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楽器アンプ Andrews Amplification SpectraverbのPDF 操作マニュアルをオンラインで閲覧またはダウンロードできます。Andrews Amplification Spectraverb 13 ページ。

FOR TECHNICAL TYPES

We have provided this information for those who have a technical interest,

proper equipment and a DIY attitude. CAUTION! GUITAR AMPLIFIERS

CONTAIN LETHAL VOLTAGES. If you have any doubt about your ability to

safely perform this procedure, refer the job to a qualified technician!

Bias Adjustment Procedure:

Precautions:

• Lethal voltages are present inside the chassis and at the tube pins. Do not

open the chassis or insert any objects into any openings other than where

directed by these instructions. The entire procedure can be accomplished

without opening the amp.

• Vacuum tubes get very hot. Always allow the tubes to cool completely before

touching them.

• When replacing output tubes, use only the very highest quality tubes or the

amplifier may be damaged. For more details, see the section below regarding

tube replacement.

Bias Adjustment

1) Unplug the amplifier and allow the tubes to cool. The output tubes are the two

matching tall tubes.

2) Spread open the retaining clips that hold the output tubes in place and remove the

tubes. Install a new matched pair of the same type of output tubes that came

installed in your amp. ie: 6V6 or 6L6 (5881 can be used in place of 6L6 tubes).

3) Utilizing a digital multi-meter, set the switch for DC Volts or millivolts measurement

and select a range that will show 0-100 millivolts. Insert the black meter lead into

the black test point terminal and insert the red meter lead into the red test point

terminal.

4) Insert a small flat blade screwdriver into the adjustment control hole and gently

turn the control to its mid position. The adjustment control is located on the

underside of the chassis near the bias test points.

5) Plug in the AC cord and turn on the amplifier's main power switch. After waiting at

least one minute, turn on the standby switch. The meter should display a few

millivolts (mV).

6) While taking care not to touch any hot tubes, insert the screwdriver into the

adjustment control slot and very slowly turn the adjustment until the meter reads

65mV to 90mV for 6L6GC tubes or 50mV to 70mV for 5881 tubes. The test point

shows the combined reading for both output tubes.

7) It's a good idea to re-check the bias periodically (every 500 hours of use) as the

idle current can drift over time as the tubes age.

NOTES: Adjusting bias to the higher end of the scale will provide a warmer more

driven sound but will shorten the life of the output tubes and increase the chances of a

tube failure. Adjusting to the lower end of the scale will increase tube life while

providing a "colder" less driven sound. Try different settings and listen for differences

and make your choice. Factory settings are in the middle range.