This topic comes up a lot! Someone will email me with, “I want to build {insert project here} from your web site. But…”. Sometimes it’s just that part availability varies. Sometimes people want to use parts on hand which are slightly different. Sometimes people want to substitute tubes, transformers, or whole assemblies. And sometimes people want to actually change the topology! So at what point is the amp being built no longer the design on my website?
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A Quick History Lesson
For anyone who is interested in a little more of the history of feedback development, I have posted an article from the Proceedings of the IEEE from 1999. It’s a relatively quick but informative read about the topic.
Continue readingA Quick Note on Feedback in Audio Amplifiers
This may seem a non-sequitur to some. After all, I don’t post designs on this website that make use of feedback. This is simply because I don’t like the way feedback affects the sound of an audio amplifier. But that doesn’t mean that I don’t understand feedback and make use of it in other applications.
Continue readingThe Next Amp
So I’ve been thinking about my next amplifier project. And I thought I had made up my mind. Then things changed… again.
Continue readingThat “Other” Project
I have been working on the new SET chassis design but that’s not all I’ve been doing. This morning I got a little surprise when I checked on my sump pump under the house. It’s starting the rainy season here and I wanted to make sure everything was ready to go. Unfortunately, I found myself replacing a GFCI outlet and the sump pump that had failed and taken the outlet with it. Since the morning was shot, I decided to finish up a couple of other little projects this afternoon. Last week I mentioned another project, the portable class D amp. We’ll, I took a little time this afternoon to finish off that one.
Continue readingIntroducing the 6CY7 Zebrawood
So it’s been a while since I first grabbed the plank of Zebrawood in my shop and envisioned it wrapped around an amplifier. That was June 13th. Here it is a little over two months later and I now actually have a functioning amplifier. I have to say I’m pretty happy with how it turned out.
Continue readingSlow Progress
As some may already know, I’ve been working on a new version of the 6CY7 amplifier. There is a new chassis specifically designed for this amp and some circuit changes to improve performance. But here’s the issue, I can’t seem to get much done. Let me explain.
Continue readingWood and Metal
Well, the new version of the 6CY7 amp is coming together. The wood for the amp has gone from a raw 11″ x 58″ plank of Zebra Wood {Microberlinia brazzavillensis} into a finished amplifier chassis complete with four coats of Tru-Oil finish. I think it looks pretty good.
Continue readingRevisiting Past Endeavors
So, I was sitting here on this rainy Sunday morning going through some amplifier designs and looking through my stash of tubes and various amplifier building supplies. While standing there looking at the shelves of vacuum tubes, transformers, and various piece-parts, my eyes drifted up to an amplifier sitting on the top shelf. It was my 6AS5 µ-power UL amplifier documented here. But why was the little amp sitting on a shelf collecting dust? Then I remembered.
Continue readingGrounding Philosophy
I keep getting questions about amp grounding so I thought I would consolidate some of my previous notes on the subject. The first is a reprint of a forum post I made back in 2013 on the DIYAudioProjects Forum.
Warning: It has been brought to my attention that some people reading this post mistakenly believe that I am advocating the override, disconnection, or elimination of the safety ground (or bonding) connection in some pieces of equipment. This is not correct! The safety ground or bonding requirement for every piece of equipment is a firm requirement. At no time should any signal cable or independent wire be expected to fulfill the safety ground requirement for any piece of equipment. The process of “ground lift” is simply to provide a different signal ground reference in a piece of equipment.
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