Dear Lynn,
Thank you for convincing me to use an interstage transformer for driving 300B in my SET. I installed Hashimoto A305 into my amp. I put 82K Ohm Kiwame load resistors.. First I measured the 6f6 driver stage with an oscilloscope. There is no overshoot on a square wave. (Thanks to Ralph for noting how to check the correct load that prevents transformer ringing). The frequency response -3db on small signals is 6Hz to 95KHz. The driver stage gives 150v peak to peak without visible distortion (with 300B working point Vg -65v). The output stage now has almost symmetrical clipping (and it was very asymmetrical with RC driver coupling). As a result, maximal power is significantly bigger than before.
Most importantly, the sound quality jumped to a different level. Much more transparent, higher resolution, bigger soundstage, more air and separation between instruments and together with its sound is less harsh, less grained. Even my DAC Chord Qutest sounds much more "analogue".
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.
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@alexberger Fantastic! I love success stories! I came around to really good ITs on this project. LC coupling was next best, but once I got the custom wound Cinemag IT, designed specifically for the circuit it was no contest. Enjoy your amp. You have installed a top shelf IT and now you know why:) There is no going back to coupling caps..... |
Dear Don, |
Once you hear the difference an IT makes, you realize: "Aha! So that’s what RC coupling sounds like!" And then you start hearing that coloration everywhere in mainstream audio equipment, and can never forget what it sounds like. This is an experience no reviewer ever has, even if they have $250,000 systems. Because why would they? Everything has been handed to them on a platter. They don’t know what’s inside the pretty box... it could be elves doing magic tricks for all they know. What drives this exploration is curiosity. What will this sound like? Well, you don’t know until you try, and why take somebody else’s word for it? That’s no fun. Grounding in the physics of tube function helps, because you get a feel what the device "wants to do". Pilots have a saying, "the airplane wants to fly". If you’ve ever been at the controls of an airplane as it lifts off the runway, you feel it. The vibration stops, the wings lift, the ground falls away, and you keep moving forward, a creature of the air, not the ground. You are now in a different realm. Tubes are the same. They want to amplify. It’s what they’re made for. Our job is to get out of the way and let them do that, so we get into load-lines, the most linear region, what happens as the current dips downward, staying away from trouble spots, etc. I made a little post a few days ago on Facebook, quoting a meme from my Ukrainian friend, Misho Myronov. When asked what his amplifiers amplify, he replied: "Happiness! My amplifiers amplify happiness!" All of us who create tube amps get this. We do it because it makes us, and our friends who listen to them, happy. In the comments to Misho’s post, I added: "I was just talking to Karna, and said, an amplifier is like a dance partner for the speaker. If the partner is dull and disengaged, the speaker will be bored and not interested. If the dance partner is lively and fun, the speaker will light up and come alive." All of us who have solved a difficult technical problem, or just got a better amplifier, will hear the speaker really come alive and surprise us. That’s the happiness. |
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