When 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 readingI had the opportunity today to sit down and finish up the wiring on the source selector unit chassis. It has been a productive week for this project. Now that the chassis is in good shape, I’m free to move on to the assembly and wiring of the vacuum tube circuits.
Continue readingI took some time this afternoon to get the metal work completed (mostly) for the Source Selector Unit/Preamp. All the drilling is complete and everything is properly fit to the chassis. The only metal work left to do is four holes in the mounting brackets which need to be drilled and tapped. These four screws will hold the top plate in place and make swapping tubes easier.
Continue readingI 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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