[LAU] Behringer ADA8000 phase

[Ricardus Vincente]

On 07/01/2013 05:29 PM, Fons Adriaensen wrote:

> Hello all,
> 
> The incredible happens.
> 
> The electronics of the 'Lampadario' at the Casa del Suono in
> Parma consists of a rack with an RME ADI468 converting MADI
> to 8 ADAT outputs, 8 Behringer ADA8000 converters, and 8 QSC
> amplifiers of 8 channels each. The rack was wired (very neatly)
> by a firm specialising in this sort of work.
> 
> When I installed the software four years ago, I found out
> that 25 of the 64 channels had their phase inverted. For one
> of those it was an error in the speaker wiring, which was easy
> to correct. The other 24 corresponded exactly to 3 groups of 8,
> and the speaker wiring was OK. I assumed that the cables between
> the ADA8000 and the amps were to blame - this is a non-standard
> cable which had to be hand-made by the whoever did the wiring.
> If two technicians had worked on that, they could have had
> different ideas of what were the correct connections. 
> 
> Since I didn't want to take the rack apart, resolder 24 wires
> and put it all back, and since there was only one SW app driving
> the installation at that time, those 24 inversions were corrected
> for by that software. So far so good.
> 
> Recently I re-measured the IRs of the whole thing. There
> were again 24 channels out of phase. But not the same ones.
> One of the groups of 8 had turned in-phase, and another
> one was now inverted. 
> 
> The only thing that has happened to the installation over
> the last years is that some of the Behringers failed (power
> supply blown up, one per year on average) and were replaced.
> So I checked those separately. And yes, some of them had their
> output phase inverted w.r.t. the others. Apparently the thing
> exists in two versions, but apart from measuring there's no
> way to tell which is which. So I'll have to recheck things
> each time any of them are replaced again. Thank $GOD we didn't
> use those for the WFS system.
> 
> The incredible happens.
> 
> Ciao,

 Wow. Tricky.

 I think the original Black-faced ADATs would record the audio out of
phase to tape, and then correct it on the way out. So if you had tapes
recorded in a Black-faced ADAT, and played it in a silver XT, or had
tapes recorded in a Silver XT, and played it in a Black-faced unit, you
were 180 degrees out of phase on playback.

 Rich...