One of my best friends and ex-colleague at HP just passed away and left behind him the largest collection of HP Test & Measurements instruments and computers in the World with over 750 pieces, most of them in working order! You can read your heart content about his journey at www.hpmemory.org
One of his most recent acquisitions was a very rare so-called Barney Oliver amplifier.
This product has been made in a very limited series of less than 500 units, manufactured by HP employees, following HP manufacturing quality standards (the famous Class B...) after hours and was sold at cost to HP employees and their families. Interestingly enough, a number of them have survived and are still working as well as when they were built more than 40 years ago in 1972. I personally worked for HP from 1978 to 1992 and it has certainly be one of the highlights of my career. Barney Oliver passed away in 1995 and I don't think I ever met him. Even if I have, I never knew he was an audio freak of the highest order, a fan of JBL speakers and the V15 Shure cartridge, components for which this amplifier was optimised. I had a chance to exchange a few emails with Siegfried Linkwitz regarding this amp, but Siegfried was not a fan of JBL, so he didn't bother with the Barney Oliver design...and I couldn't get more info out of him. Fortunately, a few other HP and non HP people have come forward who still have this amplifier. I have approached them for some inside stories and up-to-date measurements and listening notes. I will keep you posted as soon as I hear from them. Ideally, I would really like to be able to make up my own opinion and I am calling out for help to see if anybody would have one to loan me for a few days either here in Australia, or willing to ship one to me (Christmas is around the corner...)
Interestingly enough, Barney Oliver designed his amplifier with quite a limited bandwidth and a high level of negative feedback. One could also reduce the bandwidth further with filters at 5, 8 and 10 KHz, primarily to listen to 78 RPM records or poor FM reception. Even though, here is what somebody has to say of his listening experience:"This amplifier sounds incredible on virtually every level. First and foremost, it is a very sweet sound – a bit on the warm side but not overly lush, and highly detailed but not at all analytical – it is a very musical and involving amplifier with excellent dynamics and literally no listener fatigue. Another aspect of the sonic performance that is amazing is the extremely quiet noise floor, even at full volume. The clarity is also astonishing, with extremely low harmonic distortion that specs out to less than 0.01%, 2 mw to maximum power for all frequencies."
It sounds like this amplifier has some of the qualities of a tube amplifier, but with all the muscle and low noise and distortion of a transistorised design: not a mince feast!
And this is the reason why I am keen to do more measurements on the impulse response/slew rate of this amplifier, as I know from experience with many amplifiers and with my own Bryston 3B this is a key factor in the timbre accuracy, dynamic range and overall enjoyment of long listening sessions...
Born in France, well travelled, relocated to Sydney in 1997.