Q: What are the basic features of the OctoPre? A: Eight mic pre's, eight compressor limiters, optional 8-channel A/D conversion (2 formats available.) Q: Is the compressor just a global compressor across all eight channels? A: No, each OctoPre channel features a unique, independent compressor/limiter, so you have EIGHT discrete compressors in total. Each can be set independently to act as a brick wall limiter, or to add increasingly heavy amounts of compression to a given channel. Q: Which applications is the OctoPre suitable for? A: The OctoPre can be used as a multi-channel front end for Digital Audio Workstations, allowing multi-channel recording to HD. Equally it can be used simply as the perfect interface/ A/D converter for synths/other line level devices. It provides additional channels for anyone who has run out of mic pre?s on their analogue console (either live or recording,) and is especially useful as a source of additional mic pre?s for digital consoles. Finally, anyone who needs 8 channels of compression/ limiting will find the OctoPre extremely useful. Q: How many rack spaces does OctoPre take up? A: The OctoPre is just a 1U device. Q: Does the OctoPre support phantom power on each channel? A: Yes it does. Q: What rear panel connections are featured? A: The OctoPre has 8 XLR connectors for microphone input, and 8 line level inputs and 8 line level outputs connected via two 25-pin d-sub connectors. This allows the OctoPre to be connected to a patch bay and have every input connected at all times for easy operation. (Note: some competitive products make you physically remove the unit from your rack to switch between +4 and -10 operation, and cannot be permanently wired to a patchbay.) Q: What other connections are on the back panel of OctoPre? A: The fully loaded unit features a 9-pin D-type connector allowing digital output in AES/EBU or S/PDIF format, and two Lightpipe ports for 96kHz ADAT (aka S/MUX2.) Q: Is the OctoPre a Class A device, and why is that important? A: Yes, the OctoPre is a Class A device. Why? Class A is a type of amplifier design in which you have a standing DC current running through your amplifier circuits all the time. As the signal comes along you vary what you're taking from that, rather than switching between supplying a positive current for one half of the waveform and a negative current for the other half. This results in the ability to represent audio in a linear (distortion free) manner all the way through the circuit. Cheaper processors use IC amplifiers which run close to Class B and don't have the same standing DC current, which means the transistors inside the chips are switching on and off, inevitably resulting in less linear performance. Q: Should balanced connectors be used with the OctoPre? A: Yes, where possible. However the line level analogue inputs and outputs (although balanced, operating at +4 dBu,) can operate with unbalanced ?10dBV input sources. Alternatively, if using an unbalanced instrument source, you can connect to the unbalanced 1/4" inputs on channels 1 and 2. Q: Does the OctoPre have the same kind of spectacular bandwidth that has given the Red and ISA range units their reputation for 'open-ended' sound? A: Yes. The audio bandwidth of the OctoPre is 10 Hz to 200 kHz! Q: Is there an optional digital input card? A: No, because all the processing in the OctoPre is entirely analogue - so even if there were a digital input, the digital signal would have to immediately pass through a D/A converter to allow processing! Q: Why is the 24-bit 96kHz specification important? A: An A/D converter works by sampling the audio waveform at regular points in time, and then quantizing those values into a binary number, which relates to the number of bits specified. The quantized signal must then be passed through a D/A converter before it becomes audible. In simple terms, the D/A essentially joins the dots plotted by the A/D converter when the signal was first converted to digital. The number of dots to join, combined with how little those dots have been moved, determines how accurate the final signal will be compared to the original. The greater the sample rate and bit rate, the more accurate the whole digital process is. So 24 bit/96 kHz performance will ensure more accurate digital transfer of your audio information compared to the old 16-bit/44.1kHz standards. This is especially important if further digital signal processing is to be applied to the signal once converted to digital, as any mathematical operations taking place on the data, (for example as a result of a gain change, or dynamic effect process,) may result in quantization and rounding errors. The higher the resolution of the digital data, the smaller the audible effect of these errors will be. Q: What if my system only operates at 16 bit, 44.1kHz? A: No problem, the OctoPre features dithering and supports most sample rates, (simply select the rate you need from the OctoPre's front panel,) so you can use an OctoPre with a 16, 20 or 24 bit system operating at 44.1, 48, 88.2 or 96kHz. Q: What is dithering? Why do I need it? A: When dropping down from e.g. 24-bit to 16-bit, quantizing errors occur because 24-bit sampling involves more samples than 16-bit, so when you reduce the bit depth the extra samples have nowhere to go. At high signal levels these errors are random and not audible, but at lower signal levels the errors correlate more closely to the audio and become audible as distortion. Dithering effectively 'randomise' the truncation errors at lower levels, causing the 'least significant bit' distortion to disappear. Q: Can I retrofit a digital board to an analogue OctoPre at a later date? A: Yes, and you can do it yourself - it can easily be retro-fitted at any time without any soldering etc, just a few screws to undo, and one clip-connector to join to the main PCB. Q: How can the OctoPre operate with the ADAT lightpipe format at 96kHz? I thought the maximum sample rate for this format was 48kHz? A: Not any more. The OctoPre supports the new 96kHz ADAT specification, using two discrete optical ports. Q: So how are the multiple digital outputs configured at 48kHz/96kHz? A: At 48kHz or lower: the 8 AES or SPDIF (switch-selected from rear panel) outputs can run simultaneously with 8 ADAT outputs, plus 8 ADAT outputs from the second port (hence 24 simultaneous digital outputs in total.) The ADAT outputs in this mode are exact duplicates of each other. All output formats put out the same set of 8 channels in terms of sample rate, dither etc. At 96kHz: outputs are the same as above, except that the two ADAT ports carry output channels 1-4 and 5-8 respectively (hence 16 simultaneous digital outputs in total). In simple terms, the A/D puts out three separately buffered sets of 8 channels at 48kHz, or two separately buffered sets of 8 channels at 96kHz. The digital outputs can always be fed with any mix of mic, line or instrument inputs. Q: When the A/D is used, are my analogue outputs available for use? A: Yes. The line outputs can run simultaneously with both the ADAT and AES or S/PDIF outputs, providing, all at once, 8 line level analogue outputs, 8 Lightpipe ADAT outputs and 8 AES or S/PDIF outputs. Q: Are the OctoPre 25-pin d-sub connectors (analogue outputs) wired for TASCAM or Mackie wiring spec? A: The OctoPre sub-connectors are wired to the TASCAM specification. Q: Do I need to buy an option cable to use the analogue outputs on the OctoPre? A: Yes. We recommend the following models from Hosa: Line output d-sub connection to 8 x XLR: DTM805 Line input d-sub connection to 8 x XLR: DTF805 Q: Do I need to buy an option cable to use either of the A/D cards? A: Yes; ADAT optical cables are available from many sources, and Focusrite will offer their own 9-pin to 4 phono (RCA) connectors S/PDIF cable and 9-pin to 4 XLR connectors AES-EBU cable. Q: Do the OctoPre's A/D options feature WordClock as standard? A:Wordclock may be fed in via a BNC connector on each A/D to allow synchronisation to any Wordclock master source. Q: Why do I need Wordclock anyway? A: When using multiple pieces of digital equipment it is necessary to make sure that their bit-streams are all in sync. In order to do this all equipment need to be synchronised to a common Wordclock system. Somewhere in this system a Wordclock 'master' must be dictating the Wordclock for the rest of the equipment, ('Wordclock slaves') to follow. Failure to sync. all pieces of digital equipment to a common Wordclock source will result in audible clicks and glitches in programme material. Q: What is the function of the ocean blue LED on the OctoPre's front panel? A: i.) It indicates when electricity is flowing though the unit. ii.) It looks very cool in low-light conditions.