OEP A262A3E Wiring

[Seabstudio]

Hi Everyone !
I start a built of some API 312 clone for my personal use
I have question about the A262A3E from OEP ( i know isn't the best

)
So if I refer to the datasheet , to get the good ratio for a mic transformer , i need to wiring the primary in parallele ( 150ohms ) and the secondary in serie ( 25K)
In shematic I find on the web , the designer wired the 2 bobbins but in "opposite" phase , both on primary and secondary
If you can check witch is the correct one please ?
I attached , "my" version
and the other is the shematic from the other designer ( Tunca )
Thanks in advance
Seb from France

 

[Whoops]

The document "OEP Wiring" shows the correct connections for an 150r primary and 25K secondary

 

[ruffrecords]

Unless you are using a 50 ohm microphone you do not want a 150 ohm primary. For 'normal' mic inputs I would recommend you wire both the primary and secondary in series. This will give you the best primary inductance (essential for good bass response). Load the secondary with 62K so it 'looks like' 1500 ohms from the primary.

Not, the primary inductance of each winding is listed as 125mH so even in series this will only total 0.5 Henries. In theory this means the response will be 10dB down at 20Hz with a 150 ohm source. Fortunately the inductance of most transformers rises as frequency drops so in practice it will not be as bad as this. I have lost count of how many times I have told transformer manufacturers that the inductance at 1KHz is no help to a designer.

Cheers

Ian

 

[Seabstudio]

Unless you are using a 50 ohm microphone you do not want a 150 ohm primary. For 'normal' mic inputs I would recommend you wire both the primary and secondary in series. This will give you the best primary inductance (essential for good bass response). Load the secondary with 62K so it 'looks like' 1500 ohms from the primary.

Not, the primary inductance of each winding is listed as 125mH so even in series this will only total 0.5 Henries. In theory this means the response will be 10dB down at 20Hz with a 150 ohm source. Fortunately the inductance of most transformers rises as frequency drops so in practice it will not be as bad as this. I have lost count of how many times I have told transformer manufacturers that the inductance at 1KHz is no help to a designer.

Cheers

Ian

Ian , thanks for your time again ! ( as usual in this forum )
Ok make sense for the primary in serie instead of parallele
For the 10 db down at 20hz , isn't a problem , a free HPF ahaha , generally i cut everything below 40hz in mixing process , i HATE sub frequency that kill most of the headroom, so I will use the OEP transformer for cymbal in my drum setup and keep good transformer for Kick , snare , Toms !
Best
Seb