300b lovers

I got a little side tracked with this thread, I'm back into the 300b theme .

I did not share, that on Sunday 25-06, I was able to attend a demo' of a 'new to me' system, which has Klipsch Jubilees as the resident speaker.

The resident system in use was quite special.

Following the Lunch recess, a friends P-P 300b Power Amp' was put to use.

The 300b is a late 90's model of which Tim De Paravicini has an input to the design. This Amp is now overhauled and a few circuit tweaks are carried out.

The system owners reaction to this Amp' was immediate, the Cheshire Cat Grin lasted for many tracks.

All attendees were thoroughly impressed by the way this Amp' interfaced in this system and it really shone out for its attractive traits.

That is not the whole story, the systems pre-amp was swapped out for a Bread Board mounted, part completed pre-amp build.

This addition of the New Pre-Amp had a substantial impact in conjunction with the 300b. 

My take is that the design of the 300b in this Thread, has another 25ish Years (50 Years Combined) of experiences of Two Amp Designers, put to use, to help create this latest design.

I would get great pleasure from receiving a demo' of these mono's, to see where there are sonic traits that stand out as being more of a attraction and very much wanted to be kept.   

I’ve been a little quiet since I got whacked by Covid on my return to Colorado. Got an intense sore throat on Tuesday, tested positive on Wednesday, and started Paxlovid that afternoon. Doing better today ... actually, mostly better, and my mind is finally clear again. The metallic taste Paxlovid is famous for hasn’t been too bad, and it is fast-acting. (I tick three of the boxes for "high risk", so Kaiser Permanente of Colorado prescribed it right away.)

Strongly suspect the Denver or Seattle airports as the culprits. Total zoo in both places. If I go next year, I will ask for airline assistance getting to and from the gates. Two things that did work well were TSA Pre-check and Express Bag Check-In.

Don continues to evolve the Blackbird. Full-size chassis, some excellent parts choices, and bringing elements of the much-loved Raven to the Blackbird. The people on the Spatial Audio pre-order list are going to like them ... a lot.

Lynn, I hope you bounce back soon from Covid.  I got Covid in the remote state of South Dakota last year so go figure.  Your meds will  surely alleviate the symptoms.

Pindac, I heard the Jubilees in a local dealer's room and they are truly sublime, really stunning, fit for a way big room.  

I visited with the owner of Whammerdyne Audio who had his 2A3 SET amp driving the stellar Songer speakers.  As far as I can tell, the Whammerdyne designer has a different amp design philosophy than Don and Lynn, who favor a P-P design. Both Don and Lynn loved the sound of the Whammerdyne/Songer room at the Seattle show so that might say that there a lot of paths to get tube amps performing in an excellent fashion. I would have liked to hear those exemplary Songer speakers with Don and Lynn's 300b monos.  Yes I would and I bet Don and Lynn would too. 

I had a couple of flea watt tube amps including an excellent 8wpc Dennis Had amp that just ran out of gas even with my easy-to-drive Spatial Audio speakers.  Don and Lynn's 300b monos have ~27 wpc, which can drive a boatload of speakers.  Their mono's drive both my Spatials and Cube Audio speakers with alacrity, no question, no limitations.  And with dead silence between songs, more so than some of my excellent SS amps.  

Matt Kamna, the designer of the Whammerdyne, is an old Tektronix guy I’ve known since the late Eighties. We were at the second meeting of the Oregon Triode Society, and were both so impressed by what we heard at the meeting we set aside a project on a transistor amp .... for the simple reason it is much easier to get good sound than with transistors. Tubes are simple to work with and sound great, right out of the box.

Back in 1996, when I lived in Portland, Matt physically built the first Amity amp, although it was 100% my design from the ground up, and my first amplifier project. At the time, Matt went down the path of gigantic and extremely rare Western Electric power tubes in the transmitter class, I moved to Washington State, and then to Colorado.

Matt approached me a few years back and wanted me to write the user manual for the Whammerdyne 2A3 amp. He had definitely moved in a new direction. Matt’s an old friend and I didn’t mind some spare change, so yes, I agreed. The Whammerdyne 2A3 has some interesting user setup settings, and I had fun coming up with various names for the internal features of the Whammerdyne. Yes, I know what’s inside, in order to write the fairly complex user manual. (NDA’s were signed, etc.)

Internally, the Whammerdyne 2A3 couldn’t be more different than the Amity, Karna, Raven, and Blackbird (which are all closely related). Matt’s design is almost the anti-Blackbird, but what can I say, it works really well. I know from personal experience these things don’t design themselves. They look simple, but I can tell you, they are tricky to get right.

It was delightful to hear the latest Whammerdyne at the 2023 PAF. It physically looks more or less like the original, but sounds much more refined and elegant. It’s clear they’ve been working on it, and good for them for doing it. And it works really well with the Songer Audio speaker, another Portland company.

It’s interesting the SET folks are all-in on the single-ended concept, and have been since the early days of Sound Practices magazine. I certainly fell in love with direct-heated tubes, but felt from the beginning that the colorations of push-pull amps (compared to SETs) could be solved with a little creative thinking, and a return to the well of Western Electric research. I credit Vacuum Tube Valley and John Atwood for pointing me in the right direction.

Since I’m on a roll (and thankfully nearly out of the woods on Covid), let’s talk about PP coloration. It exists, it is real, and if you spend time with top-quality (not junk) SET amps, the absence of that coloration is wonderful and refreshing. Compared to Golden Age amps, everything is so clear, so open, so natural with wonderful tone colors. (Again, you never hear this with junk SET amps, which are murky and dark.)

The magazine conventional wisdom would tell you that clarity and beauty is "euphonic coloration". That’s complete horse****. Euphonic colorations can’t add detail, resolution, more depth, and more in-the-room presence ... colorations can twiddle with subjective tonal balance, and usually adds mush, murk, or grain. They don’t remove it. Build your own amps and you find this out right away (I can see Don nodding his head). The magazines have had this wrong for forty years.

Back to PP coloration. The mainstream "alternative" view is that it is inherent to to all PP, so just build SET and forget about it. Entirely aside from power considerations, SET has its own universe of colorations unique to SET, and they can be quite severe. What I call "junk" SETs sound like old antique equipment. So designing a really good SET isn’t quite as simple as it appears at first glance. At the top of the performance spectrum, it gets fiendishly difficult, with costs and complexity reaching into the stratosphere, and all charm and simplicity lost.

I’m in the small minority that feels the colorations of PP are very real and not imaginary, but can be solved. The Golden Age amps of the Fifties and Sixties, and the modern copies from the big name vendors, all have remarkably similar circuits, boiling down to three types (Williamson, Mullard, and Dynaco, with a handful of variants). These were adopted because they were well understood, responded well to feedback, and were cost effective at the time. Even Marantz and McIntosh were part of the watts-per-dollar race, which only ended when the Crown DC300 and Phase Linear 700 came on the market, putting all tube amps in the shade. From then on, if you wanted Big Watts, you got a transistor amp. Still true today.

But Golden Age is not the only way to build a tube amp. There were other, pre-war circuits, before the Williamson wiped out everything in 1948. The pre-war "floating paraphase" phase inverter ... not as perfectly balanced as later circuits, but more powerful. Transformer coupling, which passively inverts phase, but demands ultra-performance transformers, and also rules out global feedback. And other methods.

The prewar era had a lot of interesting byways and interesting circuits, which all disappeared by the 1950’s. And they do sound different, and get away from the 1950’s monoculture which dominates tube audio. The tubes don’t care; they cheerfully work in any circuit, provided you pay attention to operating point, loading, and stability (part of any amp design).

At any rate, when you stop using Golden Age circuits, the "PP sound" changes. It’s no longer a thick blanket that lays on the sound. It might be a brand-new coloration, or might go away. That’s where the fun starts.