Nächste Seite: The Phono Preamplifier
Aufwärts: AH PRE-1 Highend-Preamplifier Development
Vorherige Seite: Abbildungsverzeichnis
Inhalt
Unterabschnitte
The preamplifier should fulfill the requirements as listed below:
- Inputs
- 5 asymmetrical line level inputs
- 1 asymmetrical MC-phono input with about 150 V sensitivity
- Outputs
- 1 output for a tape recorder
- 1 output to drive the power amplifier
- 1 output to drive a headphone of normal sensitivity and medium impedance
- Control elements
- separate source selectors for listen and record
- no tone controls
- no balance controls
- a switch to route the output alternatively to the headphone or to
the power amplifier
- requirements regarding the sound quality
- external power supply
- no coupling capacitors within the signal chain
- no DC offset servo control loop to prevent ``pumping''
- frequency response should start at DC if technically possible
- all switching done by relays located as short to the signal chain
as possible
- simple circuits with as few active parts within the signal chain as
possible
- separate power supply regulation for every circuit module
The preamplifier contains two amplifier modules:
- a phono preamplifier on its own circuit board which amplifies the
signal of a MC phono pickup to line level
- a buffer amplifier connected to the volume control potentiometer which
buffers the line level signal and amplifies it by about 10 dB to drive
both head phone and power amplifer.
There is no buffer before the volume pot simply because you don't
need one and it would just add more distortion. The same is true for
the buffer for the tape recorder output: there is none.
There is a 1 x 6 source selector switch connected to the volume pot
which is used to select the source you want to listen to. The switch
itsself is a cheap one as the audio signals are switched by very good
relays.
There is a second 1 x 6 source selector switch connected to the tape
recorder output which is used to select the source you want to record.
The switch itsself is a cheap one as the audio signals are switched
by very good relays.
Nächste Seite: The Phono Preamplifier
Aufwärts: AH PRE-1 Highend-Preamplifier Development
Vorherige Seite: Abbildungsverzeichnis
Inhalt
ah@despammed.com