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

Showing 5 responses by byang12

It has been well debated 20 years ago during golden years of  direct heated power triodes.

 

Based on tests on ALTEC/JBL horn systems:

300B is middle of the road of all those small/medium signal direct heated tubes.

It has good/mellow middles, lose/weak lows and not very sweet highs. 300B has longest life among those DH tube.

PX25 has best low end quality among all < 8W tubes.

VT25A/10 has best high end, I built and love the sweet sound.  However, the tube is very fragile, did not last.

 

if you want to best balanced sound, push/pull 45/50 can give you what you need.

For small signal (pre-amp) tubes, 26 sounds the best, and same time is hardest to build the amp due to sensitive to hum and very low heater voltage.

 

@lynn_olso

FYI,  the guy who published DH tube comparison more than 20 years ago uses the same driver and same speakers as well the same signal source during his blind listening tests.

I can confirm his report that PX25's bottom is much solid and deeper than 300B. 300Bs could not even match 7A1's deepness.  The common sense is 300B could not be driven into A2 region w/o distortion, so I consider 300B is a good candidate for pre-amp/headphone amp which always worked at A1 region.   Also, the measurements of output impedance from 300Bs is way higher than PX25s.  FYI, my 6336 SE amp beats my 300BXL (beefed up 300B) amp hands down at bottom spectrum.

You are right about driving stage quality is the bottleneck of MOST commercial SE DH amps.  but the reason is not what you stated.  The real secret of making best SE amplifier is to SHUNT REGULATE POWER SUPPLY for the driving stage. Push Pull amps are less critical of regulated power supply for its driving stage.

 

@lynn_olson

IT-coupled PP DHT’s have a power and majesty unlike anything else in audio. Bell Labs and Western Electric knew what they were doing back in 1935.

 

Western Electric is also pioneer of "Ultra Path" circuit design for SE amplifiers which removed local feedback which is evil in true audiophile amps.

 

Long tailed symmetric push pull is another WE originated design.

Only modern circuit design which enhanced WE golden edge SE DHT amps is solid state CCS which a magnitude better than tube CCS.

@alexberger 

your choice of 6sn7 as driving tube is not good (high output Z, low max plate current...)

Now, your choice 1 of implementation is the better one, only your concern is invalid.

High output Z does not automatically leads to narrow bandwidth.  Bad Interstage transformer causes it.  High Z tube can't drive 300B into deep A2 so you never get 8W  class A output from 300B that way. However, you can use Western electric's classic Ultra path design pattern, combining a CCS with a 0 DC current nickel 1:0.75 interstage transformer and achieve pretty good result if you bi-amp the speaker.