ENGLISH
11
FAQs
1. Who is the main ‘target audience’ for the
ISA 220?
The ISA 220 was designed primarily for use in high end and project
recording studios, audio/video post-production and voice over facilities etc.
Owing to its combination of a mic pre and a comprehensive range of
processing types, it can be used both for tracking, and as a mix-down tool.
2. What are the main features?
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Many types of class A dynamic and EQ processing in one box
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Focusrite-quality audio throughout, e.g. huge bandwidth: 10Hz-
150KHz
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Focusrite professional Mic Pre (dual-gain transformer-based)
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Upgraded version of the original ISA 130 Class A Focusrite VCA
Compressor
•
Focusrite 4-band parametric EQ derived from the original Focusrite
circuit designs
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New opto de-esser utilising phase-cancellation de-ess technology
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New opto multi-band limiter
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Can be used for tracking, mix-down, or as a stereo A/D converter
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Optional 24 bit/96 kHz digital output board
3. Is the EQ based on the original Focusrite
designs?
Yes, the ISA 220’s EQ uses the same EQ curves as those used in the
original Focusrite console, (but with 4-way instead of 6-way shelving
selections.)
4. Is the ISA 220 a Class A device? Why is
that important?
Yes, the ISA 220 is a Class A device. 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 signal arrives, a Class A device varies what is taken
from that standing DC current, 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
switching off and on, inevitably resulting in less linear performance.
5. What if I want my dynamics processing
to occur pre-EQ?
No problem. The EQ and dynamics sections can be switched so that the
dynamics processing precedes the EQ section, (a single push of the ‘Pre-
EQ’ button on the front panel.)
6. Is there any way to configure the ISA 220
as a stereo unit?
Yes. Although a single ISA 220 can act only as a mono unit, it’s possible to
link 2 ISA 220s together, using the ‘dynamic link’ socket on the rear panel.
Using a single stereo TRS jack cable, this allows stereo operation of the
compressor, plus dual mono EQ. You can also use a single ISA 220 as a
stereo A/D converter, (see questions below for a full explanation.)
7. How do I control which ISA 220 will be
the controller and which will be the slave
when using two together for stereo
compression?
Whichever ISA 220 is generating the greater control voltage will be the
controller- So, set one of the ISA 220 compressors to minimum ratio,
maximum threshold, and the other compressor will then always be the
‘controller,’ with any changes made on the controller’s knobs affecting both
channels in the same way.
8. Does the ISA 220 have the same kind of
spectacular bandwidth that has given the
Red Range its reputation for ‘open-ended’
sound?
Yes. The bandwidth of the ISA 220 extends from 10Hz to 150kHz!
9. Can I use all the different sections of the
ISA 220 at once?
Yes. If you want to use the mic pre, hi- and lo- pass filters, parametric and
shelving EQ, compressor, de-esser, limiter and digital output all at the same
time, as one huge ‘super channel,’ you can. You can also take any section
out of the signal path independently with a single button push.
10. What is the ‘blend’ feature in the
compressor section?
The blend feature allows the user to mix uncompressed elements of the
original source signal together with the post-compression signal. The result
achieves the required gain reduction without making the audio sound
‘over-squashed.’
11. Which sections are VCA-driven, and
which use optical technology?
The Compressor uses a VCA, the De-esser and Limiter use optical
technology.
12. Can I use the ISA 220 as a 24/96 stereo
A/D converter?
Yes, the external A/D input, in combination with either the INT A/D direct
I/P, or the mic or line inputs (bypass on,) can be used as a stereo feed to
the optional A/D converter. All inputs also pass through the three-band
limiter before reaching the A/D, preventing digital clipping.
13. Are the ISA 220’s mic and line inputs
transformer-based?
Yes, the ISA 220 comes as standard with mic and line input transformers,
so you are guaranteed the classic ‘warm yet transparent’ Focusrite
signature sound loved the world over. There’s also a MU-metal shielded
power transformer (to prevent hum.)
14. What about metering?
The main input meter can display input level or compressor gain change.
Additionally, there are 16-LED peak-reading output meters for internal and
external signal levels, which measure the output(s) at a point just after the
limiter. You also have an independent overload LED that is fed from 3
different points in the circuit, to warn of overload at the input stage, in the
EQ processor, or in the dynamic processors. There are also status LED’s
for clock select, bit rate select, external sync, and meter select.
15. The limiter is described as ‘frequency
adaptive.’ What does that mean?
It’s a kind of multi-band limiter. Our 3-band "adaptive attack" limiter has
different limiting properties for each of the three frequency bands, giving
true distortion-free limiting. Basically the HF content requires a faster
response from the limiter than the mid or LF, the mid is different from
either HF or LF and so on, so the limiter's slope is designed to be different
for each of the three bands. It's genuinely multi-band, as each of the 3
frequency bands is split, and then sent through different, discrete circuitry.
Thus a large increase in LF will not cause any change in the limiting of the
HF band for example, so the limiter is simple, effective and musical.
16. How does the de-esser work?
The de-esser uses Focusrite’s proprietary phase invert technology. Once
the user has selected the frequency at which the de-ess is to occur, the ISA
220 generates a 180º out-of-phase signal at that frequency which cancels
the specific frequency selected at the moment it occurs, without having a
negative effect on other related frequencies.
