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Summary of Contents for Pass Laboratories Aleph 1
- Page 1 Pass Laboratories Aleph 1 Owner's Manual...
- Page 2 Introduction The Aleph 1 is a single ended Class A audio power amplifier, the most powerful product produced by Pass Laboratories. It combines completely new design thought applied to a traditional topology and the experience of twenty five years of amplifier design.
- Page 3 Setup The amplifier has three sets of connections and one switch: The first connection and switch is the AC line power system. The amplifier's voltage and current rating are indicated on the bottom. It will be either 240 volts, 120 volts, or 100 volts. 100 and 120 volt units are equipped with a 15 amp 3AG type fuse.
- Page 4 At rated power, the amplifier draws approximately 500 watts from the wall, and most of this energy will appear as heat on the heat sinks. Good ventilation is vital to the proper operation of the amplifier. It has been adjusted for optimal performance at room temperature, but will work well between 50 and 90 degrees Fahrenheit (10 to 33 Celsius).
- Page 5 There has been a failure in the attempt to use specifications to characterize the subtleties of sonic performance. Amplifiers with similar measurements are not equal, and products with higher power, wider bandwidth, and lower distortion do not necessarily sound better. Historically, that amplifier offering the most power, or the lowest IM distortion, or the lowest THD, or the highest slew rate, or the lowest noise, has not become a classic or even been more than a modest success.
- Page 6 should be done very carefully). As an experiment it has the virtue of only changing the bias and the expectations of the experimenter. As the bias is reduced the perception of stage depth and ambiance will generally decrease. This perception of depth is influenced by the raw quantity of bias current. If you continue to increase the bias current far beyond the operating point, it appears that improvements are made with bias currents which are much greater than the signal level.
- Page 7 PRESSURE (bars) VOLUME (M /Kg) FIG 1 CHARACTERISTIC OF AIR Fig. 1 shows the single ended nature of air. We can push on it and raise the pressure an arbitrary amount, but we cannot pull on it. We can only let it relax and fill a space as it will; the pressure will never go below "0".
- Page 8 “Class A” amplifiers on the market, you might say I opened a Pandora’s box. Until the output current reaches the single ended bias point of the Aleph 1, it is considered a single ended Class A amplifier as the bias is provided by a constant current source attached to the negative power supply.
- Page 9 A single ended Class A design would ordinarily clip at currents greater than the bias point, and for this occurrence the Aleph 1 has a proprietary circuit which increases the value of the constant current source so as to operate it in push-pull at power levels beyond the 150 watt...
- Page 10 Mosfets provide the widest bandwidth of solid state power devices, however they were not chosen for this reason. The design of the Aleph 1 does not seek to maximize the amplifier bandwidth as such. The capacitances of the Mosfets provide a natural rolloff in conjunction with the resistive impedances found in the circuit, and the simplicity of the circuit allows for what is largely a single pole rolloff characteristic.
- Page 11 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.
- Page 12 50 degrees C. Warm up time 1 hour minimum Dimensions 16.6 " W x 16.5 " D x 10.5" H Shipping Weight 122 lbs. PASS PASS Pass Laboratories 21555 Limestone Way Foresthill CA 95631 (916) 367 3690 (916) 367 2193...