We got some unseasonably nice weather here today. Clear blue skies and about 72° outside. This meant I got some time in my shop to move projects forward.
Continue readingAn Update, Update, Update?
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Tone Controls?
For the last couple of days I’ve been revisiting an idea for a “tone control” preamp. I had originally decided to go one way with the design, but then something happened to change my mind. My ears got involved.
Continue readingAn Update on the Update
I haven’t talked about the new amp in a while so I thought I’d share current progress.
Continue readingSome New 6L6s
Yesterday I auditioned some new reissue Tung-Sol 6L6GC STR tubes in the 6L6 “Spalted Alder” amp. I was quite surprised at the results.
Continue readingThe Other Bits
I seriously despise cheap interconnects. And I don’t mean inexpensive, I mean cheap.
Continue readingCathode Bypass and Frequency Range, Part II
In my last post I threw in a comment at the end pointing out that lowering plate load resistance will play a part in how the cathode bypass capacitor behaves. Someone asked, so I thought an example of how this affects things might be in order.
Continue readingCathode Bypass and Frequency Range
There seems to be a little confusion concerning the true effects of cathode bypass on low frequency amplifier performance. The truth is, gain benefits from cathode bypass are limited. And not by capacitor size, but by the basic design of the amplifier stage.
Continue readingShifting Priorities
Remember when I said that you can’t always get what you want? Well, it turns out you can. At least in this case. Especially if you are willing to shift some priorities.
Continue readingHere We Go Again
Remember back in the beginning of January when I traced the failure of the Lacewood amplifier to a failed JJ power tube? Well, here we go again.
Continue readingYou Can’t Always Get What You Want
Lately I’ve been looking at a revised amplifier design based on the Marblewood project. The intent of the redesign effort is threefold. First, a different and more widely available rectifier tube. Second, an improved, if slightly more complicated, power supply design. And third, some potential improvement in the low frequency response. As it turns out, you can’t always get what you want. But also, two out of three ain’t bad.
Continue readingImproving Testing with Modern Technology
There are lots of practices in the DIY world that are more than a little out dated. I’m obviously not talking about using vacuum tubes but rather the methods used in building and testing the circuits we build with them. Many of these test methods came about for very good reasons; perfectly applicable at the time. But as technology has advanced the reasons for many of these practices are no longer valid. And there is really no better example of this than the practice of testing audio amplifiers with square wave (or various sawtooth or triangle wave) signals.
Continue readingA Cautionary Tale
After a busy Christmas season, including a brief trip out of state between Christmas and new year, I have finally managed to get the Lacewood amplifier back up and running. As part of this effort I also identified the root cause of the initial failure. And frankly I’m a little angry about it.
Continue readingI Spoke Too Soon
Remember a few weeks ago in the post When it Rains, It Pours! I said that the Lacewood V2 reservoir capacitor had likely failed? Well, I was wrong.
Continue readingThat Didn’t Go Well!
Have you ever made a mistake? Not a typical everyday little mistake like forgetting to run an errand, but a blunder of such proportions that you’re shocked by your foolishness? One that leaves you thinking you couldn’t have been that naive, that foolish? Well I did. And it left me with significant embarrassment, as well as some smoke coming out of an amplifier.
Continue readingWhen it Rains, It Pours!
Would you believe it? Today while listening to the 6V6 Lacewood V2 I heard a funny little popping sound and a short duration whine. It only lasted a few seconds, then it was gone. But when I walked over to the amp there was a distinct smell of “magic smoke“. Once again, the game’s afoot!
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