help needed to build T-13 or U87 Transformer like 9:5:1

[Jobair Ahmed]

Can anyone tell me the Primary and secondary voltage of this kind of transformer? it's a 9:5:1 U87 Microphone Transformer
i want to build it by myself but i need to know the primary and secondary voltage.
the main reason is i live in Bangladesh, i can't find these kinds of transformers in local market and if i bring it from Ali express it will cost me more than $60-65 USD for a single transformer.
i want to build ORS 87 Stripped down microphone
https://groupdiy.com/threads/open-s...7-stripped-down-u87.86814/page-3#post-1137386
like this


please help me out to build this transformer
i have some small transformers which i collect from damaged Desktop Power supply.
View attachment 1645133295UTM_Catalog2B_025.jpg

 

[Khron]

https://groupdiy.com/threads/open-source-diy-mic-project-ors-87-stripped-down-u87.86814/post-1174277

There's no need to post the same question in every subforum you can see...

 

[RuudNL]

i have some small transformers which i collect from damaged Desktop Power supply.

I don't think transformers from a power supply are suited for audio...

 

[Jobair Ahmed]

I don't think transformers from a power supply are suited for audio...

I don't think transformers from a power supply are suited for audio...

can you please tell me how can i build this ? as i saw a lot of videos on youtube about transformer making. so I'm willing to build some for me.

 

[Jobair Ahmed]

https://groupdiy.com/threads/open-source-diy-mic-project-ors-87-stripped-down-u87.86814/post-1174277

There's no need to post the same question in every subforum you can see...

i'm sorry for that, the thing is I've waited for a while, after seeing that no one is responding. i posted same thing on this post.

 

[Екатерина]

ASTDS T13？oh，This is a transformer from China that I did not immediately use after obtaining it. After receiving measurements from a friend, I obtained data that the primary of this transformer is only 17H and the secondary is 200mH, which is not a good parameter for audio equipment. It begins to decay at 300Hz, with approximate parameters of 20Hz-9db, 100Hz-5db, 200Hz-1db, 300Hz 0db, 5kHz-1db, 10kHz-2db, 20Hz-3db, which is not a good parameter for audio equipment

 

[micolas]

ASTDS T13？oh，This is a transformer from China that I did not immediately use after obtaining it. After receiving measurements from a friend, I obtained data that the primary of this transformer is only 17H and the secondary is 200mH, which is not a good parameter for audio equipment. It begins to decay at 300Hz, with approximate parameters of 20Hz-9db, 100Hz-5db, 200Hz-1db, 300Hz 0db, 5kHz-1db, 10kHz-2db, 20Hz-3db, which is not a good parameter for audio equipment

I agree with some aspects.
It may look like a copy of the AMI T-13, but it doesn't even come close.
On the other hand some like it in the 87 topology, maybe because its frequency response achieves a de-emphasis for very bright cheap capsules and attenuates the lows without using the hi-pass of the circuit, somehow resulting in a claxon tone associated with the 87.
But obviously for a few extra bucks I chose Igor's transformer, UTM0587.
Edit:I remember @Wordsushi reconsidering his stance on AliT-13 and even managed to make it sound interesting in some ORS87 builds.

 

[gyraf]

..we need to know what source impedance the T13 was measured at, otherwise the frequency response indicators does not make sense. The above comment, that it had a measured -3dB point of ca. 150Hz, would indicate that it was driven from a source impedance of 16K Ohm (150Hz@17H). And this is probably an unrealistic use scenario..

 

[Drosselmeier]