HiLetgo 5pcs EI14/EI-14 Audio Coupling Isolation Transformer Audio Transformer 600:600 1:1

works well

For my purpose works well for audio and intercom dry coupling. Very similar to all others, seem to have good response doesn't saturate at line level. Doesn't block dc well and will start to cook like some others. I put 10uf @50 VDC (NP) Non-Polarized caps on both sides to keep phantom and ICM power out without much low-end loss. I make up on inexpensive pc board put in small plastic project 2"x2"x1" project box with XLR Male / Female respective wired with audio cable through an 1/8" hole for in and out. Could be 1/4" TRS also. I do not couple chassis ground in my case. I use whatever is over in my shop to build like recycled XLR connectors. Most times it is left at venue or if it gets broken by moving equipment cases. If I used my standard fare, I would not want to leave, it that be a lot of money.

Some comments suggested a difference between the red ones and yellow ones; mine came yellow. One description said they are 290 mH, so I was going to use two, but the ones I got measure 500-600 mH on each winding, and so are just right for my current purpose, which is for the filter in a DIY wah-wah pedal. All of them seem fine, but I have neither stressed them, nor used them as isolation transformers. They are small (1/2 inch cube) and light (5g or 0.2 oz).

DCR = 85 ohms. L = .33 uH 3nF primary to secondary saturate at pretty low voltage, not useful for line level signals, eg guitar ABY box I'll keep them for possible future projects

I'm making some audio interfaces and needed the isolation from ground loop. These did the trick 100%. Will probably be ordering some more.

I needed one of these to make a digital interface to a ham radio. Quality is good. Shipped very quickly.

The transformers are not the ones pictured they are yellow but work the same

these are good if you get red but the yellows are not and I had to resend back for the correct pic ones , just a fact