Hoefer PS500XT Lab PSU

Modifying an electrophoresis generator for lab usage Hoefer PS500XT – Electrophoresis HV power supply modified for tube lab purpose. 500V at 400mA should suffice for many circuit developments. Changes : replace the large on/off/timer switch by an isolated, quick-to-operate, safe switch added a fan on the back, outside of the Read more…

Capacitor holder

how to fix Motor Run Caps Several tube amplifiers use motor run caps nowadays. These high-voltage capacitors come in large cans. The one on the picture below is 150mm long and 55mm in diameter. I do not like these monsters protruding through an amplifier top-plate, so I hide them inside Read more…

Ogonowski Transformers

HV and 5k/4+8Ω Leszek Ogonowski design, build and sell beautiful transformers for tube-amplifiers. I received these 3 models a few days ago. I will use them for a single-ended amplifier, along with NOS Telefunken tubes. Specifications power transformer primary : 230 V, 50 Hz secondary 1 : 750 V CT Read more…

Toroidy Transformers

High-voltage and 8k/4+8Ω output transformers Toroidy build and sell beautiful toroidal transformers for tube-amplifiers. I received 3 models a few days ago. They will be used in a push-pull amplifier. power transformer primary : 230 V, 50 Hz secondary 1 : 560 V (280 – 50 – 0 – 50 Read more…

Frudua Stage 312 Sub-Fi

Bass fixed

I have got this huge, heavy, Frudua bass guitar speaker to fix. A friend of my son almost threw it away, right before I salvaged it. The passive circuit was ok, all drivers as well, all it took was some re-shaping of the internal wiring. Not really sure it works Read more…