The Barney Oliver from Hewlett Packard

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First 'super op-amp' as power amp? The first I encountered was the HK Citation 12, but it was largely cribbed from an RCA ap-note of the period, so obviously not new. I don't recall what the JBL amp with Locanthi's "T" output stage looked like on the front end. Don't remember the exact chronology of Dan Meyer and SWTPC, but I think it was a couple years later. Didn't the Marantz tube amps use a "long tail pair" for input and phase splitter. That would almost qualify, though not DC coupled due to the output transformer.
 
The input circuit was pretty good, being differential. Still, it had a single ended driver that ruined the symmetry.
Dan Meyer's complementary differential input stage came out years later, maybe 5 years.
Earlier Meyer amps were more conventional.
 
We just dug out a Barney Oliver from the back room at work! I managed to get it half running. there was a shorted cap in the power supply and i need one MJ4502 to get it back to 100% unfortunately the wood sides and metal top seem to be MIA. but wow what a cool amp!
 
I just acquired two of these and a manual. A little work and they should be up and running. Typical HP build quality of 1972.
 

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I was very lucky in getting this pair of amps. I met the owner stepping out of my plane and he gave me someflying tips. It turns out he was the father of the HP calculator line and we started talking about electronics and he said he wanted me to have them. Just a super guy with a ton of great stories.
 
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