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

I second what Don just said. Building a kit is far more rewarding than messing around with cables or component-swapping. You get to hear for yourself what XYZ capacitor sounds like, instead of reading random comments on the Internet. I can’t emphasize enough you just can’t trust what people say on the Internet ... but you can trust your own perceptions, first, last, and always.

It’s super educational, and focuses your attention on tuning the power amp, which is where it should be. Likewise, if you build your own speakers, you get to tune your own crossover. This is where the big payoff is, and it trains your ear in what to listen for.

Amp and speaker tuning set the sound of your system. Find out how to do that, and you are most of the way home.

Here is Eleckt schematics:

http://4tubes.com/2-SCHEMATICS/BY-BRAND/ELEKIT/TU-8600/TU-8600R-Amplifier-300B-Schematic.jpg

Global negative feedback, parallel 12au7 driver, 12ax7 input, semiconductor bias control and power supply stabilizers.

chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/http://4tubes.com/2-SCHEMATICS/BY-BRAND/ELEKIT/TU-8600/TU-8600R-Amplifier-300B-leaflet.pdf

The question is about of calculating C-Miller for a pentode tube in triode mode. If we have no data of C input at triode mode, or also no data of Cg1-g2, then how do we calculate C-Miller?
How is big the total input capacity in 6V6 in triode mode compared to real triods like 45 or 6EM7, 6BX7,...?

It’s a safe guess it’s about the same ... in the 60 to 80 pF range. Most true 3-element triodes, triode-connected beam tetrodes, and triode-connected pentodes fall about there. So-called ultralinear mode is probably about half that. Pure pentode is a little higher than the socket capacitance, so about 6 to 8 pF.

The 45 and triode-connected 6V6 are similar, with preferred operating points: 250 to 275 V on the plate, 28 to 32 mA cathode current, and dynamic plate impedance (Rp) around 1800 ohms. The big difference is gain and bias voltage ... the 45 has a gain of 3.8 and negative 45 to 50 volt bias, while the triode-connected 6V6 has a gain of 8 and negative 14 to 15 volt bias. But otherwise similar, including Miller capacitance.

P.S. If anyone does bring back the 45 at a sane price, I’d love to see it in Arcturus blue glass. That would be very stylish, and a nod to its famous predecessor.

Arcturus 27

Vinyl Savor (Thomas Meyer) discusses the 45