O W N E R S M A N U A L
Decware High Fidelity Engineering Co., East Peoria IL, USA www.decware.com
HOW TO USE THE BIAS BALANCE KNOB
Approximately 30 to 40 seconds after the power switch has been turned on, the
heaters inside the output tubes (part that glows) will begin to emit electrons and
current will begin to flow. You will want to watch this happen in real time by keeping
your eyes on the meters and watching them climb and seeing if the both stop at the
same number.
After the tubes heat up the meters will show how many milliamps of current each tube
is adjusted to. If they don’t match, simply adjust the control until they do. If you turn
the control the wrong way, the difference between the two meters will increase
suggesting that you turn the control the opposite direction until they match.
As the tubes heat up during the first 15 to 30 minutes, you’ll see the current draw of
each tube drift a bit. This is normal and requires only another fine adjustment to get
the tubes balanced and then expect them to stay that way until you turn the amplifier
off. When you turn it on again for your next listening session, you’ll find the tubes
will bias up right where you had them set once they have fully warmed up. Of course
you can make fine adjustments at any time, and if music is playing, just turn the
volume control all the way down to make your adjustment.
Later on you will notice that music effects the meters at higher volume levels. In fact
the meters can dance pretty readily when the amplifier is at it’s maximum 60 watt
output level on musical peaks. That means you can visually SEE when your amp is -
running out of power and starting to distort. Keeping your amp from making the
meters move excessively (more than 20 mills) ensures long life for your output tubes,
speakers and your hearing.
Now that your amp is on and the
meters read the same value on each
side, lets learn how to adjust what
that value is.
In the picture, the amp is set to 60
mills per side. This is an ideal
operating point. You can run it at 70
mills per side which tends to add
weight to the sound but you may
think is sounds better at 60 mills.
There is no right or wrong setting,
just trust your ears.
