Aliexpress input transformers

I have no experience of those, they must be a fairly small core size judging by the outside dimensions of the can. I have experience of the EE25 type (not screened) like this : https://www.aliexpress.com/item/32903876809.html
I'm completely inexperienced with using transformers. I see a pair of EE25 10k:10k on ebay with primary/secondary specs hand written on tape of 2.12k/1590H. Not sure I trust those specs since they're written out as having dual/center-tapped primaries, but it's obvious by the pictures that they only have 2 primary pins.

Assuming those are the specs, what's the difference between them and similar EE25 10k:10k transformers I see with much lower resistance and inductance? Would they be OK to drive a 1-2k load on each secondary from a low impedance source, or would a 600:600 be better for that?

Thanks
 
The inductance of a trafo is a function of a couple of parameters - the number of turns and the core material. The higher the number of turns the more volts a trafo can handle before it saturates. You can get an impression of how many turns from the DC resistance.

As a general rule of thumb I'd want the trafo's DCR to be less than 10% of the load resistance. Driving a 2k load then would be best driven from under 200R. What voltage do you need into your load? The 600ohm trafo will likely be much less capable voltage-wise than the 10k.
 
I need a 20Vrms differential output from a 2Vrms input. The input will be a non-inverting opamp and the outputs will be inverting opamps. I wasn't sure if it's better to use a step-up transformer or put the gain on the non-inverting opamp. I'd like to avoid gain with the output opamps if possible.
 
I need a 20Vrms differential output from a 2Vrms input. The input will be a non-inverting opamp and the outputs will be inverting opamps. I wasn't sure if it's better to use a step-up transformer or put the gain on the non-inverting opamp. I'd like to avoid gain with the output opamps if possible.

I very much doubt you'll get 20VRMS signal handling down to lower freqs with any Taobao audio trafo, that'd need a custom design. I'd be happy to advise if you want to PM me.

@matejsirk I've had good experiences with the EE25 trafos (20k:600 and 10k:10k), as far as I can tell they're audibly transparent and deliver very good value at the asking price. I should add that I've kept signal levels below 2VRMS on the 20k winding, down to 20Hz there's no problem with the FR.
 
Can you make quality electronics with components from aliexpress ? Maybe with screws and test boards ...
🤓
Do you think with other countries/ sites it would be better? More reliable? And why?
In my* country several well known transformer companies exist. Only one of them presents datasheets and is reliable, other companies make ???? We don’t know……

*The Netherlands
 
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Do you think with other countries/ sites it would be better? More reliable? And why?
In my* country several well known transformer companies exist. Only one of them presents datasheets and is reliable, other companies make ???? We don’t know……

*The Netherlands
Since Menno van der Veen and Amplimo (= Ringkerntrafo) don't seem to work together anymore, there are now two well known transformer companies in The Netherlands that present datasheets of their transformers and are reliable (atleast in my view).

But I agree with your point (and Menno atleast has part of his transformers being manufactured in Serbia).