"Mike Dobony" <sword@[EMAIL PROTECTED]
> wrote in message
news:2brbgaz4it8k$.12r5yjxibm55x$.dlg@[EMAIL PROTECTED]
> On Thu, 10 Apr 2008 23:00:17 -0400, Sean Conolly wrote:
>
>> 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.
>
> Both are true. If you set each channel's gain to their proper setting,
> around zero when PFL'ing each, then you will maintain good gain at the
> channel fader and the main fader. This is fine for only a few channels,
> 2-3, but as you add channels then the combined signals increase the
total
> signal strength at the mains. To compensate for this you need to adjust
> each individual channel to a negative setting. This is the formula I
have
> in Excel, =LOG(C8,10)*-10, where I have the number of channels in cell
C8.
> Check it out a RANE.
>
> Mike D.
while the channels do add when many channels are open
its just not a issue with desks above the mackie/behringer low end yamaha
stuff. a well designed desk will pass ALL channels running at zero
without
overloading the mix bus
it will also supply a full 48 volts to every channel at the same time
this is a dividing line between MI and Pro level gear
If you need 22 channels slamming zero with condensor mics on phantom
power,
you need a desk designed for that use at its core, that desk is not a
mackie
or any of the popular BIC(as in disposable Bic lighters) mixers
George
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