Owner`s manual
Owner's Manual 444
The diagram below shows some simple measurements (in that particular case taken with our Amp
TWO, a 110 Hz, 150mV sine wave, which is similar to the 'A' strings first harmonic of a Humbucker
guitar). The amp impedance switch has been set to either 4 (blue color), 8 (orange) and 16 (yellow)
Ohm and in every of these settings a reactive load of 2, 4, 8 and 16 Ohm has been attached to the
power amp. Let's point out only the two essential characters.
1. When the amp impedance switch and cabinet load are matched, the wattage is nearly identical
in either 4, 8 or 16 Ohm case;
2. The higher the load the higher the wattage, or equivalent the lower the load, the lower the
wattage.
Is it as simple as that? Yes and No.
No, as mentioned above this is not as linear as it looks at first glance as it is dependend from several
parameters.
Yes, because - and this is the main fact for all the 444 users – it will never be the other way round. The
Power will not increase when the load impedance is lower than the chosen amp output impedance
(surely as long as we are talking about valve driven amplifiers). And not only the wattage will not
increase, also the voltage - primary and secondary – decreases with a lower load.
For those who are interested, the current increases. On the primary side it does not exceed the
maximum current flowing when the amp impedance switch and load are set to its minimum position
(most often 4Ohm). The current flowing on the secondary side increases slightly about 10-15%.
The 444 is capable of switching 1 or 2 cabinets to any of the connected amplifiers. That means, the
load to the amplifiers output will change when the second cabinet is assigned to it. Let's assume your
amplifiers impedance switch is set to 16 Ohm, you run a single 16 Ohm cabinet with your amplifier and
you add a second 16 Ohm cabinet, then the total load will change to 8 Ohm.
Now refer to the diagram and you see the power of the amplifier drops.
17
0 2 4 6 8 10 12 14 16 18
0
5
10
15
20
25
Wattage dependent from load
Amp Imp switch 4 Ohm
Amp Imp switch 8 Ohm
Amp Imp switch 16 Ohm
Cabinet
R Load / Ohm
Power / Watt