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

@carlsbad2 

I hope that you have a wonderful time at the Pacific audio show. I’m interested in your listening impressions.

Charles 

Great news - I own a fully tricked out one of Dons SP14 builds.  Fantastic preamp.

Will this new 300b push-pull require that much gain from a preamp (6SN7), or will it have normal input sensitivity?

I'd also be very interested in an integrated version... don't know if that's on the cards. 

Could it even be a DIY kit (Elekit style 😁)... unlikely perhaps, but at least Don wouldn't need to build them anymore.  VK Music seems to do well enough from this business model.

Where do I sign up?

Ralph has written in the past that the 6SN7 is a sufficient driver tube “dependent “ on its implementation in a given circuit. I have been told that the 6EM7 provides much more current, power and drive capability compared with the 6SN7.

I will say that I’ve heard an excellent sounding PSET 845 amplifier that utilized the 6SN7. I could certainly be wrong, but isn’t the 845 a more difficult tube to drive than the 300b?

@charles1dad The issue is always how much voltage swing will drive the tube to full output and how much grid capacitance is there. The more grid capacitance, the harder the tube is to drive.

You can get a 6SN7 to drive a single 300b no sweat. But doing it the way is traditionally done in SETs will likely but the tube at a disadvantage.

The 6EM7 does have one section that is considerably more gutsy than a 6SN7 has. But you will always be looking on the collector's market for replacements.

The way to get a 6SN7 to really do the job is to have it wired as a cathode follower direct-coupled to the grid of the power tube. In this way the coupling cap used in the amp stays rather small since its driving the 6SN7 rather than the output tube. Smaller caps are more transparent...

This is the technique we've used in our OTLs for several decades now. Its very reliable. One 6SN7 section is thus able to drive a number of highly capacitive triode grids with the voltage swing needed. I do not understand why this approach hasn't been used in SETs since the design consideration is similar. It might be because a negative power supply would be needed. But from what I've seen, SET users are not particularly worried about cost if the amp gets the job done for them.

 

@atmasphere 

I do not understand why this approach hasn't been used in SETs since the design consideration is similar. It might be because a negative power supply would be needed. 

Ahh, I see. The usage of the 6SN7 with your preferred utilization mandates a negative power supply. Does this add noticeable complexity and cost to accomplish successfully? This could be the explanation for its lack of popular use.

Charles 

Gavin,

Don is licensing the production of his Valhalla integrated amp that owners on this forum have praised.  I recall that the Valhalla amp is one of several that Clayton Shaw uses to demonstrate the best aspects of his speakers.  

I am the least knowledgeable guy on this forum about electronics. I clearly admit it.  I remember listening to Roger Modjeski explaining the design of one of his preamps at Burning Amp a few years ago where an attendee asked about worthy driver tubes.  RM's minced no words in responding that 6SN7 tubes were a very poor choice of tubes -- "better employed in old TV's", because of their inherent high noise levels.  Well, I had had Don's first preamp with 6SN7 tubes (derivative of the Roy Mottram's SP14 design and with Roy's full approval), and his Kootenai amp with the same driver tubes, and wondered how to square away RM's comment with the dead quiet sound from my system.  When I shared RM's comment with Don after the show, oh boy, it was an interesting conversation.  It is true that few audio designers use this tube in their designs (Modwright and Supratek come to mind), but Don does and is doing so with his new 300b monos and my ears tell me that Don is correct in his use of the octal tubes in all of his designs.  Hearing in believing.