Help / questions wiring up AMI T13 Transformer in my Warm Audio WA-87 (U87 Clone)

Thread Starter


Joined May 17, 2019
Hello all. I recently acquired an AMI / TAB Funkenwerk T13 Transformer -- To replace the stock Cinemag CM-2480 Transformer in the WA-87.

I was wondering If anyone was familiar with the WA-87 + T13, and could tell me how to wire it up.

I've read that the T13's are commonly mis-wired at the factory -- and rather than following the wiring diagram for the T13 -- one should manually "measure the resistance of every pair of wires. The higher resistance wires connect to the capacitor and ground."

So, I did that and lo and behold, the factory mis-wired my T13!

Resistance between yellow wires = 21 Ohms
Resistance between black wires = 452 Ohms

So based on this, the yellow wires from the T13 should go to XLR pin 2 and pin 3, and the black wires from the T13 should go to capacitor and ground -- Is this correct?

My question is, and what I need help with, Is figuring out where the yellow and black wires go to on the WA-87 -- and ensuring the polarity is correct. The way the Cinemag 2480 was originally wired up was the following :

Red Wire to T1 on the WA-87
Brown Wire to T2 on the WA-87
Yellow Wire to T3 on the WA-87
Orange Wire to T4 on the WA-87

Some pictures I took :

Front :

Back :

Transformer removed, showing where the XLR Pins go on the board :

I assume the blue wire Is ground because it goes to the middle? Is the red wire Pin 2 (+) of the XLR, and the yellow wire Pin 3 (-) of the XLR?

I would be forever grateful if someone could instruct me (based on factory mis-wired my T13) where each wire goes (T1, T2, T3, T4).

Normally the company ZenPro charges you $150 + Shipping for you to send them your WA-87 to do this Mod. This thread will surely serve useful for others attempting the same mod at home as a more affordable alternative!

Thank you so much in advance!