Yes, it is quite surprising how sensitive these two circuits are to parts choices. Much more so than any I have ever worked with. I am used to coupling cap differences, and I have my favourite types, but there are several film caps in here that make as much or more difference. Also, I have been through several versions of anode loading, and it is clear in this circuit that a custom designed interstage transformer walked all over the other choices in the amps. We developed a new twist on the regulated supplies for the preamp, and now we will extend that idea to the power amp and then we are done. As Lynn said, I think we are reaching the limits of what the circuits can do. Also, I am trying the excellent Monolith Magnetics transformers as soon as they arrive. I will see if this pushes the amps over the top! As I believe I said earlier in the thread, this is pretty much a cost no object project to see what is possible with these circuits. They sound unlike anything I have ever heard or worked with. The better you make them, the less they sound like anything at all, which is about the highest compliment I can give an amp or preamp.
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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@bcurtis1 I looked that piece up. It has absolutely no tubes of any sort in it at all. Can you enlighten me? Did I miss something? |
Since this is (mostly) a 300B thread, I’m still curious about the general circuit of Ralph’s 300B amp. He’s been doing this a long time, so his design choices are of considerable interest. I have my own way of doing things, and that was strongly influenced by my research when I was writing for Glass Audio and Vacuum Tube Valley. John Atwood, in particular, showed me the Bell Labs archives and other primary sources. Charlie Kittleson, the magazine’s founder, had a treasure trove of working 1930’s electronics, which sounded very different than anything I’d heard before ... not like the Fifties sound at all. They clearly had different priorities back then. John Atwood and I have a lively interest in early technology, particularly early monochrome and color TV in the USA, the UK, France, Germany, and Russia. Developments in color TV filter technology went on to influence Neville Theile in Australia, modern crossover design (Laurie Fincham in the UK), and the time-switching technology used in the GE/Zenith FM Stereo multiplex system. |
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