Advertisement
Two LEDs Light Up Continuously
This tells you one of two things: Either these tubes
are not delivering enough current and has to be
replaced (see the instructions for one illuminated
LED), or the Power Soak is active. In the latter case,
two tubes are switched off automatically and the two
illuminated LEDs are indicating this.
One LED Flashes, Another Lights Up
Continuously
The tube assigned to this flashing LED is generating
too much current. It has been shut down and has to
be replaced. In this type of power amp, it takes a pair
of tubes working together to produce the best sound.
The defective tube's counterpart has been switched
off so it doesn't degrade the other pair's tone. This
tube's LED lights up continuously to indicate it
has also been shut down, but there is no need to
replace it. You can continue playing, though output
is halved from 36 to 18 watts for as long as the LED
remains illuminated. If this occurs in a conventional
amp, its fuse usually trips and you can't operate it
until you replace the tube and fuse.
4.2 Manual Read-Out
TSC™ checks tubes' bias points to let your determine
if pairs match. This is easily done by inserting a pick
into the appropriate slot while the amp is on (rather
than in STANDBY mode). The LEDs will flash.
How many times the LEDs flash matters, but what
matters more is the difference in flash counts. TSC
will ensure optimum sound if the difference is no
greater than four flashes. If the difference in flash
counts is greater than four, we recommend installing
a matched set of tubes to improve the tone. This is
strictly a matter of tone - technically speaking; the
amp will continue to operate safely.
HEADS UP: The two inside tubes and the two
outside are matched pairs. If just a single tube is
swapped, ensure the replacement tube's rating matches
that of its counterpart. If all tubes are replaced, ensure
they all share the same ratings.
The table below shows Hughes & Kettner tube
ratings and how flash counts translate to a rating.
For example, if the TSC display flashes six times
you need a tube with an S2 rating. The chart also
tells you that its bias point is set to 13 volts. You can
buy a replacement tube from your local dealer. The
original Hughes & Kettner rating (S1-S7, 0-12) is
shown on a sticker on the tube.
Flashes
Rating
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Bias [V]
S7
10
S6
10.6
S5
11.2
S4
11.8
S3
12.4
S2
13
S1
13.6
0
14.2
1
14.8
2
15.4
3
16
4
16.6
5
17.2
6
17.8
7
18.4
8
19
9
19.6
10
20.2
11
20.8
12
21.4
*
22
*
22.6
*
23.2
*
23.8
*
24.4
17
Hide quick links:
Advertisement
