As Lynn said, the amps have dual regulated supplies, one for the 300b and one for the input and driver tubes. IF the specs on that KEF speaker above are really what the review said, then the amp would drive them. Also, as I said far above somewhere, the first stereo prototype of this circuit with only one power supply per channel drove a pair of experimental Spatial Audio Labs X4 prototype speakers that were approximately 87 dB 4 ohm to insane levels, much as what Thom was describing above. The monos have dual supplies in each amp, so would be even more capable. All that said, I would stick to speakers that are 88+ dB and very well behaved. The spatial audio X4 current model is 88 dB 4 ohm (and very well behaved) and the amps will happily drive them to ear splitting levels in reasonable room.
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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As @atmasphere has made the point eloquently on past occasions, easy load impedance (Higher ohms and less fluctuations ) speakers are less stressful on amplifiers. In addition he has pointed out that they are lower in distortion compared with low impedance speakers. Charles |
@donsachs There are now class D amplifiers that have a distortion spectra that if you had one on the bench you would be completely convinced you were measuring a really well-behaved triode tube amplifier. There are three reasons for this: 1) its really easy to get really high Gain Bandwidth Product values, such as 20MHz with class D, so feedback can be supported across the entire audio band (no rising distortion with frequency- like a zero feedback amplifier in this regard) 2) the feedback node can be very linear so the feedback signal does not get distorted prior to doing its job. 3) the things that cause non-linearities in the circuit tend to generate lower ordered harmonics. Despite inexpensive power being available, I still prefer higher efficiency loudspeakers for the reasons Lynn outlined above. In addition, the harder you make any amplifier work the higher the distortion. For this reason I feel that higher efficiency and higher load impedance is an advantage to all audiophiles. |
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