Studio Technologies 42 - Manual (Page 15)

Issue 1, July 2004 Model 42 User Guide
Page 16 Studio Technologies, Inc.
It’s interesting to note the reason why
typical IFB circuit audio quality is less
than pristine. It’s not hard to notice the
background “hiss” that is always present
on pin 2 (DC with channel 1 audio) of the
interface connector. Technically, it’s white
noise that comes from the adjustable
voltage regulator being used as an “AM”
modulator and current limiter. The noise
is an artifact of the design topology and
simply can’t be overcome. How does
Studio Technologies know this? Because
our first “breadboard” designs used this
method and achieved the same poor
results! Only after the problem came to
light did work on an improved circuit
begin. The results were worth the effort.
Specifications
General Audio:
Frequency Response:
Pin 2 Outputs (DC with Channel 1 Audio):
20Hz-20kHz ±2.5dB (80Hz-20kHz ±0.25dB)
Pin 3 Outputs (Channel 2 Audio): 20Hz-20kHz
±0.25dB
Distortion (THD+N): pin 2 outputs (DC with
channel 1 audio) 0.01%, ref +4dBu in, measured
at 1kHz
S/N Ratio: pin 2 outputs (DC with channel 1
audio) 80dB, ref +4dBu in, 20Hz-20kHz
Crosstalk: 81dB, typical, ref +4dBu in,
20Hz-20kHz
Audio Inputs: 8, organized as four 2-channel
inputs
Type: transformer balanced, capacitor coupled,
compatible with balanced or unbalanced sources
Impedance: 10k ohms, nominal
Nominal Level: +4dBu
IFB Circuits: 4
Type: “wet” (DC power with two channels of
unbalanced audio)
Connections: common on pin 1, DC (+30V
nominal) modulated with channel 1 audio (–10dBu
nominal) on pin 2, and channel 2 audio (–10dBu
nominal) on pin 3
Maximum Level:
Pin 2 Outputs (DC with Channel 1 Audio): +9dBu
(+23dBu on audio input)
Pin 3 Outputs (Channel 2 Audio): +14dBu (+28dBu
on audio input)
Connectors:
Audio Inputs: 1, 25-pin, female, D-subminiature,
4-40 threads
IFB Outputs: 4, 3-pin, male, XLR-type
AC Mains: 3-blade, IEC 320 C14-type (mates with
C13-type socket)
AC Mains Requirement:
100-230V, 50/60Hz, 0.7A maximum @ 100V, 0.4A
maximum @ 230V
Dimensions (Overall):
19.00 inches wide (48.3cm)
1.72 inches high (4.4cm)
9.58 inches deep (24.3cm)
Mounting: one space in a standard 19-inch rack
Weight: 6.4 pounds (2.9kg)
Specifications and information contained in this
User Guide subject to change without notice.