5.1 to 7.1 matrixing on Onkyo 805

[Rike255]

So I've been told that the 805 is able to convert 5.1 audio signals to 7.1. First of all is this true? I read through the manual and couldn't find anything other then matrixing a stereo source to 6 channels.
If it is possible, does anyone know how to turn it on?
And lastly, what exactly happens? Does it just copy the surround channels to the rear surrounds or is there some actual conversions and stuff done?

Thanks!

[billbillw]

Just switch to PLIIx and it will fill your back surrounds in on either stereo, or 5.1 sources. It leaves the front channels alone when it does this.

[Rike255]

Oh well that's easy enough. So it just copies the other channel there's no signal processing going on. Great thanks.

[fumoffu]

I have the 705, but the 805 is very similar. There is probably no less then 12 different matrixing options available to achieve this. PLIIX, Neo:6, EX, ES, THX... there should be a HUGE table in the manual that spans about 4 pages which tell you when you can apply different processing options.

I myself keep it on PLIIX for TV watching, so it can handle 2-channel, 5.1, etc well. I don't use audessy equalization, but that would be applied there too.

For movies I use THX Select2 Cinema (your case would be Ultra2 Cinema). The will not apply audessy equalization, but instead optionally applies THX Re-EQ, which I like because it reduces the brightness of my room. I also use high bit rate audio which streams True-HD and DTS-MA, along with the older version. THX Select2 Cinema works nicely with this because it will auto-magically apply EX, ES matrix decoding.

Both of these will use all 7.1 speakers.

Enjoy, and play a round with the different modes to see what you like best, there are really to many option available!

[billbillw]

Oh well that's easy enough. So it just copies the other channel there's no signal processing going on. Great thanks.

There is signal processing in the surround and rear channels. It doesn't just copy them, it actively fills them in based on the signal in the surrounds.

And yes, you can use this on TrueHD, LPCM, or any other 5.1 signal.

fumoffu is right, there are many options, but I prefer to keep away from the THX modes due to their application of the THX equalization curve, which dulls things in my room. I prefer to keep the Audyssey equalization intact.

[kuntasensei]

For movies I use THX Select2 Cinema (your case would be Ultra2 Cinema). The will not apply audessy equalization, but instead optionally applies THX Re-EQ, which I like because it reduces the brightness of my room.

Actually, Audyssey's equalization is always active after you've run it, even in THX modes, unless you manually turn Audyssey EQ to off (or don't run the auto-setup with the mic). What it does is switch from the Audyssey target curve (which has a roll-off of highs similar to THX) to Audyssey's FLAT target curve when you use a THX mode. This keeps the benefits of flattened response that Audyssey is so great for, but prevents the Audyssey curve's rolloff from cascading with the THX rolloff. This is true of the 705, 805 and 905. Sadly, you can't leave your Onkyo set to THX w/o Re-EQ (which gives you Audyssey's FLAT mode) because Re-EQ defaults to ON when you power cycle the receiver.

Incidentally, both rolloffs at the high end are VERY similar. Professor Tomlinson Holman (the TH in THX) is Chief Scientist at Audyssey, and the two rolloffs are designed for the same purpose. The difference is just in the way they're implemented, though I find that after proper mic'ing for Audyssey, I don't lose high-end detail as much as I do with THX Re-EQ. Personally, I don't use the THX modes on my 705 because I don't care for the decorrelation of the surrounds... and I LOVE DPL-IIx Movie mode for 5.1 to 7.1 conversion. It creates a very natural and directional soundfield that works great with both movies and video games (where you can pan around in 3D and hear the sound very precisely placed between speakers, often giving you an edge).

Just curious, fumoffu... why didn't you like Audyssey? I've found that it takes some careful attention to proper mic setup when running it to get the best results (especially with the shallow mic that Onkyo provides that can throw off response if not carefully aimed), but especially with my Polks, the results are worth the 30-40 minutes of careful calibration.