Question about Tamura 80071 transformer for 1176 input

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JW

Well-known member
Joined
Jun 8, 2005
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1,100
Location
Portland USA
Gonna experiment with a different input transformer for my home brew 1176.

This Tamura is used for both mic and line input in the Yamaha PM1000 console. It is padded down when the switch is set to accept line input. It is a 600:3K ohm step up transformer that is loaded with a 4.7K ohm resistor on it's secondary in the Yamaha circuit.

My question is, if I flip this around for a 2:1 step down in front of the 1176 circuit, is there an appropriate termination resistor I should apply?
 
Using the Tamura as a step down will give approx 2.2:1 ratio.
Load resistor should be chosen in order to avoid ringing problems. Easier way is to use a square wave test signal and adjust the load resistor value for the best result.
I would start with 1k5 or 1k8.
 
Is there a 270 on there already?

Maybe remove that and put a 1 k pot in its place and season to taste.

Maybe the tamura is good enough to work with no resistor at all. Easy to find out. Low ratio transformers usually have very little ringing, the resistor can act to reduce distortion . What are you plugging into the 1176? That might make a difference in which resistor you use as the source will see that resistor via the XFMR.
 
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