Setup; Caution; Technical Features - QUAD PA-One Owner's Manual

SETUP

Connect the source to the input of the unit and select the balanced or unbalanced input in appropriate. Plug your headphones
into one of the front panel jack according to the impedance rating of the headphones. Set the volume to minimum, connect the
unit to the main supply and switch on. It takes 30 seconds or longer to warm up before you can use it.
This PA-One is able to drive both high and low impedance headphones. 'High impedance' means 100ohms and above; 'low
impedance' is below 100ohms. (Typically, high impedance headphones are 200ohms or 600ohms, while low impedance
types are 32ohms.) A specification for impedance will normally be included in the instructions that come with the headphones,
or you can judge the impedance type of your headphones by following the steps below. Connect your headphones to a low
impedance ('Low Z') socket. Turn up the volume slowly while listening to a familiar music track. If the volume seems low, even at
maximum volume, your headphones are probably high impedance. Turn the volume down to minimum level and reconnect the
headphones to a high impedance ('Hi Z') socket. Turn the volume up slowly again and check that the volume if it is satisfactory.
High impedance headphones will clearly play louder when plugged into a high impedance socket. Low impedance headphones
will play slightly louder when plugged into a low impedance socket.
Interconnect cables should at low capacitance and well screened. Avoid excessively long cables.

CAUTION

The volume should be set to minimum when you switch on the unit. When the unit is playing a music track, adjust the volume
knob slowly and keep the volume at a comfortable level. Listening to the loud sound for a long period can damage your hearing
permanently. If you feel uncomfortable while listening, or if there is a whistling in your ears after a listening session, you may
listening too loud. Turn the volume down.
There are no user adjustable settings inside the unit. Please do not remove the top cover as this will expose high voltage parts
which present a danger to life.
The unit generates heat while working, so it should be placed in a well ventilated position, and enough space is required behind
it to ensure that leads are not unduly strained or damaged.
Very frequent switching on and off in any electronic equipment put some stress on components, particularly in the power supply.
The unit should be switched off when at night to save electricity and to maximize operating life of the valve.
Do not plug in the charged case headphones, earphones or may cause damage.

TECHNICAL FEATURES

It uses 6SL7 valves, and uses 6SN7 valves as the enhanced drive of 'triode mode', properly matched to the load through
different impedance taps of high-performance audio transformer, which can be adjusted by the switch, to delivers nearly 1W of
high quality, low distortion power into high or low impedance headphones.
The use of EZ81 valves as rectifier makes the sound very soft and gentle, which is more suitable for headphone listening. It can
also be used as pre voltage amplifier due to its function of pre output. The circuits use cathode feedback instead of negative
feedback loop, contributing to a very small distortion and well dynamic performance. With the function of USB, coaxial and
optical input, they can be connected to sources from computer or other devices. It is manually welded with unique manual craft.
All components in the amplifier have been carefully selected to give consistent high performance over a long period.