Saturday, May 6, 2023

Dual Terratec Phase 88 Rack audio interface repair

Terratec Phase 88 Rack is mid 2000 8 channel in/out audio interface. It has 8 balanced/unbalanced input, 2 of them phantom powered, and 8 balanced/unbalanced output. It can reacord at 96 kHz.

For more than 2 channel recording I'm actually using the ST Audio DSP2000 interface, running it on linux. You can find the full article here:

Like the ST Audio, the Terratec also it's based on a Rack + PCI interface design. And you guess... the PCI is running the IC Ensemble Envy24 I/O controller chip too, nominally the ICE1712.

It happens to find a good deal for a couple of Terratec. To me it means to have 16 channels of recording power instead of 8. I don't really use that card to much, just to record drums, but that deal was so good I couldn't let it go.

Terratec Phase 88 Rack PCI Full specifications:

  • 8 balanced analog inputs, 1/4" jack
  • 8 balanced analog outputs, 1/4" jack
  • 8 gain controllers on the front for setting levels for analog inputs (20dB range)
  • 8 input signal and clipping LEDs on the front panel
  • 2 XLR/jack microphone inputs on the front panel as alternatives to the Line inputs 7 and 8, inputs 7 and 8 switchable between microphone and line/instrument levels, switchable 48 V phantom power for microphone inputs
  • 2 separate MIDI interfaces (5-pin DIN)
  • 24-bit/96 kHz A/D converter with 100 dB (A) SNR*, 100 dB(A) typical @ 48 kHz
  • 24-bit/96 kHz D/A converter with 110 dB (A) SNR*, 109 dB(A) typical @ 48 kHz
  • WordClock I/O
But the deal has a price... the supply is missing, and one of the card has channels 7 and 8 that does not work. Also, driver for Windows are a question mark, I can not find a sure answer if they work or not, but for me that was not a problem cause my first plane was to use linux as a recordind station.

The package has been delivered, I've opened it and connect both the PCI and the related rack to a Core 2 Quad 2 Q6600 with 8Gb of RAM, and 500Gb SSD I would like to use for this project. It's not the best PC for mixing but I will use it just for recording. It will suffice.

The rack needs a 12V AC 1.5A AC supply, I've one 3.5A the just fits both the rack.

To my surprise, the latest 5.51b driver from Terratec works on Windows 10 x64. I've configured one card as master, and the other as secondary, calibrate them throgh the driver mixer software, I've reboot... and they works. I can see cards input and output in Reaper using the ASIO driver from Terratec.

Now it's time to repair the channel 7 and 8 of one rack. That channels emit just a white noise, no matter if I try the line input or the mic input. I have to open the card and trace out the problem. Of course there is not schematic for this card, so I have to trace the signal using the continuity functionality of my multimeter. Signal goes straight from the inputs (line and mic) to a relay, that is driven by software, then to the LM833 op-amp. This is the first stage driver for the input. I take my multimeter out, feed a 100mV 500Hz sine in the line input and find out that for both the channels out from the first stage of the LM833 there's a DC signal that has nothing in common with the expected sine. So I've ordered a few LM833 and replaced the two of channels 7 and 8. Channels now works! For a few bucks now I've got a 16 channel recording station. As for my DSP 2000 ST-Audio station I will use it just for recording, this time I'm on Windows but even if the PC is not that powerfull it works fast if used just for this end.

I've also try the Terratec on Linux, but the Envy24 driver are not compatible with this specific hardware, I think one has to download the driver code, fix it and recompile the kernel, but to me just using Windows is enough.


  • read risk disclaimer
  • excuse my bad english

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