Transformer reflected primary impedance

[merlin el mago]

I know 10K 300 ohms reflects @ primary 10K if the load secondary is 300 ohms but what happens when the source isn't 10K is for example 50 ohms?

 

[45]

I know 10K 300 ohms reflects @ primary 10K if the load secondary is 300 ohms but what happens when the source isn't 10K is for example 50 ohms?

10K is the load. The source can be anything. Of course it will have a crucial impact at both low and high frequency. With 50R it will likely have very good low frequency response. At high frequency it will likely peak around the transformer resonance. In general it really depends on the ratio of leakage inductance and capacitance the transformer has. There is no precise answer.
If you know them you can figure out the merit factor and know how smooth or how peaky is the response. Then there is the actual load connected at the 300R end that can smooth response out or make it worse respect to a plain resistive 300R load! If you know that the transformer has been designed for 50R source then it might likely have smooth HF response.

 

[pieter t]

Watch out professor 45,
with your reply you provoke Felipe for at least ten more questions....

 

[45]

Watch out professor 45,
with your reply you provoke Felipe for at least ten more questions....

No worries. I know Felipe since a long time ago.🙂😉

 

[merlin el mago]

The 50R load is the source impedance of Amanero USB-I2S and the characteristic impedance of filter designed by abraxalito (thank you) and the load is always 100K. I guess the better way to connect is the 300R primary to Amanero and 15K to secondary.

 

[20to20]

edited.. not relative

 

[merlin el mago]

I'm expressed bad as usual due to English isn't my native language, sorry.

I don't know if I do well the maths for a tx 15K:300R

-Turns ratio 50:1 (15000:300)
-Impedance ratio square root 50 = 7 aprox. = 7:1 impedance ratio
-15K secondary tx in parallel with 100K load (26 preamp or 5687 headphone amp) = 13K043 secondary load
-13K043 secondary load / 50 turns ratio = 260.86 primary impedance instead 300R

I guess the tx loading primary have to be x2 x3 times so 50 ohms x 2 or 3 times = 100-150 Ohms, it's ok to load the primary tx x6 times?? I guess yes but I understand the secondary loading and ho affects the impedance but I don't know if the real 260.86 primary impedance can affect the characteristic impedance of abraxalito's filter & Amanero output impedance.

 

[merlin el mago]

I think I will do wrong the maths:

-Turns ratio 50:1 (15000:300)
-Impedance ratio square root 50 = 7 aprox. = 7:1 impedance ratio
-15K secondary tx in parallel with 100K load (26 preamp or 5687 headphone amp) = 13K043 secondary load
-13K043 secondary load / 7 impedancia ratio = 1.863R primary impedance instead 300R

How can affect the characteristic impedance of abraxalito's filter (50 ohms) & Amanero output impedance (50 ohms). Normally primary load tx is x2 or x3 times in place of x37,26 times, or it's OK?

 

[DF96]

15K:300 is an impedance ratio of 50, and a turns ratio of about 7.

 

[merlin el mago]

Thank you.

 

[merlin el mago]

-Impedance ratio 50:1 (15000:300)
-Impedance ratio square root 50 = 7 aprox. = 7:1 turns ratio
-15K secondary tx in parallel with 100K load (26 preamp or 5687 headphone amp) = 13K043 secondary load
-13K043 secondary load / 50 impedance ratio = 260.86R reflected primary impedance instead 300R

Loading opt tx x2 or x3 times so 50 ohms x2 or x3 times = 100 or 150 Ohms and here is x5.72 times, this affect the output impedance of 50 ohms of Amanero & the abraxalito's filter with characteristic impedance of 50 ohms?