The F5Pi -- F5P Voltage Gain Stage + M2 Output Stage = Perfectly Integrated

This weekend, I have substantially finished the build of an F5Pi using USA mosfets as provided in the recent group buy, while varying a little from the current group buys for F5Pi PCBs.

I used the relaixed system from Jos von Eijndhoven for source selection and attenuation, along with separate supplies for front end and output stage. The chassis is made from sheet alu cut to make the individual panels, as I had some damaged heatsinks of the appropriate size, I pressed those into service rather than see them go to waste. The front panel is 8mm black acrylic.

I mounted most of the "amplifier" parts on each heatsink - output stage power supplies, front end and power boards, and the speaker protection keeping cable runs as short as possible. It also helps with thermal management for the regulated output stage supply. The floor of the amplifier then has the aux power supply, relaixed soft start module, an earthing circuit breaker, transformer (hidden under the platform with front end supplies) and the front end supplies themselves (the ones with the blue talema transformers). The source select and attenuator board is mounted on the rear panel to keep lines as short as possible.

The amplifier both measures well, handles reactive loads well, and sounds great. For those who might be planning a build using the group buy boards, you will find there is a significant amount of work in the build, but you will be very well rewarded at the end. I would also say my work was increased because of the extra metalwork.

Modules mounted on the heatsink:

800px-9378.jpg

Internal view of the completed amp. Transformer is under the platform at the front of the chassis under the smaller front end transformers.

800px-9379.jpg

Finished front view - excuse the tripod showing the photo, its hard to avoid reflections in what is really a mirror!

800px-9383.jpg
 
  • Like
Reactions: 13 users