Butler Audio MONAD A100 User Manual

BK Butler’s  MONAD A100 is a 300B Class A vacuum tube-driven 

monoblock power amplifier. Both RCA and true BALANCED 
precious metal plated input jacks of the highest quality are 

provided.  The RCA input jack and the 5-way speaker output binding 

posts are top of the line Cardas.   The 300B vacuum tube is 

proprietary Butler design and manufactured per our specifications. 

Sprague polypropylene capacitors, Vishay-Dale mil-spec 1% 

resistors are employed throughout the entire audio chain.  Internal 
circuitry interconnections are positive military-type screw 

connectors utilizing #10 hardware. 

 

 

Power Output: 
The MONAD A100 is powered by a 700W toroid power 

transformer, which easily provides the necessary reserve power 

necessary for continuous operation. An exceptionally large heat 

exchange area on the internal heatsink is coupled into the large bulk 

and mass of the CNC custom chassis for remarkably cool 

operation.  The MONAD A100 has reserve power 

capable

 of 

producing 200 Watts into 4 ohm loads.  Therefore an appropriate 

source of   120VAC nominal input line voltage with a minimum 

current supply of 5A is required.  230-240 VAC models require 

approx. 50% of the current rating of 120V models. 

 

Listed below are the various types of internal protection provided 

for unexpected conditions: 

 

1. AC input fuse for protection against any major system power 

fault.  Do not replace with a fuse of higher current rating. 

 
2. Thermistor-protected against AC input line transient voltage 

spikes and surges.  

 

3. Soft-start vacuum tube filament warm-up:  Provides safe, fully 

regulated, gentle turn-on 5.0 VDC for the 300B tube heater 

filament. This technique promotes longest tube life. 

 

4. Turn-on and warm-up transient delay:  This circuit will not allow 

the speaker relay to close (connect power module output to 

speaker posts) for a delay of approximately  5 - 8 sec. after 

turn-on.  This provides for safe vacuum tube warm-up and 
output stabilization.  

 

5. DC Offset Voltage at Speaker Output:  Continuous monitoring 

circuit immediately opens the speaker relay upon the 

detection of any excessive DC voltage level. 

 

6. Short circuit protection:  This continuously active circuit 

becomes effective to the speaker output below a load of 

approx. 2 ohms.  It will prevent a catastrophic over-current