I see now that Joseph Crowe Audio Products is listed in room 345 for the Toronto Audiofest. So that is where we will be and I hope to see at least a few of you there!
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.
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Hello 300B audio gurus, I have a technical question regarding the AC 300B filament in my SET amplifier. Upon measuring the filament voltage, I found it to be 4.85 volts. |
@alexberger If the correct filament Voltage cannot be obtained I find it preferable to err on the low side rather than the high side as that will likely promote tube life. Filament Voltage is important. As the filament cools off, the output impedance of the circuit will rise, output power will fall and distortion will go up. The opposite is true with the filament Voltage increased. But the filament has a life span independent of the rest of the elements of the tube. Running it at a high Voltage than spec will shorten its life. AC line Voltage variation is why you hear the system sound great one day and maybe not so good at other times. There are DC to DC converters available these days that allow you to run a DC Voltage. They can keep the filament Voltage spot on regardless of the AC line Voltage. I recently used some in a push pull amp using 45s, which have a lower filament Voltage than can be pretty tricky to set up otherwise. The DC to DC converters were quite compact and allowed me to float the supplies for the tube- no hum problems, no noise problems so I could wire the cathode circuit as needed. They worked a treat!
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Hi @atmasphere Thanks for your input. Can modern DC-DC switch-mode converters inject HF/RF noise into a SET amplifier system? Given the high sensitivity and purist nature of SET topologies, do these modern converters pose a risk of radiating EMI/RFI or polluting the ground plane? |
@alexberger Its all in how you bypass the device so it doesn’t make noise, and if you are using one that is quality built. If you’re not careful, you can certainly have noise problems. If you are careful its no worries at all. Usually a small capacitance is enough to shut them up. I’ve not seen an SET circuit that was particularly high sensitivity. A phono preamp or the like would be more sensitive! I recently installed a 48V supply in a multichannel microphone preamp that had 6 tube channels. The supply, made by Meanwell, injected quite a lot of noise but a small bypass capacitance shut it up entirely. I placed the capacitance at the other end of the wiring harness that fed the 48V to the phantom power connections of the microphone inputs, so not directly at the output of the supply. Once that was set up the preamp was silent and I could not find any noise when using the oscilloscope. The biggest problem IMO is not noise, but the longevity of the SMPS or DC to DC converter- one day it might not run anymore. So I like to have a spare on hand if I install one. If you go on some of the DIY sites that have SET construction threads, you’ll see that people are using such supplies for filament circuits. |
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