Unofficial Mackie User Forums > DL1608/DL806/DL32R/ProDX Mixers
FAQ: High Frequency Noise on Auxes
WK154:
The general rule on balanced to unbalanced is to leave the shield floating at the receiver (amp, instrument etc.) end and to tie return and shield together at the sender end (DL1808). A detailed explanation of grounding and tracing ground issues can be found here and is well worth reading.
http://www.jensen-transformers.com/an/generic%20seminar.pdf
Definitely do not lift AC ground.
TRS end -> TS end
S connected -> not connected
R -> S
T -> T
Not sure if that's what you had in mind RR. This is with a standard 2 wire plus shield audio cable. If the ground currents are significant between equipments a isolator would be needed.
sam.spoons:
Agreed but that doesn't solve the aux noise issue on the DL, see my post above.
prosoundco guy:
--- Quote from: RoadRanger on March 28, 2013, 02:50:16 PM ---The conclusion of a six page thread on the old forum seems to be that using unbalanced connections (AKA TS or instrument cables) between the DL1608 aux outs and a powered monitor or amp will be noisy. One guy "solved" this by disconnecting the AC ground on the power supply but that's dangerous at best. Has anybody had any luck running unbalanced?
--- End quote ---
I think that you'll find that using unbalanced cables a noisy option using any board. Best solution is to use a TRS to XlR short cable from the Aux outs into an XLR mic cable for the run to the monitor(s).
sam.spoons:
--- Quote from: prosoundco guy on April 25, 2013, 01:29:30 PM ---
--- Quote from: RoadRanger on March 28, 2013, 02:50:16 PM ---The conclusion of a six page thread on the old forum seems to be that using unbalanced connections (AKA TS or instrument cables) between the DL1608 aux outs and a powered monitor or amp will be noisy. One guy "solved" this by disconnecting the AC ground on the power supply but that's dangerous at best. Has anybody had any luck running unbalanced?
--- End quote ---
I think that you'll find that using unbalanced cables a noisy option using any board. Best solution is to use a TRS to XlR short cable from the Aux outs into an XLR mic cable for the run to the monitor(s).
--- End quote ---
I suggested trying the DL with the safety earth disconnected, but strictly as a diagnostic (though I did surmise that a safety earth on a low voltage device may not be strictly necessary). In the event it did not solve the problem however the lead detailed above did solve the noise issue on my rig.
to reiterate at the DL end use a TRS plug, leave the Ring unconnected, tip = hot. sleeve = ground
at the unbalanced amp end use a TS plug, tip = hot. sleeve = ground
This works with my DL sending a line signal to my AER Compact 60 (used as a monitor), a TS-TS lead or any other connection scheme generates the high pitched noise.
The DL aux outputs are impedance balanced and an explanation of why this wiring works can be found here http://community.avid.com/forums/t/58612.aspx
prosoundco guy:
--- Quote from: sam.spoons on April 25, 2013, 01:53:38 PM ---
--- Quote from: prosoundco guy on April 25, 2013, 01:29:30 PM ---
--- Quote from: RoadRanger on March 28, 2013, 02:50:16 PM ---The conclusion of a six page thread on the old forum seems to be that using unbalanced connections (AKA TS or instrument cables) between the DL1608 aux outs and a powered monitor or amp will be noisy. One guy "solved" this by disconnecting the AC ground on the power supply but that's dangerous at best. Has anybody had any luck running unbalanced?
--- End quote ---
I think that you'll find that using unbalanced cables a noisy option using any board. Best solution is to use a TRS to XlR short cable from the Aux outs into an XLR mic cable for the run to the monitor(s).
--- End quote ---
I suggested trying the DL with the safety earth disconnected, but strictly as a diagnostic (though I did surmise that a safety earth on a low voltage device may not be strictly necessary). In the event it did not solve the problem however the lead detailed above did solve the noise issue on my rig.
to reiterate at the DL end use a TRS plug, leave the Ring unconnected, tip = hot. sleeve = ground
at the unbalanced amp end use a TS plug, tip = hot. sleeve = ground
This works with my DL sending a line signal to my AER Compact 60 (used as a monitor), a TS-TS lead or any other connection scheme generates the high pitched noise.
The DL aux outputs are impedance balanced and an explanation of why this wiring works can be found here http://community.avid.com/forums/t/58612.aspx
--- End quote ---
Most powered monitors I've seen only have XLR inputs anyway. So TRS to XLR is the way to go.
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