RedPlate Magica Operations Guide
6
BIAS PROCEDURE
1. When new EL-34 output tubes are installed it is important to re-bias the amp for optimal
performance.
2. ALWAYS HAVE A SPEAKER CONNECTED.
3. Use a digital volt meter set to DC volts at lowest scale (MV). Makes sure the black lead is
the common terminal of the meter and the red lead is the DC voltage terminal of the meter.
4. Place the Amplifier in operate mode with the Master Volume set to zero.
5. Set the 50 WATT/ 18 WATT switch to the 50 WATT position.
6. Place the red meter lead in the test point hole (red tip jack) and touch (or clip) the black
meter lead on one of the metal output tube retainer clips.
7. Use a small flat blade screwdriver to adjust the bias pot for the bias number as stated on
the rear panel ( ± 5 MV). The reading is the sum of the idle current for both tubes.
8. Recheck the reading after 10 minutes of operation, and again after a week or two of
operation.
INTERNAL TRIM POTS
The Magica has 3 internal trim pots:
1. PI Balance
– Useful for working with unmatched 12AX7 tubes in the phase inverter
position. Refer to qualified personnel for proper setting.
2. Clean Boost Level
– sets amount of footswitch boost for the clean channel
3. Lead Boost Level
– sets amount of footswitch boost for the lead channels.
REMOVE THE POWER CORD AND PLACE THE STANDBY SWITCH IN OPERATE
POSITION TO BLEED OFF HIGH VOLTAGES.
RedPlateAmps Warranty
At RedPlateAmps we pride ourselves making products that are built to last. The workmanship in
your RedPlate amplifier is warranted to be problem free for the lifetime of the original owner, or in
the event of resale a onetime transfer to a new owner for coverage for 3 years from the original
manufacture date (please inform us of an ownership change to insure coverage). The actual
electrical components in your amplifier are warranted for a period of 3 years. Exclusions are
vacuum tubes, reverb tanks, cables, speakers and cosmetics which are warranted for 30 days.
Improper handling or product misuse or product abuse or unauthorized repair work or
unauthorized modifications may nullify your warranty. Eligibility for coverage and covered items
are at the sole discretion of RedPlateAmps.
RedPlateAmps
1812 W Cinnabar AVE
Phoenix AZ 85021
www.RedPlateAmps.com
email:
Thanks again for joining the RedPlate Family
– Henry
