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Prototype HP Solid State Stereo Amplifier

R

RayParkhurst

Active Member
I picked this up at the estate sale of a HP executive yesterday. It seems to be similar to the famous Barney Oliver amplifier but I don't think it is one, though it could be an early engineering prototype. It is of course built like a tank, with beautiful HP instrument-grade point to point wiring inside, and classic instrument looks in a rack mount case. I'm hoping someone can shed some light on this as I'd like to properly attribute it. Here are a couple pics:

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I did open top and bottom to see if I could find any clue to a model # etc, but there was nothing, and didn't take pics. Suppose I'll need to open it up again to figure this out.
 
only thing I can tell you is that the case looks like the one from my 8640B. Fair guess they used a chassis that was for some production test gear for this build.

If thats a prototype, someone really did a nice job with the labeling and such.
 
Wow! That has to be the absolute coolest amplifier ever seen on AK.

You have a real collectors item there. What are the date codes on the cap/output transistors? And what is this- handwriting?

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I think you'll find it'll be around 40-50Wpc. Only a single pair per channel and small heatsinks.

Awesome. :)
 
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Agreed, awesome cable routing. Way back in the day we had a tech at Analog Devices who could wire like that... Ozzie if you are reading this, you are not forgotten! :beerchug:

My guess is that said exec commissioned this as a pet project - or maybe personally designed it and had engineering build it for them. The parts cost and assembly time required to turn that into a production item would have been very high indeed.

We had a saying during my time at Bolt, Beranek, and Newman (BBN), when Cisco and Wellfleet were quickly driving us out of the market: "You can buy a faster packet router, but not a more expensive one." :)

Tim
 
restorer-john said:
Wow! That has to be the absolute coolest amplifier ever seen on AK.

You have a real collectors item there. What are the date codes on the cap/output transistors? And what is this- handwriting?

...

I think you'll find it'll be around 40-50Wpc. Only a single pair per channel and small heatsinks.

Awesome. :)
Click to expand...

Looks like the date codes range from 1964-66 on the caps. The output transistors look to be 1967. So this thing significantly pre-dates the Barney Oliver.

The writing where you indicated is "Level Meter" in pencil. The cans just below are labeled "Loudness Comp" so I guess the "Level" switch on the front must adjust the Loudness compensation level.
 
gadget73 said:
if this is a one-off, someone spent serious time designing and building this. The guts are electronic art.
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And it's very period, can caps and mosfets. Solid state but looks designed by someone used to doing tubes.

But good sized pcbs there, do they have any writing or codes?
 
As it seems this amp was probably built in late 1967 based on the output transistor date codes, could this have been an early project by the folks at the newly-created HP Labs? Maybe Barney Oliver had some ideas right at the beginning and built this thing?

Edited to add: I did verify that the owner worked for HP in Palo Alto from 1963-1970. After that he took several foreign service assignments. One of the Revox A77's I got at the sale has shipping documentation for shipping back from Athens where he was on assignment.
 
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