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5 CLIP LED
The CLIP LED will indicate when the power amp starts to distort. Occasional flashing is OK. If the LED is on
continuously , turn turn the LEVEL control down. Amp distortion produces "square wave" power that is harmful to
your speakers.
6. EQ IN/OUT SWITCH
If you require the Graphic Equalizer, push the EQ IN/OUT switch IN. Volume levels will be similar in either position
providing the graphic sliders are in their center—neutral position.
7. GRAPHIC EQUALIZER
The 9 band Graphic Equalizer in the FET401 provides a wide degree of tonal flexibility. To properly use the
Graphic EQ (equalizer), set all sliders to their center position. With the sliders at this position, there is no effect on
the audio signal. When you raise the slider above the center position, you boost levels in a narrow frequency band. If
you lower the slider below the center, you are subtracting levels. When using these sliders, think of them as volume
controls that can add or subtract tones in narrow bands.
Frequency: The 63 Hz slider is for deep sub bass level adjustments, the 125 Hz is for higher bass adjustments, the
250, 500 and 1K Hz is for mid and higher mid tone adjustments, the 2K and 4K Hz is for mid treble adjustments,
and the 8K and 16K Hz sliders add to the very high end treble.
Adjusting: It is recommended that all sliders be set in their center position before equalizing your tone. Typically low
frequency feedback is in the 125 and 250 Hz range while high feedback is in the 2k and 4k Hz range. Occasionally
you may have to turn one frequency (slider) off to -12dB to help stop feedback. But you should never turn the
adjacent sliders off too. Instead, set the adjacent sliders to -6dB to form a gentle negative curve. Likewise, if you
need more deep bass, boost the 63 Hz by 10 dB and the 125Hz by 5 dB. Or, if you need more treble, boost the 8k
by 6 dB and the 16k Hz by 4 dB. Note—there is not much signal at 16k so you may not hear any difference except for
added noise. If you raise or lower all sliders at the same time, the EQ will act like a volume control because you are
effecting all frequencies. Take care not to over-adjust as this will drastically alter your over-all sound. Use the EQ in
addition to proper microphone and speaker placement for the control of feedback.
Rear Panel Connections
1. AC LINE CORD
The FET401 employs a heavy duty removable grounded AC cord and should only be plugged into a grounded " 3
prong" power outlet. If a grounded outlet is not available, the amp should not be used. For safety, no attempt
should ever be made to defeat the ground pin of the AC line cord.
2. AC LINE FUSE
The FET401 fuse is built into the AC receptacle socket—marked by an arrow on the rear panel pointing to the
receptacle. The fuse can be changed by removing the AC cord and wedging a slot-head screwdriver under the top to
pull out the fuse holder. Once out, the fuse can be replaced (there is room for a spare fuse in the tunnel). 120 volt
fuses are available from Radio Shack: Part No 270-1175 for a 5 Amp slow-blow fuse for 120 volt use and 2.5 Amp for
220 volt use. Use slow-blow 5 x 20mm fuses only.
3. SPEAKER CONNECTIONS
The FET401 incorporates two speaker jacks and two speaker binding post. You may use any of these connectors
for your speaker hook ups. Note the positive and negative polarity on all speaker connections for proper speaker
phasing. All jacks and binding posts are wired in parallel. As you connect speakers to the FET401, the impedance will
reduce in half as you add more speakers. Do not use Mic or Guitar cords or any cord that is shielded. Your power will
be reduced because of the lighter gage wire. Use 16 gauge wire or heavier.
4. INPUT CONNECTORS
The FET401 features a D3F balanced connector designed to take any balanced impedance source from 150Ω to
100KΩ. Use this connector for cable lengths over 50' or if you are having a grounding problem from your signal
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