Peavey 5150

The Peavey 5150 is an all-tube guitar amplifier made by Peavey Electronics from 1992 on, initially as a signature model for Eddie Van Halen. Since Van Halen and Peavey parted ways in 2004, the name of the model was changed to Peavey 6505, with Van Halen taking the 5150 name for his company, EVH, to name his 5150 III amplifier. The 6505 was named in celebration of Peavey's 40th anniversary (1965–2005).

Several aspects of the amplifier, likely responsible for its success, are its rigid construction and reliability, excellent frequency response (largely attributable to the vacuum tube amplification), and clarity with heavy gain, a feature generally synonymous with the amplifier's image in its market demographic.

While the product was designed around a centered printed circuit board (PCB), an aspect sometimes considered "impure" among audiophiles, its cascading five preamps (actually four preamplifiers and one phase inverter) and four tube amplifiers were implemented in a very simple manner. This design and implementation allowed the individual components to carry themselves (such as by placing the transformer so as to ensure acoustical integrity by minimizing transconductance), in addition to commonizing the system's ground by way of a multilayer PCB, thereby avoiding a large source of unwanted nuances in most poorly grounded musical applications.

The Peavey 5150 I shipped with four Ruby Tube 6L6 Power Tubes, and five 12AX7 Tubes in the preamplifier staging (with one as a phase inverter.) Despite its shared "plain" PCB, each component was generally high quality, allowing manufacturing ease while providing high quality tone at an affordable price.

A defining attribute largely responsible for the 5150 sound is the fixed bias. Commonly described analog a car engine and its respective idle, the 5150 bias was set to a lower value (lower engine "idle") which resulted in the Power Tubes running at a lower energy commonly known as "cold-biased." While the electrical theory behind this can easily be examined and theoreticized, the 5150 and its configuration resulted in a more controllable gain setting (ie. having a more forgiving sonic range than similarly "hot-biased" configurations. This engineering choice set the 5150 up to intrinsically sound its best with minimal augmentation. Since tube-amps are still uncontested in music amplification as far as tonal quality is concerned, (see hard-clipping) the optimal setting for tubes are when they are pushed to natural distortion (ie. Increases in "volume" or Bells(dB).) Thus, by allowing such a heavy amount of gain to be applied without sacrificing tonal definition, the amplifier could then be pushed due to the "colder" biasing requiring more current, versus a "hotter" setting from the beginning (volume knob or potentiometer knob "value of 1.")

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