Legend Audio ISA 828 - Manual (Page 16)

FAQs
Q: What are the basic features of the ISA 828?
A: Eight Focusrite mic pres, eight line inputs, four instrument inputs, optional 8-channel 192kHz A/D conversion.
Q: Which applications is the ISA 828 suitable for?
A: The ISA 828 can be used as a multi-channel high quality front end for Digital Audio Workstations, allowing multi-
channel recording to HD. Equally, it can be used simply as the perfect interface or A/D converter for synths/other line-
level devices. It also provides additional channels for anyone who has run out of mic pres on their analogue console
(either live or recording), and is especially useful as a source of additional mic pres for digital consoles.
Q: Which Focusrite pre is featured in the ISA 828?
A: It’s the original transformer-balanced mic pre that featured in the classic analogue Focusrite consoles in the 1980s.
This is also the classic pre that features in the ISA 430 MKII and 428.
Q: Do the pres have the usual phantom power and High-Pass Filter controls?
A: Yes, and more… each pre has switchable mic impedance so that you can match to your chosen mic’s impedance,
or ‘mismatch’ for creative ‘input response colours’. Also, there are inserts per channel, plus fixed 75Hz HPF, phase
reverse, and phantom power.
Q: What’s significant about the impedance switching for each pre?
A: Each pre can either be matched perfectly to any microphone (vintage or modern), or offset to offer a variety of
‘response colours’ by interacting with any particular microphone. The impedance of each preamp is switchable (via
a single switch labelled ‘Z In’) between 4 settings: original ISA 110 (Zobal network influence for the classic Vintage
Focusrite sound), Low (600 Ohms), High (2.4k) and Higher (6.8K, relatively lively, great for room ambience). For more
information, read the impedance guide in the Applications section.
Q: Are insert points featured?
A: Yes, switchable in- or out- of circuit on each of channels 1-8.
Q: What do the insert switches actually do?
A: Activating an insert switch for an input switches the signal fed to the ADC (for that channel) to the corresponding one
received at the ADC Input on the rear panel. This is so that the mic/line/inst signals can be sent to additional hardware
such as compressors (using the analogue outputs) before being converted by the optional digital card.
Q: What are the four extra inputs on the left hand side of the front fascia for?
A: They are unbalanced inputs that enable you to easily connect unbalanced sources like guitars/basses to the unit
without the need for an external DI box.
Q: What’s the specification of the A/D option?
A: AES (both single and dual wire specs), S/PDIF and ADAT™ formats, sample rates selectable between 44.1, 48, 88.2,
96, 176.4 and 192kHz, (ADAT™ above 48kHz is, of course, via 2 ports), internal or external word clock, and 256X clock,
S/N Ratio better than 121dBFS ‘A-weighted to AES17’. Connections are via a 25-pin D-type connector and standard
lightpipes, word clock is via BNC in and out.
Q: Does the ISA 828’s A/D option feature word clock as standard?
A: Yes, word clock may be fed in via a BNC connector on each A/D to allow the 828 to synchronise to any word clock
master source.
Q: Why do I need word clock 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 needs to be synchronized to a common word clock system. Somewhere in this system
a word clock ‘master’ must be dictating the word clock for the rest of the equipment (‘word clock slaves’) to follow.
Failure to sync all pieces of digital equipment to a common word clock source will result in audible clicks and glitches
in programme material. Note that the 828 regenerates word clock at its BNC output, further boosting word clock stability.
Q: How many rack spaces does ISA 828 take up?
A: The ISA 828 is a 2U device.
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