Monarchy Audio: High-End at Low Cost

Pair of Mono Block Tube Amps

  • 100 Watt tube amp using KT-90 tubes
  • 75 Watt using 6550 output tubes
  • Williamson circuit with factory circuit diagramoriginally built in San Jose for Allen Organs
  • Upgraded by Monarchy Audio with high quality capacitors and wiring
  • Dual Input stage bypassed for simpler signal path
  • Very easy bias adjustment with externally mounted terminals
  • Choice of output tubes:
    • With 6550 output tubes: 75 Watt, $1,100 per mono block
    • With EH KT-90 output tubes: 100 Watt , $1,200 per mono block.
  • Shipping weight each amp: 50 lbs
  • Audition available in South San Francisco

Due to the overkill design and choice of over-sized AC and Output transformers,output up to 120 Watt is possible with the higher power KT-150 tubes, aftereasy bias adjustments. The amps are offered with a more conservative output.

Although not part of the current offer, the buyer might be interested to know that these mono blocks can be very easily upgraded to higher power by replacing the KT-90 with the newest Tung Sol KT-150 tubes. The bias can be easily re-set to bring the optimal operating values for these tubes.A single pair of these tubes, driven by the cathode outputs of the driver tube(6SN7),could yield a more coherent and linear sound output than a bunch of 6550 bundled together to achieve higher power. (See image below.)


Pair of Mono Block Tube Amp

Mono Block Amp
Williamson Mono Block


KT-90 Tube Option




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Monarchy Audio
380 Swift Ave., #21 South
San Francisco, CA 94080, USA
Call: 650.873.3055
Fax: 650. 588.0335

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