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Re: Which Lundahl transformer(s) to use for MC step-up?

152.163.188.5

Posted by KevinC on October 27, 2002 at 05:44:55

In Reply to: Which Lundahl transformer(s) to use for MC step-up? posted by Saurav on October 27, 2002 at 00:15:33:

You nailed all of the reasonable candidates.

The 9206 and 1636 have identical cores and coils, but the 1636 has an electrostatic shield between primary ans secondary. This is put there for mic pre service and isn't really necessary for MC step-up use. The 1678 is like the 9206, but has a higher step-up ratio, 4dB to be exact, so it might be necessary for one of those 100uV MC cartridges in combintation with an active phono stage with relatively low gain. The impedance requirement os your cartridge are met by either adjusting hte step-up ratio (gain) or the loading resistor at the input to the active stage, which is typically 47K. Since transformers transform impedance as the square of gain, then a 10x (20dB) voltage step-up produces an impedance increase of 100x (10 times 10). This indicates that the load seen by the MC cartridge is 470 ohms (47K divided by 100). Consult the cartridge manufacturer's load impedance recommendaton for your cartridge and do the math to see whare you need to be. For most MC step-up purposes the 9206 is the unit of choice.

Prices are per transformer.

Kevin

Edits: 12/03/20 12/03/20 12/03/20 12/03/20 12/03/20 12/03/20 12/05/20

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