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.
Hi @donsachs , I have two questions about your new amplifier:
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@alexberger All tubes have response to DC. If you hear a difference with the ability to play bass, its not the tube type that's causing it. The reason we like to use 6SN7s is there are several that are new manufacture and most of the NOS types are great so there's a lot out there to support the design. 5687s OTOH aren't being made AFAIK. I like the plate curves of the 6SN7 better too- a bit more linear which is helpful in a zero feedback design. |
Here is an example of direct coupling: http://www.single-ended.com/Lagarto/shishido/811A.png Is 6f6 grid load easy enough for SRPP? ECC82 can be changed for 6sn7. What do you think about this schematic? |
Hi @atmasphere , I meant that tube with less internal impedance with a transformer load with the same inductance has wider bandwidth in bass. I agree unfortunately 5687s OTOH. |
@alexberger It needs grid stop resistors. Its usually a good practice to bypass the output of a regulator like the LM317 with some kind of capacitance to improve transient response; 1uf is a good typical value. You might want a bit more capacitance after the 180 Ohm resistor since any voltage variation where the regulator meets the driver transformer can cause intermodulations. The 6F6 grid is no problem for the SRPP and you should be able to sub a 6SN7 since their characteristics are so similar. Here's something to think about: many tubes perform better when a cathode bypass capacitor is employed. Yet there isn't one in the output stage. To install one you would need two parts, one for each side of the filament and its 30Ohm resistor (plus pot). It would not have to be a high voltage part but it would need to be a fairly high capacitive value- perhaps about 2,200uf on each side. 10Volt parts should work nicely since the voltage across the resistors and pot might only be 2 Volts. |
