you can't be far off Mark because the 3.25 amp 20v laptop supply I am using to power the uTracer was heating the GM70 without a hitch. It might be how the particular smps's are designed.IslandPink wrote:Worth mentioning here, as well as the GK-71 thread, that a Dell 90W laptop SMPS ( 19.5V 4.62A ) goes into current protection & doesn't work, when connected to a cold GK-71 .
I remember the switched mode lighting transformers having a part which porevented them working when insufficient current was drawn. they have a window of operation in both directions and won't do a thing outside that window.
My humungous computer supply I use to heat the pair of 833a's has to be started with a resistor in series which I switch out once the filaments have heated to an extent, as the cold filament is a dead short. this protects the filament too. that supply like most computer supplies must have a draw on the 5v rail, for which I use a TY4-400 which then I employ as a shunt valve since I have lit it.
Inspight of being on entirely the wrong thread I shall now digress. you are experimenting with bass tone and the effects on DC filament supplies on that. My best sounding 212 was heated with AC and hum was negated by insufficient power supply filtering. People liked it that day in my dining room, the one where the picture of me climbing over the packs of laminated floor to change a record, where I put a show of different 212 versions on the mantle piece. Someone must have a picture.
Ultimately my quest remains to work with AC.
It was the same AC heated version I took to Chris's flat when Morgan Jones and 7N7 were there, and we photographed a whole row of NOS 212's we had just imported together (Me Chris and Darren) from Australia. Te picture was used in the Triode Mafia front page.
That day on Chris's Martin Logan Panel the 212 was sublime, I thought I was hearing a Cello in 3d right where the speaker belonged. Wanderful experience.
