aussievintage Posted January 23, 2020 Share Posted January 23, 2020 These cheap isolators are intended for use in cars I think. Only about $10 on eBay, so I ordered one to find out what you get. It comes as a small black plastic case with RCA fly-leads of opposite sex. Two screws to take it apart. Here's a picture - it contains just what I expected, two small transformers on a neat little board. I connected my D10 DAC using it, and it sounded normal, so I suspect frequency response at low signal levels is OK. Have to do more listening. However it will be a useful tool in diagnosing ground loops. 2 Link to comment Share on other sites More sharing options...
audiofeline Posted January 23, 2020 Share Posted January 23, 2020 I'm not familiar with these devices. I assume it has a 1:1 transformer to isolate the signal circuit. The one pictured can be found on eBay for $6 incl. postage. Would the only use for it be to manage a ground look hum? Other similar devices on ebay - • The GL301 comes in a clear case at about $19. It's circuit board includes capacitors. Interestingly it includes spec's: 1.3db of gain, and 0.5db linearity from 20-20,000hz. How would capacitors improve the one above without them? • At the other end of the scale I note that there is a similar looking device (in a cylindrical casing) at AU $1,462.08 - I would hope that this one has much more exotic transformers in it! Link to comment Share on other sites More sharing options...
aussievintage Posted January 23, 2020 Author Share Posted January 23, 2020 1 minute ago, audiofeline said: 'm not familiar with these devices. I assume it has a 1:1 transformer to isolate the signal circuit. That's what they look like. It's certainly how they are wired. 1 minute ago, audiofeline said: The one pictured can be found on eBay for $6 incl. postage. Yes, I paid a fraction more to get it faster from an Aussie supplier. 2 minutes ago, audiofeline said: Would the only use for it be to manage a ground look hum? I think so, yes. In cars, it is used for engine noise / spark suppression, induced into the loop. Same purpose. 3 minutes ago, audiofeline said: The GL301 comes in a clear case at about $19. It's circuit board includes capacitors. Interestingly it includes spec's: 1.3db of gain, and 0.5db linearity from 20-20,000hz. How would capacitors improve the one above without them? Firstly, on something that cheap, I am not sure I trust the specs I presume the caps are sized to filter high frequency noise that might couple through the simple device in my picture. 4 minutes ago, audiofeline said: At the other end of the scale I note that there is a similar looking device (in a cylindrical casing) at AU $1,462.08 - I would hope that this one has much more exotic transformers in it! They can't be worth anything like that. 1 Link to comment Share on other sites More sharing options...
audiofeline Posted January 23, 2020 Share Posted January 23, 2020 3 minutes ago, aussievintage said: ...They [the mega-expensive model] can't be worth anything like that. Yes, what I thought. I wondered if they are actually the $10 put into a new case with a different label. But I am aware that some transformers do have exotic hand-windings and do command a reasonable price. But can't see anyone applying that to car audio! Link to comment Share on other sites More sharing options...
pete_mac Posted January 23, 2020 Share Posted January 23, 2020 Jaycar also stock two different types: https://www.jaycar.com.au/ground-loop-isolator-stereo-rca/p/AA3084 https://www.jaycar.com.au/galvanic-isolation-filter/p/AA3075 Link to comment Share on other sites More sharing options...
aussievintage Posted January 23, 2020 Author Share Posted January 23, 2020 1 minute ago, pete_mac said: Jaycar also stock two different types: https://www.jaycar.com.au/ground-loop-isolator-stereo-rca/p/AA3084 https://www.jaycar.com.au/galvanic-isolation-filter/p/AA3075 I wonder if the transformers inside are any different? I actually looked at both of them first, but decided the in-line arrangement of the one I bought, was the most convenient, especially for testing. Link to comment Share on other sites More sharing options...
A9X Posted January 24, 2020 Share Posted January 24, 2020 1 hour ago, aussievintage said: Firstly, on something that cheap, I am not sure I trust the specs I wouldn't. They're too small based upon the many I have used from Lundahl, Jensen and Cinemag, all of which have actually met spec. I would expect the LF distortion to rise from a fairly high frequency as there is unlikely enough primary inductance to support good LF performance. The type and quality of the core material will have a large effect also. 1 Link to comment Share on other sites More sharing options...
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