ICBM and channel delays

I am considering a Denon DVD-2200 or 2900 in the near future. I have an Arcam AVR200 receiver (no analogue bass management) and Boston Acoustics VR-M60s front, VRC centre, VR-M50s rear and PV700 sub. Either Denon applies channel delays to DVD-Audio (SACD lacks this feature in every universal player I can afford). Will the ICBM interfere with the channel delay settings in the DVD player or will it take them into account? An answer to this will go a long way in determining whether I get an ICBM. Thanks.

In the ICBM's manual, Outlaw recommends against setting any delay values on the input side of an ICBM.

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If the ICBM will be located between your player and your receiver, best to set delays after the ICBM, if your receiver allows for delay settings.

If no delay settings are possible after the ICBM, then you are faced with a choice: no timing difference between channels, as Outlaw suggests, or set the delay before the ICBM. You could try it both ways and judge the results. If you can hear little or no difference, leave all channels with identical or zero delay. If setting the delay per instructions of the unit ahead of the ICBM has the effect of “dramatically opening the sound stage” or similar when applied, and you notice no degradation of the bass from the subwoofer(s), then you may allow the delays to be set in a non-identical manner.

Slightly differing delays before the ICBM have the effect of mixing the sub-bass from one channel slightly out of phase with another channel by a millisecond or two. The lower the frequency, the less net effect this one or two milliseconds will have on the shape of the mixed wave. Mixing frequencies above the subwoofer range this way would lead to easily notable results, as would having delays set where the delays differ from each other by several milliseconds or more.

If your mains, center and surround speakers are similar in distance from the prime listening area, I would leave the delays at zero, or identically set.

Is this also true if I use the delays without the ICBM?

While I am not privy to the signal path layout of your receiver, if I were designing a unit where the delay of individual channels or groups of channels was possible, and the bass management portion of my unit mixed the lowest frequencies of several channels together in its bass management section, I would put the delays into effect after the lowest frequencies were summed, not before.

Because the ICBM is not designed to provide delays, it relies on the incoming signals to arrive at the ICBM inputs with the same timing as the original source outputs. Delaying one or more channels before the ICBM will mean that the frequencies below the selected crossover point will be mixed with those lowest frequencies slightly out of time with each other. Depending on the amount of any delay(s) and the frequencies being mixed, this will have anywhere from a negligible effect to an easily noticeable effect. This is why it is easiest to leave all the delays at zero or set identically and not be concerned about the mixing of sub-bass frequencies with a time shift in place.

I only suggested trying your system both with and without differentiating delay settings for you to hear the results. Without differentiating delays, the sub-bass mixing will be unaffected. With differentiated delays, the arrival of sound from each speaker is timed such that the listener in the ideal location hears each speaker as if it were equidistant from the listener. Which is more important to you?

The need for speaker delays at all is something that is VERY exaggerated in it's importance. Why the manufacturers chose to make this "feature" available at all is beyond me. Mundane things like the room's acoustics and the placement of the speakers in that room make a much larger difference in the final sound than a few milliseconds here or there in speaker delay.

[This message has been edited by soundhound (edited March 09, 2004).]