Hi Raimund,
Thanks for doing the tests and confirming the HPF is in the digital domain. I
see that Tascam state the limiter is analog but as was suggested this could
indicate peak detection on the digital signal controlling an analog gain
reduction circuit.
I don't think anyone should be too surprised that the DR-680 has been built to
a price point. Portable 8 track recorders have tended to be at the top end of
the market: SD 788T ($5,995), Sonosax MiniR82 ($4,926) and SX-R4 ($6,110), the
6 channel Nagra VI ($8,200), the 10 track Zaxcom Deva Fusion ($7,995) and now
also the Tascam HD-P82 ($5499), and in my opinion this is the kind of gear that
really deserves the epithet "stellar" . Even so, to be able to engineer a 8
track recorder for under $1,000 and still provide decent preamps is quite an
achievement.
cheers
Paul
On 12/04/2010, at 5:36 AM, Raimund wrote:
> If the filter was located in the analog section in front of the ADC, then
> there should be no distortion at the lower frequencies below the cut-off
> frequency. However, it can be seen that sine signal is indeed distorted at
> those lower frequencies, where the recorder itself did not indicate any
> clipping. So, the block diagram is obviously correct.
>
> Tascam obviously chose that less than optimal design in order drop the price
> of the unit...
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