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There is an alternate way to drive this network, which is also shown in Fig. 2. The positive
input is actively driven by the source circuitry of whatever preamp you might choose to use.
The negative input is passively terminated at the source to ground through whatever
impedance matches the output impedance of the active source. In the case of Fig. 2 the
source has an output impedance of 100 ohms, so a 100 ohm resistor is used. This gives full
value to the noise rejection capability of the balanced input, and avoids having to drive a low
impedance negative input. This circuit is well suited to adapting unbalanced sources to the
balanced input, as it will retain the desired rejection figures when the negative input is
terminated at the source.
The maximum short term output current is about 50 amps, which corresponds to about 2500
watts peak into 1 ohm. The AC line fuse will blow after a short duration of 50 amps. Over the
longer term, the thermal protection will possibly activate on heavy non-musical continuous .
These conditions are very unlikely when the amplifier is used for amplifying music.
Please feel free to contact the factory for information or advice when considering difficult
loads or unusual circumstances.
Load impedances do not make much difference to the character of the amplifier. The amplifier
is indifferent to the reactance of the load. As a single ended Class A device, the worst
dissipation case is idle, and current flowing into a reactive load does not particularly alter the
dissipation. Current flowing into a resistive portion of a load will generally make the amplifier
run cooler. A reactive load will not increase the distortion of the amplifier, in fact it typically
will reduce the distortion slightly.
The amplifier is powered by a toroidal transformer which charges .1 Farad capacitance to 500
Joules. This unregulated supply feeds the output transistors with a full power ripple of about
.5 volt.
The chassis of the Aleph 1 is made entirely of machined aluminum; no sheet metal is
employed. We mill the chassis components ourselves from aluminum stock on four computer
controlled vertical milling machines. We also do the chassis engraving on the milling
machines, which we built ourselves. The pieces are grained and anodized at the finest plating
house on the West Coast.
The Aleph 1 is warranted by Pass Laboratories to meet performance specifications for 3 years
from date of manufacture. During that time, Pass Laboratories will provide free labor and
parts at the manufacturing site. The warranty does not include damage due to misuse, abuse,
or modification to the amplifier and also does not include consequential damage.
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