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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
atmasphere's avatar
atmasphere
11,901 posts
 

@donsachs @lynn_olson @thom_at_galibier_design 

I confirmed a theory I had about OPTs over the weekend. You might give this one a try; its inexpensive. Replace the bolts that hold the OPT together. Typically these are made of steel and are insulated from the transformer by fiber or plastic shoulder washers.

You can get non-magnetic stainless bolts to replace the steel bolts. Its not a big change, but in the case of SETs or lower powered tube amps in general, every drop counts. I measured about a 7% increase in amplifier power. I suspect this will vary depending on the transformer design as well as the specific alloy of stainless bolt used.

The shoulder washers are supposed to take care of the problem of a magnetic short of course and for the most part they do. But they don't do the job perfectly and I suspect that since this technique is 70-80 years old, tradition has set in and caused no-one to look into it further.

I found out decades ago that the mounting bolt in a toroid transformer, commonly made of common steel, would heat up more than the transformer because the actual toroidal mag field was sloppier than theory. So the bolt was a short to the field. By replacing it with non-magnetic stainless the transformer ran at a lower temperature.

I've been working on a low power PP tube amp recently so decided to give this a try.

abd1
157 posts
 

I just scanned through this thread and while some is over my head, it is extremely informative. I love reading the journey behind the development of a new product, especially when the main driver is to create the best sound instead of the most profit. I am only sad because I was planning on going to PAF this year since I missed the first one, but I now have a work event that will not permit me to attend. If I were to attend I think I may be signing up to order these amps/preamp. Hoping and expecting those who attend will post their reactions here, thanks.

gladmo's avatar
gladmo
364 posts
 

Fascinating read. I'm definitely stopping by the Spatial room at PAF

lynn_olson's avatar
lynn_olson
358 posts
 

You want a technical presentation, here’s my talk at the 2004 European Triode Festival:

2004 ETF Presentation

As for the lengthy previous post, I am not sure about the impact of dynamic variations in output impedance. One way to measure the impact would be to measure distortion harmonics at a constant voltage output, compare 4 and 16 ohm loads, then repeat again into a reactive loads.

The key point stands: Push-pull Class A triode has the most linear interface to loudspeakers. Nearly all loudspeakers generate significant back-EMFs, which are resonant in character, that reflect back into the output devices. Other topologies have nonlinearities or discontinuities that interact with these resonances, which exaggerates speaker coloration.

There are planar-type speakers that present essentially resistive loads, but the reason for this flat impedance curve is very low magnetic coupling between the diaphragm and the magnetic system. As the magnetic coupling (BL product) becomes more intense and efficiency increases, resonances appear in the impedance curve, as well as smaller narrowband divots that reflect stored energy. Regrettably, speakers are inherently resonant, particularly as efficiency goes up. It has to be kept in mind that most speakers are stupendously inefficient, ranging between 0.3% and 1.0%.

byang12's avatar
byang12
39 posts
 

 

@lynn_olson 

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.

 
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