300b lovers


I have been an owner of Don Sachs gear since he began, and he modified all my HK Citation gear before he came out with his own creations.  I bought a Willsenton 300b integrated amp and was smitten with the sound of it, inexpensive as it is.  Don told me that he was designing a 300b amp with the legendary Lynn Olson and lo and behold, I got one of his early pair of pre-production mono-blocks recently, driving Spatial Audio M5 Triode Masters.  

Now with a week on the amp, I am eager to say that these 300b amps are simply sensational, creating a sound that brings the musicians right into my listening room with a palpable presence.  They create the most open vidid presentation to the music -- they are neither warm nor cool, just uncannily true to the source of the music.  They replace his excellent Kootai KT88 which I was dubious about being bettered by anything, but these amps are just outstanding.  Don is nearing production of a successor to his highly regard DS2 preamp, which also will have a  unique circuitry to mate with his 300b monos via XLR connections.  Don explained the sonic benefits of this design and it went over my head, but clearly these designs are well though out.. my ears confirm it. 

I have been an audiophile for nearly 50 years having had a boatload of electronics during that time, but I personally have never heard such a realistic presentation to my music as I am hearing with these 300b monos in my system.  300b tubes lend themselves to realistic music reproduction as my Willsenton 300b integrated amps informed me, but Don's 300b amps are in a entirely different realm.  Of course, 300b amps favor efficient speakers so carefully component matching is paramount.

Don is working out a business arrangement to have his electronics built by an American audio firm so they will soon be more widely available to the public.  Don will be attending the Seattle Audio Show in June in the Spatial Audio room where the speakers will be driven by his 300b monos and his preamp, with digital conversion with the outstanding Lampizator Pacific tube DAC.  I will be there to hear what I expect to be an outstanding sonic presentation.  

To allay any questions about the cost of Don's 300b mono, I do not have an answer. 

 

 

whitestix

One of the really fun things about designing an amplifier from scratch (not from 1950’s schematics) is you can hear for yourself when you make a change. Reviewers can only treat these things as "black boxes", and customers can only work at the margins with cable swaps. Don and I can change topologies, power supplies, tubes, basically everything.

Every change is audible, but some are far more important than others. Driver design is right at the top of the list. That’s what makes or breaks an amplifier. I wish more designers understood this.

I shouid add there is no 1950’s or 1960’s tech in the power amp or preamp. All of the tubes were designed in the 1930’s, and the circuit is a combination of 1930’s and 21st-century tech. No relation to Golden Age tech, in other words.

Lynn,

I have a burning question that you, Don, or Ralph might be able to answer.  So you start with a new design with caps and resistors and power supplies, etc. and then you put it on the bench to test it out and of course give it a good listen.  Conventional wisdom is that caps etc take a while to run in so do you have to run in the whole design for a a while to get the true sense of it and then tinker with the component parts thereafter.... and then wait for them to run in again before making an evaluation?  I would think this would be an even more difficult process with speaker drivers... which clearly  need to loosen up.   My Spatial Triode Masters sounded awful for the first 50-100 hours but gradually came to life.  At the risk of teeing up a disputatious topic, I often wonder if it is our ears that break in or the audio components.  Breaking in speaker wire just seems silly to me, something I have never honestly experienced. Any insights would be welcome on this tangential issue. which would give us a glimpse into the design process 

Fortunately, Don and I know where the "bad actors" are, and it’s no secret. Caps. Specifically, film caps. They’re the parts that need the 10 to 50 hour run-in. I do not like this ... it suggests the plastic film is undergoing a very slow chemical change while it is being charged, and a further change when the charge is modulated by an audio signal.

But direct-coupling is a whole another can of worms. The worst is that failures in one part of the amplifier cascade through the amplifier, and can even destroy loudspeakers. This is the typical failure mode of solid-state amplifiers ... a DC servo circuit, or voltage regulator, fails, and then destroys everything that is DC-connected to it. Cap-coupling or transformer coupling limits the failure to one part of the amplifier, and limits the scope of the failure to no more than a few parts.

Also, Don and I have prior experience and expectation to guide us when we try XYZ change. Is it audible at all? Is it better or worse, or just different? I don’t know about Don, but I can hear changes in ten seconds or less, and have a better, same, or worse reaction, or sort of a mixed feeling.

The mixed feeling is a danger sign and indicates that there’s something I don’t like but can’t describe or pin down. That’s pretty common at the serious design level, by the way. You often hear or feel things that just make you uneasy, which is a sign to turn it off immediately and take a good, hard look at the circuit and see what you missed. Maybe a wiring error. Look again. Stop, think, reflect, do something else. It happens to us all.

Yes, fresh film caps often sound dull, flat, and dynamically compressed. There are often subtler colorations I describe as "glossy" or softened, a kind of over-processed Photoshop impression. You hear it a few times, and you know it immediately.

But compared to an outright circuit error, that’s nothing. Those sound much worse, grainy, shrill, shouty, almost always something very very wrong, and almost always in the high frequencies. Does it sound "electronic"? Yeah, that’s bad. Find out what’s wrong. Look hard enough and you’ll find it.

@whitestix 

I make a change and live with it for at least a few days or a week before deciding.  Yes, the film caps have to run in.  With this amp project I built a stereo version first because I had a few of the Kootenay amp cherry cases laying about.  So I made it all fit.  There are different topologies to try.  The first was full "silicon assist" where the driver tubes each have a CCS on the plates.  I took this version to Spatial Audio a year ago and we all agreed it was the best amp any of us had heard.  But then I tried LC coupling and it was better to my ear.  So then I had Dave Geren of Cinemag design me a custom interstage transformer for just this circuit.  As Lynn said above, the 300b is a hard tube to drive.  Dave likes a challenge, and his interstage transformer sounds better than either previous version.  The IT version is more "musical" and "relaxed" sounding, yet has an insane level of detail.  Then we decided to go to mono blocks because we could improve the power supply considerably with more space to play with.  So my point is these things evolve over a year or more and I listen to each variation for quite a long time.   The mono 300b amps going to Seattle for the show are the result of a year of listening to different ways to build the circuit.  You have a pair of them and they are pretty special to my ear.  It took a lot of experimentation, guided by theory to get to this point.  That and patience of course....

Guys,

Just love reading about different type topologies that went into this 300b design and it’s quite amazing the time, effort and dedication it took to come into fruition...

I know this is going to be a special 300b as I am a current owner of Don’s Kootenay 120 ...😁

Wig 👍