[linux-audio-dev] Latency and feedback problems: soundcard with live microphone pass-thru, optimal solution ?

[Dan Mills]

On Saturday 29 October 2005 22:25, fons adriaensen wrote:

> Frequency shifting will give a few dB extra, not more. It's based on the
> fact that a typical room response will have many very narrow peaks only
> a few Hz or less apart, and shifting the frequencies will smooth out the
> response as the sound circulates around the loop.

Actually it also causes the phase shift around the loop to be variable and 
thus tends to remove the required phasing conditions in fairly short order.

Very helpful for conference work where the suits just will not speak into the 
damn mic. 

> It's less useful for stage monitoring for two reasons: first, there is
> usually a dominant direct path from the monitor to the artist and the mic
> (otherwise the monitor isn't very useful), and the room response has less
> impact on the loop gain, and second, the combination of the direct sound
> and the shifted one can be very confusing for the artist.

The second is the real kicker here, the difference between the direct sound 
(mostly bone conduction), and the frequency shifted one can make it almost 
impossible for a vocalist to work. 

However monitors can almost always be tamed by correct placement and mic 
choice, for example, when using hypercardoid vocal mics, two monitors placed 
30 degrees off axis will be FAR better then one, look at the mic polar 
diagram for why!

Ohh yea, putting the guitar cab on a flightcase so it is at ear level can 
really help reduce overall stage volume! I want to find out where they teach 
guitar players that they have ears in their knees, then nuke from orbit!  

Regards, Dan.