Page 5
Interconnects and Speaker Cables
We have a general recommendation about interconnects, which is that they should cost less
than the amplifier. We have tried a lot of products and most of them work well, but as a
practical matter we cannot make blanket recommendations.
The amplifier is not sensitive to source interconnects. It is also not sensitive to radio frequency
pickup, which allows some flexibility in choosing source interconnects without shields.
We prefer speaker cables that are thick and short. Silver and copper are the preferred metals.
If you find any cable made of gold, please send me a couple hundred feet.
Fortunately the amplifier is not sensitive to the capacitive/inductive character of some of the
specialty speaker cables, so feel free to experiment.
We have found that about 90 per cent of bad sounding cables are really bad connections, and
we recommend that special attention be paid to cleanliness of contact surfaces and tight fit.
Speaker cables should be firmly tightened down at the speaker output terminals, but do not
use a wrench. They will not withstand 100 foot-lbs of torque. Hand tightening without
excessive force is plenty.
Fun Hardware Facts
The X5 has a power transformer, rated at 1000 watts, continuous duty. Under actual
conditions in the amplifier the transformer will deliver about 1800 watts for short duration.
To avoid huge inrush of current during charge up, each of the transformer primary coils has its
own inrush suppressor, which keeps the inrush down to 100 amps or so.
The X5 has 4 computer grade (the old large style computer capacitor cans, not the new dinky
ones) capacitor cans at 31,000 uF and 50 volts each. These are used to create the
unregulated output stage rails at plus and minus 30 volts at 20 amps.
In the X5, additional voltage for the front end is derived from separate windings on the main
transformer. This extra front end supply lowers the distortion and noise of the system, and
allows the front end to swing the output stage rail-to-rail with losses on the order of only a volt
or so, extracting every last possible watt.
The circuit of the amplifier is completely DC, with no capacitors in the signal path. There are
also no slew rate limiting capacitors in the circuit.
All the transistors in the product are power Mosfets, actually Hexfets from International
Rectifier and Harris. These are hyper-matched parts, with gate voltages matched to 0.5% and
all devices taken from the same lot codes (made on the same wafer). The speed and noise
critical gain devices in the front end, (that is to say the actual balanced pair of transistors) are
ultra low noise and distortion matched JFETs having a low (.02 S) transconductance figure.
The JFETs are made on the same substrate for prefect matching.
