DAT 850 (don't shoot)

#1

Hi,

I have my living room setup complete.
Last weekend I was trying to record the vinyl TRON album from Daft Punk to DCC and DAT.

My main amp is a Marantz SR7000 which can also do the A/D conversion.
I have a Marantz DD-82 for DCC and a Philips DAT850 for DAT.

When I try to record digitally, the DD-82 simply records.
To my amazement it records both analogue and digital in 44.1 kHz according to the display.
Is that normal?
DCC600, DCC951 and DAT all record analogue in 48kHz with no way to change it.
(DAT can be set to LP which reduces samplerate to 32kHz)

The DAT850 keeps flashing ‘copy prohibit’.
Only when doing an analogue recording, the DAT850 allows recording.

What am I doing wrong?

#2

I’m not familiar with your receiver or with the DAT850.

As long as the SPDIF output on the receiver is configured to send PCM stereo (not Dolby or DTS), at 32 or 44.1 or 48 kHz, any DCC recorder can record it digitally. I assume this should be true for the DAT850 as well.

All DCC recorders can record through one or more analog inputs. If you make an analog recording, the recording is always encoded at 44.1 kHz. The built-in ADC in DCC recorders can’t sample at any other rate than 44.1, though some recorders (including your DCC951) can process 18 or even 20 bits per sample instead of just 16 bits.

Digital recording is only allowed from an original, but not from a copy. This is because of Serial Copying Management System, also known as SCMS. You can make a digital copy of a CD, but that recording cannot be copied any further unless you make the second generation an analog copy.

If you want to make a second-generation digital copy, you will need some way to defeat SCMS. There are devices you can buy to change the SCMS codes on an SPDIF line. I don’t have any recommendations; I use an SCMS defeater that I bought as a kit in the 1990s, based on an article in Elektor magazine. It not only resets the SCMS “copyrighted/non-copyrighted” and “original/copy” bits, but it also changes the source bits. This is necessary because some digital recorders (including the DCC951) have firmware bugs that misinterpret the bits in the input format. I own a CD-single where the audio was accidentally encoded with one of the bits set wrong, and my 730 refuses to record it without the SCMS defeater.

You can also work around the SCMS limitations by grabbing the audio with a digital audio receiver device on your computer, and then using a digital output (e.g. an HDMI to DVI+SPDIF splitter) to play it back.

Bottom line: you’re not doing anything wrong; it’s just the way it works. To make it work better, you have to probably buy some gear to work around SCMS. Or just make an analog recording.

===Jac

#3

@Jac thanks for your in depth answer.

I was just perplexed because the DD-82 simply accepts the digital audio and records, where the
DAT850 has SCMS go berserk.

I hoped to skip the step where I need the audio interface to do my recordings to PC before writing them to DAT.

PS: the auto function on the DD-82 worked almost perfectly. It only missed one track transition when recording Daft Punk ‘TRON’ vinyl.
(those titles did not have >2s silence in between)

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#4

If you connect your recorder to a CD player via S/PDIF, it should record the track markers correctly (unless you switch it off in the recorder settings) even if there’s no pause in the music at at all. Note, modern optical disc players (like DVD players or BluRay players) often don’t send the track markers over S/PDIF anymore but any CD player from the 1980s or 1990s will do it.

===Jac

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#5

Good to know.

Do the recorders also place markers to stop you from copying that recording digitally to another device?
(or is SCMS on DD-82 not implemented)

#6

Yes! The recorder does such a thing. @Jac has a complete description about this. All nineties digital recorders have this Serial Copy Management System…

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#7

All DCC recorders implement SCMS. The 3rd generation recorders have a firmware bug that (I think) makes them evaluate the SCMS codes wrong in some cases, for example when handling incoming signals that are not from a CD player. I’m not exactly sure what the problem is, I don’t have the equipment to test it, but if I understand and remember correctly, the SCMS bits are inverted if the source is something other than a CD player (so a DAT recorder would trigger the bug and you might not be able to record from DAT even if the DAT tape is an analog recording, which you SHOULD be able to record). I have a CD that has the copyright bit cleared (probably by mistake), which should make recording and unrestricted copying possible, but without my SCMS defeater, my 730 won’t even make a first-generation copy of that CD.

It’s pretty easy to get around the SCMS limitations nowadays but even if you can’t get an external device to defeat SCMS, it might be possible to hack the recorder itself. I have some ideas but I don’t know if or when I’ll get to it. For example the SPDIF receivers can usually be rewired to work in standalone mode so they don’t need a microcontroller. Or it might be possible to connect a secondary SPDIF decoder to generate the signals for the I2S bus while the original one is disconnected but still listening to the microprocessor.

===Jac

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