I’ve been moving some amplifiers around today, listening to some that have been idle for a while and doing a little side-by-side comparison. And I’ve been reminded of a very important fact about amplifier performance.
Continue readingThere is truly nothing like the smell of a freshly wound transformer.
Continue readingWhen looking at schematics and builds of vacuum tube amplifiers employing output transformers some people notice a curious inconsistency. On some amplifiers, the output (i.e. secondary) side of the transformer is grounded, on others, it is not. This can lead to a dilemma for amplifier builders: To ground, or not to ground? Luckily, there are some simple guidelines which will almost always yield the correct answer.
Continue readingIn my last post, I talked about the changes I’ve made to my 807 prototype jig so that I could investigate the 400v, triode strapped, plate voltage limit. Now I’ve managed to spend some time playing with the high voltage prototype power supply and my newly modified jig. As a result, I’ve learned a surprising amount about the 807 operating as a triode.
Continue readingA comment by “Dave K” a few days ago got me thinking about how I intend to run my 807 power stage and the limitations listed on the data sheet. So it shouldn’t be a shock to anyone that I’ve decided that a little more testing is required. And that required an update of my 807 test jig.
Continue readingI have the initial set of data with the power supply prototype using the Edcor XPWR011 power transformer. It is enlightening and clearly shows which amplifier I need to build next.
Continue readingBe sure to look carefully at the environment where you do your work. Failure to look too closely may result in you sacrificing time and effort to the gremlins in the machine. At least that’s what just happened to me.
Continue readingOne of the risks of becoming too familiar with vacuum tube electronics is that it’s easy to become a little careless when working around high voltages. And because of this learned carelessness, sometimes we don’t take as many precautions as we should. Especially when prototyping.
Continue readingIn the modern western world there is this pervasive, and slightly bizarre, idea that the advance of all things (e.g. technological, medical, political, personal comfort, success, etc.) is a monotonic increasing trend from awful to awesome. And that just because something was once done or existed, then that thing is now “in the books” and there is no reason to ever revisit that thing, whatever it was. It’s a belief that once it’s been done, it’s easy to do again. But the universe is ruled by entropy. And if you stop fighting to reduce it, it just keeps growing.
Continue readingI was looking at some web page data this morning and I think I may have given a false impression in my post “You Never Really Know…” back in early November.
Continue readingI’ve finished modifications to my test jig to allow the testing of the 6BQ5/EL84. It’s really a shame that so few other 9-pin power pentodes use the 9CV pinout. The 6CW5/EL86 is the only other really common one.
Continue readingSo as I said in my post The Next Amp, I kind of settled on the triode strapped KT88 based on the power supply. Now I’m not so sure.
Continue readingSo I’ve had an experience recently that surprised me a little. And I’m wondering if this is what other people are experiencing.
Continue readingJust in case anyone was wondering, I have made a decision about my next power tube optimization.
Continue readingSo I’ve been thinking about my next amplifier project. And I thought I had made up my mind. Then things changed… again.
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