Ok, I've moved ahead with the phono pre-amp by completing the wiring of both the power supply and the pre-amp chassis. They are connected together for preliminary tests: are voltages in the right place; is anything smoking?
An obvious problem is that my current monitor doesn't work and I don't know why. It was tricky because it has an itty-bitty IC on it, and I may have overheated it when soldering or made a mistake when hand-wiring it. Remember that my idea was to apply a higher-than-normal voltage to ignite the voltage-regulator tubes, and once ignited (as shown by high current conduction,) I'd drop the plate voltage to reduce current source dissipations. So for now I just use a timer that allows the plate voltage to build and ignite the VR tubes, then drop the voltage. Maybe I'll fix the current monitor some day.
So I don't know yet if the stages are ringing or are following the RIAA rules, but at least they are in boxes and run for at least ten minutes without exploding or overheating.
I have attached a few pictures as eye candy.
| Attachments: |
|
File comment: Pre-Amp with lights off Pre-Amp_loDef_Crop_dark.jpg [ 53.59 KiB | Viewed 6760 times ] |
|
File comment: Pre-Amp with lights on Pre-Amp_loDef_Crop_lite.jpg [ 86.44 KiB | Viewed 6760 times ] |
|
File comment: Current Monitor Board Current_Monitor.jpg [ 76.69 KiB | Viewed 6760 times ] |