Siegmund Big Boy 330, Owner'S Manual

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9
Use this guide to find the bias numbers for your desired configuration:
Speaker imp Speaker imp Speaker imp Speaker impedance edance edance edance Bias Bias Bias Bias Power Power Power Power Peak Peak Peak Peak
2 ohm
2 ohm 2 ohm
2 ohm 200 mV
200 mV 200 mV
200 mV 330 Watts
330 Watts 330 Watts
330 Watts 43
43 43
430 Watts
0 Watts 0 Watts
0 Watts
4 ohm
4 ohm 4 ohm
4 ohm 200 mV
200 mV 200 mV
200 mV 26
26 26
260 Watts
0 Watts 0 Watts
0 Watts 30
30 30
300 Watts
0 Watts 0 Watts
0 Watts
4 ohm
4 ohm 4 ohm
4 ohm 240 mV
240 mV 240 mV
240 mV 300 Watts
300 Watts 300 Watts
300 Watts 350
350 350
350 Watts
Watts Watts
Watts
Only bias to 240 mV with a 4 ohm load - Never with 2 ohm, or the tubes will wear prematurely.
Biasing tips:
Biasing tips: Biasing tips: Biasing tips:
•
Always do bias adjustments with the power tubes fully warmed up after playing.
•
From time to time check the Bias
Bias Bias
Bias setting of both LLLL and R
RR
R to make sure all tubes are
working properly.
•
A dead or premature worn tube will give a noticeable lower reading.
In that case remove one tube at a time and look for none or the least change in the meter
reading and replace that tube. Then reset using the Bias procedure above.
•
Readjust Bias Bias Bias Bias as tubes wear down over time to maintain balance between LLLL and R RR R
•
Reset Bias
Bias Bias
Bias after replacing one or more power tubes.
•
Balance Balance Balance Balance can only be adjusted when the amp is played and Master is at least half way up.
Tube Replacement Procedures Tube Replacement Procedures Tube Replacement Procedures Tube Replacement Procedures
1)
Allow tubes to cool down before handling.
2) Pull off the tube retainer.
3) Gently pull out the tube by its base with a light circular motion. Don’t use excessive force
and take your time.
4) Inspect each tube before inserting, for straight pins and an undamaged locating pin in the
center.
5) Line up the locating pin with the socket, by rotating the tube until it locks into place.
Caution:
Caution: Caution:
Caution: Power tubes will be especially hot!
Power tubes will be especially hot! Power tubes will be especially hot!
Power tubes will be especially hot!
Never touch hot tubes with your bare fingers! Never touch hot tubes with your bare fingers! Never touch hot tubes with your bare fingers! Never touch hot tubes with your bare fingers!