New article - DIY Nutube Preamp
New posting of updated DIY LXmini crossover info.
Also, new article The Venerable Triode (previously in Positive Feedback online)
And Mike Rothacher's piece FAOW (First And Only Watt) amplifier Version 2
I made a batch of 2nd Harmonic Generators to give away at the Burning Amp Festival next Sunday. Here is the article I wrote to accompany them.
Silly me, I forgot to post my little article on the Korg Nutube preamp from the 2017 Burning Amp Festival.
Also, Lxmini analog crossover kits are available in the store at www.diyaudio.com starting at $49.
I have posted the owner's manual for the SIT-3. They are finally being shipped....
I have posted the LX-mini analog crossover article which also serves as the technical and assembly manual for the kit(s) that will soon be available in the store at www.diyAudio.com. You will find it at the top of the Articles section here.
I posted revised info on the SIT-3. A few pieces are in the hands of reviewers, and I have finished matching devices for production. The yield in the matching process came to slightly over 500 pairs, which means that we will be able to build as many as 250 of the amplifier.
Also new is the active analog crossover network for the Lxmini, the first of a series of crossovers to be made available soon in the store at www.diyaudio.com . More information on these kits and future efforts will be posted soon.
Speaking of DIY, the Amp Camp Amp 1.6 has been released at DIYaudio, and the initial run of 2,000 channels sold out in a few days.
More to come soon...
The pilot run of SIT-3 amplifiers is filling all the remaining space in my Sea Ranch assembly area, and I expect to send these off to my buddies, reviewers, and of course to Pass Labs production, who will be building the next run.
You can download the preliminary information sheet on the design: SIT-3 Info
Also, still pretty much on schedule are the DIY active crossovers and the DIY Sony VFETs – More on both of those soon.
Thank you for your patience. What can I say, I've been very busy. The results will be out soon.
We have a new amplifier, the SIT-3, which will be the last of the “VFET” type amplifiers using the SIT power transistor custom made for me by SemiSouth, unfortunately no longer in business.
Originally I did not expect to have enough SIT transistors to create a third amplifier. I set aside a sizable quantity for warranty repair, but this has not been needed, freeing up parts for a new design.
The SIT-3 is a stereo single-ended Class A amplifier with more power, lower distortion and noise, and better damping than its predecessors. It features the single SIT-1 in a unique circuit using “Common-Drain” mode without feedback, and has the ability to drive lower impedance loudspeakers.
Also, there is at least 1 new version of the B1 preamp - “This time with gain!”
New on the DIY front, there are several new projects:
DIY versions of the analog active crossovers for the the Linkwitz LXmini and Lxmini+2 loudspeakers using discrete JFET stages, as well as other DIY crossovers and equalizers in various flavors.
New DIY Sony VFET amplifier channels using up the last quantities of the Sony VFET stash from Singapore. Like the SIT-1 projects, the VFETs have been freed up by the reliability of the previous projects. This time, we will do something very cool with them.
Look for all this in March-April.
A nice person sent me a note the other day asking after my health, as I had not posted in quite a while. “Still above ground,” sez I, but thanks for asking.
Burning Amp is at Fort Mason in San Francisco this year on Nov 12. Possibly the biggest event yet, certainly the most effort and money and attendance by audio luminaries, so mark your calendar.
Getting new things ready for release, including the SIT-3, which you will see this year. Also lots of DIY toys, including some great crossover filters (including LX-mini), EQ filters of various utility for loudspeakers, and the Amp Camp Amp #2, the DEF Amp, and the DEFiSIT.
F7 continues in production, the J2 is still available (thanks to Stereophile), but you should get it while you still can. Everything else is limited to Reno's stock and what you can find used.
Tom Craggs sent me a note pointing out that with a B4 if you set a high pass filter on “12” you want to be sure that the Pole 1 has a value. If it doesn't and you instead only select a value for Pole 2, then the result is unpleasant. Similarly for high pass filter set on “24” - make sure that Pole 3 has a value before you set Pole 4. This is not in the manual. On the bench, this allows the filter buffer to pick up noise and distort, but more importantly it lowers the frequency of the cutoff to something like 1 Hz, so that the high pass filter outputs the full audio signal. Apparently in Tom's case it took out a (fortunately) cheap tweeter.
And one last time, no more Jfet updates on F1 and F2, free or otherwise. I closed these out years ago, but I'm such a softie that I have still done a few. But no more! Not even for a case of 2000 vintage St. Emilion. Well, maybe for that.
Time flies. I've been quite busy, and stuff piles up. I have posted a batch of the most recent reviews on product, to be found at the top of the list in the Reviews section. Of particular note is the Amplification Component of the Year award from Stereophile...
New First Watt products will find their way to market this year, and to make way for them, I am announcing “Last Call” on several models – the SIT-1, SIT-2, F6, B4, and B1. You can still get them new, but don't wait around. The J2 and F7 remain in production.
Final draft of DIY SONY VFET is posted.
For my 65th birthday, I have a present for the DIY community, the first draft of the DIY SONY VFET AMPLIFIER, found at the top of the articles section.
B5's are officially discontinued.
I don't usually post customer comments, but Dave Banowetz wrote a thoughtful review of the F7, so I put it in the Review section.
The F7 review by Dick Olsher is pending in The Absolute Sound, and other reviews will soon appear from from the usual suspects.
This has always been about making amplifiers.
Dick Olsher famously remarked that “The first watt is the most important watt.” With this in mind, I created First Watt in 1998 as a "kitchen-table" effort, exploring unusual low power amplifiers with an emphasis on sound quality. I wanted to design a variety of amplifier designs in what I think of as neglected areas - amplifiers that might not fit into the mainstream and are probably not appropriate to my more mainstream business, Pass Labs.
Fourteen years later I have largely accomplished that goal, but along the way it seems that I have created a commercial enterprise that has outgrown my ability to handle alone. I tried addressing that by hiring my nephew and son to help, but they wandered off to their own careers (as offspring will do), leaving me with all the work.
Don't get me wrong, I like work - It's good for you. Building product is fun and keeps me grounded, but production demands are not leaving me with enough time to pursue the vast array of yet-to-be-designed amplifiers. So I am doing the logical thing, which is to hand the business end of First Watt over to Pass Labs, bringing my three business partners to the table as well. My relationships with these people stretch back to 1972 with ESS, through the Threshold years and for the 25 years of Pass Labs, and I'm certain they can do the job flawlessly.
Starting in April, Pass Labs will be building First Watt amplifiers and will also take responsibility for marketing and distribution. Support and service policies will remain the same.
I will continue at what I do best, the fun part.
Tom Craggs wrote a review of the B4. You can see it here.
Now for something completely different: an amplifier which incorporates positive current feedback.
The F7 amplifier is now in production with availability in March.
The F7 page including links to the owner's manual and reviews.
The short article Zen With GA10JT12 has been posted.
I am pleased to announce the posting of the Sony VFET Amplifier Part 2 in the articles section.
You will see that I have also posted the original Sony VFET 40 Year Commemorative Amplifier article.
M2's are officially discontinued to make room for new product. Reno HiFi has purchased the remaining stock and probably still has some availability.
The DIY Sony VFET amplifier part 2 will be released later this month, and there are still some 2SJ28 and 2SK82 parts available from www.circuitdiy.com . This amplifier can be built with unmatched parts for the single-pair-per-channel version and requires matched parts for the two-pair version. Also it will work well with other complementary depletion mode parts. Next up is the 2SK77B amplifier.
Not a lot new, site updated with more reviews and a couple more links.
The DIY version of the Sony VFET amplifier part 2 is coming up for release soon.
Also coming up, articles on SIT (VFET) single-ended amplifiers, one using 2SK77B and the other with 2SK180 power devices. These will not be commercial products as I do not have enough stock of these parts to build more than a few.
The pilot run of the revision of the B4 active crossover is nearly finished and will be shipping in June. It is followed by a larger run in production now, and scheduled to be available probably in July, so supply will be good.
This is the crossover that many of you have waited for, with the features most often requested, including flat sums for 6, 12, 18, and 24 dB/octave slopes and/or frequency range from 25 to 6375 Hz in 25 Hz steps. Direct-coupled NOS Toshiba Jfet buffers with no feedback and polypropylene capacitors.
Here is the link to the newly rewritten owner's manual: B4 Owners Manual
I have been quite busy in my new fortress of solitude, so there's more to come shortly...
Here is a new DIY oriented article, entitled “Sony VFETs in Push-Pull Class A - part 1: Common Source Mode, Transformer Coupled”. You can download the pdf file HERE.
I am stuffing up the first (small) production run of the revised B4 crossover boards. After the shakedown run, I plan to have them in regular production. They will be pretty spectacular, well worth it for those who have patiently waited. Disregard the details of the first B4 manual.
Also, I haven't updating the reviews or links, but I'll get around to it...
Where does the time go? I have received enough concerned messages that I had to work up a standard response:
My apologies. I have been unbelievably busy the past few months with moving two companies and my residence, remodeling a guest house, getting the X.8 amplifiers finished and launched, building First Watt production, designing the Sony SIT amplifier, designing four new First Watt power amplifiers, two DIY Sony SIT amplifiers, two Yamaha SIT amplifiers, another slot loaded OB speakers for Lowthers, and redesigning the B4 crossover network, B2 and B3 pieces. And these are just things I can tell you about.
I guess I'm trying to get everything done before I get old.... Anyway, everything's great and I'll have a bunch of goodies for you shortly.
I am happy to announce that I finally got around to finishing the article “Beast With a Thousand JFETS” and it is posted HERE. Those of you who have seen the coverage of the 2011 Burning Amp Festival have wondered what the hell that was in the photos, and now you can see it with more detailed design information so that you can dream of making your own.
The F6 article has also been posted HERE on this site as well as 6moons. The amplifier is sufficiently unique and pleasing that I have decided to go ahead and make a few available for sale. If you want one, keep an eye on this page for the announcement.
And there are whales today.
The design of the F6 is complete, and was the subject of a talk at the Burning Amp Festival last month in San Francisco. The edited transcription of that talk can be found HERE on 6moons, and will appear on this site later on.
At this moment plans to produce this in quantity have not solidified, although I will build a few, even if only to use as a reference amplifier. Even if you can't buy it commercially, the article contains all the information you need to build it yourself, and I also refer you to the F6 thread on www.diyaudio.com
Sad to relate, SemiSouth, the manufacturer of Silicon Carbide (SiC) Jfets and SIT devices has announced that it is closing its doors. Fortunately for First Watt, I have a large inventory of the parts used by the J2 and the SIT-1 and SIT-2 amplifiers. These products will continue to be made, and there are plans for new product in the future using this technology.
B4's are shipping. You can access information from the link: B4 Manual
The F6 is still waiting for the smoke to clear, as is the Beast With a Thousand Jfets and some new unmentionables...
SIT-1's and SIT-2's are shipping. The first run of each is going to the U.S. and Japan, and sales will expand to the rest of the world in the second runs.
New article being posted today, the F5 Turbo
The F6 design is done and I'm listening to one, but the article will have to wait a little bit.
Also, the SIT-1 and SIT-2 amplifiers are approaching the end of the production line. More information on these will be posted shortly. B4's are also in production and will follow on the heels of the SIT amplifiers.
My son and nephew have gone off to pursue their own careers, so it's just me. I'm old and slow, so you'll just have to be patient...
Seems like yesterday, but as I type this I note that it's been a year. Oh well, I'll try to make for it with lots of new announcements.
The explorations into SITs (Static Induction Transistors) that began with a custom fabrication for me by SemiSouth in 2010 have begun to bear fruit. Two designs have emerged which will be made available shortly. I have written an article on these devices which will appear in the next issue of Linear Audio magazine ( www.linearaudio.net ) and also a shorter introduction on the subject that you can read: SIT intro. This can also be downloaded as a pdf file: SIT intro.pdf
The SIT-2 put in an appearance earlier this month at two audio shows in Japan. The result of over a year's work with the SIT transistors, this stereo amplifier delivers exquisite audio with single-stage single-ended Class A operation without feedback or degeneration. They are in production now, and will be available for purchase in January.
Also displayed in Japan, the SIT-1 is a mono-block version of the same amplifier with an even more severe aesthetic – the SIT is the only semiconductor in the circuit, surrounded only by resistors and capacitors. It features a user adjustable operating point which helps to optimize the performance for individual loudspeaker characteristics. This amplifier is beginning production and will appear late January.
At long last, the B4 will be available for sale in January. This is the adjustable electronic crossover which delivers 6,12,18 and 24 dB/octave slopes and is adjustable from 20 to 1260 Hz in 20 Hz increments and 200 to 12600 Hz in 200 Hz increments. DC coupled Jfet buffers with no feedback give 0.001% distortion and bandwidth from DC to 500 Khz.
The B2 is finally in also production. This little box is a must-have for people who are serious about using dual amplifiers (bi-amping) to drive loudspeakers through their passive crossover networks. It has a very high input impedance and a low output impedance and allows wide adjustment of the relative levels of the low frequency amplifiers versus the mid/high frequency amplifiers.
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