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. 




I suspect any electrostat is fine. The weird capacitive/inductive load will not bother a zero-feedback amplifier.

What will not work is something like Wilson Audio or B&W speakers, with low efficiency, a band split into three or more drivers, complex crossovers, and big woofer arrays. Or MBL. They really do need 200 to 500 watts with a high damping factor (lots of feedback). Transistor amps, in other words.

Hi @lynn_olson ,

According to your comparison between RC coupling and IT coupling, IT coupling between input and driver stage should increase slew rate (dynamics, trancients, speed) similar as it does between driver and output stage. Isn't it?
On the other hand, the input stage doesn't have a big voltage swing, and as result of it a linearity issue. It shouldn't drive the driver stage in class A2. 6sn7 with IT has less wide bandwidth compared to 6v6, 6f6, 45 that can be used in driver stage (in my amplifier 6sn7 18Hz-35KHz vs 6f6 6Hz-95KHz -3db ).
Is It wars to try interstage transformer after the 6sn7 input stage in my 300B SET?

I certainly confirmed that the 300b monos will drive the Dyn's to the full measure of their sound in my 13'X26'X9' room.  Lynn points out the need for speakers of a certain design, as he listed examples off, to have lots of power (current) to those speakers with amps which have a high damping factor.   My main speakers are Cube Audio Jazzon single driver speakers which by design, require an amp with a very low damping factor, such as most tube amps I can imagine and ss amps like the Enleum 23R and most of the Pass Labs First Watt amps.  

I am very happy that these 300b monos drive both my Cube speakers as well as the Dynaudio C-1's so I conclude that these monos are much more compatible with a larger variety than probably typical ~8wpc 300b amps would drive. 

I started this thread with reference to my Willsenton r300 300b tube amp with 8 wpc.  I swapped that into the rack to try to drive the Dyn's and it ran out of clean power pretty darn quickly, while the 300b monos cruised along easily and cleanly at very high SPLs.   It is a very unfair comparison, but here it is... a 300b tube amp that will drive a lot of speakers that many others likely would not.  This fact dramatically broadens the selection of speakers one could pair with these fantastic amps because having a tube amp that only pairs with high efficiency speakers is awfully limiting as one's choice of speakers today might not be the same speakers you have down the road.  

No, the comparison isn't really fair.  The little Chinese amp is a nice value for the money, but it is a single ended design made of, shall we say, "cost effective" parts.  It probably makes 7 or 8 watts per channel.   The mono 300b amps are built with cost no object parts and custom wound transformers, with state of the art power supplies, and they really are about 27 watts/ch.   They cost multiple times what the Willsenton does.   The Willsenton has a chance on efficient speakers.  It doesn't have a prayer on a speaker presenting an inefficient and difficult load.

Reflecting on a recent phone conversation with Don (he’s in BC Canada and I’m in Colorado, a bit north of Denver), I suggested that SET amps are kind of like a paint-box, and a much more fun way of tuning a system than messing with cables. If you are DIY’ing, there are many ways of changing the tone color ... which coupling caps, what kind of passive power supply, which rectifiers ... the options are endless. And a lot of fun if the amp is on a breadboard and you can solder in new parts in a few minutes.

The characteristic SET sound works in your favor, giving a lot of leeway with parts selection. And the amp is fundamentally simple and easy to understand, a godsend when you are tuning with many variables. Like I said, a paintbox. When you learn painting, you learn color harmony and the art of mixing. Nothing teaches faster what XYZ cap sounds like than heating up the soldering iron and swapping parts.

A balanced amp is a harsher taskmaster. Yes, more transparent, potentially by 20 to 30 dB, but not nearly as forgiving. Colorations can sound pretty ugly if the wrong part is in the wrong place. And there is no feedback to tidy up the mess. Maybe more like working with an airbrush, or transparent watercolors, instead of pigments. There’s still balancing to be done, but the high level of transparency, and lack of feedback, exposes everything. I found this out the hard way with the original Amity amplifier back in the Nineties.

And the colorations from different part selections are not the same as SET. This makes sense when you reflect on it ... the balanced circuit is cancelling most, but not all, colorations, and the residue left over can be unwelcome and surprising. The SET experience can be a very rough guide telling you which parts sound really awful, but it will not tell you which sound the best.

This mirrors working with speakers. As transparency goes up, tolerance for coloration goes down. In the absolute sense, this is wonderful, because now you’re really hearing the music. In a way, I’m not surprised the simplest topology won ... less to go wrong, and with the most efficient plate-to-grid coupling.