Ashdown 60 Amplifier Head Gebruiksaanwijzing - Pagina 10
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SPEAKER OUTPUTS
These are for connecting the amplifier to one or two speaker cabs.They are wired in parallel.
SPEAKER SELECTOR
This is for selecting the output impedance of the amplifier. It can be set to either 16, 8 or 4 Ohms.
IMPEDANCE SELECTION ADVICE
It is important to ensure the correct impedance is selected for the load presented to
the amplifier. Failure to do so could cause damage to the amplifier.
Never run the amplifier without a speaker connected as this will damage the output
transformer.
The speaker sockets are wired in parallel.When using two cabinets, make sure they are of the same
impedance. Set the impedance as shown below:
Number and impedance of
Setting of
loudspeaker cabinets
impedance selector
One 16 Ohm cabinet
16 Ohms
Two 16 Ohm cabinets
8 Ohms
One 8 Ohm cabinet
8 Ohms
Two 8 Ohm cabinets
4 Ohms
One 4 Ohm cabinets
4 Ohms
TUBE GUIDELINES
SETTING THE BIAS
1.
Connect speaker cab and select correct impedance.Turn gain and master controls to zero (fully anti-
clockwise).
2.
With STANDBY engaged, switch on amp and allow to warm up for 2 mins.
3.
Disengage STANDBY mode and leave for another 3 mins.
4.
Select tube to be adjusted on the BIAS METER SELECTOR using a screwdriver or small coin.
5.
Turn the corresponding ADJUST BIAS CONTROL very slowly until the meter on the front panel reads
0 VU (beginning of red section).
6.
Repeat steps 4 and 5 until all tubes have been adjusted in this way. It is intended that the tubes are
adjusted in the order on the BIAS METER selector.This ensures that the current through the
transformer is equalised.
7.
Altering the bias of a tube may have a slight effect on the bias of other tubes.When all four tubes have
been set once, return to the first tube and repeat steps 4 and 5 as many times as required
to obtain 0 VU on all tubes.
8.
When finished, turn BIAS METER SELECTOR to audio before playing. Please be aware that using the
ADJUST BIAS controls will alter the bias of the tubes regardless of the position of the BIAS METER
selector.
It is ok to run the tubes below 0 VU (under-biased), BUT NEVER IN THE RED! Over-biasing
by running the tubes in the red will damage the amp and invalidate the warranty.
USING THE METER TO CHECK THE OUTPUT TUBES
1.
If no reading on the meter is obtained when a selection is made, it is possible that the tube's fuse has
blown (next to the ADJUST BIAS CONTROL). If this is the case replace with a 20mm quick blow fuse
rated at 300 or 315 ma. (Note: If the fuse keeps blowing, replace the tube. Never fit a fuse of a higher
rating.)
2.
If, when adjusting the bias of a tube, the correct reading cannot be achieved then the output tube
must be replaced.
REPLACING A TUBE
1.
Disconnect from the mains and allow 5 mins for residual voltages to discharge. If the unit has been in
use for some time, allow to cool down for at least 15 mins - the tubes get very hot!
2.
Remove the back panel of the amplifier (this is held on with velcro).
3.
Remove the defective tube and fit a new one.
4.
Replace back panel.
5.
Perform the bias setting procedure.
Replace output tubes with same type and make. Do not use cheap tubes.The Peacemaker 50 Head is fitted
with 2 x Sovtec 6550s.The Peacemaker 100 Head is fitted with 4 x Svetlana EL34s.
If you have any doubt about replacing tubes, please email us at the address shown on the back cover of this
manual.
A NOTE ON HANDLING YOUR AMP
The tube is a precision component and careless handling of the amplifier may result in irreversible damage
to it.Tubes are particularly sensitive when they have been active for some time and are warmed up. For
this reason, after disconnecting the power allow 15 mins for the amplifier to cool down before you move
the unit.
A NOTE ON EARTHING
The earth connection (green & yellow wire in the plug) must never be disconnected. If you are
experiencing earth-loop problems (hum), ask at your local music shop for a telescoped jack-lead (i.e. a
cable in which the earth is disconnected at one end).