tube fanatic

Have you run older 6BG6s at much over 19 watts dissipation without issue? If wanting to do that I recommend picking up some Phillips 6BG6GAs from Mike Marx at SND tube sales. They are truly equivalent to the 6L6GC and will run at 30 watts dissipation all day without issue. Maynard

For those who like the 6BQ5 or EL84 go with a 6GK6 which can be purchased NOS for about $8. It is electrically identical but with a different pinout and was used in many tvs. You can even go with a 16GK6 for about $3! Maynard

Rodrigues was a genius! Maynard

Many of the power supply and other questions were previously raised by former forum member xxJPMxx in the original thread, and answers were provided. If the amps are constructed as mono units with the specified parts, the only voltage reference really needed is the plate to cathode voltage of the 6Y6. We can safely assume that the other voltages will follow. The reference point for specified electrode voltages in manufacturer tube data is always to the cathode in tubes having one. In the original thread, John Lumley posted his power supply variant which some may find interesting and informative. And, former forum member wdecho posted his FFT measurement of the amp which is interesting as well. I agree with Henry that his build thread should be kept on the non-technical side. His implementation has worked very successfully and anyone emulating his work should expect to obtain similar results. I suggest starting a new thread for improvements to the original design for those more technically inclined. Suggesting changes to the design based on calculations without experiencing the original is analogous to a chef wanting to improve a recipe without tasting the original form. Maynard

Since Henry mentioned Deckert’s Zen Triode, prospective builders of their first tube amp may enjoy watching Deckert actually build one. Be sure to watch all 12 videos. Seeing a point to point build in real time gives a somewhat different perspective from seeing still photos. https://www.youtube.com/watch?v=n1ENOdYN6iA Henry, if you think this will dilute the thread, I will delete it. Let me know. Maynard

Henry, it is unfortunate that we live so far apart. We could sit on the porch of the general store reminiscing about the good ol’ days. I am also a bald old timer, but 50# underweight. A local farmer offered me a job as a human scarecrow. If I had time, I would take him up on it! Maynard

Nick, how are you planning on configuring the 12AV7? Getting around 21V rms from one section to fully drive the 6Y6 as used in the Sweetie will bring the distortion of the 12AV7 into the 5% range. This is not a bad thing in my opinion. You could set up the 6SJ7 for minimum gain to allow use of your preamp and minimize driver distortion if desired. Maynard

Hey folks! It has been a while so Henry twisted my arm to say hello. The plate curves of the 6Y6 are very similar to those of the 2A3. The former have the distinct advantage of being inexpensive and abundant, and don’t have the DHT filament issues to deal with. It is a wonderful tube all around. I have taken a break from amp design and building for now due to a number of old radio restoration projects which have accumulated due to the move 6 months ago. Hope everyone is well. Maynard

Educational. There are many “experts” claiming that one type of mask is vastly superior to another. This study found little difference between two popular types. Maynard

Since this is about influenza virus, and not COVID, perhaps it won’t be deleted: https://jamanetwork.com/journals/jama/fullarticle/184819 Maynard

Joe, Travis will not be happy that you posted this! I am waiting for his response to my questioning why he believes the patents have anything to do with anti-vaxxers and conspiracy theorists. They do prove quite well that COVID was lab engineered for a very specific purpose. Maynard

Travis, if you get the chance, PM or email me with your reasoning that the patents enumerated in the video have anything to do with anti-vaxx beliefs or conspiracy theories. What social media sites say is quackery means nothing, and YouTube would have deleted the video if it was not valid. Fuellmich, the attorney, appears to be highly respected as well. The patents cited are pure science and were granted to our own government agencies, Fauci, Baric, Moderna, et al. Maynard

[Deleated, so far off topic. Are you vaccinated, worried about side effects] Waiting to get banned……. Maynard

And here is the disclosure Pfizer made to Japan’s ministry of health. Scroll down to the section in English on organ distribution which reveals how we have been told lies about the vaccine remaining in the injection site: https://trialsitenews.com/wp-content/uploads/2021/06/Pfizer-report_Japanese-government.pdf In case, you didn’t see it, look at the thread I started on patents and download the links before they are deleted. You will be shocked what the patents say. Maynard

Jeff, I applaud you for stating your feelings and I am surprised your post was not deleted for presenting a view which is not mainstream. This video explains how mRNA vaccines work and I have read multiple studies which support the mechanism presented and the resulting vascular damage. https://www.bitchute.com/video/uD98ksu0PzQg/ And we know that FDA approval means nothing! Maynard

Voltage regulation in SETs is unnecessary due to the near constant dc current draw under all operating conditions. Of course VR tubes are pretty to look at in a dark room! Deckert is using the option of different voltage drops among some of them to change the plate voltage of the driver which, of course, changes the distortion characteristics to tailor the sound to suit. This could more easily be done other ways but that would not have the “coolness” factor of the VR tubes. Only you can decide if it is worth the extra cost. Maynard

It would be fine to use the 1627 although it may not be much better than the 125ESE in this application. The bandwidth of the latter is extremely wide due to being operated at such a tiny fraction of its output power rating. Personally, I would build the Millie as shown and keep the size and weight down. Look at George Anderson’s measurement of the 125CSE to gain some insight about transformer bandwidth as a function of output power: http://tubelab.com/articles/component-testing/budget-output-transformers/ Maynard

Those who can live with less power can achieve 2A3 performance with a triode strapped 6Y6 which can usually be found NOS for around $4.00. The curves are very similar. And, of course, a pair could be used in parallel for a little more “oomph.” Maynard

Yes, the alternate grounding scheme may be of some use although this amp is dead silent in every system in which it has been tried. The Millie is quite a contrast to the SET monster you posted the picture of! Good to have you on here Nick! Maynard

Is your wife still using post surgery drops? They can sometimes worsen an existing dry eye condition. Did the ophthalmologist recommend a trial with cyclosporine? The latter is often very helpful in dry eye patients. Maynard

Mixing brands is fine. With intermittent tube problems it is easier to replace the suspect than to try to figure out what is going on. A tube tester rarely picks up such issues. With push-pull stages I recommend replacing the pair and buying from a seller who can match them using a curve tracer. Maynard

Zen, are you saying that the American Academy of Ophthalmology is spreading disinformation? I sincerely hope not. If you believe that a general practitioner knows as much about ocular conditions as an ophthalmologist then I wish you luck! Maynard

Well, if a person who has had corneal grafts develops symptoms and sees their family doc who is clueless and loses their sight as a result I imagine they will be more depressed! Knowing the possibility would likely result in their seeing an ophthalmologist instead and saving their eyes. Maynard

Beautiful work George! A forum member in Tennessee is looking for someone to build him an amp. PM me if you are interested and I will get you in touch. Maynard

Wearing glasses cannot cause them to get weaker faster. The brain can get accustomed to the level of clarity which glasses or contact lenses allow. If you try to take that away after a length of time a person can feel “blind” although nothing has changed. This is seen across all age groups and with correction for myopia, hyperopia, and astigmatism. Maynard