I read a few different articles and threads on grounding but am a little it confused on one thing I found on the Grounding white paper on Aiken amplification's website.
In the second section, "What is 'Star Grounding'"?, it states the the OT secondary ground should have a connection to the first filter cap. (I understand the OT secondary ground should also connect directly to the output jack).
In the fifth section, "What about the output jacks?", it is stated that when using global negative feedback, the OT secondary ground should also have a connection to the ground of the preamp section where the negative feedback is sent to.
I assume this means to choose one connection or the other, depending on whether the circuit uses negative feedback or not. I would imagine that using both would make a ground loop.
Thanks
In the second section, "What is 'Star Grounding'"?, it states the the OT secondary ground should have a connection to the first filter cap. (I understand the OT secondary ground should also connect directly to the output jack).
In the fifth section, "What about the output jacks?", it is stated that when using global negative feedback, the OT secondary ground should also have a connection to the ground of the preamp section where the negative feedback is sent to.
I assume this means to choose one connection or the other, depending on whether the circuit uses negative feedback or not. I would imagine that using both would make a ground loop.
Thanks
The secondary needs to be grounded otherwise the feedback isn't being applied, as the winding I'd left floating.
Hooking to the can cap - or the input jack - will work. Go with whatever hums less.
Hooking to the can cap - or the input jack - will work. Go with whatever hums less.
The OT ground side is the feedback return and should be treated as an INPUT ground. If you think of it as the same as what connects from the minus input of an op amp to ground the proper connection becomes obvious.
Oh, goodness. No. The transformer secondary -floats-. That is why tubes are better than transistors (let's call a Cost a Bonus). His "5A" can only go to the speaker, NOT to the power supply.
The OT SEC MUST be tied to safety ground in case the OT insulation fails. But it does not have to be a heavy, short, or "starred" tie.
As wg_ski says, if there is NFB then the OT has to return to that point's common so the NFB works.
Aiken is 98% right which is a lot better than most pundits. But here his fingers got ahead of his thinking.
"Grounds are Commonly Misunderstood" and . . .
"Ground Loops are Commonly Misunderstood"
Puns intended, but the above are also the truth.
All ground wires are actually a resistor in series with an inductor. (all wires for that matter)
When the parasitic resistance and parasitic inductance is large enough versus the application in the circuit it is used in, that can become a problem.
I remember one of my customers that had an electronics lab.
The electronics equipment had a very fast rise, very high current pulse, and a very large diameter, and long vertical ground return wire.
He measured 100V from the bottom of the ground return wire to 1 foot up on the same wire (which was at least 6 foot long).
He wanted to know what was wrong with the measurement . . . I said "nothing, you are experiencing the natural result of self inductance of the ground return wire that has a fast rise current pulse through it".
"Ground Loops are Commonly Misunderstood"
Puns intended, but the above are also the truth.
All ground wires are actually a resistor in series with an inductor. (all wires for that matter)
When the parasitic resistance and parasitic inductance is large enough versus the application in the circuit it is used in, that can become a problem.
I remember one of my customers that had an electronics lab.
The electronics equipment had a very fast rise, very high current pulse, and a very large diameter, and long vertical ground return wire.
He measured 100V from the bottom of the ground return wire to 1 foot up on the same wire (which was at least 6 foot long).
He wanted to know what was wrong with the measurement . . . I said "nothing, you are experiencing the natural result of self inductance of the ground return wire that has a fast rise current pulse through it".