Japan has a very good used audio stuff market with Tango, Tamura transformer; Kondo, Acrolink cables; used amplifiers and CD player,... Japanese people sell all this stuff on the internal market. A very few used stuff from Japan is sold internationally , for example, on eBay. And because Japanese people don’t use eBay, all used Japanese audio equipment sold by hucksters - prices on eBay are at least twice higher than in the local market.
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.
Showing 18 responses by alexberger
Hi @donsachs , Will Spatial be in the Montreal AudioFest on March 22-24 ? |
I finished my integrated 300B SET project with two external power supplies. It took me about 40 hours to drill chassis (thank you for my friend who helped me do it) and to assembly all parts together. The amplifier sounds from scratch batter than my previous DIY amplifiers which was disassembled for parts for the new project. And it should sound much better after break-in. Thank you guys for helpful advices. |
Thank you @lynn_olson @donsachs @atmasphere for your advice and answers to my question that helped me to build the 300B SET amplifier. https://photos.app.goo.gl/4LUJVLJ3LuuW32yE7 The amplifier sounds realy good - fast, transparent with deep controled bass, PRAT and realistic tone of instruments.
|
Hi @lynn_olson The driver tubes are 6f6 in thriode mode. 6f6 are Torvac brand (probably made by Mulard). |
Hi @donsachs , Thank you for good words and help. My next project will be a phonostage. I have a DIY phonostage I built in 2011 based on EAR834p schematics. In my phonostage I used better parts (air capacitors) and power supply (with LCLC power filter and 0A2 shunt stabilizers). |
Hi @atmasphere , I have balanced connection from the cartridge to SUT. But from SUT to phonostage it is SE connection. In my next phonostage project, I plane to put SUT close to the first tube inside the phonostage. But I think to make balanced first amplification stage of the phonostage can be very helpful. |
Hi @atmasphere ,
Which problem? Can you explain? I saw Cintation 1 schematics. It is difficult to understand capacitors values and how do switches exactly work from these schematics. The first pair of ecc83 works for gain only (10000 voltage gain with a feedback) . After that we have a passive RIAA. The second pair of ecc83 has feedback that looks like the second part of RIAA (that is active).
|
Hi @lynn_olson I use EAR834p schematics in my current DIY phonostage.
The second ecc83 miller capacity for RIAA equalization. It is also using small capacitors in the RIAA equalizer. So I use air capacitors in this RIAA. I also use the LCLC power supply filter plus 2x 0A2 voltage regulators. In general I like the sound of this phonostage.
The main drawback of this schematics is output cathode follower that drives feedback and output RCA cable. When I tried different ECC83 tubes in this position - speed, dynamics and bass were changed dramatically. If I reuse this schematics for the new project I am thinking about adding an output buffer. It can be 6SN7 with the output transformer.
https://www.diyaudio.com/ I did something more similar to this (just without a fixed bias for the second ECC83): http://www.romythecat.com/Forums/ShowPost.aspx?PageIndex=2&postID=9161#9161 |
Hi @lynn_olson I upgraded my 300b SET amplifier. I replaced 6f6g Torvac driver tube to 6v6 Psvane. 6f6 worked with idle current 26ma. 6v6 with the same cathode resistors gave 24ma. I changed cathode resistor to get 29ma. In result much better bass control and dynamics, better instruments separation and higher resolution. The difference between 6v6 and 6f6 drivers is huge. It similar to changing RC coupling between driver and 300B to IT coupling! Conclusion, the more powerful driver is better for 300b. I know some folks (including Sakuma) end by 300b driver for 300b. |
Hi @lynn_olson @donsachs When did you play with the driver tube to your amplifier? Which tubes did you try except 6v6 and kt88? Did you try 5881, KT66, 6L6, EL34? If yes can you compare the sound of these drivers? |
Diar @lynn_olson Thanks for the informative answer. I used a 6f6 driver in my single-ended amplifier, which I have been improving for many years. For some reason, Shindo used this tube in the driver of his 300V amplifier, and the person who made the first version of my amplifier followed in his footsteps. That guy (who built my amplifier) also tried to compensate for 300b 2nd order distortions by 6f6 driver distortions. But I don't think it worked. In the end I increased 6f6 current to make it work in a more linear range.
|
Another thing that drove me mad, my SET sounded too analytical and sterile. It took me 6 month to find the source of this issue. It was a Vishay Z-foil resistor in input stage 6sn7 cathode. When I changed it to a Shinkoh 2W resistor all this sound sterility was gone! Z-foil worked OK when I used RC coupling between input and driver stage. RC coupling softened sound. But when I changed it to more transparent IT coupling, the extreme sharpness of Z-foil resistors showed up. |
Hi @atmasphere I just found schematics with a cathode follower 12BH7 300B driver. Is it similar to the schematics you were talking about? https://www.diyaudio.com/community/threads/300b-schematic-recommendations.340133/page-2 Just don't need pentode input and global feedback thought input tube cathode. |
Hi @lynn_olson , I’m working on my DIY 300B SET amplifier, which has three stages coupled by transformers. The first stage uses 1/2 6sn7, and I’ve been experimenting with different driver tubes: 6f6, 6v6, and 5881. I’ve noticed that the more powerful the tube, the better the performance. My findings so far are that the 6f6 is the least impressive, sounding somewhat forward and harsh. The 6v6 offers a lush and warm tone, while the 5881 provides the largest soundstage and the best instrument separation in complex musical passages. The interstage transformer I’m using between the driver and the 300B is a Hashimoto A-305, which I understand is based on the renowned Tango NC-20. The challenge with this transformer is its 40mA maximum idle current. Currently, I’m running the 5881 at 36mA, and it seems to be working well within this limitation. My question is regarding potentially moving to even more powerful driver tubes such as the EL37, KT66, or KT88. What would you estimate to be the minimum idle current required for these tubes to perform well in single-ended (SE) mode? I’m also aware that if I switch to a more powerful driver tube, I’ll need to upgrade the filament transformer from a 25VA Antek to a 50VA Antek, which isn’t a major concern. The main constraint seems to be the idle current limitation of the interstage SE transformer. Any insights you could offer on the minimum idle current for the EL37, KT66, or KT88 in this context would be greatly appreciated.
Best, Alex |
Hi @lynn_olson , I think the Hashimoto a-305 is an extraordinary transformer. The measured frequency response of this transformer (with 6f6) in my amplifier is 6Hz to 90KHz -3dB. The difference in sound between RC coupling and this IT was huge, it is a completely different amplifier. http://www.tube-amps.net/images/Hashimoto_Specs/A-305.jpg I also can recommend 5881 over 6f6. With 5881 the sound is bigger, more air around instruments and better separation. 6f6 gives more chamber and lush sound. Hi @atmasphere , I understand your point. I will not implement it in my current amplifier, but I can try this idea in the next project. I have another question, how do you balance a number of tubes in parallel on your OTL amplifier without fixed bias. Is it necessary to select all these tubes by parameter or the amplifier circuit balances all parallel tubes automatically? |