A while back in this post, “6L6 SE-UL Primed for Progress“, I mentioned that I would no longer be painting the exposed bottom plates of projects which won’t be seen. What that statement actually meant was that I would be leaving the aluminum in a bare “as delivered” finish. Or maybe with just a little steel wool polishing. But I’m now modifying that stance slightly.
Continue readingI first announced this SET on September 18th, 2020. It’s only taken me about 19 months to get to this point. To be fair, that 19 months was fairly eventful, including both my retirement and much of the COVID madness. But tomorrow, the slow methodical process of testing can finally begin.
Continue readingToday I was once again reminded of the perilous state of human fallibility and the risks of personal hubris. The cost of today’s lesson? One ruined KT-88. And a little smoke in the office.
Continue readingAbout a year ago my television display died and I was forced to buy a new TV. I had been using the Lacewood V2.0 amplifier for the sound system and, when I plugged in this new TV, it formed a bad ground loop with the amplifier, introducing a nasty hum. This was not an insurmountable problem. I simply dug through my parts closet until I found a little line isolator I had built about a decade previous for some project I was working at the time. I installed this isolator and the problem went away. But that’s not the end of this story.
Continue readingI took some time this week to get several coats of oil on the chassis for the Dual Triode Test Station. Even though I’ve already used it for the mystery tube investigation and to compare some 12AU7s, it’s good to have it finally complete.
Continue readingI spend a lot of time experimenting with various vacuum tubes circuits. It is a past time which I really enjoy. It also gives me an outlet for my creative tendencies when the workshop is too cold to make custom furniture (and amplifier chassis). As a consequence I have amassed a fair amount of test equipment and miscellaneous cables, adaptors, probes, and other odds and ends over the last decade or so. And regardless of the fact that I want to concentrate my attention on my vacuum tubes, sometimes it’s the other things that demand my attention.
Continue readingBack in November, in my post concerning Tubes and Tube Testers, I talked about how I was not really a fan of generic tube testers. In that post I sited a statement from the RCA “Receiving Tube Manual”, RC-30, about testing tubes.
The tube tester cannot be looked upon as a final authority in determining whether or not a tube is satisfactory. An actual operating test in the application will give the best possible indication of a tube’s worth.
So I thought that as a simple demonstration I would collect some data from a couple of tubes; one new and one rather ‘used’. The results are really kind of surprising.
Continue readingThis has happened to most of us at some point or another. You come upon a tube with no markings whatsoever mixed in with a bunch of miscellaneous tubes. Or, like I just did, you get a “lot” of tubes from a reseller and most are marked but a few are wiped clean. But how does one go about positively identifying the mystery tube? Especially with the numerous types of 7 and 9 pin miniature tubes in existence this can seem to be a rather daunting task. However, just like a game of “20 Questions”, it is actually simpler than one might think.
Continue readingI had thought that the coupling capacitors I ordered on Tuesday would not arrive until this Saturday. However, the gods of DIY decided to smile down upon me and the capacitors showed up in today’s mail delivery. In my opinion, two days from order to delivery is exceptional. I spent some time this afternoon with a soldering iron in hand and the Color Preamp is now fully assembled.
Continue readingIgnoring the wood chassis for the time being, I made significant progress on the triode test jig today. I just thought I’d post a quick update. Parts are now mounted and some wiring is underway.
Continue readingI’m working on two projects simultaneously right now; the 6AS7 SET and the Triode Test Jig. In the last couple of days I’ve made progress on both. However now I appear to be at an impasse.
Continue readingThe weather has finally returned to normal here and I got to spend a little time in my shop today. I decided that I wanted to be able to finish the base of the SET and my new triode test jig at the same time. So I needed to get going on the test jig base.
Continue readingWhen I talked about designing the Dual Triode Test Jig in the “More on Tube Testing” post I mentioned an indulgence. Well the results are in.
Continue readingWe’ve had a chilly rain/snow mix today at CascadeTubes so it’s a little too cold to work on the SET chassis in my unheated shop. Instead I’ve been thinking about my new triode test jig and have been going over the tube list that it covers. There are lots of tubes on the list with which I am not intimately familiar so I’ve been pulling data sheets and doing some investigations. And I’ve received some pleasant surprises!
Continue readingEver since I completed the Optimization of the 6V6 SE-UL I have been saying that I was going to do the SE-UL optimization process for more tubes. So yesterday I finally started to make plans.
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