Hello, Gang. I hope the New Year is finding you all well. I'm going further down the audio rabbit hole for sure. I had a few tube amps fall in my lap and it's re ignited my curiosity for valves. I picked up Jolida JD 302B and received, on loan, a Dynakit ST-35 and a Macintosh MC240. They are all in various conditions. I'm here to learn more about mods and the intricacies of the designs. I'm looking forward to the collective wisdom of the group. Thank you! Here is a pic of the 302b. Evidently this one has been worked on. I'm hoping that someone can tell me why they did what they did.
Looks like it was recapped with “audiophile” caps. Possibly some additional bypass caps in the power supply. I don’t see any issues with changes like that other than the pocketbook. If there are fundamental changes to the circuit topology I would undo them.
Rabbit hole in general. Before modding, I would get things working with new electrolytic caps and any other repairs needed like cleaning pots or replacing out of spec parts. Learn the original designs and measure performance before doing any serious mods so you have a baseline to work from. Most of these classic designs are already highly optimized and mods often degrade performance.
Rabbit hole in general. Before modding, I would get things working with new electrolytic caps and any other repairs needed like cleaning pots or replacing out of spec parts. Learn the original designs and measure performance before doing any serious mods so you have a baseline to work from. Most of these classic designs are already highly optimized and mods often degrade performance.
The first thing for you to do is reverse-engineer them, and generate a schematic.
