Rega Aethos Stereo Amplifier

Description

The Aethos stereo amplifier is housed in a brand new custom
designed case. Employing four 160 W 16 Amp output transistors per channel, this
delivers 156 W per channel into 6 Ω. The Aethos is a dual mono design using a
custom wound toroidal transformer and regulated supplies for the sensitive
amplification and driver stages. The pre-amplifier stage uses class-A discrete
circuitry throughout. The Aethos is a no compromise product with one goal, to
deliver your music as faithfully as possible. The Aethos has been built to
Rega’s high standards of reliability and quality to ensure many years of
musical enjoyment.

DESIGN INNOVATION

Our time, effort & money have been spent on developing
the circuit and construction, utilizing the highest specification of components
throughout. As part of the design we have included useful features such as the
switchable direct input and preamplifier output, to enable the new Aethos
amplifier to be used in a wide combination of systems. The headphone
socket has been integrated such that the speaker switching is performed by
the output mute relay as so not to obstruct the signal path and degrade the
sound quality.

Rega has taken the design concepts underpinning the multi
award winning and hugely successful Elex-R and Elicit-R and propelled the
performance to the next level and beyond with a 125watt dual mono design with
features such as fully discrete FET based line amplifier, polypropylene
capacitors throughout the signal path, K-Power reservoir capacitors, power
amplifier regulated supply and a high current output stage comprising of four
160w Sanken output transistors per channel.

VOLUME CONTROL AND LINE AMPLIFIER TECHNOLOGY

The Aethos uses a high performance combined feedback and
passive volume control plus line amplifier, which was originally developed for
the Elex-R.  Improvements have been made to the volume control and line
amplifier stages in the Aethos with the use of discrete FET input operational
amplifiers using the Linear Systems LSK389 FET and the well-respected RK27
‘Blue Velvet’ potentiometer. The feedback and input levels are varied to set
the required volume level. The level and tracking between the two channels is
set by the close tolerance parts in the pre-amplifier circuit and less by the
actual potentiometer itself, thus keeping the mismatch of channels due to
volume control tracking irregularities to a minimum, further improving on the
performance of the RK27 potentiometer. As well as keeping tracking
irregularities to a minimum, this method also reduces noise and input overload
as the control will only ‘use’ the required gain to amplify the signal. This
form of volume control is normally only found in professional broadcast
environments where accurate low noise control of levels is required.

POWER AMPLIFIER TECHNOLOGY

The power amplifier used in the Aethos is an improved higher
power version of the power amplifier used in the Elicit-R and Elex-R. The
output amplifier used in the Aethos, was born after extensive research by our
engineers to develop a low source impedance emitter follower Class-A driver
stage. This is based around two complementary pairs of 160w Sanken Darlington
output transistors. The technical and sonic improvement gained by the use of
low impedance drivers is well known, however, it can feature high standing
currents in the driver stage when using standard transistor configurations. By
combining the low impedance driver with the Sanken Darlington transistors (with
their imbedded thermal bias network running at a lower standing current), this
combination forms a complementary emitter follower emulating Class-A conditions
with good thermal stability and lower standing currents in the driver stage.
Due to the nature of the Rega power amplifier circuit we are able to run two
complete output stages in parallel, this includes the output transistors, bias
network and pre diver transistor this is instead of paralleling just the output
transistors as normally found. This ensures the 125 watt output is achieved
with complete ease.

SPECIFICATIONS

Power outputs at rated 230/115 V supply voltage:

125 W RMS both channels driven into the rated load of 8 Ω

156 W RMS both channels driven into 6 Ω
Note: Continued high level use into 6 Ω may cause the case to
exceed 40 °C above the ambient temperature and activate the thermal shutdown.
Headphone output:

No load 12.5 V
32 Ω 2.7 V
54 Ω 4 V
300 Ω 9 V
Source impedance 109 Ω
Record output:

Record output level (with rated input levels) 219 mV

Record output impedance 560 Ω
Pre-amp output:

Pre-amp output level (with rated input levels) 840 mV

Pre-amp output impedance 100 Ω
Input sensitivities for rated output level:

Input 1-5 and record input sensitivity 224 mV @ 17 kΩ

Maximum input level 11.5 V (record output amplifier overload point)

Direct input sensitivity 840 mV @ 50 kΩ

Power amplifier gain 31.6 dB
Frequency response @ 100 W into 8 Ω:

Line input 1-5 and record 10 Hz (-0.8 dB point) to 30 kHz (-0.5 dB point)

Direct input 10 Hz (-0.8 dB point) to 50 kHz (-0.5 dB point)
THD+Noise @ 100 W into 8 Ω:

Direct input (Power amplifier only) Typically 0.007% @ 1kHz (measurement
bandwidth 22 Hz to 30 kHz)
Line input Typically 0.007% @ 1kHz (measurement
bandwidth 22Hz to 30KHz)
Power consumption Maximum output: 415 W @ 230 V / 220 V / 115 V /
100 V into the rated load of 124 W RMS into 8 Ω
Fuse ratings T3.15 AL 250 V – 230 V/ 50 Hz and
220 V / 60 Hz

T6.3 AL 250 V – 115 V / 60 Hz and 100 V 50/60 Hz
Dimensions W 433 mm x H 95 mm x D 360 mm
(including speaker terminals)
Weight 17.5 kg