mode (which basically means it doesn't have a centre speaker and the centre channel is switched off). As for not using a subwoofer, These can be tucked away out of sight (which should mean out of mind to). A Rel TZero Mk2 is one of the most compact on the market at £300 mark whereas the Kef KC62 still very small is at a different scale of the market. If you didn't want to run a woofer at all, again, its like the centre channel where your speakers need to be set to "full range" and the woofer is switched off which will send all the low frequencies to the front speakers. The only real down side to this is all speakers have a limit of what frequencies the can produce and once you have hit that limit, you will hear nothing else below that. So for exciting explosions and the likes, the system may sound a little lifeless

So, as to whether there is a small av receiver, almost any will do the job from the Yamaha RX-V4A to the something more elaborate like the Anthem MRX-740, the list is endless :)
Many thanks for your very full reply. I will explore those options.
 

rccarguy2

Well-known Member
You'd need to get mid range avr with full set of pre outs.

Also if your valve amp lacks HT bypass you'd need to set the valve amp to pre marked level everytime you use the home cinema.

You can set mains to large, however I think you'll lose the dedicated .1 lfe I'm not sure if it's redirected to mains. Also means mains are full range and quite a demand on valve amp
 

hoverdonkey

Standard Member
You'd need to get mid range avr with full set of pre outs.

Also if your valve amp lacks HT bypass you'd need to set the valve amp to pre marked level everytime you use the home cinema.

You can set mains to large, however I think you'll lose the dedicated .1 lfe I'm not sure if it's redirected to mains. Also means mains are full range and quite a demand on valve amp

That's good advice, thank you.
 

hoverdonkey

Standard Member
I have being browsing around, looking for a decoder without amplification (that doesn't cost the earth), and have come across these:



It can output to 4.0. Quality is the worry however, even though I only want this for occasional use it's got to be acceptable (whatever that is!) The reviews seem okay though...
 

rccarguy2

Well-known Member
Pickup something like a lexicon mc-8 or similar
 

rccarguy2

Well-known Member
Also your tl speakers.may go low and ok spl, and for music that's ok, but for movies the extra demand on to speakers on SPL and dynamic range may be too much for that and your valve amp, you really need a sub to divert that low bass from your speakers.
 

rccarguy2

Well-known Member
I have been looking at that. I see it has musicast - would that allow me to send front channels across the room (with a MusicCast WXAD-10 to pick them up?)

That Yamaha lacks pre outs you need to aim for about £800 or so for a av amp with pre outs
 

rccarguy2

Well-known Member
If you want hdmi routing it's going to cost you.

If you're ok with Pro logic DD and DTS over coaxial or optical just get a older av amp with pre outs.
 

hoverdonkey

Standard Member
If you want hdmi routing it's going to cost you.

If you're ok with Pro logic DD and DTS over coaxial or optical just get a older av amp with pre outs.

An older AV amp might be enough, it is only for occasional use. I will never be allowed to have the full kahuna that I would love! I suppose that I can always go to the cinema for that... when Boris allows it again!
 

hoverdonkey

Standard Member
Just reporting back for anyone looking for closure on this thread, as I have now got a rudimentary DTS setup together to test my household's appetite for surround sound.

I ended up getting one of these decoders: 108.16US $ 36% OFF|HD920 5.1CH Audio Decoder Bluetooth 5.0 Reciever DAC DTS AC3 Dolby Atmos 4K HDMI compatible Converter SPDIF ARC PCUSB Sound Card|Digital-to-Analog Converter| - AliExpress (which came in about a week, which was great, and the seller is repsonsive to questions). It can downmix to 4.0 (or 4.1), which is perfect for my situation. It has decoded all the surround content I have thrown at it from the Xbox One S (in DTS mode) over the last few days (e.g. blu-ray, Netflix, Disney+, DVB). It's SQ is acceptable, good for the price really. It has remote (IR) volume, which my source (Xbox One S) can't do, which is very useful. I am currently using it in 4.0 but, I agree with previous advice, a subwoofer would be nice to take the load off my front pair. I will look into that at a later stage.

I realized that the Cat6 run that I already have in the walls could be used to get the audio signal to the back of the room using RCA-ethernet baluns (I found a pair of Intelix V2A2 on Ebay). The SQ is adequate for my needs at this stage.

For the rear channels I dug-out some old Mordaunt-Short MS302 satellties plus a Lepy 2024A Plus amp (but I will try my old Cyrus Straightline.. once I have found the blimin BFA plugs that it requires!).

I now have surround sound!
 

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