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Suncoast Audiophile Society Message Board Main discussion area (visible to non-members) › Ground loops, cable isolation, and dedicated lines

Ground loops, cable isolation, and dedicated lines

Alan N
user 13931748
Group Organizer
Tampa, FL
Post #: 637
Russ, you might have nailed it! C-J uses a "minimalist" unbalanced RCA-only designs in all their gear. However, some owners (and reviewers) have commented on their increased susceptibility to noise. However, I never had this much hum before, and haven't added any new gear, so not sure what changed (other than the geometry of my rats nest of cables <g>).

Fortunately, the Stinger SGN20 seems to work well in isolating the video noise. I couldn't resist taking it apart this morning!



Looks to me like it's really a "mini" isolation transformer, as I can see two adjacent cores inside the enclosure. Lots of glue, so I couldn't slide the entire assembly out. I presume the underlying circuit board is just for the interconnect solder points, as there isn't much room for a resistor or diode. I'm ordering a couple more to try elsewhere as audio interconnects, just for kicks, though I suspect they must have some detrimental effect on the audio signal.

Will post an update after some extended listening.
Alan N
user 13931748
Group Organizer
Tampa, FL
Post #: 638
Hah! The parent company of Stinger is AAMP of America, located right here in Clearwater... http://aampofamerica....­ I emailed them asking about the design concept and/or schematic for the SGN20.

FYI, Parts Express sells a similar device for even less... http://www.parts-expr...­
Alan N
user 13931748
Group Organizer
Tampa, FL
Post #: 641
Interesting discussion on AA re refractory hum/ground loop with various proposed solutions including isolation transformers (Edcor or Jensen recommended)... http://www.audioasylu...­

Looks like this particular situation was actually due to a faulty amp ground, which the manufacturer repaired. Regardless, lots of good suggestions in the thread.
Alan N
user 13931748
Group Organizer
Tampa, FL
Post #: 642
... I suspect they must have some detrimental effect on the audio signal.

Will post an update after some extended listening.
Unfortunately, despite its published specs (Output Impedance <150 ohm, Freq Response 20Hz - 20kHz +/- 2dB, Input/Output Ratio 1:1) the SGN20 attenuates the audio signal ~10dB, so I need to crank my preamp to achieve equivalent listening volume. Otherwise, frequency response and imaging seem pretty much unchanged. I can live with this as a temporary "fix" but am wondering if a higher quality isolation transformer (e.g. Jensen) might offer something closer to 1:1 signal throughput (or perhaps better impedance matching).

Anybody on board who's an isolation transformer expert? Would love to hear you chime in on this!
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Tampa, FL

Founded Feb 3, 2011

Organizers:

Alan N, Edward Matura, Ernie Kautzmann, francis endryck, Richard Setera
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