User manual

4. Turning the Dirty Boy ON: Once the Variac and the Bias controls are set to “0” and
COLD, move the power switch on the front of your Dirty Boy to the “ON” position.
Allow at least sixty (60) seconds for warm up, which is the minimum recommended.
Note that longer warm up allows the tubes to stabilize. If you have the luxury of
allowing your amp to warm up for 5 minutes, this would be optimal. Once the Dirty
Boy has sufficiently warmed up as indicated, move the “STANDBY” switch to the
OFF position (down). The Dirty boy will become operational.
5. Initial Tone and Feel Adjustments: We suggest turning the boost OFF for your first
power up test. Once the amp is operational, we suggest turning up the guitar volume
while SLOWLY rotating the Variac to the appropriate power level test your sound..
You can then adjust your Bias to the desired tone and feel and set your volume.
Note that setting the Variac to 100% and the Bias between 70-75% is a normal
operational setting. Also note that when the bias control is set to “COLD” the Dirty
Boy power amp section is effectively cut-off at low power levels. Adjust the bias at
low power levels until desired sound quality is obtained. At higher power levels DO
NOT run the amp at full hot unless your playing the amp clean. See the Bias control
section below for further explanation.
Section 2: Operating the Dirty Boy.
1. Understanding the Variac. At the heart of the Dirty Boy amp is the Variac. The
Variac is an adjustable power transformer used to vary the power on the EL34
power tube section of the Dirty Boy amp. It’s purpose is to allow a combination of
power level changes and sound texture results from the resulting power level
differences. The power supply rectifier tubes (5U4) are controlled by the Variac. In
turn, the Variac should not be dialed rapidly back and forth. Doing so may cause
damage to the rectifier tubes and or the EL34 power tubes. We STRONGLY
recommend you use common sense and treat the Variac with high a degree of
carefulness. If you rotate the Variac slowly, you will get better results form the amp
and safer operations on your power supply tubes as well as audio power output
tubes. Additionally, we suggest at anytime when you have powered your amp down,
that you also set your Variac to 0 volts. This allows the amp to be powered back up
from 0 to your previous setting.
2. Understanding the Division Lines. We will describe the Dirty Boy Control settings
in percentages. Looking at the Dirty Boy control panel, you will see the smaller
division lines. These smaller division lines are equal to 5%. There are also five
longer thick lines on the dial. They are referenced at 0%, 25%, 50%, 75% and 100%.
The larger divisions are spread equally along the control panel and are separated by
the smaller 5% division lines. Basically, you have a control dial that reads from
0-100%. The Variac is also 0-100% but its divisions are set at 2% increments. 100%
Variac equates to 120VAC power to the rectifier tubes. 50% Variac would equate to
60 VAC power fed to the rectifier tubes. Therefore, the Variac does not equate to
power or voltage levels in the direct sense. If you set the Variac at 75%, the actual
voltage is not 75 volts, but rather 75% of 120 VAC, which is actually 90 VAC. This
Dirty Boy User Manual