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Tascam DA-3000 DSD Recording Qestion

Posted: Sat Oct 18, 2014 14:45
by hereigo

I have a question according proper levels for DSD recordings using Tascam Da-3000.

According Pyramix SACD production guide:

"Reference Level
All DSD peak-meters are aligned to "0 dB SACD". The SACD reference level ("0dB SACD") is defined as -6dB FS PCM.
Final DSD Edited Masters can have levels as high as +3.1dB SACD, a.k.a -2.9dB FS PCM for very short durations. In
practice, for safety, we recommend a general rule of not going over 0 dB SACD. Levels higher than this value will
be clipped if using the same master for doing the CD layer of the SACD master and might also have an adverse
effect on SACD playing time. Even worse, such a master may be rejected by SACD manufacturing facilities."

and then:

Maximum Allowable Signal, HF noise and DC levels
Signal Level (a.k.a. modulation level)
Maximum Peak should only very occasionally be allowed to reach +3.1 dB with respect to the SACD 0dB Audio
Reference Level in accordance with Annex D3. As a general rule, we recommend keeping the Maximum. Peak
level at 0 dB SACD."

Then in Tascam Manual:
The level meter OVER indicators will light at the following levels. If the DSD mode is set to +3, though, they will light at +3dB and higher.
PCM recording and playback: 16-bit-full-scale
DSD recording and playback: 0dB

So let me know if in case of DSD recording on Tascam in connection to Pyramix guide should I record to 0dB (like Tascam says) or maybe -3dB or even -6dB FS. I did not notice any signal level change when I choosing between PCM instead DSD and vice versa... So in this case 0dB = 0dBFS on Tascam level meter... but I should be at -6dBFS when I'm on DSD. I'm a little bit confused... I asked Tascam and on gearslutz with no reply...

With Best Regards!

Re: Tascam DA-3000 DSD Recording Qestion

Posted: Fri Oct 24, 2014 07:36
by Graemme
It all depends on how Tascam define their -0dB' position. Based on what you reported about the DA-3000, it seems that the levels between it and Pyramix should be equivalent, if the Tascam is set to it's '0dB' DSD mode (not +3). I'll speculate that the Tascam's '+3' position allows fort he maximum level specified in the SACD 'Scarlet Book' requirements, which is the '+3.1 dbSACD that I mentioned in the Production Guide...

Comparing DSD and PCM won't tell you much other than that Tascam apparently compensates for the 6dB difference between DSD and PCM.

PCM is aligned to an absolute maximum ('full scale' or 'full code') where '0dBfs' is the absolute maximum value (100%). DSD is a different animal, somewhat analogous to PDM (Pulse Density Modulation) and is therefore not directly comparable, in terms of maximum levels and best signal linearity. 50% modulation (DSD) is considered to be the 'sweet-spot' with respect to the even distribution of ones and zeros. Beyond 50% modulation (0dB 'SACD' or -6dB fs) a DSD signal becomes increasingly distorted. That's why (in very simple terms) the cautions in the production guide are there.

Of course, the best way to find out is to record signals at various levels into the Tascam and then load them into a Pyramix DSD project (not DXD!) and see what you've got...