Boulder 250 Power Amplifier
Documentation on the Boulder 250 is thin. Period sources do give a few concrete details about this early power amplifier.
The 250 appears to have been a serious, professional-oriented design, built to drive difficult loads reliably.
The amplifier was built around a 1,200 watt toroidal power transformer with four filter capacitors. Sound-and-Communication (June 1986, p.47) reported that the 250 handled reactive loads without issue - specifically a 1.5 ohm load at 60 degrees impedance - and held a closed-loop bandwidth of 200 kHz, an unusual specification for the era. Output connections were gold-plated five-way binding posts.
Boulder's "rentclamp" protection circuit let the amplifier keep operating even under extreme overload. Mix Magazine (November 1988, p.214) described the chassis as black anodized aluminum with stainless steel hardware, in a 19-inch rack-mount or free-standing configuration. The amplifier appears to have been offered in a "250AE" variant, advertised in Audio (January 1989, p.7) as a component for serious music systems.
Exact power ratings, production years, and original pricing remain undocumented in known sources.
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