ULN-2 Users Guide
152
Sleeve (Shield)
Tip (Hot)
Ring (Cold)
Tip
Sleeve
Instrument
Mobile I/O
Sleeve Ring Tip
Figure 7.7: Telescoping Shield Cable for Instruments
If you want to use the TRS inputs with balanced microphones, you will need an XLR female to 1/4” TRS
balanced plug adapter cable. These are available commercially, or you can construct one easily. The con-
nections are Tip to Pin 2, Ring to Pin 3 and Sleeve to Pin 1:
1
2
3
Tip
Ring
Sleeve
Sleeve Ring Tip
XLR CONNECTOR MALE OR FEMALE
BALANCED TRS 1/4" CONNECTOR
Figure 7.8: XLR to Balanced TRS Cable
On output, the situation is a bit more complex. If you are driving an unbalanced load, you will get the best
performance by not connecting the ring of the TRS jack to ground. In order to do this, you can simply use
a balanced TRS/TRS connector with the unbalanced gear. You can also construct a special cable with a
TRS connector and a TS connector. In this cable, you just let the ring of the TRS connector float:
NO CONNECTION
TIP
TIP
SLEEVE (SHIELD)
SLEEVE (SHIELD)
BALANCED 1/4" TRS CONNECTOR
UNBALANCED 1/4" TS CONNECTOR
Figure 7.9: TRS to TS Unbalanced Cable
Alternatively, the TS connector can be replaced with an RCA connector for interfacing with gear that has
RCA unbalanced interconnects.
NO CONNECTION
TIP
PIN
SLEEVE (SHIELD)
BARREL (SHIELD)
BALANCED 1/4" TRS CONNECTOR
RCA CONNECTOR
Figure 7.10: TRS to RCA Unbalanced Cable
Making a 1/4” connection
When you connect a 1/4” plug to a ULN-2 jack, insert it straight and firmly, ensuring that the plug is fully
inserted into the jack. If the plug is not fully inserted you will get level shifts, phase flips, distortion, or
no sound.
