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IT1      Isolation Transformer


  • True Floating Transformer Isolation for Unbalanced Line-level Outputs
  • Input, Output and Loop-Thru XLR and 1/4" (6.3mm) Phone Jack Connectors
  • Can Be Used As Line Level Direct Box
  • Ideal for Portable and Permanent Sound Systems
  • High-Quality Transformer-Isolated Output
  • Rugged ProCo Uni-Box Construction Provides Protection and EMI/RFI Shielding


The ProCo IT1 Isolation Transformer Unit provides an easy-to-use, high-quality solution for interface problems that demand the high degree of electrical isolation that only a transformer can provide. Transformer isolation minimizes interference from SCR lighting dimmers, radio transmitters and 60 Hz AC power wiring with a common-mode voltage range that makes it far more forgiving of improper connections or fault conditions than any electronically balanced or “differential” transformerless circuit. This makes transformer-floated outputs essential for safeguarding portable sound reinforcement systems and installations.

Sound system technicians can use the IT1 to break ground loops between pieces of equipment connected with unbalanced lines (for instance, to float the unbalanced output of a mixer that must drive long cables connected to power amplifier inputs). For musicians, the IT1 is a line level direct box for connecting line-level sound modules, samplers and the like to “live” or recording mixers, providing a floating output without the voltage stepdown of a high-to-low impedance conversion. For broadcast and ENG, the IT1 is a handy unit for deriving a remote feed from a press conference or meeting room public address system.

Male and female XLR-type connectors in parallel with two 3-conductor 1/4” (6.3mm) phone jacks for LINE IN/OUT provide nearly universal loop-through capability. Parallel jack and male XLR connectors deliver the ISO OUT to balanced or unbalanced loads. The use of the ProCo LOT-P transformer allows the IT1 to provide a floating, low-impedance output with wide, flat frequency response, ultralow distortion, and no ringing or overshoot to degrade transient response. 

The IT1’s “Uni-box” construction” enclosure is formed of extruded aluminum side channels and 16-gauge steel top 
bottom and end plates and is designed to protect switches and connectors from accidental damage. The use of steel also provides excellent magnetic shielding for the transformer from 60Hz AC hum fields. Top-quality connectors and switches provide trouble-free service even in abusive situations such as remote broadcast and recording operations. 



All measurements made with 0 Ω source feeding Line IN/OUT and 600 Ω load on all ISO OUT to simulate typical "real world" source and load. LOT-P transformers configured for 1:1 operation.
0 dBv ref. = .775 volt.

Phase response and rise time measurements are essentially those of the driving amplifier used rather than those of the LOT-P transformer.

Frequency Repsonse:

20 Hz - 20 kHz, ± 0.5 dB @ 0 dBv output.
-3 dB @ approximately 85 kHz.

Total Harmonic Distortion:
<.25% 20 Hz - 20 kHz @ 0 dBv output.
<.5% 30 Hz - 20 kHz @ +18 dBv output.
<1.0% 20 Hz - 20 kHz @ +18 dBv output.
Phase Response:
<-3 degrees @ 20 kHz (ref. 1.0 kHz).

Rise Time:
<4.5 microseconds (2.0 kHz square wave, 10%-90%).

Input Impedance:
>680 Ω @ 1.0 kHz.
>680 Ω @ 10kHz.
Nominal source impedance is 0 Ω.

Output Impedance:
<120 Ω @ 1.0 kHZ.
<120 Ω @ 10 kHz.
Nominal output impedance is 600 Ω.

Voltage Loss:
<2.0 dB @ 1.0 kHZ.

Maximum Input Level for 1% THD:
+20 dBv @ 20 Hz.
+24 dBv @ 30 Hz.
+30 dBv @ 50 Hz.