Glad I was able to help, Lowrider.
... removed CDP from pwr. cond. in rack (which is shared w/ preamp), used cheater plug and put back in rack AC receptacle.
If I understand correctly, when you added the cheater plug to the CDP’s power cord you plugged it into the same receptacle that it had previously been plugged into, on the Furman power strip. Correct me if I’m misinterpreting.
Do you think the problem is that all components are in the power strip?
No. In fact having components plugged into outlets that are in different places can contribute to ground loop issues.
I would like the ground loop explained if possible.
I won’t go into what would be a lengthy technical writeup on the theory of ground loops. But very briefly, a ground loop involves the interconnection of the circuit grounds of the two components that occurs via the interconnect cable; the interconnection of the chassis of the two components that occurs via the AC safety ground wires in their power cords (if both cords are connected to AC outlets, as opposed to being defeated with a cheater plug); the connection between the safety ground pins of those outlets in the power strip or other external AC wiring; and the manner in which AC safety ground/chassis is connected to the circuit ground within each component.
Depending on all of those variables the result can be the introduction of hum, high frequency noise, or both. What I was envisioning is that high frequency noise was being coupled into the output of the CDP and/or its AC input, and making its way via unintended circuit paths within the CDP that are inevitably present to some degree (such as stray capacitances, grounds that are less than ideal, etc.), to the point at which D/A conversion is performed, and causing jitter in the timing of D/A conversion.
Ground loop-related noise will result in greater than normal sensitivity to interconnect cable differences, since the signal return conductor in the cable connects the circuit grounds of the two components, and the characteristics of that conductor will vary considerably between different cables. In some cases it will be a shield, in other cases a wire within a shield (connected at one or both ends), and in other cases a wire with no shield. And differences among different cables in the resistance and inductance of that wire or other return conductor can affect ground loop-related noise significantly.
As you are probably aware, some audiophiles use cheater plugs as permanent solutions to ground loop issues, but I would strongly recommend against doing that. The resulting safety risks (fire and electrocution) are extremely unlikely to ever occur, but it cannot be said that the risk is zero.
What I would suggest is that you call the Jensen transformer people and discuss choosing and ordering one of the transformers shown
here. Ideally you would want a model having RCA input and output connectors, which would be designated as a PI-2RR. They don’t show that configuration on that page, but I would expect that they could provide it on special order, and in fact a PI-2RR configuration is shown in
this datasheet.
An alternative to consider, also, would be a PI-2XR, having XLR inputs and RCA outputs, although you would have to provide a pair of XLR cables to connect between it and the CDP. Also, the specified maximum amplitude of the CDP’s balanced outputs, 5.4 volts, doesn’t provide a great deal of margin relative to the +17 dbu worst case input rating of the transformer. (The 2.7 volt spec of the CDP’s RCA outputs is very comfortable in that regard).
That kind of transformer requires that its **output** be connected via a **short** length of **low capacitance** cable. BlueJeans LC-1 would be fine for that purpose, in a length of 1 or 1.5 or 2 feet. You would connect the transformer’s input with your present cables.
Obviously I can’t be 100% certain that inserting this transformer between the CDP and the preamp would provide results that are as good or better than what you now have using the cheater plug and the BlueJeans cable. But it **will** break the ground loop between the two components, and a number of other members here who are highly experienced audiophiles and have expensive highly resolving systems have reported good results using them.
Best regards,
-- Al
