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Prototype HP Solid State Stereo Amplifier

OK, more information...

Turns out the owner was not an executive, just an electrical engineer who moved up through the ranks and ultimately became a Regional Manager. He retired from HP in 1999 and passed away in 2020. His name was Richard (Dick) Hornor, and you can read his obituary (self-written) here:


He worked at the HP Dynac Division, which was renamed Dymec Division due to copyright issues, and ultimately to the Palo Alto Division. You can read about the Dynac Division history here:

en.wikipedia.org

HP 2100 - Wikipedia

en.wikipedia.org en.wikipedia.org

Here are some quotes from the wikipedia article:

"HP formed Dynac in 1956 to act as a development shop for projects the main company would not normally undertake."

"Dymec originally made a variety of products for the HP family, but over time became primarily an integrator, building test equipment and similar systems that were used by HP."

So Dick Hornor worked for a division of HP that made one-off equipment like this amplifier, and who had to change its name due to copyright violations and confusion with the new Dynaco company.
 
If HP made audio test equipment, it would make sense to have an audio amp to develop and test it. I only remember an audio signal generator from mid 1970's that was the go to, and maybe still is. I don't remember what other test equipment HP made. Paul.
 
bowtie427ss said:

HP Catalogs - The Hewlett Packard Archive

Catalogs Vintage catalogs are hard to come by! One of the cornerstones of this website is searchable PDF versions of HP catalogs. Early catalogs did not have pricing or regular publication schedules, so our collection of vintage price lists and advertising can help date early instruments. Also...
hparchive.com hparchive.com
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Amazingly I did not know of this resource. Thanks for the link, already useful.

restorer-john said:
All in all, it's a fantastic piece of history and arguably so rare it has no price. Personally, I'd love to see what it can do, performance wise on an analyzer, bone stock after 60 years.

Just an incredible find. So happy for you @RayParkhurst :)
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Thanks, but I'm reluctant to turn it on. Only reason I might is to see how well the Phono preamp works, but that's just a small part of this beast. I only picked it up out of curiosity since it had an hp logo. It turned out to be much more interesting than expected, but alas I don't see myself keeping or using it.

loudnoises said:

Maybe this guy might know more.
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Another useful site I was not aware of, thanks! I emailed Ken to share the info I know and to see if he could fill in any gaps.
 
RayParkhurst said:
Thanks, but I'm reluctant to turn it on. Only reason I might is to see how well the Phono preamp works, but that's just a small part of this beast. I only picked it up out of curiosity since it had an hp logo. It turned out to be much more interesting than expected, but alas I don't see myself keeping or using it.
Click to expand...
You got to do it for all posterity, so break out your variac and DBT to see if she'll act right.
 
RayParkhurst said:
It turned out to be much more interesting than expected, but alas I don't see myself keeping or using it.
Click to expand...

It looks like (from your photos), that there's a ton of trimmers all through the unit. They look to be sealed with lacquer/paint, so that suggests careful level, biases and DC control right through the preamp stages. You only get that on absolute top of the line gear (vintage Accuphase etc) or test instrumentation- which HP is was an expert in.

You simply must power it up with a safe current limiter. (dim bulb will do) It will be be immensely more valuable if you can demonstrate or at least supply performance data on the unit to any prospective new owner.

It's by far the most interesting amplifier we've seen on AK or anywhere else for the last 20 years. Can't believe it just turned up at an estate sale in 2026.

Not speculating on value (against the rules) but I reckon there's a nice weekened escape holiday and a few special dinners for you and your partner at least. It's basically a one-off.
 
eiraved said:
You got to do it for all posterity, so break out your variac and DBT to see if she'll act right.
Click to expand...

restorer-john said:
It looks like (from your photos), that there's a ton of trimmers all through the unit. They look to be sealed with lacquer/paint, so that suggests careful level, biases and DC control right through the preamp stages. You only get that on absolute top of the line gear (vintage Accuphase etc) or test instrumentation- which HP is was an expert in.

You simply must power it up with a safe current limiter. (dim bulb will do) It will be be immensely more valuable if you can demonstrate or at least supply performance data on the unit to any prospective new owner.

It's by far the most interesting amplifier we've seen on AK or anywhere else for the last 20 years. Can't believe it just turned up at an estate sale in 2026.

Not speculating on value (against the rules) but I reckon there's a nice weekened escape holiday and a few special dinners for you and your partner at least. It's basically a one-off.
Click to expand...

OK, OK, I will power it on carefully and report back. May not be today though. I'm working on troubleshooting the two Revox A77's I picked up at the same sale. Blown fuses, but I may have a handle on it from helpful folks on the AK Tape forum.

I just installed yet another component I got at the same estate sale, a Technics SU-9200 Preamp, and am finding it totally synergistic with the SL-10 and AT312HEP. Really amazing sound from that trio.

It really was a great estate sale! Thanks Dick, your stuff is appreciated.
 
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