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

A quick note: Don and will not be making the part-Mullard or the suggestions made by others in this thread. The Raven and Blackbird are where our attention is, and that’s where it will stay. Our focus this year, and the next, is getting production moving smoothly, making sure the Raven and Blackbird are reliable as possible, and growing the customer base.

On my part, I’ll be completing the long-awaited "Beyond the Ariel" speaker project over on DIYaudio, with the assistance of Troy Crowe in Canada. I do my best work collaborating with others, and Gary Dahl, Bjorn Kolbrek, and Thom Mackris have made a real difference on that project. I’ve been meditating on an appropriate name for the speaker, and "Phoenix" feels right, considering how many times it has been re-born.

Scope pr0n. Same pix as earlier, just more zoomed in.

Don Sachs scope photo of Blackbird at 30% power (8 watts) at 1 kHz. Zero feedback, with no grid resistors to "trim" the response.

Hi @donsachs ,  

I changed a load resistor 56K Ohm (Alan Bradley 2W), in my SET amplifier. And still have a 2-3 times bigger overshoot vs Blackbird has. However the sound is more balanced compared to the 120K (Kiwame 2W) load resistor I had before. I'm still waiting for more break-in time.

So far IT compared to RC coupling between 6sn7 and 6f6 - IT sounds more fast, more precise rhythm and pace, faster transient, more clean in upper frequencies. But I don't hear a big difference in terms of low level resolution. The tonal balance is a little colder too. Bass is more fast and controlled but less deep.

Which resistor will you recommend for power supply? Now I use Ohmite gold 10w and Milles 12.

The problem with two successive stages that are balanced and DC-coupled to each other is that DC drift is a big deal. A 1 volt shift on a 150 volt plate is normally inconsequential, but becomes a serious concern when the grids of the following stage have a 1 volt offset between them ... which is what DC coupling does.

In the post in which I suggested a differential topology, I also suggested several cures for this problem, which I pointed out in that post.

Hi @donsachs and @lynn_olson ,

Here is square wave 1KHz on my amp output:

https://photos.app.goo.gl/jcdjn88Q71WaEvoR9

Output transformer and driver IT have much wider bandwidth compared to input to driver IT. During the measurement the 6sn7 current was 7.2mA. I just increased it to 8.75mA. Load resistor is 56KOhm.