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. 




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".

@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,

I'm also going to make an independent power supply for the driver and input stages. Now I use one 5u4g rectifier for both channel tubes 2x 300B 2x 6f6 2x 6sn7. The total current is 180mA. Is to much for one 5u4g. Now I have very big B+ capacitors, 2200uF for each 300B and 900uF for each 6f6 and 6sn7. But the independent power supply for the driver gave me better PS separation between output and driver plus gave me the option to increase driver tube current and decrease load on the rectifier tube.
I think I will continue to use the same 5u4g rectifier for 2x 300b and SS rectifier for driver and input tubes. Can you give me any advice, what is important to do for driver + input power supply?
I am also going to use the Lundahl plate choke LL1667 for 6sn7 input tubes instead of resistor load.


Electronics Engineer (EE)

Volume Control (VC)

For me and the amount of Typo's I keep making, it would be great if I could abbreviate a lot more words.