RedPlate BlackVerb Operation Manual page 10

RedPlate BlackVerb Standard Operations Guide
Re: Model BlackVerb88 (with 80 watt KT-88 output section)
This manual is applicable for the BlackVerb88 with the following changes:
1. There is no cathode bias option switch.
2. The output tube type is KT-88 only.
1. When new KT-88 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 read lead is the DC voltage terminal of the
meter.
4. Place the Amplifier in operate mode with the Master Volume and Reverb controls set to
zero.
5. Set the HI/LO POWER switch to the HI 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 KT-88 tube spring retainer mounts.
7. Use a small flat blade screwdriver to adjust the bias pot for a reading of 92MV ± 5 MV
(FYI - the plate voltage is 500 volts). 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.
RedPlateAmps
1812 W Cinnabar AVE
Phoenix AZ 85021
www.RedPlateAmps.com
ADDENDUM
BlackVerb88 BIAS PROCEDURE
10