A 1200 Ohm resistor is shown in series with the transformer's Red output lead.
Jensen recommends a 2.43k Ohm resistor for "Perfect Transient Response".
The 1K level pot (VR-2) in series with the 1200 ohm resistor presents a 2.2K loading and reasonably satisfies this requirement. A 1500 ohm resistor is a closer value (resulting in 2.5K) and should be readily available at Radio Shack.
** A TRS (Tip Ring Sleeve) 1/4" stereo jack may be used instead of an XLR-F connector.
Tip would be plus (XLR pin 2) -- Ring would be Minus (XLR pin 3) -- Sleeve would be Ground (XLR pin 1)