Model 1707 Integrated Amplifier User Manual
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Glossary
– Some General Terms
AC
Alternating Current
– the type of supply used in normal house wiring and to power consumer appliances like
TV’s, washing machines and high fidelity systems
A-D or A/D
Analog to Digital
– an electronic technique whereby an analog signal is sampled at short, regular intervals
and the sampled value converted into a representative numeric value that is stored in computer memory, CD
or some other mass storage media
Analog Signal
A voltage or current signal that varies continuously with time. Examples are the pickup signal from a
turntable, or the output signal from a microphone. All natural world signals are analog.
Balanced Audio Signals
A method whereby audio is transferred between equipment using two connections without reference to
ground, making it highly immune to ground loop induced hum and extraneous noise pickup. Uses XLR
connectors. See Unbalanced or single-ended audio signals
Bipolar Transistor
A three-terminal semiconductor amplifying device
CMT
Current Mode Topology
– a type of audio amplifier wherein the peak current into the main amplifier stage is
determined directly by the output voltage and the gain setting resistor. Also known as CFA (Current
Feedback Amplifier)
D-A or D/A
Digital to Analog
– the technique of converting digitally stored samples into a continuous analog signal
Damping factor
A measure of an amplifiers load impedance divided by its output impedance. The higher the figure the better.
In a modern amplifier, any figure above 50 should be considered adequate and above 100 excellent
DC
Direct Current. Examples would be the type of current supplied by a battery
Decibel or dB
A logarithmic measure of an analog signal with respect to a reference, or expressed as the difference
between two signals. 20 dB = 10x and 40 dB = 100x while 100 dB = 100 000x. By way of an example, if the
S/N of a preamplifier is -100 dBV, it means that the noise is 100 000 times lower than 1V
– i.e. 10 millionths
of a Volt. The ‘V’ in dBV refers to the reference which is 1V and is an industry standard of measure
Digital Audio Signal
An audio analog signal is sampled at discrete time intervals and the resultant samples converted to a
numerically representative value. An example is a CD, where the original analog signal (e.g. the voice of a
singer) is sampled 41000 times a second and each sample converted to a 16 bit digital representation using
an A-D which is then written to the CD
Digital signal
A binary coded numerical value represented by 0’s and 1’s where the ‘0’ value corresponds to 0V and the ‘1’
corresponds to 3.3V, 5V or some other non-zero voltage. Digital signals are either parallel or serial format.
Examples of digital signals would be the co-ax output from a CD drive (serial digital signal), or the data on an
Ethernet cable used in communications (also a serial digital signal)
Distortion and Noise
The presence in any electrical signal of unintended harmonics and/or noise. Reducing distortion and noise
are key goals in any equipment that reproduces audio signals
EMI or Electro-Magnetic
Interference
Noise and/or extraneous signal introduced into a system through magnetic or capacitive coupling
mechanisms. Filtering, bandwidth limiting and careful design and equipment layout can reduce the effects
orders of magnitude below human hearing threshold
EQ
Equalization
Frequency Response or
Bandwidth
The extent of frequencies an amplifier can reproduce to within a specified range. Human hearing covers
20Hz to 20 kHz. Audio amplifiers should cover at least 2 Hz to 100 kHz (-3 dB) to ensure a flat response
within the human hearing range of 20 Hz to 20 kHz
Input Sensitivity
The level of input signal required to produce a given output from a preamplifier or a power amplifier.
IR Remote
Infra-red Remote control
JFET
Junction Field Effect Transistor
– a three terminal semiconductor amplifying device that somewhat emulates
vacuum tube triodes in its performance characteristics.
Ω
Unit of electrical resistance. Most loudspeakers are rated at 8
Ωs
Output Power
Measured in Watts, the amount of electrical power that can be delivered into a loudspeaker load by an
amplifier. Always quoted into a known resistive load
– usually 4 or 8 Ωs
Phono socket
The small round sockets
– usually grouped in Left (WHITE) and Right (RED) pairs on the rear side of audio
equipment. Also referred to as ‘RCA Phono’ sockets
RC5 IR
The protocol by which commands from the remote are encoded and transmitted via infra-red to the receiving
equipment which then executes them. Invented by Ph
ilips in the 1970’s and now one amongst 4 or 5
industry standards
RIAA
Recording Industry Association of America
– The association that standardized the LP/vinyl playback
equalization curve in the early 1960’s that is still the standard for LP/vinyl today
Signal to noise ratio (SNR)
A measure of the amount of noise in a system against the nominal output signal of that system. In modern
equipment, any figure lower than -90 dBV should be considered very good, and lower than -100 dBV
excellent
Slew Rate or S/R
The fastest rate of output voltage change that an amplifier can sustain. For consumer audio amplifiers, any
figure above 100 Volts per microsecond (100 V/us) should be considered excellent
Small signal rise time
A measure of the speed (i.e. rate of change) of an amplifier or preamplifier when dealing with low level
signals in the 1-2 Volt range. Small signal rise time and slew rate (S/R) are not equivalent
Unbalanced or single-ended
audio signals
With this type of interconnection, the audio signal is transferred between equipment using a ground
connection and a signal connection. It is more common than balanced audio signals due to its lower
implementation cost, but much more susceptible to noise pick-up
VMT
Voltage Mode Topology
– a type of amplifier wherein the peak current into the main gain stage is limited to
that of the input stage ‘Long Tail Pair’ (LTP) current source. Also known as VFA (Voltage Feedback
Amplifier)
XLR
The standard interconnect format for balanced audio signals
