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 added specific transformer and configuration information to the Tubes and Applications page. There have been numerous inquiries about a small parts kit for this board. I have decided to offer a kit containing all of the parts to populate the PC board. Most of the parts have been ordered and I should have everything some time in November.
There have been far more questions about the Tubelab SE. The parts list has been modified to reflect the changes outlined below.
If you have a Tubelab SE 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 Simple SE 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.
A Tubelab SE in a clear Lexan case
A new Tubelab SSE Amp
Sherri’s stepfather passed away about a month ago. Sherri’s had to go stay with her mother to help her deal with all of the associated issues. She has been gone for 4 weeks, and will not be back for at least two more weeks. This has left me to deal with all of the things that she usually handles. Those in the USA know what time of year this is. Personal income taxes (ours and my mothers), corporate (Tubelab and G&S programming) taxes, and corporate annual reports all must be done. I have less than two weeks left to complete them, and I am not done yet. There has been no activity related to Tubelab in the last month.
Sherri's mother had relied on her husband to handle all of her finances for the past 20 years. She had not touched a checkbook in 20 years, and had no knowledge of insurance policies, retirement accounts, house and auto ownership deeds etc. These things are real hard to figure out after after the fact. This experience has let me see just how much I have relied on Sherri to handle all things financial. Fortunately she is still a phone call away. If this describes your situation (or your parents) do all you can to learn about this stuff before something happens.
My new computer is finally operational, and most of my applications and data have been migrated. Microsoft has decided not to offer anymore upgrades to the Front Page software that I have been using to make this web site. They now offer Microsoft Expression Web as the upgrade path. I purchased Expression Web and loaded on my computer. I tried to use it on my web site. It doesn't work with my site. Expression does not support the navigation structure built by Front Page, and tells me that my Web site was not built to current web standards. I bought a couple of books, and decided that this is not going to be easy. I am still using Front Page for now.
I have been on the road for almost every weekend so far this year. Most of this web update was written from the passenger seat of a car on my laptop. Some pages are still incomplete, but I decided to post what I have since it has been a while since the last update. Most of the SSE manual is complete, except for the wiring diagrams, parts list with vendor part numbers since I don't have internet access in my car, and the assembly pictures of my latest amps, since I haven't been home to take the pictures. I built (and documented) the Industrial amp shown above in December, and haven't had time to listen to it since then. I haven't touched a soldering iron yet this year either.
I have not yet figured out how to set up an internet shopping cart on my web page. It must be set up interactively on the server, and again, I have not been home to figure it out. I plan to begin listing the PC boards on Ebay as soon as the parts lists and wiring diagrams are complete. If my current work schedule does not change, this should be in a couple of weeks. My Ebay ID is Tubelab*com. There is nothing posted there currently.
I have fallen far behind in answering email. I thought that I could catch up over the holidays, but my planned two week vacation turned into 6 days off from work. I spent one to two hours per day answering email. During this time I received more email that I answered. I still have several hundred emails in my in box, and 5 or 10 come in each day. I have come to the realization that I may never catch up. All email from purchasers of my boards has been answered promptly. Much of the other email concerns PowerDrive. The PowerDrive cookbook page is not finished yet, but I have posted the first part. More email concerns the availability of the PC boards. They will be available shortly, and the ordering info will be posted here. Email that requires considerable time, like those asking me to design a special circuit, or modify or test an amplifier that I have never seen often does not get answered. I simply don't have the time to design one off circuits until I get caught up.
Many questions (e-mail and diyAudio forum) relate to the PC boards. I get questions that ask about the "SE board". I have no way of knowing which board you are referring to, since there are now two different SE boards. I have also received questions asking how to wire a DHT into the SSE board and vice versa. This is not really practical. Each board was designed and optimized for the type of tubes listed in the assembly manual. I simply do not currently have the time to assist with a custom design or application for these designs.
The most popular questions are," Where can I get a board" and "When can I get a board". I plan to offer the boards directly from an online ordering page on this web site. I have that option on my current hosting plan. I may also offer them from an Ebay store. I will do this as soon as the assembly manual is finished. Most of the manual is finished (all of the fun amp building stuff). I need to finish processing about 200 pictures and organizing all of the text. I have about 3 weeks worth of work at my present rate, but I can not predict the demands of my full time job, which have been considerable, and require 8 to 10 hours of sitting in front of a computer per day.
The progress will be posted here on this page, and ordering information will be posted here as well.
It has been over 1 month since I ordered my new PC. It is still in pieces, occupying my workbench. I returned the defective memory, but have not received the replacements. Two of the three shiny new PC boards shown above are impatiently awaiting assembly into amplifiers, but I have no bench space. The middle board already has a happy home in a new amplifier. I have not been here much anyway.
Last Thursday was the Thanksgiving holiday here in the USA. Traditionally it is spent with family. I drove to Tampa to celebrate Thanksgiving with my mom and brothers. The Friday after Thanksgiving has evolved into a major shopping event with half of America going to the shopping malls. This is a tradition that I do not choose to support, so I dropped Sherri and friends off at a mall near Orlando. A friend and I went to Daytona for the Turkey Rod Run. A 5 day celebration of all things automotive, where I spent 5 hours before going back to Orlando to pick up Sherri, and return to Ft Lauderdale. A page full of pictures has been added to the automotive pages.
Saturday and Sunday was spent working on the SSE assembly manual, and updating this web site. I have added more of the assembly manual, with more to come after it has been proof read by a few others.
Monday I returned to work, and was rewarded with another "must be done before years end" project. This means more days like today, 11 hours in front of a computer.
My father would have been 85 today. My 5 year old PC has been acting erratic for the past year. I decided that It would be wiser to replace it than to keep repairing it. I usually build my own PC’s but I decided that I would order a custom built PC to save time. I chose a Core 2 Duo computer from a company that has a 3 or 4 page ad in several major computer magazines. They offered a special deal featuring next day shipment and a fat discount, so I ordered one. It two weeks to get the computer and it wasn't configured as I ordered. I then spent almost 2 days loading it up with all of my applications, and copying almost 100GB of data on to it. As I loaded software on to it, it became more and more unstable. After 2 more days it became totally unusable. At first my e-mail and phone calls went unanswered or not returned, or I got responses like "you shouldn't be using 64 bit Windows". They sold it to me! I asked twice for an RMA # to return the whole PC. Then I finally got to e-mail a tech. By this time my whole workbench is covered in dismantled PC and software. It has been almost a month since I placed the order, and I finally have figured it out (with some help from their techie). It seems that the machine will pass a complex suite of memory test software (the one on the Suse 9.3 distribution CD) for 6 hours with 0 errors, but the system memory is schizophrenic with 64 bit Windows, stupid with 32 bit Windows, and just plain dead with Suse Linux. Two memory SIMMS from a local store and the machine is happy, and awesomely fast too. Now I get to load the software all over again. Maybe I will have my workbench back in a few days. I think this could have happened if I built my own machine as well, but I have built a lot of PC's (50 to 100) in the last 20 years, and I have never seen memory that passes a complex test suite, but fails in normal use.
I am posting this update from my laptop.
I have added the schematic for the entire Tubelab SSE amp.
I have uploaded parts of the Tubelab SSE manual. Pages that I have had the time to finish, proof read, and have an associate use to assemble a board are posted. Much of it was written on my laptop in the passenger seat of a car. I have been away for 5 of the last 6 weekends. I will be away for the next two weekends also. I plan to finish most of the manual during the traveling time. If all goes well the shopping cart will go live during the last week of November.
Because I wrote most of the assembly manual while traveling, there are probably errors that we didn't catch. If there are any, please e-mail me and I will fix them. I have fixed the ones that I received e-mail about (mostly wrong pictures). Please e-mail me if anything is not clearly understandable.
It has been about two months since I last updated this web site. A lot has happened since then, and I have not had time to update this web site. I should have known what was waiting for me after almost a month off of work. I have been working a lot of hours since my return. Most of my time away from work has been spent on the SSE assembly manual. It is nearly done.
I received about 1000 e-mails while I was away. Unfortunately some spam artists have acquired my e-mail address and filled my mailbox with offers of sex pills and penny stocks. This caused my email box to fill up (twice) and some e-mails may have been lost. E-mail that gets caught by the spam box still counts against my quota until I empty the box. If you e-mailed me in late August or September and never got a reply, your e-mail may have been lost. Please send it again. I try to answer all serious e-mail. E-mail from customers with questions get priority, everything else gets answered in order of receipt. I am currently about two weeks behind answering e-mail. My current work schedule only allows me time to answer e-mail on weekends.