H7600 total bypass, ground loops

[Josch]

Hello everyone,

I am planning to get an Eventide H7600 and change it with my H3000 in my guitar stereo setup. The H7600 should go in the same place like my H3000.
Signal path sould be:
from G-System L-Out (unbal. 1/4" jack) to H7600 CH1 In (XLR),
        G-System R-Out (unbal. 1/4" jack) to H7600 CH2 In (XLR).
H7600 CH1 Out (XLR) to DBX 266 CH1 (unbal. 1/4" jack),
H7600 CH2 Out (XLR) to DBX 266 CH2 (unbal. 1/4" jack) …

Now I got some questions:

1) With my H3000 at this position I am used to have the H3000 power turned off and the signal is still going through, it is not muted or cut by the H3000 (power off). I feel very comfortable with this, so at home I let the H3000 turned off sometimes, e.g. for practicing sessions. Is it the same way with the H7600?

2) The Eventide knowledge base wiring page shows for each H3000 Out XLR to unbalanced 1/4" jack Pin # 2 should be left unconnected. I understand this is done to prevent ground loops.
For H7600 it is recommended to have Pin # 1 and # 3 connected to 1/4" ground and Pin # 2 to 1/4" Tip. Don't you get ground loop problems (and hum) with that, I expected to leave Pin # 3 left unconnected?
If there are no problems, what is the difference here between the H3000 and H7600?

3) With the recommended wiring of the H7600 (see question 2) do I get hum-problems if I use the H7600 in the signal chain with power turned off (see question 1)?

Thanks a lot for answering my special questions.

[nickrose]

In general we would recommend that you use XLR wherever possible in preference to 1/4".

1) It is the same with the 7600 if you use XLR.

2) Ground loops are created by misuse of pin 1, not 2 or 3.  Depending on the design of your rig (beyond the scope of this forum) you may want to leave pin 1 disconnected. The main difference here between the H3000 and the 7600 is that with the 7600, both pins 2 and 3 need to be connected to something.

3) If the grounding is wrong you will probably get hum problems whether or not the 7600 is switched off. If it is right, there will be no issue.

[Author]

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