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previous: MasMusica Thank you for your reply. I unders... -- 4/13/2004 11:00 PM

Re: Power Ground

4/14/2004 12:14 AM
bnwitt	Re: Power Ground Mas, All PT heater windings have the potential to burn if a Tube shorts and causes excessive current on the heater circuit. The whole thing with the artificial ground, is that it is suppose to allow the two 100 ohm resistors to act as fuses and protect the heater winding of your PT in the event of a tube shorting as you say the single resistor is suppose to do, but most people will tell you that depending on the type of resistor used (cc metal film etc) it might not open in time to save the PT heater winding anyway. Putting a single 47 to 100 ohm resistor on the center tap would theoretically do the same thing I guess, but for a maybe result, I would just ground the center tap and be done with it. If you really wanted to protect the heater winding, you would need to use a real fuse (designed to open on current excess) with the proper rating to prevent the current in the heater winding from exceeding the rated level and frying. The real point of the two resistor set up is to produce a ground reference for the heater winding when the PT does not have a center tap and thus produce hum reduction.

4/14/2004 12:14 AM

bnwitt

Re: Power Ground

Mas,
All PT heater windings have the potential to burn if a Tube shorts and causes excessive current on the heater circuit. The whole thing with the artificial ground, is that it is suppose to allow the two 100 ohm resistors to act as fuses and protect the heater winding of your PT in the event of a tube shorting as you say the single resistor is suppose to do, but most people will tell you that depending on the type of resistor used (cc metal film etc) it might not open in time to save the PT heater winding anyway. Putting a single 47 to 100 ohm resistor on the center tap would theoretically do the same thing I guess, but for a maybe result, I would just ground the center tap and be done with it. If you really wanted to protect the heater winding, you would need to use a real fuse (designed to open on current excess) with the proper rating to prevent the current in the heater winding from exceeding the rated level and frying.

The real point of the two resistor set up is to produce a ground reference for the heater winding when the PT does not have a center tap and thus produce hum reduction.

Replies:

Howard How about using a 3A fast acting pi... -- 4/14/2004 5:18 PM