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PS Audio finalise BHK Signature 250 amplifier for CES 2015

  • CES_2015The new power amplifier from PS Audio has been in the oven for some time now. Head honcho Paul McGowan explains how it has seen yet further tweaking since its outing at last October’s RMAF. “Finally!” exclaims McGowan, “the BHK Signature 250 is 100% ready to go”.

    BHK? Those are the initials of circuit designer Bascom King, he of Constellation Audio, Conrad Johnson and Infinity fame. An engineer for hire, King has been designing amplifiers for fifty years but not wanting to wear his experience on the his sleeve, King’s name appears in full only on the PS Audio amplifier’s back panel. In Las Vegas, McGowan could be heard regularly referring to the BHK Signature 250 as “Bascom King’s Magnum Opus”.

    250? This amplifier drives 250wpc into 8 Ohms and 400wpc into 4 Ohms.

    Signature? Ya got me there. However, McGowan seems as pleased as punch that his new baby runs flat all the way out to 200kHz!

    Paul McGowan, founder and CEO of PS Audio

    And the BHK box is a BEAST. Shipping to some territories might not come cheap. The larger of the two transformers runs the MOSFETs, twenty per channel, in a fully balanced configuration. Underneath the centred PCB sits the second, slightly smaller toroidal which juices the input stage above. It’s a no-feedback design isolated by REL caps.

    McGowan confesses to previously being leery of valve action because “they wear out and are incredibly microphonic”. It would appear Arnie Nudell – whom McGowan refers to as “The God of Tubes” – managed to bring him around, ultimately voicing the input stage with a pair of Genalex Gold Lion 6922. Rolling in your own is simple enough – unscrew the removable plate on the back panel for full access. McGowan reports the BHK Signature 250 to be incredibly sensitive to tube changes.

    There’s no SMD (surface mount) here either – it’s all through-hole. A subcontractor in Kansas City handles the boards. I asked how long each amplifier takes to assemble. “10 hours” was the speedy reply.

    The stereo version on display in PS Audio’s suite in the Mirage comes with a retail price of US$7500. The first fifty units will ship in April with full production ramping up in June.


    Monoblock versions will also be available. Each will feature the same number of MOSFETs as the stereo version as well as a slightly different input board (with a single tube). Doubling-up like this threatens 300wpc and 500wpc into 8 and 4 Ohms respectively, twice the current delivery and half the output impedance. US$15000/pair.

    McGowan says that selling amplifiers is a tougher game than selling DACs but he’s quietly confident that Bascom King’s unit will kick goals. It’d better – his wizardry has been retained for PS Audio’s forthcoming pre-amplifier project.

    Further information: PS Audio

    CES 2015 coverage brought to you by…


    John Darko

    Written by John Darko

    John currently lives in Berlin where creates videos and podcasts and pens written pieces for Darko.Audio. He has also contributed to 6moons, TONEAudio, AudioStream and Stereophile.

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    1. Ohhhhhhh valves.
      I’m a fan having been seduced firstly by the old school technology, looks and sheer pride of ownership of valve amplifiers and secondly but more importantly the ‘valve sound’. Is it pure Hi FI i.e low distortion and masses of power to produce huge pressure waves of sound? on paper no but my goodness it sounds wonderfully musical to my ears.

    2. A pair of 6922s in the input stage wont wear out any time soon. Plus they’re easy to change, so having them shouldn’t put off many people. I wonder what the price is Downunder?

      • Not sure – that’s a question for the local distributor when the time comes to ship I guess. A lot will depend on the AU$-US$ ex-rate and shipping cost$.

    3. Hi Paul,

      I can’t resist pointing out that the BHK amp is not particularly revolutionary as Harvey Rosenberg, and George Kaye, of NYAL approached this idea with the Moscode series of power-amps. back in the 80s.., tubes on the front end, Mosfets on the output stage. Since Harvey passed away, George has continued to building a much improved version, in the 400 series. So where’s the difference? I have a couple of 300s myself modified by Stephen Sank of Tucson and a ribbon mic expert. He happens to love “Moscodes”, and it shows. These amps sound wonderful.

      • Hey Ben. Not sure if Paul McGowan reads these comments so probably best contact him directly. I do recall McGowan saying (on more than one occasion) that the tubes input stage was never intended as such from the outset and that tubes were only introduced after many other devices were tried and discounted.

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