The Bose PAS comes Mono. What does this mean ? Does anyone really know about the PAS architecure ? compared to the regular PA Systems.

The use of stereo outs from a KBD is VERY Important, so how can we compromise in order to send sterio out to the PAS and get all the benefits of panning ??

In order to get sterio from a KBD we NEED to use 2 or more outs. So, using 2 or more outs has anybody tested the PAS for KBD clarity ?

Can some Techies from Bose or anywhere shed some light on the PAS structure because IMO mono and stereo dont apply for the PAS output. Anyway the PAS gives amazing surround and full sound, so mono and stereo dont apply (IMO).

Michael

This has been discussed here a lot already. Search through the forum for Bose or Stereo discussions and you'll find the info. Short summary: stereo PA or amps sound better for keyboards if you want to go to the expense (yes, in the case of the Bose system you would need to buy two for stereo). If you go mono, there's a possibility of phase cancellation affecting your sound. Some people can live with that, some can't.

Phase cancellation occurs when two sound waves intersect at a single point. This can happen in a large room or an intimate one. A good trick to avoid this acoustic phenomenom is to take the stereo outs from your source - use two separate channels, and EQ them differntly, so the sound wave produced by each signal is slightly different. For example:
Thate the mids DOWN onone channel, and boost the mids UP on the other channel.
This is an old studio trick (in reverse) that used to simulate a stereo feed from a mono source. Try to find that one "swet spot" that works for your particular sound, and the cancellation just may disapear.

My feeling is that a truly high quality sound NEEDS to sound good in mono as well as stereo. The rooms are too different to expect that only one setting will cover all bases. Mono is a neccessity sometimes.

WTF? EQ won't eliminate phase cancellation. A digital delay is pretty much the only solution that will work if you have the equipment to be able to see the phase well enough to know how much to offset the left signal from the right.

Sound waves are like ocean waves - phase cancellation occurs when a wave that is cresting up meets it's opposite cresting down. EQ might keep a few specific frequencies from colliding (I wouldn't even bet on that actually) but it's not possible to EQ all of the summed frequencies enough to prevent all cancellation.

This isn't just a discussion going on here but in every keyboard discussion forum on the web currently. Many people have been trying all sorts of tricks to prevent phase cancellation, and so far the only viable solution I've seen is by delaying the left or right signal just enough to keep the phase problems from happening. I even read where one person was trying to use a short cable on one channel and a very long one on the other when running stereo keyboards to a mono amp... obviously this isn't an exacting way to solve the problem but I think it's on the right track.

The people who are using mono amplification are just learning how to live with the reduction in sound quality. The ultimate answer is to just try your rig in mono and stereo and decide for yourself.

A graphic works better in this task, but mark my words, you CAN alter (reduce or eliminate) some cancellations by EQing the two signals in opposit manners. Try it.