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]

 

[micolas]

View attachment 142275

Hi, @Drosselmeier !
I didn't know this model existed. Can you tell what the differences are in the specs?

 

[Drosselmeier]

 

[micolas]

View attachment 142283

ASTDS T-13 is apparently made by Desheng:

http://www.zgdes.com/product/902.html

What about the T-13XL?
Do you have a link where it can be bought or where it is made?
However, it seems strange to me that with comparable core sizes and close ohmic/dc resistances they have such different inductances, even if they had coils with slightly thicker wires and more turns.
For the T-13XL the inductance is given at 100Hz, and for the T-13 at 1kHz. Could it be a mistake?

 

[Khron]

For the T-13XL the inductance is given at 100Hz, and for the T-13 at 1kHz. Could it be a mistake?

Is it a coincidence the inductances measured are (also) at about 10:1 ratio?

 

[micolas]

Is it a coincidence the inductances measured are (also) at about 10:1 ratio?

That's what I was wondering too.
The inductance ratio is almost 10:1
??
Is there a linear relationship between frequency and inductance?

 

[Khron]

Is there a linear relationship between frequency and inductance?

The reactance will vary with frequency, but it'll depend on the inductance meter they used.

 

[micolas]

The reactance will vary with frequency, but it'll depend on the inductance meter they used.

Exactly. But there are many unknown variables here. In addition, we have a whole chain of tolerances.
(all my Ali T-13s measured differently in dc)

 

[OneRoomStudio]

Hello, @Jobair Ahmed - as you can probably tell from the discussion, making a decent microphone transformer is not a simple thing. There’s a lot more to it than just having the right turns ratio. I think you’d have a harder time finding the right laminations and wire to make your own than you would finding something suitable off the shelf. Does Neutrik have distribution in Bangladesh? If so, the model “NTE10/3” transformer is usable in the ORS-87 circuit: https://www.neutrik.com/en/product/nte10-3

 

[micolas]

Hello, @Jobair Ahmed - as you can probably tell from the discussion, making a decent microphone transformer is not a simple thing. There’s a lot more to it than just having the right turns ratio. I think you’d have a harder time finding the right laminations and wire to make your own than you would finding something suitable off the shelf. Does Neutrik have distribution in Bangladesh? If so, the model “NTE10/3” transformer is usable in the ORS-87 circuit: https://www.neutrik.com/en/product/nte10-3

Agree with OneRoomStudio
Is it possible for Guosheng to deliver the 3u gzt-87 transformer to Bangladesh? Personally, I like it even more than nte10/3.
Edit:
Unfortunately, he does not deliver in my country, but maybe I will be able to contact him. Does anyone know what eMail he has?

 

[Whoops]

Does anyone know what eMail he has?

I've contacted Guosheng straigh from the email that is on the 3U Audio website

 

[micolas]

I've contacted Guosheng straigh from the email that is on the 3U Audio website

Thanks @Whoops !
On another group, several people claimed that 3u no longer delivers to the EU, just as it happened to me on ebay, but I will give it a try.