I just want to know for sure: is it Mic -> Fader -> Preamp -> ISO Track.
I think there's a lot of confusion around this, though perhaps it is my confusion about the terminology being thrown around. If in the above diagram "Fader" equals "the Fader gain stage" and "Preamp" means the "Kashmir mic preamp gain stage", then I guess that is a question to be answered by Sound Devices, though I assume the "Fader gain stage" always comes after the "Kashmir mic preamp" stage. Otherwise, I think there might be confusion around how gain stages work.
Much more than likely it isn't really a question of
Mic -> Fader -> Preamp -> ISO Track vs. an alternative of
Mic -> Preamp -> Fader -> ISO Track.
Gain stages aren't configured like that these days, esp when you're developing a preamp that is as quiet as the Mixpre series or can accept as wide of a mic input range as it does (from a very quiet low-level mic signal to a really hot mic signal up to +14dbu). That is, you don't really have either pathway above where the fader is something like an attenuator in line with the preamp gain stage (before or after).
Instead, the channel knobs/fader control the amount of gain coming from the gain stage. So it is like this:
Mic ---> Preamp ---> ISO track
^^
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Fader
So the fader/gain control/channel knob doesn't come either before or after the preamp, it just controls the amount of gain coming from the preamp.
Beyond this, Sound Devices probably has several gain stages built into the Mixpre series, including their Kashmir mic preamps. This is a block diagram they've shared of the 6-series mixer/recorders:
The Mixpre-6/-3 probably looks something like this, with a (guessing here) trim gain stage (Kashmir mic preamps) providing say 0-70db of gain, a fader gain stage providing -20db to 20db of gain (in basic mode, -infinity for advanced mode), and 6db at the output stage. Thus, 3 gain stages combine to provide a maximum of 96db of gain, or a range of -14db of gain to 96db of gain in basic mode, as has been reported before.
For a 3-stage gain set up like this (again, my guess, though it conforms to the gain block diagram SD has provided for the 6-series), you'd have a final output gain fixed at 6db and then the Kashmir mic preamp gain stage combined with the fader gain stage to provide -20db to 90db of gain (before the final 6db output gain stage).
So the signal path diagram is: Mic input -> Kashmir mic preamp (0-70db gain) -> Fader gain stage (-20db to 20db) -> output gain stage (fixed 6db) -> ISO tracks.
In any case, the fader/channel knobs wouldn't come after or before the Kashmir mic preamps, they'd just control the amount of gain provided.
Now whether the basic mode puts the fader gain stage before the kashmir mic preamp gain stage, or whether in Basic mode the mixpre switches from a 3-gain stage configuration to a 2-gain stage configuration (kashmir mic preamps and output gain stage, skipping the fader gain stage), I have no idea. But if overall the Mixpre across the full signal path provides an EIN of -128dbu and a dynamic range of 120db, I'm not sure why it really matters.
Topic: Sound Devices MixPre-3 and 6 (Read 113590 times)