Magenta ACRH-1 User manual

ACRH-1
Integrate Hybrid
Audio Amplifier
User Manual

ACRH-1 Hybrid integrated audio amplifier
It is well known that a good preamplifier is the heart of an
audio system. With this in mind, Margules Audio has
undertaken the task of developing an integrated amplifier that
blends an extraordinary tube preamplifier with an excellent
solid-state power amplifier,thus allowing the end user the
ability to upgrade and/or customize his system based on the
preamplifier.
For example: perhaps the owner of an ACRH-1 wants to
upgrade the system so he buys a tube amplifier. In this case
the internal power amplifiers of the ACRH-1 can be used with
an add-on component from Magenta such as an active
crossover to power a subwoofer. Or to power another pair of
loudspeakers controlled remotely by an external controller. Or
a quad power unit that, when connected, will convert the unit
from 75W/channel to 220W/channel.
Also, with an external processor, the ACRH-1 may be used to
power a pair of surround speakers.
Description:
Preamplifier section
Tube Preamplifier
The preamplifier unit is based on two dual triodes (12AU7) per
side that act as unity gain buffers coupling the source and the
power amplifier. The circuit is based on the knowledge and
experience acquired in developing the highly acclaimed
Margules SF220r.
Regulated Power
The power supply of the preamplifier is fully regulated. Good
regulation reduces the loss of signal integrity that occurs when
the signal itself shifts the preamplifier's operating point. The
filament supply is DC (not AC) for minimum hum. It, too, is
regulated.
Remote-Control Operation
The remote operation is unusually versatile. Besides input,
volume, on and off, you can also switch the AC power to
associated equipment drawing up to 20 amperes (2500 watts).
All input switching is through electromechanical relays. The
audio signal never passes through a semiconductor device.
Amplifier section
DC coupling
The topology of the power amplifier is designed in such a way
that all coupling is direct thus avoiding interstage capacitors that,
in most cases, result in higher distortion.
All discrete bipolar transistors
The power amplifier does not utilize any integrated circuits.
Variable Bias
The output stage is designed with a variable bias. This optimizes
the operating point of the semiconductors to avoid the typical
overheating in Class A operation and reduce the Class B
distortion.
The ACRH-1's innovative design is complemented with precision
metal-film resistors and a silver coated PC board.

Connections:
All inputs and outputs of the preamplifier are unbalanced RCA
connectors.
The back panel is organized by blocks from left to right: the
first contains the input connection to the amplifier; the second
is for the outputs of the preamplifier; the third has four inputs,
all of which have the same gain and input impedance; and in
the fourth section are the tape monitor inputs and outputs.
This feature allows the monitoring of a tape recorder at the
same time that it is recording, or can be used as a loop for a
processor.
The phono preamplifier is external and it is not included. It is
marked for labeling purposes only..
Your unit incorporates two preamplifier outputs per channel
that are connected in parallel.
Normally one will be connected to the amplifier input, making
it an integrated system. The other output remains available
for connection to an active subwoofer or perhaps a multi-room
extension adapter or the surround system etc.
At the very moment you connect the unit to the power source
the filaments of the two tubes will be on as well the remote
control receiver thus allowing you to see the last selector
position.
To turn the unit on press the on/off button on the remote
control. This will activate a light at the upper right corner
indicating that the unit is on. This will turn on the high voltage
of the preamplifier and the output semiconductors amplifiers.
The filaments are always on, so the turn on will be immediate.
The life expectancy of the tubes shouldn’t be diminished
significantly by being on continually.
The unit is provided with a switched power outlet with a
capacity up to 20 amps, so you can control the on/off of an
associated component via the remote control.
The power cord of the unit can be interchanged for other types
than the one supplied so the tonal characteristics can be
changed.
Note:
When the preamplifier is first plugged in, or when the current
from the wall is absent for a several seconds, it is necessary to
initialize the system.
To do so, press the input selector switch at the remote control.
Allow the filaments of the tubes to warm up for a few seconds;
then turn on the preamplifier with the on/ off switch on the remote
control.
It is normal to have the input selector on all the time that the unit
is plugged to the wall.
In the case of a fast sudden black out the unit may require to be
reset, in that case you have to unplug it from the wall and redo
the initialization procedure. You will know it, because it wont
have the selector input indicator, or it will have two or more miss-
indicating LED’s on.
Trouble shooting:
No sound:
No light is visible but unit is plugged in:
Check the initialization procedure.
The selector light is on but there is no sound:
Make sure the unit is on by seeing the power
light on in the upper right corner.
Check that the signal source to be plugged in the
correct input.
Check that the tape monitor selection is in the
proper position.

General comments:
The unit is always warm so it should be placed in a well
ventilated area.
Always mount your unit on a firm platform to avoid external
vibrations from loudspeakers, etc.
You can change the tonal characteristics by placing the unit
on different types of supports like footers, spikes, etc.
To minimize unwanted noise in the system:
Avoid excessive length of the interconnect cables.
Avoid having the signal cables near the AC line.
Avoid ground loops between components.
Break in:
The break in period requires about 150 hours of music
reproduction. To simply have it turned on without music will
not accomplish the necessary break in.
Tubes:
Life expectancy:
For optimal performance we recommend changing both tubes
every three years even though they should last for a longer
period.
Type:
The unit is supplied with 12AU7 or 12AT7 but can be
interchanged with 12AX7 or other similar tubes without
adjustment.
Never take the tubes out of the circuit while the preamplifier is
plugged in to the wall outlet.
Characteristics
Integrated:
Frequency response 10-50 KHZ
Power at 8 ohms 75w./Channel
Total Noise < 0.5mv.
Maximum total harmonic distortion 0.07%
Weight 15KG.
Power consumption
Standby 17 W.
At max.
Output and 8ohms 320W.
Preamplifier:
Frequency response
(Volume potentiometer full counter clock wise) 4-80KHZ
Noise <0.1mv
Gain 1DB
Harmonic distortion 0.04%
Amplifier:
Input voltage for max. Power 0.8V
For more information please contact us at:
Mexico
Uruapan #17-4
Col. Roma
Mexico D.F. 06700
Mexico.
Tel. [phone]
Toll free 1-888-538 8605
FAX [phone]
Email: [email protected]
Visit our home page in internet:
http://www.margules.com.mx
EUA
14038 Tanglewood CT
Dallas 75234, Texas
TEL. [phone]
FAX. [phone]