Hi guys,i'm new here.

Thought maybe someone can help me out with SDT issues.I have here a 120V musical equipments.So i need a SDT to operate it in 230V country.The tech person told me to get a "non-center tapped" SDT to prevent noise related issues.

So i'm wondering whats a "non-center tapped" SDT?

 

Non-center tapped step down transformer.

I assume that's what is meant as I'm not sure of "SDT"

Transformers can have the windings tapped for various reasons just get a transformer than has only a primary and secondary winding with no taps off either.

 

Go to any Hobbiest shop. Most sell 230 to 120volt stepdown transformers already boxed with plugs and sockets attached. Make sure that the Wattage of the stepdown transformer is in excess of the total wattage of the devices you intend to power.
Don't get sucked into buying one of those cheap electronic stepdown units.... it will destroy your gear.
A proper transformer will be big, and heavy... but necessary.

BTW, your friend may have been talking about the Auto-transformer style units, which are not isolated from the mains. Others are isolated from the mains, and often do not have the earth pin connected, which may or may not contribute to earth loop hum problems.

 

To my knowledge Non centre tapped transformer means the transformer with no centre tape at the secondary windings.

Transformer normally has two regions

* one is primary winding
* another is secondary winding
The primary winding will end up in the mains cord(ie we connect that to 230 0r 110 ac power supply) The secondary winding may have minimum of two leads, centre tape at the secondary winding will be grounded normally, but i don't know what difference will it make in the noise output