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4 How to get the best out of your amplifier
Do not leave the amplifier switched on all the time. This is not necessary
Do not switch off and on without a short rest of 60 seconds (to reset the ‘soft start’)
Do not adjust the output valve grid bias unless you know how
Do not switch from Ultralinear to Triode without first switching off
Do not swop the output valves round as they are set up individually
Do not operate the amplifier without loudspeakers connected
Do not use valves other than listed as there could be danger of shock or overheating
Make sure the speakers are in phase.
Use the best possible source material.
Use efficient, well-designed speakers.
What is safe maximum volume?
The Stereo 40i Classic will run happily all day long
at full undistorted power; the valves are not
stressed any more at full power than at zero
volume. Running into gross distortion will however
stress the whole amp and valves. To find the
maximum safe volume, play full range music and
advance the volume until distortion occurs, (this is
normally between 12 and 3 o’clock on the volume
control) back off the volume control about 30
degrees, this is approximately full power. However
this position will vary according to the level and
type of music and the output of the source unit.
For example CD players tend to be higher than
say tuners.
Triode Switch.
This switch causes the EL34’s to
operate as Triode valves.
As switching can
stress the output transformers we would
recommend that switching be done when the
amplifier is switched off.
You may notice that
there is a slight reduction in volume in Triode
mode; this is due to the lower gain that the EL34s
have in this mode, advance volume to
compensate.
Leaving the amp switched on
People sometimes ask if the amp should be left
running 24/7 without switching off. Whilst the
amplifier will sound at its best when it is properly
warmed up, there is no advantage leaving it
switched on when it is not in use. It is using
electricity and as valves have a finite life.
Conversely the valves and other components are
stressed more at switch on; therefore do not
switch on and off unnecessarily.
We would
always advise that any item of home
electronics is switched off when not in use
‘Burning in’
Although the amp should sound good within
about 10 mins it can take up to an hour to
sound at its best and will take several months
of regular use before it is fully ‘run in’.
Upgrading Valves!
This can be a controversial subject, but in our
opinion quality valves sound better, but have a
good service life, maintain their performance and
should be reliable, the last three items will make a
valve sound better longer. The upgrade valves
supplied with selected models are the result of
careful comparison with other makes.
Cabinet Care
To remove dust we suggest gentle brushing of the
polished stainless steel cabinet with a soft
paintbrush. Other marks can usually be removed
with a damp cloth. The Perspex valve cover may
need a gentle wipe with soapy water and drying
with a duster. On no account use anything wet on
the amplifier, and always clean with the power
disconnected.
5 Trouble Shooting
Amplifier Dead
Check the 1.6 amp mains fuse at the back of the
amplifier. To gain access, remove the mains lead.
The fuse is in a small plastic drawer, which forms
part of the socket assembly. To open insert a flat
bade screwdriver or similar and prise open.
The
fuse in use is the innermost
the outer is a
spare. Should the replacement fuse also blow
there is a fault. Replacements should be 1.6 Amp
‘anti-surge’.
The fuse in the plug should be a 3 or 5 amp fuse,
although unlikely, this should be checked if the
amplifier fuse is OK.
No sound
Have you selected the right input? Are the
connections OK? Is everything switched on? Are
the speakers connected?
Distorted sound.
Try another source; if sound improves then it’s
probably something wrong with the first source. If
no improvement try different speakers, if no
improvement could be an amplifier problem.
Hum Problems
If you experience hum, try disconnecting all
inputs, if hum persists this is probably an amplifier
fault.
If not, Identify which input is causing hum.
Connect one input at a time. A common cause is
a ‘hum loop’ caused by having to many earths,
and may be identified by unplugging each input
source from the mains. One remedy for this is to
use an interconnect which only has the screen
connected at one end. Other causes of low-level
hum can be from adjacent equipment, so
