Wednesday, 28 December 2016

Name plate attached

So the courier brought my name plate this morning, I fastened it to the amp and it looks as good as I had hoped:
Looking good with the name plate in place. The image was made by tracing around outlines of photos of the valves in Photoshop. 

Not sure I'm too happy with the placement of the LEDs for the input indicators, but too late to do anything about that now.


While I had the amp off the cabinet to screw on the brass plate, I also decided to take a photo of the rear panel, since for some reason I hadn't done that yet.

The business end. 4-Ohm  and 8-Ohm taps for the output. USB power for the Chromecast. Switched mains output for the separate phono preamp.


Remaining to be done now - just the 3D-printed cover for the power transformer.

The amplifier has been delighting us with its performance and power; despite its tendency to run rather warm, it seems entirely reliable. Its longest runtime so far has been around 6 hours, after which I looked inside carefully to see if there were any signs of thermal distress. Happily, there were none.

Current through the KT88s are stable - I've biased it at 28W idle disspiation per valve.

The amp is driving the big 4-Ohm KEF floorstanding speakers with commanding power and finesse at the same time. Noise level (hiss) is negligible, slight hum is audible with ear glued to speaker but 1m away is inaudible. Clarity and separation of the signal is excellent, bass is strong and authoritative and in no way flabby, nothing dominates at the expense of anything else, and when you need the power, there's ample headroom. We've had the walls rattling with this thing already.

Sadly the mains transformer is physically a bit noisy though, hopefully the cover will muffle that a bit. When the music is playing you don't hear it anyway. 

The transformer slowly gets warmer and warmer as well. Haven't had it too hot to touch, but definitely on the warm side. 

The remote control and input switch and remote power switching all work well.

I am going to call this project a success.

On to designing the next one....

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