"Sean Conolly" <sjconolly_98@[EMAIL PROTECTED]
> wrote in message
news:LuALj.21499$9O.10523@[EMAIL PROTECTED]
> This is a little late to add to George's topic, so I'm starting a new
> thread...
>
> To summarize, the classic method seems to be to get as much gain as you
> can out of the first preamp stage to get a good S/N ratio, with enough
> headroom, and then set the following stages to maintian this all the way
> to the amp. Not going into what is enough headroom or how you determine
> it, this is the jist of the idea.
>
> Another school of thought that I've been exposed to is to optimise the
> levels for unity gain after the the first stage - i.e get as much gain
as
> you *need* from the first stage so you don't have to attenuate or
amplify
> the level at a following stage. It's based on the idea that idea that
> changing the gain level always has some detrimental side effects, so get
> as close as you can at the first stage and then try to keep the
following
> stages close to unity gain. In practice this frequently means reducing
the
> trims to keep the faders near zero.
>
> Is there any validity to it is this just another garbage idea that I
> picked up decades ago? The electronics have improved so much (or maybe
I'm
> just using better gear) that the noise floor of the source signal is
much
> higher than anything in the board. I'm just not convinced that unity
gain
> in a preamp stage is the same as a 'wire without gain'.
>
> Thanks in advance,
> Sean
>
> *just to clarify my terms - by preamp stage I mean any in-line amplifier
> circuit intended to drive a following circuit, and not a speaker.
>
>
I do mostly theatre work with radios (as an unpaid pro;-)) and I find it
helpful to run the desk with channel faders at around 0db, if only for the
visual reassurance, as I often find myself riding the faders throughout
the
performance to cope with on-stage groupings and variable orchestra levels.
Having a known visual reference point to bring the level back to seems
useful. I generally adjust the pre-amp trims to achieve this - within
reason. It surprises me that I have to do this at sound check prior to
every performance - no two are the same. Apart from the obvious need to
avoid overdriving the pre-amps, I can't honestly say that running them at
less than "max without clipping" makes any appreciable difference to
background system noise, which is inaudible relative to normal theatre
noise
such as coughing, aircon, stage action, etc., etc.
Chas
PS Why is it that channel mute indicators are wired "in reverse", i.e. the
light (if indeed there is one) is ON when the channel is OFF (i.e. muted)?
I can understand that it is a warning to the desk operator that the
channel
is off, but in a situation where channels are being switched in and out
frequently through a performance I find it much more comforting to get a
positive visual indication that it is ON. For this reason I often use the
channel faders as mutes - this being another good reason IMHO to adjust
them
for 0dB at set up.
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