I am building an Ampeg B-18-N/B-15-ND Clone. Looking at the schematic it appears that the output transformer secondary is grounded to the cathode of the PI (point "F" on the schematic attached). Here are my two (2) questions.
1) If that is the ground why is it connected through that .05 capacitor.
2) since I will be using a standard impedance selector and a pair of 1/4" jacks, should I still land my OT secondary ground at this location. and as my jacks are isolated and will require a ground wire should I also lad it on point "F".
Ampeg help
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Ampeg help
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martin manning
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Re: Ampeg help
Hi Jon,
Looks to me like point "F" is not grounded (other than through that cap) unless the internal speaker is pluged in and the jumper from pin 2 to pin 3 of the 4-pin plug is in place. This mutes the amp to prevent accidental damage to the OT from running without a load. I believe the 0.05 cap is only there to prevent a pop. If you are using a conventional selector, the 0.05 cap is not needed. Ground point "F" (or you won't get sound), and ground the OT secondary at the speaker jacks as usual.
Looks to me like point "F" is not grounded (other than through that cap) unless the internal speaker is pluged in and the jumper from pin 2 to pin 3 of the 4-pin plug is in place. This mutes the amp to prevent accidental damage to the OT from running without a load. I believe the 0.05 cap is only there to prevent a pop. If you are using a conventional selector, the 0.05 cap is not needed. Ground point "F" (or you won't get sound), and ground the OT secondary at the speaker jacks as usual.