300b lovers

There was a reviewer from Stereophile who came twice.  I let him play what he wanted, but I certainly did not chase anyone out of the room, so maybe that was someone else in the rear.  I assure you that Stereophile will not be getting the amps for review.  There is no free advertising as the product is not even in production yet.  Sorry you were not treated well, but it wasn't me....

I’m truly sorry you had that experience. The staff in the (fairly small) room rotated between Don, myself, and the four younger people at Spatial. (Don and I were the obvious old farts.) The Spatial people were manning the room (with a nonstop 4-hour playlist+personal requests) and Don and I were there to explain the electronics, tell various origin stories, and provide comic relief.

Reviewers popped in and out, and the famous Amir from ASR even showed up for a minute or two. Crowds came in surges, particularly on Saturday, when it was jam-packed. I was not aware that anyone had emptied the room for a reviewer, that’s certainly not what I saw when I was there. They had to take their chances like anyone else. There might have been special cases after 6PM, with private showings arranged in advance, but after-6 was mostly Social Hour for the exhibitors ... for example, I dragged all of the Spatial staff and Don to hear the Songer/Whammerdyne room, just down the hall from us. I’ve been old friends with Matt Kamna, the designer of the Whammerdyne 2A3 amplifier, so that was my after-hours excuse to get them to open the door ... "hey, here’s all my friends, can we listen for a while?" ... kind of thing.

I don’t know who the Famous Name Reviewer was. I wasn’t aware of anyone dropping by, much less closing the room for them. Our plan is to build a customer base (that’s you, folks) before we let any product get formally reviewed by the magazine or YouTube reviewer. Speaking only for myself, we’d like the Big Guns to give us a little breathing room, while we get the production machine going.

Don and I already have market identities ... we’ve been doing our respective things for thirty-plus years, with our names attached to what we do. We don’t need to build something that’s already there. So I’m not in a hurry ... at all ... to get in a review queue. People have heard about the Karna since 2003, well, here it is, in a room that’s about half the size of my living room, so please make allowances.

Wow... It's really unfortunate that you had that experience and was certainly not how I was treated and I'm just a nobody.  I stopped by 3 times across the day on Friday and while the room was quite full each time.  However, I did introduce myself to Don and had a quite nice conversation.  Shill, not really sure what that really means but I get the implication and at least for me incorrect. 

I stopped by, and it was the only room I was made to feel totally unwelcome. Someone on the way in basically told me to get out there's a reviewer. Inside there was one guy sitting down being lectured about how great blah blah blah. I was totally ignored. Asked if we could hear some music? Got a glare and a terse "in a minute" then back to being ignored. Another guy I trust managed somehow to hear it, said it was okay. Only room all weekend actually refused to play music and treat attendees rudely. 

You want my unbiased view on this thread? Never seen one so dedicated to shilling allowed to go on and on. Free advertising. Must be nice.

Yes, it was fun!  As Lynn said, there were 3 or 4 outstanding rooms and we had one of them.   It was a scramble taming the room and the internet connection on setup day, well into the late evening.  But we got it!   I would say the system was very much on song except for image height and width and that was totally limited by the small room.  But depth was very good and tonality was unaffected.   Hope a few more folks that stopped by will give others an unbiased opinion on this thread as they get home.

What. A. Show!

Just got home ten minutes ago from Seattle. The most intense thing I've done since I went to the European Triode Festival in 2004. At least I didn't have to fly to Zurich this time ... only a 2.5 hour flight to SeaTac, and quick trip in the hotel bus. But man, the SIZE of the concourses in Denver ... combined with THREE gate changes.

Lots of fun meeting people at the show, and there were three or four really outstanding rooms, including [blush] our own. The Spatial team are great people and thoroughly professional, and several pre-orders are coming in. I have a feeling several vendors will be using a flight of Ravens and Blackbirds in their rooms next year.

@lynn_olson

Tube amps, by contrast ... the tech never becomes obsolete. For that matter, all of the tubes used in the Blackbird, and the basic circuit, were first designed in the 1930’s! Talk about not going obsolete

I sincerely believe that this is true. No question that class D has come a long way sonically and will continue to do so. I acknowledge that many listeners are ecstatic about their GAN latest generation iterations. Yet, there is something Intrinsically musically right and natural with properly implemented tubes.

I believe that there are certain listeners who hear and recognize this unique and innate sound character and presentation. It would be illuminating to directly compare the Blackbird 300b amplifier with the state of the art highly praised class D amplifier offerings.

Charles

The sonic differences between the old Akido circuit and the Raven are fairly dramatic. The Akido circuit sounds like one of the best darn traditional tube preamps I had ever heard, and that is why I built it for years and kept trying to squeeze another few percent out of it with every improvement. The Raven is part of the 300b project. Both the amps and the Raven will happily play with the rest of the world, either single ended RCA or XLR, but together they can form a complete balanced chain with a balanced source. The Raven can drive the input tube grids of the Blackbird amps directly via XLR because it has an output transformer. I would not do that with a solid state preamp or DAC output stage, only something with an output transformer or coupling cap to protect the amps from DC input. A solid state device would be fine for possibly many years until one instant that it isn’t, and then DC can come flooding into the amp. That would not destroy the Blackbird, but the input tube would be really unhappy, and some nasty noises could arise from the speakers. The Raven simply cannot do that because it is transformer coupled. The RCA input on the Blackbird amps is transformer coupled, so that is always safe, but the XLR inputs can bypass that input transformer. So the Raven is made to mate with the Blackbird.

The sound of the Raven vs. the older Model 2...? Well, as much as I like that circuit and build, it sounds slightly slow and veiled compared to the Raven. The Model 2 is a great preamp and I have maybe 150+ of them out in the world in one form or another, but the Raven is a step up. There is just more resolution of fine detail, with what sounds like effortless and unlimited drive. It is not bright in any way at all, but it is highly detailed. The whole 300b system is like the iron fist in the velvet glove to my ear. It has all the subtle detail and shadings of a flea watt SET amp, but serious grunt and drive at the bottom and extension to 34KHz at the top end and a very subtle roll off after that. I suspect the final version of the amps may make it out to 50 KHz before the roll off begins. So HF is extended and airy, but again, never bright sounding. The Raven is definitely part of that experience because I built the amps first and used them with RCA inputs and my old preamp, and then I built the Raven. Like the amps, once I heard the Raven there was no going back. So then Lynn and I experimented with several power supply variations before deciding on the final topology. They all sounded quite good, but the final choice was clearly the best to my ear. At any rate, the Raven is a big part of the sound people heard at the show. My old preamp was good, but not in the same league. My 2 cents.....

The Raven was the surprise for me. You see, I’ve been listening to the Karna amps for 20 years, now reborn as the Blackbird. Yes, there are differences, but what’s at the show is very very close to what I know so well at home ... maybe a teensy bit better, with a couple more improvements Don and I are hiding up our sleeve. But the show amps are 95% to 98% of what the shipping amps will be (yes, the production Blackbirds will be even better, Don and I promise that).

But I’ve never heard a Raven before. Hoo boy, is it good. Wow. I didn’t expect that. I knew what it does, of course, because I designed it more than twenty years ago, and Don refined it and took it a few steps further. But I never actually heard it, just other people’s impressions of it. I was quite surprised when I hear it for myself, in what is a very good room.

I’m not all that good at writing puff pieces, but the initial impression is speed and power, followed by vividness, and depth of tone, an impression that grows over the course of a few minutes, and after listening to a few different selections. We keep telling visitors, no, there is no 200-watt subwoofer (or two) tucked away in a corner, and yes, the new Spatial speakers are entirely powered by ONE Blackbird per channel, with passive crossovers (sample on display at the entrance to the room), and no electronic EQ, no active crossovers, no multi-amping, and no DSP. What you see is what you get.

As for source, Don and I are joking around about our favorite DACs. He’s all-in on the LampizatOr family, while I was dazzled by the Bruno Putzey-designed Mola Mola in a nearby room. I was expecting to be bowled over by the Holo May, but nah, it’s not for me. But there’s no way I’m going to cough up the $13,500 the Mola Mola costs, especially considering how fast DACs become obsolete ... five years or less.

Tube amps, by contrast ... the tech never becomes obsolete. For that matter, all of the tubes used in the Blackbird, and the basic circuit, were first designed in the 1930’s! Talk about not going obsolete.

The older preamp is a nice, but conventional single ended tube SRPP circuit with Akido buffer (extra tube per channel).  It uses dual regulated power supplies and dual regulated filament supplies and really good signal path parts, and the wonderful Khozmo attenuator.  The Raven is a completely different approach and  circuit.  It is fully balanced and transformer coupled at both input and output with custom wound transformers from Dave Geren at Cinemag.  It will take either xlr input or rca input, and will happily provide xlr or rca, or even headphone output, and will drive even a 10K power amp impedance.   The Khozmo setup is dual mono because you have to control both halves of the xlr on each channel.  The power supply uses two damper diodes, very high quality transformer and is a true C_- L - C (cap, choke, then cap) that feeds a much higher quality regulator that is used in the previous preamp and also feeds a pair of gas regulator tubes after that.  It is dead quiet, fully balanced, and has very little sonic signature, but provides great drive for the power amp.  I really like it, and those who have been to the show have heard it driving the 300b mono amps.

Don -- can you provide a detailed explanation (without giving away the secret sauce, of course) of the technical and sonic differences between your DS2 preamp and the Raven? Thanks.  

Thanks for the positive feedback from all so far.  The room was a bit of a struggle to get things to sound good, but after a whole afternoon and evening of getting furniture moved out and putting acoustic treatment up we pretty much tamed it.  We have very good image depth, and of course the ceilings and walls limit height and width, but it is a nice sound.   Like every other team here, we work with what we have!  Hope see a few more of you today!

I attended the show yesterday (Friday) and spent significant time in the Spatial room listening and chatting with Don.  I have been a repetitive customer of Don's over the years and was excited to hear the latest.  Wow both the amps and pre did not disappoint!  I'm calling Spatial on Monday to get on the list.  .

My 4+ hour drive to the hotel ended up being a grueling six-hour battle, but I did finally arrive unscathed. After checking in and transferring our luggage to our room, I kissed my wife farewell and went straight to the Spatial/Don Sachs room.

The amps and preamp are beautiful - and have that distinctive D Sachs look IMHO. [I listened to just four songs before getting into a conversation with Don, markusthenaimnut , and his good friend Bob.] How do I describe the music? The first song was a Jennifer Warnes song <not a top 40 song>, and I didn’t analyze it...I mean I so enjoyed the music and her voice without once thinking about the highs, lows, mids, etc. I just sat and enjoyed the moment. How often can you sit down in front of unfamiliar gear; listen to a song, and just enjoy it without analyzing it? And, yes, the songs that followed were excellent.

Once I’ve had a good night’s sleep, and <hopefully> forget about the 6-vehicle smash up on I-5 near Nisqually, I’ll return to this room first thing tomorrow morning and pester Don or whomever is in charge of the music to play my favorite songs, and listen for an hour or more.

@jaytor 

Thanks for your listening impression feedback. Very encouraging to say the least. I hope that others chime in.

Charles

I visited the Spatial Audio/Don Sachs room this morning and again this afternoon.  This was the first room I visited today and I don't think I heard any rooms I liked better today, including some with systems that cost MANY times more. The friends I am with felt the same way, and we often don't agree on what sounds the best. 

Congrats Lynn and Don for building a killer amp and preamp. Very impressive. 

@larryi 

The 300b is not the only contender in the low-power weight class.

True and I don’t believe that anyone on this thread is disputing this. However, Don and Lynn have stated the very compelling reasons why their amplifier was built utilizing the 300b tube. Excellent decision and execution it certainly seems. I’m excited to hear from those who’ll listen to it at the audio show very soon.

Charles

I too am a fan of the 45 tube type.  I also like the 2a3.  But, it is not only triode tubes that I like.  I am a big fan of the 349 pentode; I wish this were not so rare a tube.  Other pentodes I like include the 350B, and thankfully not as rare 6L6.  The 300b is not the only contender in the low-power weight class.

Yes, folks that try the 46 (a direct-heated pentode that is often connected in triode) really seem to like it. By general consent, it sounds very much like a 45.

How different does a triode-connected 6V6 sound from a 45? Good question. The 6V6 was designed as a replacement for the 45 back in the mid-Thirties, and has very similar operating points (by design).

Current production Chinese 45 tubes are about $350 per pair plus shipping.  I may try a quad in my Lampi Pacific DAC.  I quite like the 46 tube there with adapters.   The current production European 45 tubes are twice that price.  That said, if run at sane operating points they may well last 30,000+ hours.  So if you like them, they are really not that expensive in the long-term.

45’s are wonderful tubes. By measurement with a spectrum analyzer, possibly the best tube of all time, with a beautifully clean harmonic structure. Which is why the Mark I Karna’s used them as drivers.

But ... NOS examples are now very rare, so it’s down to a few vendors as a specialty item. I am hoping they become more broadly accepted, though. They really are something special, and are much easier to drive than a 300B or 2A3.

@lewinskih01 

BTW, I'm running 45-type SET on my tweeters above 1 2kHz and absolutely love them. I realize 300b gets more love, though :-) 

Lovely thread. I wish it weren't the exception arou d here!

I believe that both the 45 and 2A3 tubes get much respect and admiration. For a lot of folks the higher power output of the 300b provides more flexibility in choosing matching speakers. I do quite well with the 8 watt 300b Whereas 1 to 3 watt may be a bit shy for my particular speakers.

I certainly don’t think any less of the 45 or the 2A3 tubes. However, they do narrow speaker choices. The 300b push pull amplifier under discussion here has the “potential “ to be an outstanding success given its design and higher power output.

Charles

Undoubtedy individual preference is paramount regarding "best" listening volume. I wonder how certain speaker designs might affect that as well. I'm into DIY speakers and I'm missing the palpable feeling with my 18" open baffle midbasses than I had with smaller sealed midbasses, until I turn up the volume. Midbass definition is better with my OB, but missing some slam/palpability. I run sealed subs below, so slam down low is there. I noticed @whitestix  uses Spatial Audio open baffles so wondering if there might be a correlation there. 

BTW, I'm running 45-type SET on my tweeters above 1 2kHz and absolutely love them. I realize 300b gets more love, though :-) 

Lovely thread. I wish it weren't the exception arou d here!

@ charles1dad 

So true and think my listening levels are contributed to my near field listening; 8 feet from my loudspeakers.

Wig😁

@wig 

I currently do my listening after 8 PM for a few hours and typically my listening sessions never exceed 75 db and I don't feel like I'm missing anything; excellent imaging, sound staging, low level detail, clarity and tight tuneful bass based upon the type of music I typically listen to

Yep! As we all can acknowledge this is purely an individual choice. My listening levels align with you, Don and Thom. @whitestix prefers a higher volume and I understand. Whatever results in more listening enjoyment, go for it.

Charles

Understood.  The Kootenai is a fantastic amp, as I know having one.  Let your pocketbook be your guide, but to be honest, Don and Lynn's 300b monos are in a whole different realm of musical excellence.  Maybe you can come hear them at the Seattle Audio show?  

@ whitesix

I know it would be for sure but it'll have to be a dream for now but one day...My Kootenay is maxed out and had hoped for some upgrades but not much to do other than another brand of boutique capacitors.

Wig👍

Wig,

Dandy system you have, for sure.  You have nominal 4 ohm speakers and if the Kootenai drives them to your satisfaction, then the 300b Statement monos will drive them as well, with an astonishing clarity that will be simply stunning.  Cheers.  

Counting down the days on Don and Lynn 300b debut 😁

I currently do my listening after 8 PM for a few hours and typically my listening sessions never exceed 75 db and I don't feel like I'm missing anything; excellent imaging, sound staging, low level detail, clarity and tight tuneful bass based upon the type of music I typically listen to.

Wig😎

Don Sachs Kootenay KT88 Tube Amp

Radu Tarta 4P1L Transformer Coupled DHT Tube Pre-Amp

Merason Dac 1

ProJect  CD Box RS2 Transport

Liberty Audio X-VOX (PBN) Loudspeakers

Don and Thom,

Gents, with all due respect, an 81-83 db SPL from my speakers conveys none of the emotional aspect of my music so I prefer it more around 88-90 db, thereabouts.  I want a visceral impact to the sound of my system and 83 db does not provide that.   By this, I mean when I am I doing critical listening.  

I participated in a San Francisco Audio Society listening comparison of the totl Coincidence speakers to Andrew Jones' $200  speakers, maybe Panasonic, I forget now.  We initially did an A/B session between the two pairs of speakers at a modest listening level, maybe 75-80 db, and the gathered listeners were totally flummoxed as to which two pairs of speakers were playing.  I personally could not figure out which pair was playing, try as I might.  Well, as you can anticipate, once the volume was turned up, it was 100% clear which pair was which, plain as day.

My best wishes for those that feel they are getting the full measure of their sound of their speakers at 81-83 db, but in my mind, that volume level in no possible way can portray the palpable sense of music reproduction on either my Spatial Audio speakers or my new Cube Audio Jazzon speakers.  Long term listening at 90db is an issue and am aware of that, and I don't listen to music continuously at 90 db, but I do fairly often for short periods of time, and it energizes me. 

If I were to be satisfied listing to music at 81-83 db, there are lots of inexpensive speakers available that sound just fine.  But with more volume, the better speakers begin to shine, which is why we pay the large sums of money for them.  

I know that when I have my system "cranked" and I measure the level it is about 81-83 dB.  I rarely listen at that level.  As was stated above, the hallmark of a good system is that it has enough resolution and balance that it can be enjoyed at low to moderate volumes.  There is a minimum level for the bass to pressurize or load the room, but that isn't all that loud in any house I have lived in.  I generally listen at the level where that has happened and not much higher.

@thom_at_galibier_design

I completely understand the example of your wife’s vocal power/control. At one time I played and studied the trumpet. As with any instrument you have much control over the volume you wish to provide. If I wanted to I could blow people out of a decent size room with just that single trumpet. The thing is that horn sounded just beautiful played at moderate and lower levels.

As you mentioned, audio system resolution seems to be the key factor. As this aspect of my system improved over the years I discovered I could immensely enjoy music at lower SPL levels. I’d say a very good parameter for a system is how satisfying is it to listen to at low and moderate volume?

No question however, to each their own choices. I know that some like to listen regularly at SPL of 90db and above. Their ears and enjoyment be served. It just isn’t for me.

Charles

Hi @charles1dad

Lynn,

Oh yea of little faith...  Very few speakers play nearly as well as the Spatials in less-than-perfect rooms and your front end will be tremendous so great sound is a foregone conclusion.  Your room is gonna sound sensational and I am going to be there to hear it.  Lucky me.  

Hi @carlsbad2, thanks so much for coming to see us at the show! The amp was only pegged like that so that we could then easily control the volume from software - but you were hearing it at a fraction of full output, less than half. It just helps so much with running the room smoothly. Cheers, come see us in Seattle in a week or so! We’ll be paired with a Whammerdyne statement 2A3 amp, it should be pretty special...

Best,

Ken

Yeah, no way of knowing what Seattle will sound like. Might be stunning, might be not-great, no way of telling in advance. Shows are unpredictable.

I like to listen at the volume a live performance would be at.  Obviously, Pink Floyd concerts would be loud, but a jazz combo should sound like you are in the club at normal levels, not screaming at you.   I will try to play at various levels when we demo and I have the remote:)   June 23 is the show.  I know a few folks who say they are attending, so I am sure someone unbiased will post an honest impression.  Listening rooms at shows are often hard to tame as well, so we shall see what we can do when we get there.

@carlsbad2 

Good observation. Over the years I have attended my fair share of high end audio shows. For the most part I have enjoyed these experiences quite a bit. I do get annoyed with the high volume level demonstrations. Personally I do not fine these displays impressive. Even with the very high powered amplifiers driving difficult to drive speakers.

Good quality music sounds better on a good system played at what I consider reasonable listening levels. I do not understand the attraction of the “crank it up”  approach.

The show mentioned in this thread is in 2 weeks.  There was very little at the LA show this past weekend in the way of 300b.  One that had promise was very nice japanese 300b paired with Songer field coil speakers.  But the speakers were only 93dB and every room was playing very loud to keep up witht he volume in the other rooms and the amp was literally turned up to the stop.  It didn't even sound like a tube amp to me.  I would have loved to have heard it at 1/3 volume.

Jerry

Why the radio silence folks??? Where are the impressions from the show? Inquiring minds wanna know!

Don, looking forward to seeing you at the show with your working prototype.

just get yhw alternative 2a3 maybe in paralel

I was proposing "Blackbird" as a product name for the amps, and Don said it is not just black like a raven, but "Intergalactic" black, which cracked me up (literal LOL) when he told me over the phone. Looking forward to meeting him at the show in person.

I can say the Amity, Karna, and the new amps sound nothing like other tube amps, whether SET, OTL, or conventional, or like transistor amps, either. I find them hard to describe, partly since I’ve been so close to them for the last twenty-five years (the first Amity came to life in 1998 or maybe earlier).

I’m trying to think of parallels ... maybe the first time you heard an electrostatic speaker? Kind of like that.

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.

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.

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.   

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.

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.

Lynn…. I really appreciate two comments… illusion generator… and the layman disadvantage of not hearing individual part changes…. both of which help explain why many of us go through a bunch of gear trying over and over to improve the illusion.