300b lovers

Are you at the point where you feel your Class D amps are equivalent to your best tube amps?

@whitestix Yes.  After extended listen sessions as you put it I don't find that our tube amps bring anything to the party that the class D doesn't. I really doubt that we're the only ones that can do this so this has led me to thinking that tube power amps are on borrowed time at this point- that is if sound quality is the only arbiter. People do like the glow of tubes- so do I. But I've found also that I don't miss them in the slightest, despite liking tubes so much as to make a business of them.

There’s nothing quite like twiddling with a speaker crossover or the critical components on an amplifier. That brings the guesswork to an end. You know what increasing the slew rate of an amplifier sounds like ... it’s a pretty distinctive sound, actually. Likewise, if the tweeter crossover is screwed up, you hear tweeter distortion ... lots of it.

Which makes show-going by and large an unpleasant experience (although I love to meet people). I walk by a room, without going in, and I hear problems. Big ones. Multiple problems. And yes, I know how to fix them. But I’m not going to do it for free, and besides, most exhibitors really don’t want to hear unsolicited advice from a notorious busybody like me. So I just keep on walking. There might be one, two, or three rooms where the equipment is working OK, and I’ll spend most of the show there.

This might sound cynical, but seriously, I’ve been designing speakers since 1975. I can’t stand speakers with wonky response, multiple resonances, or gross distortion. And that’s most of the famous-name speakers, so they’re out. And they certainly don’t want to hear my wisecracks at first hand.

I got into tube-amp design around the early Nineties, and joining the staff at Vacuum Tube Valley was a fabulous learning experience, especially from Charlie Kittleson, a great guitar player, and John Atwood, an engineer’s engineer, having worked at Intel, Tandem Computing, and Apple. Sadly, Charlie passed on around 2000, but I’m still good friends with John Atwood. We’re both big fans of the history of technology, and can talks for hours on end about AC distribution systems in Japan and the arcana of NTSC, SECAM, and PAL color television. His current project is restoring a TeleType machine ... because why not? He’s also a ham radio enthusiast who builds vacuum tube rigs from scratch.

At any rate, those of us who do this for a living (although I am technically retired) can spot design errors pretty much immediately. My background is speakers and electronics, which also means I cannot ethically review anything, because all I would do is criticize, which isn’t fair to the manufacturer. Besides, the various designers all disagree with each other ... my designs are completely different from Atma-Sphere, or Audio Research, or Krell, etc. etc. We are all very opinionated.

Lynn,

My local tube tech was good friends with Charlie who lived near Sacramento and he had immense respect for him.  He published a magazine which I am sure you aware of, 100% tube centric.  I never met him but he was a legend in this neck of the woods for his tube knowledge. 

Ralph, it seems curious to me that knowledgable audiophiles would rely on anything but sound to be the arbiter of their purchase decisions.  Tube gear is a hassle and costly, but to my ears, it is the price to pay for such magnificent sound. I think buyers buy tube gear because it sounds better, pure and simple.   

Charlie reached out to me and asked if I would like to be Technical Editor of Vacuum Tube Valley, and I happily agreed. First class bunch of people, including the irrepressible Eric Barbour, one of the most notorious curmudgeons in the industry ... he made me look like a mild-mannered moderate. But all of them were, and are, great people.

Back when I was on the Editorial Board of Positive Feedback (a few years earlier), Eric sent in an article so outrageous that we couldn’t publish it, but it was the funniest thing about the biz I had ever seen. No, it still can’t be published, here or anywhere else. We’d get sued for sure. Eric is one of a kind.

Well, OK, there’s Harvey Rosenberg, but his sense of humor was much more gentle. Meeting him in person at the Consumer Electronics Show in the late Nineties was pretty memorable. He would drop the clown act and get quite serious, but if he saw someone he recognized, he do something outrageous right on the spot, then switch right back. The clown act fooled a lot of people, as it was meant to. He was a very sharp observer and knew what was going on.

Once you get away from the oh-so-serious gatekeepers, there are some remarkable people you meet in the biz. The fun thing about Eric, Harvey, and myself is we were outsiders, and we didn’t have to take it seriously.

Frankly, that was part of my motivation to design the Amity and Karna ... to show, by example, that things could be done differently. At the height of the SET mania in the Nineties, Harvey was the only one who (very strongly) encouraged me to follow my own path. That encouragement, from an old pro like Harvey, made all the difference.

I have had the matching preamp running quite nicely for about 10 days and I will say the combination doesn't sound like anything I have ever heard.  First off, with my 97 dB speakers you literally have to put your ear to the woofer to know the system is on at idle (no hum).  The tube rush (hiss) varies with tubes used, but you pretty much have to have your ear to the HF driver to hear that at idle.  We are talking a Lampi Pacific DAC with DHT output stage feeding a tube preamp, which feeds the 300b amps.  All tubes and at idle it is as quiet as solid state. This gives a totally black background.   Lynn went his own way on the circuits and between the two of us we have turned them into working prototypes that are closing in on production models.   The working prototypes are what will be shown in Seattle.  Again, I hope many folks reading and participating in this lovely thread are able to come and hear them and give an honest opinion.  They do not sound like anything else I have built, or even heard.