Vikki
Well-known member
- Joined
- Jun 5, 2004
- Messages
- 276
I've managed to get hold of some more racks from a vibrarion tester, one of these is a 3 unit high rack and i was wondering if there was any point in building 2 La2a's into the one rack. I think i could just about squeeze both in with the 2 chassis running front to back. I don't know if it is best to run each one of a seperate power supply or build one higher current supply to feed both units,i think that would mean both units would have to be powered all the time?(i guess the psu voltage would rise if one units ht was switched off.)
Another question, does the mains transformer need a centre tap on the ht and heater? There seems to be a few mains transformers around quite a bit cheaper that do not have a centre tap on the ht or heater supply. I notice a few valve amps have a non centre tapped heater supply but have a pot across the 6.3v with the centre to earth to balance any hum. I think a full wave bridge would be needed if the ht supply had no centre tap? From what i've read the ht voltage is dependant on the ht current drawn which drops voltage across the resistor in the Pie smoothing circuit, can anyone tell me the ht current drawn by one la2a? Hey no one done a PCB La2a yet?
Sorry for ranting for so long.
Vikki(uk) :grin:
Another question, does the mains transformer need a centre tap on the ht and heater? There seems to be a few mains transformers around quite a bit cheaper that do not have a centre tap on the ht or heater supply. I notice a few valve amps have a non centre tapped heater supply but have a pot across the 6.3v with the centre to earth to balance any hum. I think a full wave bridge would be needed if the ht supply had no centre tap? From what i've read the ht voltage is dependant on the ht current drawn which drops voltage across the resistor in the Pie smoothing circuit, can anyone tell me the ht current drawn by one la2a? Hey no one done a PCB La2a yet?
Sorry for ranting for so long.
Vikki(uk) :grin: