Phrazemaster
Well-known member
Hey gang,
I'm building a Poctop M49 and I'm springing for a real AC701(k!). I'd like to make something fairly awesome.
My concern with such a valuable tube is accidentally destroying it's delicate innards on inrush currents. I read some things Oliver mentioned about using an RC delay for it, but couldn't seem to find how it might be implemented or what he would have suggested.
I've been doing a helluva lot of reading about it, but as I'm not an EE all I can come up with is using some kind of soft start for the B+ such as this one: http://www.kandkaudio.com/otherkits.html
I spoke with the creator Kevin and he seems to think his time delay circuit for B+ only will be sufficient since I'm using Poctop's PSU which he said had massive filtering and resistance, so soft-starting the heater isn't necessary. What's kinda cool is his little circuit will delay B+ for 30 seconds. He also has a soft-start version that additionally adds a 30-second ramp up on B+ voltage, but it uses a MOSFET.
I also considered using an NTC thermistor or a MOSFET across the mains, but these seem to come with the possibility of fire or explosion if they fail or are implemented improperly (yikes!).
What say you guys? Worth using? Will it change sonics? Decent protection or unnecessary overkill?
Thanks in advance your thoughts,
Mike
I'm building a Poctop M49 and I'm springing for a real AC701(k!). I'd like to make something fairly awesome.
My concern with such a valuable tube is accidentally destroying it's delicate innards on inrush currents. I read some things Oliver mentioned about using an RC delay for it, but couldn't seem to find how it might be implemented or what he would have suggested.
I've been doing a helluva lot of reading about it, but as I'm not an EE all I can come up with is using some kind of soft start for the B+ such as this one: http://www.kandkaudio.com/otherkits.html
I spoke with the creator Kevin and he seems to think his time delay circuit for B+ only will be sufficient since I'm using Poctop's PSU which he said had massive filtering and resistance, so soft-starting the heater isn't necessary. What's kinda cool is his little circuit will delay B+ for 30 seconds. He also has a soft-start version that additionally adds a 30-second ramp up on B+ voltage, but it uses a MOSFET.
I also considered using an NTC thermistor or a MOSFET across the mains, but these seem to come with the possibility of fire or explosion if they fail or are implemented improperly (yikes!).
What say you guys? Worth using? Will it change sonics? Decent protection or unnecessary overkill?
Thanks in advance your thoughts,
Mike