My name is Taco Dijkstra and this is my contribution to the Pass DIY gallery. I have build an Aleph-X based on the schematics of G. Rollins/ Nelson. The boards I have used are from the www.diyaudio.com group buy of 2002. It took me approximate one year to gather all the components and build this two small mono-blocks.

Specs (each channel): PCB: group buy No. devices: 4 irfp240 (matched at ~5mV) Total Bias: 4,5 amps Rail voltage: 17 volts Transformer: 330VA, dual 15 volts secondary Power supply: CRC network, with four 47.000uF caps and two 0.56 ohm resistors in parallel. Bridge: single bridge, composed of 4 fast recovery diodes LED: red signal led (color is very important :))

Construction: Every mosfet has its own heatsink rated at 0.7 K/W with a total of 4 sinks for each monoblock. Using these small heatsinks requires a support structure of L-bars for attaching al the panels. The pcb is placed on the backpanel so signal leads are as short as possible. The transformer is placed in front, so there is enough distance between the transformer and the pcb.

Sound: I use the Aleph-X in combination with a balanced linestage and small monitor speakers (sensitivity of 85 db/W). The sound is very rich of details, imaging is perfect but without sounding to analytical. The bass is tight, but with enough extension.

I want to thank Nelson Pass and Grey Rollins for the design and Edwin Dorre and Hugo de Groote for helping me out with some questions regarding the building fase.

Met vriendelijke groet,

Taco Dijkstra,

t.dijkstra@its.tudelft.nl