Below is a copy of the first Tubelab web page. It was first posted in July of 2003. It is here for historical information. It also reminds me that I change my mind too much. The principles presented in the first 2 paragraphs are still true. None of the amplifier projects mentioned in the later paragraphs were ever taken to the fully documented DIY project stage. Often the prototype was sold cheaply to someone who wanted to finish the mechanical aspect of amplifier construction. As I experimented further, I came up with better alternatives to these concepts. The A3 and grounded grid designs were rendered unnecessary by PowerDrive. I still want to explore those concepts further, but there are only so many hours in the day. I still have a warehouse full of tubes, and I have gone through 10% of them at best. I stopped searching for the "magic driver tube" when I found the 5842 / 417A tube. Now that my supply of these has dwindled, that quest continues again. Expect to see some data published in the near future. The vacuum tube car stereo amplifier remains a pet project for me. Many people think that the power supply is the hard part. It is not, you can hack a power inverter to get power. The trick is to find some tubes that are not microphonic, hence the 26E6WG military spec tubes. I have not built a car stereo amp that I am happy with yet, but I haven't had the time.
This site is currently under construction. More content will be added in late August.
Dedicated to advancing the state of the art in affordable high end audio.
We will be presenting schematics and construction details of vacuum tube and hybrid equipment. Full explanations with easy to understand theory will be provided for each design. All information presented is based on sound engineering principles (we are engineers), no new age crystals or "stones" that "clarify the sound" or $200 power cords. A full lab with an HP audio analyzer, an HP spectrum analyzer, several scopes and other equipment is at our disposal. We do not intend to repeat the same old designs that are already published on many web sites. We have already built many of them multiple times. Our customers have liked them and all of our sales have been by word of mouth advertising.
We have designed and built amplifiers that provide equal or better sound at lower cost. Initial listening test responses have encouraged further research which is ongoing. This web site will be used to disseminate the information and attempt to cover some of the cost of the research. We will be selling tubes, parts, circuit boards and vintage audio equipment, first on Ebay and later directly from this web site. If there is sufficient demand we may offer complete kits and finished equipment.
What do we have up our sleeve?
We have had good success with an operating condition we call A3. Useful for single ended amplifiers, the unique feature is grid current for 360 degrees of the audio cycle. This avoids the abrupt change in input impedance of a triode when the grid goes positive and begins to draw current. Used with "class B transmitting triodes" like 811A, 838, and 833.
We also like grounded grid operation for the same reason. The impedance change mentioned above is not present, even in A2 operation. This works with most triodes.
We have acquired over 100 thousand vacuum tubes with more on the way. We are analyzing (curve tracing) the types that we have in large quantity. We will report on types that are useful for quality audio which are commonly available at low cost. We like the 7044 (used in the Audio Note Ankoru) and the 5687 (used in the Audio Note Ongaku) for driver tubes. Both of these tubes are usually less than $5. We have built both of these amps and they do sound excellent but expensive. If you must build a 300B amp consider the first two stages of the Ankoru as your amp.
All of the amps mentioned above have been built, most of them were sold. They will be documented here shortly. We are currently developing "active current source" single ended technology to allow single ended sound with affordable transformers. We also are experimenting with "stacked singled ended" technology to allow push pull power levels without the crossover distortion.
A vacuum tube car audio amplifier has been constructed and is currently undergoing testing. It is 30WPC push pull using 26E6WG tubes.
We are also working on something really cool. We call it the "Solid State Transformer". Stay tuned for details.