STATUS - SOLD
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Description :
The VAC System has been developed with the critical ear as the major arbiter of quality, with both conventional and unique measurements providing insight and guidance as necessary. The lack of emphasis on measurements is due to the fact that engineering's arsenal of equipment and techniques do not operate on the pattern recognition principals that control human perception of sound.
Features :
- The maximally balanced push-pull circuitry, with push-pull conversion (phase inversion) occurring in the first stage,
better exploits the inherent advantages of push-pull operation and allows improved performance of the driver stage.
- Modest loop negative feedback (8 dB) ensures better dynamics, gentle clipping, and superior overload recovery.
Simple feedback arrangement avoids unnecessary multiplication of the order of distortion products.
- Completely hand wired in three dimensional space for the shortest possible lead lengths, allowing passive
components to perform much nearer to the theoretical ideal.
- All chassis are machined 1/8 inch thick aluminum, creating an extraordinarily rigid nonmagnetic platform
that is unusually resistant to vibrations that could mar the sound.
- Mechanical vibration from the power supply is completely isolated from the amplification circuitry due to
the multiple chassis design.
- Energy storage is distributed among the chassis to place it nearer to the point of demand and dedicated to
particular uses, ensuring superior isolation of the various stages.
- Output stage is based on the KT77 Beam Power tube or the EL34/6CA7 Power Pentode operated in Class A
at 54 milliamperes idle current per tube.
- Output stage may be operated in partial-triode (ultra-linear) or full triode mode, selected via a single switch.
- Impedance matching taps are provided for 2, 4, and 8 ohms.
Specifications :
Power Output...............................96 watts continuous average power at 1 kHz with less than .35%
................................THD into 8 ohms connected to the 8 ohm tap.
................................120 watts continuous average power at 1 kHz with less than .45%
................................THD into 5.33 ohms connected to the 8 ohm tap.
................................Triode mode reduces power to 60 watts.
Frequency Response....................down 0.5 dB at 6 Hz and 90 kHz, ref 0 dB = 1 watt @ 1 kHz.
.....................down 3.0 dB at 2 Hz and 103 kHz, ref 0 dB = 1 watt @ 1 kHz.
Power Bandwidth..........................down 0.5 dB at 12 Hz and 58 kHz, ref 0 dB = 90 watts @ 1 kHz.
..........................down 3.0 dB at 7 Hz and 72 kHz, ref 0 dB = 90 watts @ 1 kHz.
Slew Rate....................................Approximately 10 volts per microsecond.
Energy Storage............................Approximately 217 Joules per pair.
Negative Feedback.......................Loop feedback is fixed at approximately 8.3 dB regardless of output tap selected.
Absolute Polarity..........................The PA90 does not invert signal polarity.
Input Impedance...........................100k ohms
Sensitivity.....................................0.7 volts RMS input produces 90 watts output
S/N ratio......................................> 94 dB
Tubes...........................................4 x 6CA7, 1 x 12AV7, 1 x 12A7 per side
Dimensions(w x d x h)...................15.5 x 43 x 19.5 cm
Weight.........................................52 kg
Power Supply Unit
Dimensions(w x d x h)...................15.5 x 43 x 19.5 cm
Miscellaneous :
Made in.......................................USA
Condition.....................................9 / 10 (Good condition)
Product information :
http://www.vac-amps.com/Manual_PA90.pdf |