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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. 

 

 

whitestix
lynn_olson's avatar
lynn_olson
361 posts
 

This is very close to the production version. It is simpler and more straightforward to build than the shoebox format shown at the PAF show ... more spacious, more direct layout, and the power supplies are confined to their own section of the amp, on the right side of the chassis. The vent holes for the twin B+ regulators are visible on the right side of the amp, next to the VR tubes.

The audio-only circuit is on the left side, with very short signal paths from 6SN7 -> interstage 1 -> matched balanced 6V6 -> interstage 2 -> matched balanced 300B -> Monolith output transformer -> speaker jacks. The input selector switch bypasses the input transformer when XLR is selected. Compared to the show amps, there are actually fewer parts in the production version, with a very simple signal path from input to output. From input to output, there are only wires, transformers, and triodes, in a fully balanced circuit. No coupling caps, no plate-load resistors, no plate inductors, and no dynamic loads.

One subtle difference is each single grid is driven by a pair of balanced plates, so distortion and noise are minimized in every stage of the amplifier. In the show amps, each 6V6 grid was driven by the corresponding 6SN7 plate. In the production amp shown here, each 6V6 grid is driven by a balanced pair of 6SN7 plates, thanks to interstage 1. I was doubtful a good interstage could be made for the 6SN7, but our transformer designer came through with performance from 18 Hz to 32 kHz. Close collaboration with modern transformer design is what made this possible.

charles1dad's avatar
charles1dad
10,250 posts
 

Quite attractive with an understated elegant aesthetic.

Charles 

alexberger
935 posts
 

Hi @donsachs ,

Will you present your new amplifier in the Montreal Audio Show in March?

 

lynn_olson's avatar
lynn_olson
361 posts
 

Don did a marvelous job here. It’s actually quite functional, with a clean and direct front-to-back signal path, and with all wires in the balanced circuit equal length (yes, he went to that much trouble). You can infer that from the top plate.

The power supply side is equally tidy, with two independent B+ regulators, one in front of the other, and the three low-voltage regulators on the other side of the power supply section, all supplied by the custom Monolith power transformer. The soft-start circuit in the back of the amp keeps incoming AC power away from the front-panel power switch, as well as protecting the tubes and regulators from AC line transients.

The amp is considerably simpler to build, because signal flow is obvious, and color-coded wiring is used to keep track of polarity. It is also the same 18"/457mm width as the matching Raven preamp.

invalid
1,246 posts
 

I really like Thomas Mayer's 300B amplifiers, but I don't have deep enough pockets for that. You two seem to be on the right track with your 300B, and it's more affordable than his.

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