RCA BC-2B restoration and power supply

[mrtnasty]

Hi All,

I recently restored 2 dual channel RCA BC-2B preamps. I replaced all the caps (signal and electrolytic), wired up the inputs and outputs and supplied it power originally with a heath kit tube regulated power supply. All channels worked, but there was a pretty substantial buzz. I replaced the electrolytics in the Heathkit. The hum was still there. So just for kicks I spent $25 on amazon on one of these Chinese 280V and 6.3V power supplies:

https://www.amazon.com/Preamp-Switc...2050&sprefix=280v+power+supply,aps,101&sr=8-3

I first measured the Chinese power supply, and I saw 280V DC on the first 2 terminals, and 6.3V DC (Not AC) on the second two terminals (The 12ay7 data sheet says AC or DC is ok for the filament). After firing up the BC-2B with the Chinese power supply, it works awesome and is dead quiet!

Someone please let me know if I am missing something and why I shouldn't be using such an inexpensive power supply with such nice preamps, will the sound quality of the preamps suffer by using this cheap power supply? Otherwise I think I'll use it like this, it's super convenient to be able to mount it right on the rack. Thanks!

 

[emrr]

Interesting option. I don’t see any current specs in that ad.

 

[mrtnasty]

Interesting option. I don’t see any current specs in that ad.

I first posted about this power supply here: https://groupdiy.com/threads/cheap-tube-mic-preamp-power-supply.90042/

and mjrippe pointed out the link I shared there says the specs are 5A @ 6.3V and 200mA @ 280V. I just bought it from amazon so I could return it easy if it didn't work. The 12ay7 data sheet says one 12ay7 takes 300mA @ 6.3V and 3mA @300V so it seems to me that this power supply should work for 4 12ay7s.