The Marv II

My second Hi-Fi amp

Amp porn (click to enlarge)

 "The Marv II" (left) and "The Marv" (right).  Both are single ended.  Same power supply and output transformers, but rather different otherwise.  The Marv uses 6B4G's (directly heated triodes), fixed/adjustable bias, and a 6SL7 un-bypassed driver.  The Marv II uses 6V6 pentodes and is auto biased with a 6SN7 bypassed driver. I designed/built The Marv II for a friend who lives off the grid. Low power consumption was a must. Drawing about 22 Watts, this thing rocks his supper efficient Klipsch La Scala's.

	The Marv II	The Marv
Power Supply	222v R-core transformer, Hexfred rectified, Cap-Choke-Cap filtered, Low ESR caps	253v R-core transformer, Hexfred rectified, Cap-Choke-Cap filtered, Low ESR caps
Power Supply Ripple	32mV < 0.01%	36mV < 0.01%
Controls	3 position switch Off/Standby/On	3 position switch Off/Standby/On, Bias Adjust
Driver	6SN7 bypassed with Oscon caps	6SL7 unbypassed
Power Tube	6V6 pentode, auto biased, Class A operation	6B4G directly heated triode, fixed bias via separate supply, Class A operation
Output Transformer	James 5kohm	James 5kohm
1kHz THD	3.0% THD, 2nd harmonic: -30dB, 3rd: -41dB	1.4v pk-pk input => 3.5 Watts RMS, 2.5% THD, 2nd harmonic: -32dB, 3rd: -75dB
Damping Factor into 8ohms	2.44	4.54