SPEAKER LOAD MATCHING
Precise 4, 8 and 16-ohm load impedance matching can be attained with our Stereo
Integrated Amplifier by changing the turns ratio of the output transformers by way of
jumpers soldered to pairs of secondary terminals to form the patterns as indicated below.
4-ohm speaker:
(1 and 2) - (5 and 6) - (6 and 3) - (3 and 4) - (7 and 8).
8-ohm speaker:
(5 and 2) - (2 and 3) - (6 and 7) - (7 and 4).
16-ohm speaker:
(5 and 2) - (6 and 3) - (7 and 4).
….................................
1 o o 5
2 o o 6 o = secondary terminal
3 o o 7 1 - speaker-RED
4 o o 8 8 - speaker-BLACK
….................................
output transformer coil
It is well known that the distortion and the damping behavior (output resistance) of a tube
power amplifier is affected by the output transformer turns ratio. As our Stereo Integrated
Amp is a class-A triode amplifier, loudspeakers may be typically used with a higher
output transformer turns ratio than the one corresponding to the rated speaker impedance
(especially when the speaker efficiency is high). This would, theoretically, reduce the
distortion and lower the output resistance of the amplifier (both of which are desirable
features) at the expense of a lower maximum power output into the speaker load. On the
other hand, it is very unlikely that optimum sound quality will be achieved when speakers
are connected to a lower output transformer turns ratio than the one corresponding to the
rated speaker impedance. Thus:
It is possible to use a 8-ohm rated speaker with the 4-ohm load pattern.
It is possible to use a 16-ohm rated speaker with the 8-ohm or even the 4-ohm load
pattern.
It is not advisable to use a 4-ohm rated speaker on the 8-ohm or 16-ohm load
pattern.
It is not advisable to use a 8-ohm rated speaker on the 16-ohm load pattern.
