Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems Setting Side and Rear Surround Delay?

Is there any general formula which indicates the amount of delay (in ms.) to apply to the side and rear surround channels? My sides are 8'9" from the centered seat, and my rears are 11'6" behind the center seat. I am interested mostly for those presets utilized for movies (DD, DTS, THX, EZ, etc.). Thanks!

I should mention that I have previously provided these distances to the 861 when specifying the speakers configuration in set up. I guess my quesiton is wether the 861 will automatically provide the correct time delays based on this information, or whether I need to go back into each preset and manually enter the necessary delays based on some formula. If the 861 automatically performs these calculations, does anyone out there make changes manually? If so, with what intentions and results? Thanks!

I am curious to read the replies to this as well. I have done research (reading and contact with dealers and manufacturers) on several surround processors and have found that many of the systems actually defeat the delay option when using DTS and THX, citing that the effect of delay is supposed to be controlled by the processed signal not by the processor. I suppose that they are "assuming" that everyone has the unique ability of configuring their room in such a way as to match the "ideal" spec's that these protocols define or require.

To measure and enter the physical distances to your speakers in the setup programm of your decoder
are necassary to "synchronise" the music to your listening position.
That means that the speaker array are timecorrected to your room, or in other words,
you have the same position as the recording engineer in the studio.
So for example (as you can play in "presets" in the setup programm for your controller)
--is the rear prologic signal are delayed with 20 ms--
then the sound from your rear speakers reaches your ear 20 ms later than your front speaker signal.
So when you enter the distances in setup, you get allways the correct information independent of the size
of your room.
With digital surround sources you dont need an extra delay,because the information are allready recorded
with the proper delay (time differences between front and rear music).


[This message has been edited by robert.w (edited 12-30-2001).]

The question still remains, why does Meridian allow for further modification of delay to each surround speaker when creating a modified preset (user defined)? If the 861 automatically compensates for speakers to listener distances when processing the digital signals (DD, DTS, etc.) as well as processed sound (Musicolgic, Trifield, etc.), does anyone apply additional delays, and if so, to what advantages?

Additional delay in music modes are just to increase the size of the venue. If they are set to 0, all ambiance would reach the listener at the same time as the primary source of sound, thereby not creating any sense of ambiance at all. You have to set those delays at a position where you feel a sense of space, but not to the point where it seems to be a seperate source of sound.

To do that, you should start with the delay at 0, set the surround channel's level set at +10 or so & the filter to off, play whatever music you listen to apropriate for that DSP mode, then gradually increase the delay until it sounds like an echo coming from the surround channels. That would be your maximum delay allowable. Then you would decrease it to what you feel the proper size of the venue should be, change the filter setting until you cannot localize the surround speakers (I usually set it at 7khz) then decrease the surround level until you feel it is the right type of venue (you might want to set it to a few dB above the default if you want to hear the room, since modes like Trifield and Music utilize ambiance very subtlely.)

Ambisonice requires no delay, since the reproduced side and rear channels are the actual hall ambiance arriving from that direction as recorded by the microphone.

As far as DD/DTS w/movies, they should probably be set to 0, since nothing ever sounds natural in the movies anyway, music frequently sounding like the old quadraphonics (w/different instruments coming from different channels,) a soundfield that reach the listener from all the speakers at the same time would probably be required.

[This message has been edited by lwang (edited 01-01-2002).]

lwang is pretty much correct. However as Bob Stuart has demonstrated many times, an extra .5 ms delay on the center sounds better.