Welcome to the TUBELAB home page
Dedicated to advancing the state of the art in affordable high end audio.
A Tubelab SE in a clear Lexan case
A new SimpleSE Amp (front panel not finished yet)
The SimpleSE PC boards are now back in
stock.
A new large supply of boards is here (SimpleSE on left, TubelabSE on right)!
Are you still in business? Are you OK?
These are just a few of the questions that I have received via email lately. The tone and quantity of these questions changed drastically about 2 weeks ago, so I assume that there must be a forum post out there somewhere telling of my demise. So here are the facts. There have been several unfortunate circumstances that have forced the scaling back of the "Tubelab business plan" for the near future. Tubelab is still very much in business. I posted the picture above to iterate this a while back. I have plenty of the PC boards, and I ship them out 2 or 3 times per week.
Sherri has been home for about 4 weeks total this year. Her mother (who lives 1200 miles away) has advanced Melanoma, her husband died of cancer last year. She has been living alone so Sherri is currently staying with her. She is now entering into an experimental course of therapy at the University of Pittsburgh. Sherri took care of many of the day to day tasks that keeps Tubelab operational, including shipping and answering some email. I am now handling those duties, so there hasn't been much time for the web site, amp building, and general tube torturing. It is not known when or for how long Sherri can return.
I just had a cancerous tumor (Sebaceous carcinoma) surgically removed myself. It wasn't my first, and probably won't be my last. The doctors tell me that "I will be fine." There will be more testing and monitoring in my future.
I have a full time engineering job with 50 hour work weeks. The company that I have worked for over the past 35 years is not doing well. They have shed over half of the workforce in the last 5 years. Many of my friends have been laid off. This leads to long and often stressful work days.
Yes, I have been seen at Hamfests selling vacuum tubes and related items. This does not mean that Tubelab is going away. If my job comes to an end and I must relocate to find employment, there is no way that I can move all of my "stuff". My recent experiences have led me to the conclusion that I have far too many projects. More that I could possibly finish in two lifetimes. I have decided to sell off some of the items that I will never get to. I plan to list some of the better items on Ebay if I get time.
You haven't updated the web site this year. You never answer my email. It took you a week to answer my email.
The web site is indeed overdue for a major update. I started work on a whole new web site using new software last year. It is still far from being ready. With limited time, I have been hesitant to work on two different Tubelab web sites, so this one has been ignored. Frankly, I have not had much time to work on any new material, so there hasn't been much new to post. See the "what is next for Tubelab" section below for info on what has happened, and what will happen to this web site.
I get anywhere from 20 to 50 emails per week. Answering most of them takes all of my Tubelab time lately. All email related to the PC boards is answered first. I try to answer other email as time permits. There have been weeks where all I have time for is answering email, and I don't always get to them all. I can not answer Tubelab email from the computer at my job, and I am often there until 7 PM. I get considerable email asking me for something unique. Often it is a request for help designing an amplifier with an unusual tube, or for experiments on a unique tube. Sometimes it is a request for further information on an old experiment. Please understand that these requests require considerable time and effort to research, and I simply do not have that time. Some of these emails do not get answered due to lack of time. If your email is to criticize me or the web site, it will get read, but it will not get answered. So complain if you want, just don't expect a personal answer.
What is next for Tubelab, and the web site?
I get a lot of email asking similar questions, and of course there are plenty of questions about the SimpleP-P. First things first.
MiniTron (no update)
I got a lot of email about the MiniTron. Some called it cool, some thought it was criminal, most was positive though. Either way, the MiniTron and its derivatives will have to wait until I have more time. Circuit Cellar is still waiting for me to write an article about it for their magazine, but I don't have the time right now. The MiniTron now sits, lonely, all alone in the closet, waiting for some attention.
SimpleSE update
There have been a few questions related to the construction of amps. Many builders request an exact parts list with part numbers and transformer recommendations for the "standard configurations" It is impossible to cover all of the possible combinations, but I have gathered information from builders all over the world, and a new parts list is coming.
TubelabSE update
There have been far more questions about the TubelabSE. Many of the issues relate to the 2KS2700. I am in the process of testing several new substitutes in several different amps. The 2SK2700 worked fine in amps that ran on B+ voltages from 275 volts to 400 volts. It did not oscillate either. I am looking for the "perfect" replacement. I have been using Fairchild FQP1N50 and Toshiba 2SK3563, with my preference toward the Toshiba. Reduce the mosfet current as outlined below for B+ voltages above 325 volts with either part.
Here are four TubelabSE boards being tested. The board in the lower right is the original TubelabSE prototype. It sill works and is my "control" board. The board in the lower left is a customers board, it is for verification of the new 2A3 component values. The other two are my experiment boards. I have two more boards being tested that are not shown in the photo. Yes, the box is full of 45 tubes! I have a similar box full of 2A3's, but due to the expense I am limited to Shuguang and Sovtek 300B's. What is all of this about. It is about commitment. I am aware that the TubelabSE is not the easiest board to build, and the original parts list left something to be desired, so I am in the process of developing 3 separate parts lists. There will be a unique parts list with each set of parts optimized for the 45, the 2A3, and the 300B tubes. I plan to build one amp for each tube type and cover the build on the web site. The parts lists are being complied now, pending a few more experiments and the verification of the new parts after they arrive. At the moment, I don't have much time for amp building, so I can't say when the amps will be done.
If you have a TubelabSE and it is working OK, leave it alone. If you have any instability, or have experienced blown mosfets, make these changes. If you are starting a new build, or in the process of building one, make the following changes.
Increase the grid stopper resistors on the 5842 (R31 and R32) from 1K to 4.7K ohm. These resistors should be carbon composition if at all possible. The 5842 will oscillate if given the opportunity. The higher stopper resistor value will help. If you are using a volume pot on the board, make sure that the case of the pot is grounded. The cable from the board to the input jacks should be connected to ground on the PC board, and connected to ground at the input jacks. All ground connections to the chassis should be made at the input jacks. See the wiring diagrams for the SimpleSE for details. The oscillation occurs in the 100KHz range which is inaudible, but may be heard as a hum or buzz. It can also cause the output tube current to rise unexpectedly.
R14 and R25 set the operating current for the mosfets. The parts list shows a value of 20K ohms. This is good for boards that operate from 275 to 325 volts of B+. Boards that operate from 325 to 360 volts should use 30K ohms. Boards that operate from 360 volts to 400 volts should use 36K ohms. This will reduce the dissipation at higher voltages. The B+ voltage may be considerably higher than normal during the time that the tubes are warming up. This is especially true with low cost power transformers. Voltages of 450 volts and higher have been seen, which combined with high mosfet current can lead to blown mosfets on power up.
C6 should be rated for the full B+ voltage, and the expected rise on power up. This means a 350 volt cap is OK for 45 amps that run at 275 to 325 volts. A 400 volt cap should be used if your B+ is from 325 to 360 volts, and a 450 volt cap is needed for boards that run from 360 to 400 volts. It is unlikely that a 100uF cap that will fit the PC board can be found in the higher voltages. It is OK to use an 82 or 68 uF cap.
The SimpleP-P is coming (not soon)
OK, the word has leaked out, I have been working on the early stages of development on a push pull amp on and off for several months. Actually there will be two amps. The first, and the one that I have been working on, is a small amp of about 8 to 10 WPC using the 6AQ5 - EL90 tube for output. The driver stage is still undecided. As with the SimpleSE it will be a build and play amplifier with no adjustments needed. The PC board should be the same size as the SimpleSE so the cost should be the same. I can't even venture a guess as to when it will be ready given my current schedule. I have spent maybe 10 to 20 hours on it this year. The second amp is a larger design using any of the popular audio tubes that work in the SimpleSE. Power outputs to 60 WPC are possible. The PC board will be larger, so it will cost more. This one is still in the simulation stage, so there aren't many details yet.
What about kits?
Sherri started working on the first non PC board product for Tubelab last year. It is a "bag of parts" for the SimpleSE. It contains all of the components that go on the PC board. That came to a halt when her mothers cancer was diagnosed.
The MiniTron amplifier was designed for entry into the Circuit Cellar / Microchip design contest. In a sea of microprocessor powered IC based gizmos this vacuum tube amplifier WON ONE OF THE CATEGORY PRIZES!!! It should be featured in the Circuit Cellar magazine in the near future, and is currently on their web site. I will be posting much more information about this design in the coming months. You don't care anything about an amplifier that has more chips than tubes? I don't blame you, but this project has taught me a lot about the distortion producing mechanisms in vacuum tube circuits. I am using this information to design some radically new vacuum tube circuitry, that is silicon free, as well as some unique hybrid designs. Unfortunately the events outlined below have severely slowed down the progress. The amplifier you see above was completed in early October, and hasn't been touched since.
Progress has resumed slowly with the design of an all tube cathode follower amp incorporating some of the technology developed during the development of the MiniTron. A new page for this design will be created soon. One component of the MiniTron is the cathode follower amplifier, which still has its own page. The complete contest submission including schematics, source code, and design details can be found here:
http://www.circuitcellar.com/microchip2007/winners/MT2209.html
Boards can be ordered using PayPal or by sending a money order through the mail. Details are on the PC board ordering page.
More pictures have been added to the page of users amps. If you have built an amplifier using either of our boards, and you want the whole world to see it, send me pictures, and any details via email. Indicate if you want your name used. (the following two links are not on my web site) A SimpleSE amp built by a customer was shown at the Burning Amp Festival in San Fransisco. The pictures are here.
I have added a complete parts list for the SimpleSE board and simple pictorial wiring diagrams to the SimpleSE assembly manual page. The Tubes and Transformers page is still under construction, the data from completed amplifiers will be added with the next update.
I have started revising the TubelabSE assembly manual. A new parts list has been added, the Tubes and Transformers page has been fixed and updated with transformer information, and some other pages have been revised. More will be added as soon as I have time. New checkout instructions for both amplifiers are next.
I have begun to reorganize the web site in preparation for the eventual conversion from Microsoft Front Page to Microsoft Expression Web. I didn't realize how disorganized this web site has become. The Assembly manuals for the PC boards are now located on the Our PC boards page. The manuals illustrate how to assemble and checkout the PC board itself. A separate section has been started to illustrate the assembly of an amplifier using our boards. This is done because some amplifier designs could use either board, and more are coming.
A word about this site:
This web site is here to present the amplifier designs and circuit ideas that I have developed. Much of the information is intended for experienced tube amp builders. We do not intend to cover basic electronics or vacuum tube theory. Neither will we devote much time to the classic designs that are already well covered on the web. I have initially focused on circuits and ideas that are unique, or have the potential to reduce the cost of high end sound. It is assumed that the reader has the basic tools (digital meter, soldering iron, chassis punch, drill, and perhaps access to an oscilloscope) and the knowledge to use them.
Due to the many requests, I have attempted to add content that is useful to a vacuum tube beginner. I will attempt to write new content such that it can be understood by a beginner, but this is often impossible when dealing with advanced topics. I have recently designed an amplifier that could be built by a beginner, but is still useful to an advanced user. I have added a color coded icon to each page that attempts to demonstrate the skill level that is required by a project or a concept.
This icon indicates that this project or concept could be attempted by people of all skill levels. The reader should still understand the risks involved, and the safety required with the voltages involved in vacuum tube electronics.
This icon indicates that some knowledge of vacuum tube electronics is assumed for understanding of the concepts presented, OR that some previous vacuum tube project construction experience is needed to build the project.
This icon indicates a project or concept that requires considerable knowledge or experience to complete. Often this is because complete construction details are not presented.
This icon is used to indicate a project that involves very high voltages, or a concept that has little chance of success without considerable experimentation.
All material and schematics on these pages are (c) Copyright 1999-2007 by George Anderson and Tubelab Inc. The information presented here is intended for the personal use of the reader. You may freely use the information contained in this site to build your own equipment. You should not use this information to produce commercial equipment without a licensing agreement. It is my intention to freely share all of the designs that I have. I will not attempt to patent any of the unique designs or keep them out of the public domain.
Feedback:
My only feedback about this site is e-mail from the readers and the statistics from the web hosting company. Several changes have been made in response to your suggestions. The site is being simplified. Pages that were visited infrequently have been combined or eliminated. Many pages are being updated to answer recurring questions. The automotive pages (mostly pictures) have been expanded due to reader requests.
We will begin selling some of the "stuff" (over 100,000 tubes and other treasures) that is in our warehouses on Ebay (Ebay id = tubelab*com) to offset the web site and development costs.
I have limited time to devote to this web site since I work a full time (45 to 60 hours per week) at a large electronics company. Many of my friends who I have worked with for 20 to 30 years have been laid off. I must make my job priority #1. Work on this site happens in my spare time. I have a list of requests from readers for specific projects. Distilled down from that list is the list of my next few amplifier designs. The next one will be a plug and play SE amp mentioned above.
A word about safety:
This web site deals with audio amplifier design using vacuum tubes and high voltage solid state devices. The voltage and current levels associated with the designs presented in this web site are potentially lethal. If you have no experience working with high voltages, please enlist the help of a qualified technician who has experience with vacuum tubes. We are presenting information for use by qualified individuals for educational purposes. We are not responsible for accidents, acts of random stupidity, burning your house down, exploding parts, and other undesired actions (all of which are possible) resulting from the use of ANY information on this web site. Should you decide to attempt to build any equipment based upon information provided by this web site, you are doing so at your own risk. If this sounds serious, it is! All vacuum tube circuits operate at dangerous voltage levels. The 845SE and other powerful tube amplifiers operate at over 1000 volts. Accidental contact with an energized circuit of this nature would likely be instantly lethal.
It has become obvious to me that there are warning messages like the one above on most vacuum tube web sites, but very little information related to electrical safety. In fact I found essentially no information specific to vacuum tube experimentation. At the same time "fear of frying" has become the topic of many emails that I have received lately. Setting up a new amp and testing it seems to evoke the most fear. This is justified, since that is where the most risk is. A few have expressed the need for a good source of information, and I actually got a request for a tube amplifier design that couldn't shock you because it ran on batteries. With this in mind I have started a new section of the site devoted to electrical safety, and safe practices. I have included information outlining how to set up your bench and work on tube equipment while minimizing the risk of electrical shock. There is a section on how to use multiple meters to set up a new amp that virtually eliminates the shock risk. PLEASE READ THEM! Do not proceed unless you (or your mentor) understands the information presented here. IT MAY SAVE YOUR LIFE.
Contact information:
We welcome your ideas, circuits, suggestions, and questions that relate to the material presented on this site. I can't help you decide which amp, speakers, tubes, or components to buy. Those questions ask for an opinion based upon personal choice. My personal choice is likely to be different than yours. I will try to answer e-mails when I can, and discuss recurring topics on this site.
