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In Reply to: RE: Thank you Tweekeng posted by jea48 on April 17, 2010 at 14:50:29
Jea, I did wire the tranny as Tweekeng recommended, only now with the center taps wired to ground, same 120V output, so all is good.
I also received an email from a gentleman who recommended this;
Run the primary's in parallel
Run the secondary's in parallel
He thought this would give me twice the max. V output of a series connection
The only problem I have with this configuration is that the saturation noise is back.
Since these will be driving 140W tubed amplifiers, is peak output more important then core saturation noise?.
I hope I am asking the proper questions.
Follow Ups:
JMHO, I would forget configuring the xfmr for balanced power. Single ended will yield the full potential of the xfmr as it was designed and intended.Best isolation is to series the two primary windings and connect them to 240Vac. Secondary windings paralleled 120Vac out single ended.
I also received an email from a gentleman who recommended this;Run the primary's in parallel
Run the secondary's in parallel
Better than balanced, jmho....The only problem I have with this configuration is that the saturation noise is back.
Transformers do hum. When you had the two primary windings in series and only connected to 120V it would be quieter. You were only running the primary at 1/2 its rated voltage.Make sure you got the polarity correct...
Primary parallel for 120V in (1&4) (3&6)Secondary paralleled for 120V out (7&9) (8&10)
Also you know you have to connect one output Line,leg, of the separately derived power source to earth. This becomes the neutral, the grounded conductor. By code it has to connect to the main grounding system of the main electrical service.
The connection of the xfmr Line and earth also becomes the safety equipment grounding conductor connection. A star ground.If you decide to fed the xfmr from 240V you will need to install secondary overcurrent protection on the ungrounded Line, leg, of the xfmr.
If you decide just to fed the xfmr from 120V (parallel primary windings)
you could probably forgo secondary overcurrent protection....I am surprised no one has commented on whether they think the xfmr is big enough for a 140 watt power amp. Does it have enough head room for the amp?
Edits: 04/17/10 04/17/10
My way of thinking is that if the secondary's are wired in parallel, then I will be grounding one hole side. Is this true?.
My way of thinking is that if the secondary's are wired in parallel, then I will be grounding one hole side. Is this true?.
Yes, but the next question is which side. I am not familiar with the number markings on the xfmr. I am used to seeing X1, X2, X3, and X4.
In this case (X2&X4) would become the neutral, the grounded conductor.
I can only assume (8&10) would connect to ground becoming the neutral conductor.
If that is the case then you should connect (3&6)of the primary to the neutral side of the 120V male plug that will plug into the wall receptacle.
Maybe Tweekeng, and or, djk could chime in with their thoughts....
As for the neutral connection to earth ground I assume the xfmr will have a cord and plug that plugs into a wall 120V receptacle. In that case I assume you will use the safety equipment ground from the receptacle for the earth ground connection. I also assume you will be putting each xfmr in a metal enclosure of some type.
The secondary neutral ground connection, the metal case connection, the xfmr shield connection, and the secondary output safety equipment ground connection should all connect at one common junction point. Star grounding...
There is one more test you may want to preform. If you will be using the two xfmr as well as 120V power from your home's electrical to power audio equipment connected together by ICs you might want to check the output AC polarity of the two xfmrs as well as any wall receptacle outlets you will be using from your main electrical panel. You want all three power sources to be in phase with one another.
Just measure for AC voltage from each Hot contact of each receptacle to the other. If the polarity is correct and the power sources are in phase with one another the voltage reading will measure zero or close to zero. Out of phase will measure closer to 230Vac or 240Vac.
If it's true that the transformer already gets rid of HF grunge, then the cap is not necessary. Since I already have them, any added filtering can't hurt.
Comments?.
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