Over at Electra-Print site, it mentions grounding of output transformer. "Always ground one side of the secondary for safety."
It's not for hum issues?
It's not for hum issues?
On the "checkout" page for Tubelab SE amp, there is a mention of connecting ground wire (if there is one) of PT to ground receptacle and OPT should be connected the same way. Neither of my transformers have a separate ground wire. Does this mean connect the housing of transformers to ground?
Yes the transformer housings and all exposed metal on the amp should be grounded. This is more of a safety issue than a hum issue. Grounding the amp chassis if it is metal is usually sufficient. I will run a seperate ground wire if I am using a plastic or wood case.
The cold (black) lead on the OPT secondary should also be grounded. If a transformer should short out internally a high voltage could appear on the transformer case or speaker leads while the amp continues to function. I have seen an OPT short in this manner. Many older OPT's used wax coated paper for insulation.
The cold (black) lead on the OPT secondary should also be grounded. If a transformer should short out internally a high voltage could appear on the transformer case or speaker leads while the amp continues to function. I have seen an OPT short in this manner. Many older OPT's used wax coated paper for insulation.
The culprit has been found!!!
It was Sovtek 2A3 output tubes I was using. I was told by a reliable source (hint
) that their current draw may be more than what their spec shows and in turn it exceeds the current handling capabilities of the regulator on the board causing it to drop out of regulation and pass hum through to the output tubes. Other brands like Shuguang (Valve Art) and RCA brand 2A3 said to work fine for TubelabSE but it is apparently Sovtek that causes this problem. I changed it to Valve Art 300B tubes along with board reconfiguration which was the original plan but this incident forced me to do it sooner and I’m happy with the results so far. The hum is gone and this amp sounds GOOD!
It was Sovtek 2A3 output tubes I was using. I was told by a reliable source (hint
) that their current draw may be more than what their spec shows and in turn it exceeds the current handling capabilities of the regulator on the board causing it to drop out of regulation and pass hum through to the output tubes. Other brands like Shuguang (Valve Art) and RCA brand 2A3 said to work fine for TubelabSE but it is apparently Sovtek that causes this problem. I changed it to Valve Art 300B tubes along with board reconfiguration which was the original plan but this incident forced me to do it sooner and I’m happy with the results so far. The hum is gone and this amp sounds GOOD!
Honestly.. Both sound great!
I can't tell much of a difference. They are close enough, that by the time the amp cools, and I get the tubes swapped out and I listen again, it sounds about the same.
I'd probably be able to describe a difference if I could do instant side by side comparisons.
They're both the same brand, and are constructed exactly the same.. just different plate material.
I can't tell much of a difference. They are close enough, that by the time the amp cools, and I get the tubes swapped out and I listen again, it sounds about the same.
I'd probably be able to describe a difference if I could do instant side by side comparisons.
They're both the same brand, and are constructed exactly the same.. just different plate material.
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