Despite the fact that this synchronization protocol is one of the oldest, it raises the most questions and lack of understanding among people. Below I will describe the principles of generation and what requirements LTC places on equipment and connection.

To generate the LTC signal, you need a sound card with balanced audio outputs or a dedicated LTC timecode generator. In this article, we will analyze the first type of equipment. Later, we will describe the functionality of professional LTC equipment.

The most common connector used for LTC is the XLR audio connector. This connector has three pins, which are necessary for transmitting a balanced signal, and a latch lock, making it more reliable.

The sound industry also uses a balanced 1/4" TRS Jack connector, which also has three pins and can reliably transmit LTC. Some manufacturers use this connector type for both LTC transmission and reception, which is fully acceptable.

Standard sound cards with mini-jack outputs are not suitable for working with LTC due to the unbalanced nature of their outputs. To understand why this matters, let’s explore the key differences between balanced and unbalanced signals.

Balanced Signal:

• Transmitted over three wires: HOT, COLD (inverted), and GND.

• Equal electrical resistance from both signal wires to ground.

• Antiphase signal transmission allows cancellation of induced noise.

• Amplifier at the input sums the inverted signal with the direct signal, effectively canceling out noise and doubling signal strength.

Advantages of Balanced Connections:

1. Signal Integrity over Distance: Allows analog and digital signal transmission over long distances without significant distortion.

2. Superior Noise Immunity: Balanced lines reject common-mode interference much more effectively than unbalanced ones.

Balanced analog audio signals are specifically designed to be transmitted over long distances with minimal interference and signal degradation, thanks to their differential design (which cancels out common-mode noise).

LTC is an audio-based timecode signal, transmitted as a square wave, and it is much more sensitive to signal distortion and attenuation, especially of high-frequency components that define edge transitions.

Recommended LTC Transmission Distances:

💡 High-quality cables (e.g., Canare, Mogami, Sommer, Belden) with low capacitance and tight shielding are crucial for long runs.

📌 Practical Guidelines:

• Use low-capacitance, shielded cable (e.g., AES/EBU or professional mic cable).

• Avoid passive splitters or excessive loop-throughs — LTC should ideally be distributed using active distribution.

For longer distances (100 m+), consider:

• LTC over AES/EBU,

• or transmitting LTC via digital audio protocols like Dante or MADI for extended range.

Imagine a scenario:

• An LTC sync server is generating timecode.

• A lighting console or device 200 meters away must receive this LTC.

Unfortunately, no lighting console or client sync card has the input sensitivity to receive LTC through 200m of cable. Even worse, a square waveform degrades over such a long line due to the capacitance and inductance of the cable.

This leads to signal rounding, phase shifting, and frame loss.

Solution 1: Boost Output Signal

• Use professional audio interfaces with powerful balanced outputs.

• OR use a timecode generator/controller with adjustable LTC output levels.

Solution 2: Amplify & Reshape at Destination

• Use a high-sensitivity audio interface at the receiving end.

• OR use an LTC reshaper/analyzer that restores and boosts the signal, for example mif4 timecode controller.

✅ Best practice: Combine both methods for maximum reliability.