What a great and interesting person Bascom H. King is. I thoroughly enjoyed the day of interviews at the BHK Lab in Santa Barbara and hope you too will take the time to get to know this legendary designer.
BHK shares the story of the BHK Signature creation, its naming, the differences between MOSFET, bipolar and tubes, same sex output configurations and different amp designs he's worked on.
BHK discusses why amplifiers sound different, damping factor, the use of vacuum tubes in the front end and why the BHK Signature 250 and 300 amplifiers have such extraordinary ability to pass details most amplifiers don't.
BHK discusses preamps, the upcoming BHK Signature preamp, cables, through hole parts vs. surface mount, the types of music he uses to evaluate equipment, how the process works.
BHK talks of measurements and listening. Why some amp designs measure well yet do not deliver music's emotions. We share in some great personal stories of Harry Pearson (HP the founder of TAS), breaking down doors and in the end, Bascom plays us the guitar.
These are great Paul. I’m really enjoying them. A couple nits. Clips 2 & 3 seem to be reversed. On clip 4 (as far as I’ve gotten), Bascom starts out talking about the new preamp. That’s something a lot of folks will be interested in. I suggest you add that to the description.
And now I know Bascom is a Dead Head! I knew I liked that man for some reason.
Paul, you have my explicit authorization now to work with Bascom on that “small refrigerator-sized” fully tubed amplifier with the same design characteristics that he mentions
Lord help us! We just spent a ton on conveyor belts and lift systems so our warehouse guys won’t kill themselves on P10s and Signature amplifiers, but they will not help with refrigerators.
patentpending said
Paul, you have my explicit authorization now to work with Bascom on that "small refrigerator-sized" fully tubed amplifier with the same design characteristics that he mentions
Paul McGowan said
Lord help us! We just spent a ton on conveyor belts and lift systems so our warehouse guys won't kill themselves on P10s and Signature amplifiers, but they will not help with refrigerators.
lol I'm going to send Arnie to talk you into it. Looks like Elk's on board too
These series of videos are such a great way to learn about the history and future of this hobby. Very informative for the technical laymen, even without an electronics background, and without fully understanding everything I was able to get the gist of the design considerations.
Thanks for clarifications on slew rate & value of pre-amp.
Now appreciate that Damping Factor more important to Bascom than slew rate. I wonder if these two things (slew rate & damping factor) are usually highly correlated. Whenever I’ve preferred one nice sounding amp over another, the one I liked more had a higher slew rate. But from the examples I’ve gone back and double checked, it also had a higher Damping Factor.
Also supports why the Dutch Karan amps sound soooo good (slew rate not disclosed but Damping on the big ones (at speaker terminals) of 10000 whereas JC-1 is “> 1200” (presume also at speaker terminals). Both high enough even after adjusting for Speaker & further in-line loads.
Done some more reading, it would nice if the manufacturer’s just pointed us to Output Impedance. Seems like BHK will be one lowest output impedance amps with tube front-end. Bascom also mentioned a Soniq (spelling?).
Perhaps the small refrigerator amp currently being commissioned by Bascom & Elk (& Paul ??) should be renamed the large oven sized amp ? As a novice, I can only imagine the amount of tweaking that would go on with that amp, described as having all those tubes !!
Also wondering if the musical essence alluded to might be something not necessarily captured in a Distortion measure.
Its not hard to imagine a white noise process like Brownian Motion having a fairly small distortion level distributed around the input signal.
but an amp also with low distortion but “smoother” (less jagged) plot of output vs frequency might be nicer to the ear.
then some measure of a calculus like rate of change ‘smoothness’ might be more important, within an acceptable level of distortion.
EDIT : didn’t Arnie say he’d done (nearly) String Theory level Math - there’d be enough stochastic calculus in there … ?
also consistent with the idea that parts per billion distortion (halcro) sounds good, since the distortion is so low it ceases to matter how that level of absolute performance is achieved.
and possibly why Class D is less loved with its likely scatter gun of error terms around the input signal, even if the separation in time becomes vanishingly small (switching 500,000 times a second).
perhaps it is these “discontinuities” the ear can pick up.
reportedly CTC (Curl Thompson Crump) had one of trio able to improve their amps by ear, by listening to existing design, & picking the appropriate replacement component to improve the sound.
Just idle speculation. Usually the things that are “magic” day become science in later times (sometimes decades / centuries later).
Also, main BHK webpage has two links to BHK interview video #2 (#3 has correct thumbnail picture, but also brings up the #2 video, at least on the webpage shown to an iPhone 6+).
Thanks for watching. It was an honor to be able to travel to Santa Barbara and spend the day with Bascom. He’s just so damn knowledgable and I think a treasure within our industry.
We’ve just auditioned the first draft of his new preamp. Holy crap! We did find that the 6229 Gold Lion tubes we use in the front end of the BHK amplifier aren’t going to cut it in the preamp, which is strange - because we thought they would - assumed they would - but that’s the beauty of listening, eh? Now Arnie and Bascom are on a hunt for new tubes that are not NOS. But, with what’s in there now, holy s**t, this is going to be a monster. Never heard anything like it, not even my tricked out Calypso.
Sounds promising. Care to reveal which NOS 6922’s (or whatever) you were listening to? Have you tried those tubes in the BHK amps? I’ve been holding off on tube rolling but sooner or later it will probably happen.
I'm going to send Arnie to talk you into it. Looks like Elk's on board too 
