low pass filter for DSD

@abraxalito
Mine friend Jordi from Tarragona sent me today a couple of tx 15K : 300Ω that I want to try in place of 1:1 tx

I have several doubts about reflected primary impedance can affect your 50Ω characteristic impedance filter to match de Amanero 50Ω output impedance.

Mine maths helped with other forum members are:

-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 50Ω x2 or x3 times = 100 or 150 Ohms and here is x5.72 times this can affect the Amanero's output impedance of 50Ω & your filter?
 
I'm only a beginner with impedance specs of trafos but those impedance figures represent the load impedances not the characteristic impedance(s) of the windings themselves.

The impedance factor of 50:1 means 100k from your preamp becomes 2k at the output of the filter, this is about 2.5% reduction of 50ohm not really a problem, you could increase the 50ohm load resistor to 51ohm but I doubt its worth the effort.
 
I don't remember exactly the firmware of Amanero but isn't the latest beta. I can tell you because the computer laptop was gone.

you mean that you didn't change the firmware and use as is?
Unfortunately Ive got chinese clone, and it is dead now, amanero flashing utility cannot recognize PID and DID and refuse to program it after erasing
And I didn't expect that I am buying the clone
 
No. I changed the firmware only for DSD, I'm using Daphile as player so Linux based.

Try this one:

firmware 2005be & Cpld_for_1081

If doesn't works for you, try this other:

firmware_1099c & cpld_for_1080

If your board is a chinese clon start with firmware 1099c
 
@ abraxalito
I want to use the 1:1 OPT for a gain of 6dB (attached pic), could still use your filter without modification?
 

Attachments

  • 1=1 tx doubler 6dBs.png
    1=1 tx doubler 6dBs.png
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  • 50 ohm characteristic impedance 4th order low pass filter con tx 1=1 600 ohms.png
    50 ohm characteristic impedance 4th order low pass filter con tx 1=1 600 ohms.png
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