Toroidal vs. IE Cores

[tony]

does it help reduce EMI if the EI cores are in a separate chassis? pardon my ignorance but i'd like to understand more. also what does it mean to be "screened"? thanks!

yes, but it does not mean you can not put the psu and the amp in the same chassis.

i made my el84 set amp and there is no hum whatsoever!

i made many high powered solid state amps with big traffos and there is no noise at all!

everthing depends on layout and grounding techniques! which in turn comes from experience!

"screen": means to shield something from something! in case of traffos, the primary turns are screened by using copper or aluminum foils to shield the primary winding from the secondary winding! a single copper layer can also be used. noise from the mains can be drained to ground in this way.

[tony]

Leakage? Can this please be elaborated on. I'm not familiar with this thanks!

leakage is brought about by the fact that not all flux developed in the primary winding will be linked to the secondary winding, and this has something to do with coil geometry, or how the coils are wound.

for power transformers, this is no big deal, but for output transformers where bandwidth of 20hz to 20khz is desireable, interleaving of primary and secondary windings is resorted to in order to reduce leakage inductance.

btw, torroids beat EI's in the bandwidth race. that is why for pre-amps and low-level stages, torroids should not be used, if you want them to be quiet as possible!

[tony]

Toroid trans may exhibit DC offset (buzzing noise); depends sa manufacturing standard narin siguro or unit to unit variation. You hear the buzz when your near it. Baka lahat ng gawa Plitron wala nito, but it costs a lot.

manufacturing standards has nothing to do with buzzing, the dc present on the ac line is the real culprit!

[JackD201]

JackD201, gloriagate tapes = leakage

[red76]

Toroid trans may exhibit DC offset (buzzing noise); depends sa manufacturing standard narin siguro or unit to unit variation. You hear the buzz when your near it. Baka lahat ng gawa Plitron wala nito, but it costs a lot.

manufacturing standards has nothing to do with buzzing, the dc present on the ac line is the real culprit!

sabi ko 'siguro', so I wasn't sure. Thanks for sharing your knowledge though. So do EI cores exhibit more buzzing than toroids when DC is present on the AC line?

[red76]

the only thing going for torroids is its low footprint and wight!

Ah yes, saves on chassis real-estate. Maybe that's why some commercial manuf. use them more often these days especially for SS gear.

[tony]

no need to explain! i know you are not sure, my comment is not directed at you in particular ok?

torroids will buzz more than than EI's as torroids has no air gap to speak of, EI by nature of its construction will tolerate dc more. imagine the E and the I joined together, there you have a gap however small.

[JackD201]

Guys please keep exclamation points to a minimum in order to avoid miscommunication and misunderstandings.

Thanks.

Moderator

[red76]

torroids will buzz more than than EI's as torroids has no air gap to speak of, EI by nature of its construction will tolerate dc more. imagine the E and the I joined together, there you have a gap however small.

Thanks for sharing. BTW, I know it wasn't 'directed' at me, I just tend to 'detail' things out. I'm just too anal....