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08-22-2019, 12:13 AM
hey
Soma-84 is the exception that makes the rule
I designed this for a friend who then built it using transformers I supplied. He chose to ground the circuit at the input jack and it was quiet so he left it that way. It is not how I would do it as witnessed by all the other projects.
You can get away with certain things like this in low-gain amps, but were you to modify the amp later it would be wise to insulate the input jack and take the ground tie from the middle of the circuit.
All those old projects use Switchcraft jacks which are good and bad. The large contacts make the jacks robust but the weak part is the crimp holding the whole thing together. If you over-tighten the jack, the crimp loosens and the wafers and layers of the jack rotate out of alignment and do not stay tight any more. It is a good reason to switch to plastic jacks which are already self-insulating. With plastic jacks, Switchcraft becomes a poor choice as theirs always seem to have smaller contacts than the competition.
Soma-84 is the exception that makes the rule
I designed this for a friend who then built it using transformers I supplied. He chose to ground the circuit at the input jack and it was quiet so he left it that way. It is not how I would do it as witnessed by all the other projects.
You can get away with certain things like this in low-gain amps, but were you to modify the amp later it would be wise to insulate the input jack and take the ground tie from the middle of the circuit.
All those old projects use Switchcraft jacks which are good and bad. The large contacts make the jacks robust but the weak part is the crimp holding the whole thing together. If you over-tighten the jack, the crimp loosens and the wafers and layers of the jack rotate out of alignment and do not stay tight any more. It is a good reason to switch to plastic jacks which are already self-insulating. With plastic jacks, Switchcraft becomes a poor choice as theirs always seem to have smaller contacts than the competition.
