Or leaving conventional power supply topology behind, and using multiple independent supplies in the proper way😀
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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I have had a DIY 300B integrated stereo amplifier since 2006 built by one guy. But in all this long period of time I did dozents upgrade myself. The amplifier has 6sn7 input, 6f6 (in triode mode) driver and 300B. Cathode bias and C coupling between stages. I upgraded: output transformers, power supply choke, interstage capacitors, power supply capacitors, resistors, driver and input tube idle current... My experience shows that big value power supply capacitors (after the choke), big value cathode capacitors, correct driver idle current gave me much better improvement versus change of output transformer from James Audio to Hashimoto H30 3.5 (3 times more expensive!). Coupling capacitor quality and sound signature are very important too and cathode resistors as well. Also the quality of power supply capacitors is very important. To get big values and quality without spending too much I use a mix of electrolytic, polypropylene film and vintage German oil capacitors. I don’t understand why producers put such small capacitors after a choke in 300B amplifiers (typically 100-200uF per channel). My experience shows x10 value gives huge improvement in bass control, transparency, focus, soundstage. I don't have as much experience as @atmasphere @donsachs have. I also don't understand how audio designers make decisions. Probably a much cheaper change of schematics can lead to great sound improvement without spending too much on parts and size of amplifier. |
Hi The 6SN7 will barely drive a 300b, which is a very difficult load. I have not worked with 845 tubes nor will I given the high voltages and heat involved, but I did look at the data sheet. Yes, it takes more negative grid voltage to bias one than a 300b, but I have no idea of how capacitive a load an 845 is, and I really don't have time to research it. Ralph is right in that a 6SN7 is adequate to drive many tubes. It makes a wonderful driver for any of the usual octal pentodes like kt88 or el34, or a 6V6 or 6L6. Works great. But a 300b taxes a 6SN7. It works as in the original Reichert amp, but if you want to unlock the unlimited dynamics of the 300b you need a much better driver setup. The reason the original Dynaco ST70 was a marignal amp was it had a wimpy driver section that would clip before the output tubes, or about the same time, plus it had a very mediocre power supply. It was a pleasant amp and a zillion of them sold. But if the driver and power supply were better it would have been a much better amp. The output transformers are not world class, but they are quite good and capable of more than the rest of the amp could provide. You can also improve the performance of any driver tube by changing the way it is loaded. For example, a CCS will give far better drive capability than just typical RC coupling. But CCS circuits do have some coloration. Not so bad in a pentode amp, but very noticeable in a DHT amp. The other ways are to add inductance to the plate of the driver with either LC (choke cap) coupling or full on interstage transformer coupling. The inductance the driver tube plate sees "helps" it out to drive the 300b. There are differences in the way all of these approaches sound, but all are better than just a plate load resistor and coupling cap. I have explored all of them thoroughly for a year with the 300b project and found a solution that Lynn and I like and sounds the most musical. |
It seems perfectly rational that the driver stage of a tube amplifier is of paramount importance. If the output tube isn’t adequately driven then how could optimal sonic performance be achieved? The builder of my 300b SET chose the 6EM7 as a very suitable driver for the 300b. His reasoning was the same as you mentioned. I am not an electrical engineer but I wonder how much is it the particular driver tube versus the implementation of said tube. Ralph has written in the past that the 6SN7 is a sufficient driver tube “dependent “ on its implementation in a given circuit. I have been told that the 6EM7 provides much more current, power and drive capability compared with the 6SN7. I will say that I’ve heard an excellent sounding PSET 845 amplifier that utilized the 6SN7. I could certainly be wrong, but isn’t the 845 a more difficult tube to drive than the 300b? Anyway, no question that driver stage rivals power supply and output transformers in getting it right for tube amplifiers. So it appears that there are alternative executions that can get one there successfully. I very much appreciate the comments this thread has generated. The education never stops. Charles |
@antigrunge2 Glad you have an amp you love. What I meant above is the design of the driver section of the circuit. Your amp is using a 6L6 to drive a 300b, which is a good choice. I was referring to many 300b amps that are pushing tubes like a 6SN7 to the max and barely driving a 300b. The first rule of amp design is your driver section should never strain or clip before your output section does. As for the SET vs PP on musicality and soundstaging, well I would submit you've never heard a push pull 300b amp designed like the one Lynn and I have been working on. You might be surprised... |
Thanks for highlighting the dependence of power tubes on driver tubes as well as on power supplies and transformers. My Wavac EC300B depending on whether I use EAT300bs with their preferred Tungsols 6L6 Coke bottles or Takatsukis with their preferred Svetlana Winged ‘C’s have quite different characteristics (bold and powerful vs. subtle and detailed). When you change the driver tubes in either case a significant bit of the magic is lost. At the top end SETs are simply unbeatable in terms of musicality and soundstaging. |
Absolutely. I read a great quote somewhere about a million years ago, that a great tube amp was the sum of three things. How good is the circuit? How good is the power supply? How good are the transformers? If you take care of all three of those things you get a great amp with most any tubes. Most commercial designs that are built to low price points make serious compromises in one or more of those areas. If you take care of business, you generally get a great amp. |
@donsachs I made this point on another thread just a day or two ago. People get so hung up on the tube, whether a plus or minus, while the circuit design, which is far more important, gets ignored. |
The post from @pindac above is spot on. Most people think a 300b is a fuzzy rolled off tube. That is because they heard it in a single ended amp with a mediocre power supply, and most likely an inadequate driver section, and possibly mediocre output transformers. Such as all the entry level Chinese 300b amps. They still are pleasant to listen to, but if you use a really good driver section that never clips before the 300b tubes do and is capable of driving the capacitive load of the 300b, a really killer power supply, actually multiple ones, and really good transformers, the 300b will walk all over any of the normal output tubes such as kt88, el34, etc.... That is what @whitestix heard.... A PP 300b amp done right is very special. I really had no idea how good they were until I spent a year working on one. See some of you in Seattle. |
As someone who has done this on numerous occasions I strongly encourage you to do so. It’s worth the time and effort. You can speak directly with Don , gain valuable insights and actually see and hear his new 300b amplifier. This can be a very rewarding encounter. Meeting the folks behind the products has certainly worked out that way for me. Charles |
Not to tread on any designers toes in any way, more a testimonial to the impression a well thought out 300b design can have. I have heard 300b Valve Amp's over the years, mainly SET with low Watt Output. I have liked the vocal and simple acoustic music when replayed through them, but in general have not got too attached to these types of design. Recently I have been auditioned a Tim De Paravicini design PP 300b that was in production 30ish years ago. A friend has purchased it, who has a system I know very well and have been used to hearting Neurochrome SS Amplification and VAC Valve Amplification. The Amp' was given a pre-heat prior to my arrival, the impact the the TDP design 300b Amp has made on the presentation was quite instant. I was aware something quite special was being used and become very contented with hearing a 300b Amp' in use that were really worth making a reference to, hence I am producing this post. The Amp's owner has informed me the Neurochrome and VAC Amp were now most likely to be sold, as they do not foresee the need for them any longer. There is in my opinion a a new satisfaction in place. This is so far achieved without a Tube Roll, or a swap out of some very old Cap's. A PP 300b Amp can really work for those who have struggled with the Tubes used as a SET dsign. |
@donsachs I am seriously thinking of coming to Seattle for the audio show in June. Are you going to be there every day? I've never been to one of these shows before. Meeting you in person (finally) and seeing your 300b mono blocks is a main motivator. |
If you truly want a true reference quality SET 300 B amplifier Radu Tarta Shiny eyes products are way under the radar and No commercial brands are even remotely close to his expertise . In Europe Thomas Meyer is his equal . What most miss is the sheer quality and engineering expertise on all levels inside and out . Look at U.S Audio Mart he has a absolutely fantastic 2 box 300B amp that I have heard is stunningly good with premium tubes and choices of input tubes you can use for tastes of all music types it’s $10k+ , But if this were made by a big commercial company this would be with ease$25k,it’s that good, check it out ! |
HI It is really not my intent to get into detail here for something that is in prototyping. Yes, there have been many balanced tube preamp and amplifier circuits around for years, and I have absolutely no doubt you build an excellent balanced preamp as I know you guys build really good amps as well! This is a slightly different approach to a traditional tube circuit, and yes the transformer coupling is part of it. Also, as you well know, the quality of whatever attenuator you use is critical, and of course the power supply. Anyway, I think I am going to bow out of this thread because it was never my intent to do business here. That is inappropriate and there is nothing to sell yet anyway! Just was commenting to tell folks what I was up to in my semi-retirement. See anyone who wants to chat in Seattle! |
@donsachs I'm curious what is meant by this. We've been working on a fully balanced design since the mid 1980s, which started selling in 1989. Is it the use of transformers in the circuit path? |
HI My Pacific is XLR out with no volume control so have not tried direct to amps, but I build a really good preamp so I will continue to use it. The prototype preamp is essentially a circuit that was a thought experiment of Lynn’s for a fully balanced design that has been around for years and no one ever really tried to build and perfect it. So we did for this project. Like the amps it is conceptually simple, yet has subtle complexity. It is transformer coupled on both inputs and outputs and uses the same Khozmo 64 step remote attenuator with relay input switching I have been using, but set up as dual mono. This allows me to switch a balanced signal on both channels, plus you get a balance control if you need one. Main tube is 6SN7 and it is transformer coupled to the output with custom wound iron from Dave at Cinemag for just this circuit. I have tried ECC99 and 6H6P with adapters and they also sound good, but I always pick the 6SN7 in a shoot out, so it has octal sockets. The power supply features damper diodes into a CLC and that drives a custom regulated supply which then feeds gas regulator tubes. Because of the output transformer it can easily drive RCA or XLR outputs and headphones. It has no caps in signal path and of course no feedback or anything like that. If you use the preamp xlr outs you can drive the amp input tube grids directly. It has a level of clarity that has to be heard. Quite astounding. The prototype works well and I am working on the "real" one for the Seattle show. Dave’s iron is just superb as it always is and response is dead flat from below 20 Hz to way out there beyond 20KHz. Just having fun and we will see where it all goes. Honestly I have never heard anything like this setup.... fun. |
This sounds like a very exciting venture. Do you prefer the LampiZator Pacific DAC with preamplifier or direct into the 300b mono blocks? Best wishes for the upcoming audio show. Charles
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Hi all... Mark wrote and said he posted something so I thought I would chime in. The amps are push pull 300b monos and are 27 watts/ch. Not your flea watt 300b. It has been a really fun project with Lynn Olson. If you aren’t familiar with Lynn, just google nutshell hifi. Not your traditional push pull with phase split circuits though. A different approach. No feedback. Just a single pair of 300b tubes in each amp. Drivers are 6V6 with 6SN7 input tube. Multiple power supplies in each amp. We have driven 86 dB 4 ohm speakers quite easily with them to screamingly loud levels. They are 27 watts, but seem to have the drive of a 100 watt tube amp. The prototype amps along with their matching preamp will be demonstrated at the Spatial Audio Labs room at the Pacific Audio Fest in Seattle in late June. I have even talked Lynn Olson into coming. Should be fun! No production of anything yet. Hope to get that going in the late summer or fall. Not trying to sell anyone anything here, just letting you all know what is in the works.... Mainly we are just having a lot of fun pushing the envelope a bit. I am slowly trying to retire from production of things to more projects like this one. Trying to see what is possible with a little "outside the box" thinking. Happy Listening and hope you are all enjoying your stereos! Don |
Congratulations!!! I understand your genuine satisfaction and happiness. Don Sachs is very talented and possesses a good ear. No doubt that he can exploit the vast musical potential of the wonderful 300b tube. Realism and uncanny presence is what it is so capable of if implemented well. I believe that it will pair beautifully with the LampiZator Pacific DAC at the upcoming audio show. Charles |