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E14 1:1 600:600 cheap transformers, some measurements

Ardacer

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I've bought 10 of these for next to nothing from ebay. I needed cheap ground loop killers for my HT 7.2 setup using KRK monitors.
I've measured some other transformers I had at home for subs (I'll connect my diy subs into the whole mess) - strange and interesting results.

I have yet to install these, they seem fine for use, as it's just HT, so .. -3db is at 35 Hz, but these monitors hardly go to 50/60 hz anyway and they are at around -1.5 db there, so who gives a shit. Only issue I see is the relatively large 3rd harmonic, especially in bass area. Don't know still if that's going to be audible / too distracting.

I've read somewhere about a cool little optically based audio isolator (in analog domain, no adc-dac conversion) similar to optocouplers, but works for sinusoidal DC apparently with almost no distortion and great linearity, chip in question is il300.
This seemed much simpler to do. il300 would need some more electronics and work, and I don't really have the patience for that. I'll find it if these prove to be shit anyway.

Measured on Steinberg UR22 with REW, calibrated the card.

Obviously a proper isolation transformer is the way to go with all the complex design, internal Faraday cages and what nots...but I just don't want to buy 9 Lundahl-s for something like a HT setup I'll use once a week.


ARt6v30.png
dx2TS97.png

ha5hG8P.png
 

TimW

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I bought some of these in kits from here. The kit is for two transformers, two 3.5mm TRS connectors and a PCB to make a stereo isolation circuit. They work for preventing ground loops and I noticed no degredation in SQ but I didn't use them in a high performance system. I would also be curious about the performance of the Neutrik NTE1.
 
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Ardacer

Ardacer

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Probably similar, the core is the limiting factor if I understand correctly.
 

Hayabusa

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I've bought 10 of these for next to nothing from ebay. I needed cheap ground loop killers for my HT 7.2 setup using KRK monitors.
I've measured some other transformers I had at home for subs (I'll connect my diy subs into the whole mess) - strange and interesting results.

I have yet to install these, they seem fine for use, as it's just HT, so .. -3db is at 35 Hz, but these monitors hardly go to 50/60 hz anyway and they are at around -1.5 db there, so who gives a shit. Only issue I see is the relatively large 3rd harmonic, especially in bass area. Don't know still if that's going to be audible / too distracting.

I've read somewhere about a cool little optically based audio isolator (in analog domain, no adc-dac conversion) similar to optocouplers, but works for sinusoidal DC apparently with almost no distortion and great linearity, chip in question is il300.
This seemed much simpler to do. il300 would need some more electronics and work, and I don't really have the patience for that. I'll find it if these prove to be shit anyway.

Measured on Steinberg UR22 with REW, calibrated the card.

Obviously a proper isolation transformer is the way to go with all the complex design, internal Faraday cages and what nots...but I just don't want to buy 9 Lundahl-s for something like a HT setup I'll use once a week.


ARt6v30.png
dx2TS97.png

ha5hG8P.png
what signal levels did you put in? Does the distortion change much at lower signal levels?
5% 3rd harmonic at 50Hz is audible....
 
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Ardacer

Ardacer

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Test was measured at -3db I think. Cant remember. Measuring at different levels is a smart idea, didn't think of it then. Well actually I did change levels a bit, but I just glanced over linearity which was the same.
 

ajawamnet

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The IL300 uses two PIN diodes, with one used to servo the amplifier to get around the non-linearity of the LED:
il300.jpg



I've designed these into safety circuits - linearity is really dependent on the servo drive of the LED.

Good audio transformers are not cheap - Jensen makes some of the finest in the industry... esp. if youo need good low freq performance... they sell them pre packaged for this type of isolation application:

https://www.bhphotovideo.com/c/prod...line_input_isolator_2_channel.html?ap=y&smp=y
Ruler-flat frequency-response from 5 Hz to 40 kHz
jensen_transformers_pi_2xr_line_input_isolator_2_channel_1520868090_1344639.jpg


As to transformers, I've used a ton of Tamura and Triad. On my bench it's used to interface with a UHD 204 (which was mentioned a few years ago by our fearless leader - https://www.audiosciencereview.com/...view-of-totaldac-d1-usb-cable.1888/post-49481 )

I use it for testing balanced audio gear:

UHD-transformers.jpg

bench.jpg


These are TY-250P - here's the testing results:
ty250p.png


ty250p-distvsfreq.png

ty250p_-10-0.png

ty250p-distvsfreq_-10-0.png

At higher levels the distortion product is less except at 130Hz...
 
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Ardacer

Ardacer

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Impressive setup, @ajawamnet. Thanks for the measurements, that TY-250P seems to be very nice indeed. -0.6 dB at 20 Hz is nothing, and THD + noise is great too.

Guess that settles it, then. Will buy some. Thanks.

Edit: Wow. These are not that easy to come by.
 
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ajawamnet

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Impressive setup, @ajawamnet. Thanks for the measurements, that TY-250P seems to be very nice indeed. -0.6 dB at 20 Hz is nothing, and THD + noise is great too.

Guess that settles it, then. Will buy some. Thanks.

Edit: Wow. These are not that easy to come by.

There's even better stuff available from places like Jensen.

We use these in a lot of pro-audio and ICRI stuff we design. They seem to hold up well even in the trunks of emergency and mil vehicles.

That was tested as 1:1 with the secondary terminals 6 and 7 tied together and the primary center tap floating and just the test gear loading.

The loading will affect the response...


ty250.jpg
 
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