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Friend Chip DT20 Pro Con & DT40 Copy Con

Digital Audio Processors By Paul White
Published July 1999

Friend Chip DT20 Pro Con & DT40 Copy Con

Paul White tests a couple of simple digital audio processors that also allow you to make unlimited copies from your own SCMS‑protected DAT tapes.

A perennial complaint among recording musicians is that the SCMS (Serial Copycode Management System) employed in consumer DAT and CD‑R machines makes life very difficult, as it restricts the ways in which you can make copies from your own original material. Of course, it was brought in to curtail music piracy in the digital domain, and I can understand the reasons, but I would also agree with those who think it unacceptable that any such measures should interfere with our ability to copy and edit material to which we own the copyright. A few enterprising companies manufactured so‑called SCMS strippers to remove the offending code that prevents copies of an original DAT or CD from being themselves cloned, but threats of legal action saw most of these being withdrawn. However, it is still OK to include SCMS management in the design of a pro audio device that also has other functions — which is where Friend‑chip come into the story. They offer a couple of low‑cost processors, the Pro Con and the Copy Con, that include SCMS stripping/adding as part of their repertoire of functions.

Pro Con is a simple device for converting digital co‑axial to AES‑EBU (XLR) or vice versa, with the output selectable between the consumer (S/PDIF) and professional data formats. You can also use it to filter the SCMS code from the input signal or even to add SCMS code to material that doesn't already have it. After all, if you're going to be rich and famous sometime, you don't want other people copying your music!

he diminutive Pro Con is powered by an external PSU that's almost as big as the unit itself, but the overall construction is solid and inspires confidence. The necessary XLR and phono inputs and outputs are located on the rear panel, and all have gold‑plated contacts. The front panel houses just two momentary‑action buttons and a couple of status LEDs. Using these, you can select whether the input should be AES‑EBU or S/PDIF, whether SCMS should be added or removed and whether the output should be Consumer or Professional format. The default Consumer mode disables incoming SCMS, allowing material to be copied without restriction, while pressing and holding the Mode button puts the unit into SCMS‑adding mode as indicated by a dimming of the SCMS status LED. Pressing Mode twice puts the unit back into SCMS‑filtering mode. In addition to the format‑converting circuitry, the Pro Con includes a signal reshaper to reduce jitter. Either professional or consumer output modes can be selected, again using the right button — in Consumer mode, both the XLR and phono carry consumer signals, while in Pro mode, both carry Pro format signals. SCMS is not a part of the professional format and as such is not relevant. However, the manual warns that if a Pro format signal is already present at the input and Pro output selected, the output signal will be faulty.

If you only need S/PDIF in and out, then the Friend‑chip D4‑2 Copy Con might better fit your needs. This is a simple four‑into‑one digital source selector that includes exactly the same SCMS management features as the Pro Con. The Copy Con has three phono and one optical S/PDIF inputs that can be selected as the source, while the output also includes a monitor function that sends either the selected input or the D input signal (depending on which you choose from the front panel) to a separate S/PDIF phono output for monitoring purposes.

In use, both boxes are very simple to use, and the SCMS management works quite transparently without interfering with DAT start IDs. These are very practical and neatly designed essential tools for the modern studio.

Friend Chip DT20 Pro Con & DT40 Copy Con


  • Simple to use.
  • Compact, touch packaging.
  • Effective SCMS stripping and adding.


  • No obvious cons, other than the fact that we shouldn't have to resort to such measures to go about our perfectly legal operations.


Both these boxes provide useful functions in addition to SCMS management. They're also sensibly priced.