Harvard Electronics H3 - Futterman // Vintage / OTL Stereo Tube Amplifier / Restored and Extremely Rare (A)

The Harvard Electronics H3 is a rare and fascinating piece of vintage hi-fi history—an OTL (Output Transformerless) tube amplifier designed by Julius Futterman himself. That alone puts it in rarified company. Like Futterman’s later and better-known designs, the H3 ditches output transformers in favor of a direct, wide-bandwidth signal path, resulting in a sound that’s startlingly open, immediate, and alive. The presentation is pure Futterman: a holographic midrange, lightning-fast transients, and an unfiltered sense of connection to the music that feels almost electrostatic in character.

Built in an era when audio design was fearless and personal, the H3 isn’t just rare—it’s historically significant. It carries the unmistakable fingerprint of one of hi-fi’s most radical thinkers and offers a glimpse into the early evolution of OTL amplification. For collectors and listeners alike, this is the kind of amplifier that doesn’t just play music—it tells a story.

S/N: N/A

• Installed new 6ej7 tubes
• Adjusted bias
• Cleaned control contacts
• Verified power and distortion at 1kHz :
• Left Channel 21.2 watts RMS into 8 ohms @0.328%THD+N
• Right Channel 22.0 watts RMS into 8 ohms @0.305%THD+N

Installed new 6ej7 tubes
Adjusted bias
Cleaned control contacts
Verified power and distortion at 1kHz :
Left Channel 21.2 watts RMS into 8 ohms @0.328%THD+N
Right Channel 22.0 watts RMS into 8 ohms @0.305%THD+N