The High Cliff Soundboard 2 was an acoustic amplifier that had a piezo driven spruce soundboard instead of a speaker. It was designed by Bruce Petros. Available as both a combo amplifier and  extension cabinet, the specifications were:

• Frequency Response:  20Hz-20KHz ±0dB -1dB
• Output Power Rating: 85 watts continuous into 8 ohms, 132 watts continuous into 4 ohms (with extension cabinet)
• Total Harmonic Distortion:  Less than .05% @ 85 watts
• Inputs: 2 Input channels with separate gain controls; 1/4" phone jacks
• Input Sensitivity-20mV; Input Impedance-1 Meg ohm; Max Input Signal-6 V RMS 
• Equalization (Timbre Control): Bass Shelving Control @ 100Hz; Treble Shelving Control @ 5KHz. 5-Band EQ: +/- 14dB @ 200Hz, 400Hz, 800 Hz, 1.6 KHz, 3.2 KHz
• Feedback Elimination:  Freq: Variable from 80 Hz to 3 KHz. Cut: Variable from -0 to -30 dB
• Reverb/Effects: 1/4" Effects Send and Return Jacks (Rear Panel); Effects Return Level (Post EQ)
• Outputs: 1 Speaker Output; 1 Extension Speaker Output
• Soundboard: Solid Sitka Spruce or Solid Cedar with Sitka Spruce X-Bracing
• Soundboard Driver: Proprietary 200 watt Full-range Electromagnetic Driver
• Cabinet and Hardware: 3/4" Plywood covered in British Cocoa Vinyl with Chrome Steel Corners or Solid 3/4" Dovetailed Hardwood Cabinet in Oak, Cherry or Walnut. Custom Leather Handle; 19" Heavy Gauge Steel Rack-mount Amp Chassis
• Cover:Optional Fleece-lined, Cordura Cover with Protective Hardboard Panel, Zippered Storage Pocket and Embroidered Soundboard Logo
• Size and Weight: 85 Watt Combo Amp: 21" x 20 1/2" x 9"; 45 lbs, Extension Cabinet: 21" x 16" x 9"; 34 lbs
• Protection: If more than ±5V of DC is detected at the speaker terminals, the amplifier will switch off and remain in protection mode. To reset, turn the power off for a few seconds and turn on.