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. 





Another factor is sensitivity to parts quality. An amp with 20 dB of feedback (which is nearly all Golden Age amps) tends to wash out differences in the sonics of different parts. This is exactly what feedback is meant to do ... 20 dB of feedback is a 10:1 reduction of all sources of coloration. A zero-feedback amp, by contrast, reveals the sonics of every single part, particularly at critical nodes in the circuit. This raises costs compared to the PP KT88 equivalent.

I do not have the resources to confirm this via test bench measurements as you do. I can only rely upon listening experiences with my own audio system. When I placed my 300bSET zero NFB amplifier in my system the first time (2009) the immediate difference/improvement was the sense of naturalness. Very stark and unequivocal. In my system realism and authenticity took a step (Or two) forward.


The difference is Class D switches at 100 kHz or higher, with pulse width translating to signal level, while Class A is non-switching and like a preamp, fully analog from start to finish.

@lynn_olson most quality class D amps switch at 500KHz or more. Also to be absolutely clear, class D is 'like a preamp, fully analog from start to finish.' A very different type of circuit, but analog nonetheless. 

I do not have the resources to confirm this via test bench measurements as you do. I can only rely upon listening experiences with my own audio system.

@charles1dad Lynn is correct- if you are not running feedback then everything in the amplifier design right down to the component quality, wire and solder makes a difference. When you run lots of feedback you get rejection of things like that- often including sensitivity to line voltage.

That’s why I am agreeing with what Lynn wrote. Zero NFB seems to uncover a masking effect. The subtleties and nuance of virtually everything is revealed as noted.


Zero NFB seems to uncover a masking effect.

@charles1dad That's not quite correct. It depends on how well the feedback is executed and as I've been pointing out a lot recently, with most amps made in the last 70 years or more that's not happened.

But if its done correctly, amps using it can be amazing- no hint of dryness, nice soundstage; everything you want in an amp.

I've described what's needed often enough, no need to repeat it here.


I understand that you are referring to the approach you use with judicious application of negative feedback. I was referring to Lynn’s comparison to the “golden age “ PP amplifier which typically used 20db of NFB. Your current class D amplifiers do not fit this description.