This goes back to the fact that they have never really explained the gain stage details.
This. I really want to know how the "taper mode" we've all been using to make this act like a "normal" recorder actually works.
I've been suggesting for awhile that there is actually no control of analog gain on the MixPre3/6/10. The analog input is wide open with excellent analog limiters. But any fader/trim control is of the digital signal post-ADC.
Recently I found this quote on Gearslutz regarding SD preamps from John Tatooles of Sound Devices. In the paragraph near the bottom about the 788T I've highlighted the relevant information:
"Quote:
The 442 preamps are very similar to the 302, MixPre, MM-1, and MP-1 preamps. These are all transformer-based and we take advantage of the passive step-up gain available by the transformer. This allows these preamps to draw very low power. Some advantage of transformers:
- draw low power
- provide galvanic isolation
- excellent sonic characteristics when using quality transformers
The downside of transformers:
- physically large for quality transformers
- poor/small transformers have distortion and limit bandwidth
The Lundahl transformers we use in the mixers are the best available, BAR NONE. That said, we had an opportunity when the 7-Series came out to rethink preamps.
The preamps in the smaller 7-Series, 702, 702T, 722, and 744T use discrete transistors (old school high-current parts). This is a great sounding circuit that we are very proud of. The preamp in these products was designed in 2003.
The preamps in the 788T were designed in 2008, and there are new topologies available that just didn't exist a few years ago. The 788T mic preamps are very similar in noise, dynamic range, distortion, performance etc. to the other design, but they are completely new, and (more importantly) completely digitally controlled.
There is no analog audio running through a pot like in the old designs. This allows us precise gain matching between channels and a much more dB-linear gain curve. It also provides for hooks to control them, if we need to in the future.
The 788T preamps are also more power-efficient that the discrete transistors, which is important when you have eight of them.
__________________
Jon Tatooles
Sound Devices"