Hi Chris

Perhaps it would be useful if you had a brief explanation of what AST is and what it does for you.  Lets start with the problem first, a DSS set-up has a 'perfect' set-up which is often compromised for convenience, pure aesthetics or to simply to please your partner so you can have the loudspeakers you want :-)

The perfect setup would have you sat directly infront of your screen with the front left/right loudspeakers at an angle of 30 degrees from perpendicular.  Your surround (often mistakingly called 'rear') loudspeakers should be at an angle of 110 degrees from perpendicular and all loudspeakers should be at an equal distance from your head.

This is where the problem lies, most people cannot put their loudspeakers in the perfect position so you often have surround loudspeakers too close to your head or one loudspeaker too close to the TV etc.  As a result the spatial qualities of the recordings just fail.  You will hear the sound from one loudspeaker more than you will another.  You can correct for this to some extent using the speaker distance and level settings with the television.  However, this only corrects and optomises for one listening position, this is where AST comes in.

AST creates a sweet 'area' rather than the traditional sweet 'spot'.  This means you can have the impression of the perfect surround sound set-up, even though your loudspeakers are placed in a less than perfect position.  So, I can put the loudspeakers where Mrs Bell tells me they have to go but make it sound like it should so Mr Bell is happy too....everyone wins and we all stay married :-)

Of course, if you can setup the prefect listening position (or close to it) then you shouldn't use AST, afterall AST is using very advanced algorithms to immitate the perfect setup.  If you already have the perfect set-up then lets not try an immitate it.

Another advantage is that you can have more than one listening position.  Perhaps you have a favourite chair when you watch the sport but Mrs Bell has a different seat when she wastches the movies.  No problem, I have more than one pre-set position and just ask the TV to optomise each one accordingly.  Alternatively you might have a preferred position for watching TV and a completely different position for listening to music.  No problem, each can be set-up to give you the perfect listening position.

So in summary, you can choose which loudspeakers you would like and where you want to put them, we will make it sound like it should

Hope that helps

Doug

PS  Acoustic lenses correct for timberal faults, not spatial errors. i.e you hear everything in the performance because of the lenses, you heard it from the correct position because of AST.

Thanks for the excellent explanation. Any comments on AST where the speakers are basically in the correct locations but the possibility exists to add two more as rears that would not be ideally placed? I.E. 5.1 positions are almost ideal, but positions for extra speakers to make 6.1 or 7.1 are not ideal?

Thanks Doug, that explains quite nicely how its working etc, however I am still not quite understanding the way it works with the existing system.

If I select AST say preset 1 whilst watching a film, does it know and switch to a 5.1 surround, or does AST work only really on stereo fields?...If i select speaker 2 on the TV ( for front left & right speakers only ) then goto AST does it selct AST to work within the chosen speaker assisgnment or does it overide it in some way?

I suppose i am looking for clarification as to how AST integrates with the standard speaker 1 -4 system, as it worked pre AST the speaker function worked as follows..1 being TV 7.2 speaker only, 2 being stereo front left & right only,3 being 7.2 + front left & right, 4 being stereo l & r fronts & l & r rears together, 5 being surround sound.

So now what happens when I say want to listen to music in speaker mode 2 with AST?...do the presets in AST alter to move the sweet 'area' in this mode only or does AST just totally override the speaker options & use all the speakers in a full surround mode all the time?

I have to say so far I have found that its best just to use the front BL5's when listening to music, and then just use the standard speaker 5 ( default ) option with AST set to TV when watching a 5.1 broadcast....I am struggling to see what AST is doing for me, in that to my ears its better switched OFF...possbily as you say due to me having a fairly central listening position anyway. I dont understand though why AST set to TV ( ie off ) should be beter than AST set to preset 1 which is supposed to represent the central listening position, shouldnt these two positions be excactly the same??

Hi Chris

When AST is switched on there is no longer a speaker 1,2,3 etc option, indeed Front left/right etc no longer exist.  There are simply loudspeakers that play sound and depending on their position they might play a bit of centre channel, a bit of front channel or even a bit of surround channel as well to give the total illusion of a correct surround sound placement.

Imagine you were in the middle of a field with a perfect DSS setup and no obstructions.  If you play a sound through, say, front left you will be able to close your eyes and tell me where the sound is coming from.  Now leave those speakers where they are and put a room around you that has lots of randomly placed open windows.  If you play the same loudspeaker you will hear the sound travelling in through the windows at various volumes etc.  You will still be able to locate the loudspeaker correctly.  Final step would be to replace those windows with a loudspeaker and play through them the sound that would have come in through the window.  Each one will play a different part and will play a bit of this and bit of that to give the overall total phantom 'perfect' DSS setup

It seems to me like you have a pretty good set-up already and don't really need AST.  If you cannot hear a big difference then either you already have a good setup and don't need it or it has been setup incorrectly, I suspect your setup is good enough already not to need it.

It also seems like you only have one listening position for all sources so again, there is limited benefit for you.  Try leaving the TV in speaker 5 and moving to one extreme side of the soundstage - you will hear the sound crashing into the loudspeaker closest to you.  This is just to demonstrate how AST could help you, not to say you need it.

Doug

Hi Razlaw

AST works better the worst placed the loudspeaker are.  In other words, the nearer your setup is to perfect, the less you need AST.

I guess it depends on how badly placed your rear loudspeakers are.  Perhaps you could ask you dealer to upgrade the software and try different configurations for you.  I would say though that the upgrade and set-up isn't a simple task, it will require laser measures etc to ensure the correct readings are placed in the TV so it may take a while to do.

Doug

Thanks. We have a Bevision 7-55 ordered and I already have the extra speakers so I will probably go ahead and try it out.

Hi,

Just thought that I'd drop into this Forum to help out - since I'm the guy in Struer behind AST... Doug's answers are perfect - he said what I would have said if I had gotten there first...

I've just a couple of minor things to add...

For info on speaker placement for 7.1, a good place to look (and get more confused) is

Thanks Doug & Geoff, You have totally explained it to me. Was messing around last night with it, and yep I have found that as I am fairly central with BL9's behind left & right & BL5's up front left & right that indeed I find my sound quality better without AST on.

For music, I simply use the stereo BL5's and if I want an extra 'kick' to surround me I add the BL9's to the mix. For films then the 5.1 setup works the best.

AST works ok if I move to the extreme left or right of the room ( living room is 40 foot long,20 foot wide ), if I then select one of the presets set up for those positions then you can tell AST has moved the sound about a bit to compensate. However really for me it hasnt been money well spent as I have 3 sofa's in a C shape central in the room which is the only sitting positions one would use when watching or listening to music in that room. I have also found that without AST the sounds are much more seperate,defined and dynamic, with AST on it seems to blur the sound a little, sort of blends it all in, almost reminds me of listening to a .wav lossless music file compared to a compressed mp3 file..yes it smooths highs & lows out etc, but it looses some of the clear edge....maybe that is because the BL5's & 9's are such good speakers & as I said I am central, so they work best being allowed to do their thing with no intereference!

Anyway cool title Geoff, the Tonmeister...liking that alot!...thanks again to you & Doug for taking the time, I feel I have it all sussed out now, cheers

Hi Chris,

One thing I have noticed in more rectangular setups (you say that your living room is 40x20...) is that it might improve things in AST to "cheat" a little on your listening position. If the preset's listening position is too close to one (or more) speakers, then you might find that things misbehave a little - especially with surround material (typical symptoms are a "darker" sound color, or one channel sticking out in one speaker...).

A simple solution is to lie to your Beosystem3. When you make the AST preset, place the Listening Position more in the middle of the room than the chair that you're actually sitting in. This might clean things up a little.

Cheers

-geoff