This level-control product has been marketed in several configurations which are all basically the same function (stereo volume attenuation) but offering different input-output wiring. In this review I’m looking at the model with XLR balanced input and output connections.
The Level Pilot X is a passive stereo volume control (an attenuator, a gadget made to reduce signal level electrically). It has a weighted, analog, metal knob which lets you reduce the signal level in a stereo, balanced circuit (you can also use just one circuit for a mono fader function). A single cable feeds from the knob to the breakout-end where you’ll find standard XLR input and output connectors on a pigtail style cable end.
The Level Pilot is extremely close to being a straight-thru piece of wire (not affecting your sound) when it is UP All The Way. If you turn it down (reduce the signal level) you might notice a tiny bit of high frequency roll off happening depending on your cabling and installation (it’s a forum debate topic). Both channels (L and R) are reduced simultaneously when you turn the knob to lower level positions.
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| Ready for Installation |
OVERVIEW
The TC Electronic Level Pilot X was designed for desktop use with active studio monitors. It features balanced XLR connectors (2x female inputs and 2x male outputs) and uses a high-quality Bourns potentiometer for precise control. It requires no external power and is fully balanced to maintain signal integrity.
INPUT IMPEDANCE
The official user manual and product specifications do not explicitly state a numerical value for the input impedance. As a passive device with balanced XLR inputs, its input impedance is designed to be compatible with standard pro audio line-level sources (typically 600 Ω outputs from audio interfaces or mixers). In practice, passive attenuators like this one present a high input impedance (likely in the range of 10kΩ to 20kΩ per leg in a balanced configuration) to minimize loading on the source and avoid signal degradation or frequency response issues.
This design ensures:
- Low insertion loss at maximum volume (practically 0 dB attenuation).
- No added noise or coloration, as confirmed in measurements.
For optimal performance, keep cable runs short (the included 1.8 m quad-core cable helps) to prevent high-frequency roll-off due to impedance mismatches in passive circuits.
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Specification |
Details |
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Connectors |
Inputs: 2x XLR female (balanced) Outputs: 2x XLR male (balanced) Cable: Quad-core, 1.8 m (6 ft) |
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Volume Range |
-∞ to 0 dB |
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Potentiometer |
High-quality stereo, fully balanced Bourns potentiometer |
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Power Requirements |
None (passive) |
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Dimensions (H x W x D) |
51 x 60 x 60 mm (2 x 2.4 x 2.4 in) |
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Weight |
0.4 kg (0.9 lbs) |
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Finish |
Sandblasted aluminum with rubberized base |
USING THE LEVEL PILOT - Setting Levels Correctly
One of the most obvious uses is controlling the volume of active monitor speakers. The compact knob design lets you have the volume control right next to you if that is where you want it. The Level Pilot is designed to have a great feel, the weighted base helps keep it in place.
The correct “normal” setting for the Level Pilot knob is wide-open or all the way up. You’ll want to use the indivdual input gain knobs on your studio monitors so that they’re making “reference volume level” when the Level Pilot is at maximum. All the way UP is where the knob has the minimum impact on volume and tone.
USING LEVEL PILOT TO MAINTAIN DIGITAL RESOLUTION AND CLARITY
1. Understanding Digital Volume Control and Resolution Loss
- In a fully digital workflow (e.g., inside your DAW or audio interface before the digital-to-analog converter, or DAC), reducing volume typically involves multiplying the digital audio samples by a factor less than 1. This is essentially scaling down the amplitude of the waveform in the digital domain.
- Digital audio is quantized to a fixed bit depth (e.g., 16-bit, 24-bit, or 32-bit floating-point). When you attenuate digitally:
- You're effectively shifting the signal downward within the available bit range. For example, in a 24-bit system, full-scale audio uses all 24 bits for maximum resolution. Attenuating by 6 dB (halving the amplitude) is like losing 1 bit of resolution because the signal now occupies fewer effective bits.
- This can reduce the signal-to-noise ratio (SNR) and dynamic range. Quiet details in the audio might fall below the noise floor or get quantized more coarsely, leading to potential loss of fidelity, especially at lower volumes. Dithering can help mitigate this, but it's not perfect.
- In extreme cases (e.g., heavy attenuation), you might introduce quantization errors or need to re-normalize later, which can add distortion.
2. How Analog Volume Controls Work
- Devices like the Level Pilot X are passive analog attenuators placed after the DAC in the signal chain—typically between your audio interface's analog outputs and your powered studio monitors.
- They use a variable resistor (potentiometer) or resistor network to reduce the analog voltage level of the signal. This is a continuous (analog) process:
- The full-resolution digital signal is first converted to analog by the DAC at maximum bit depth and output level.
- The attenuator then passively "divides" the voltage (e.g., via a voltage divider circuit), lowering the overall amplitude without altering the waveform's shape or introducing digital quantization.
- Since the attenuation happens in the analog domain, the original signal's detail and dynamic range are preserved up to the point of conversion. You're not losing bits; you're just scaling the continuous analog waveform down.
3. Why This Preserves Resolution
- Full DAC Utilization: The DAC receives and converts the unattenuated digital signal at its highest possible resolution. All available bits are used during conversion, maintaining the full SNR and dynamic range from the source.
- No Digital Scaling Artifacts: Analog attenuation avoids the bit-reduction issues of digital control. The noise floor remains relative to the full-scale signal, and quiet details aren't pushed into lower-bit quantization noise.
- Passive Design Benefits: In units like the Level Pilot X (which uses a high-quality Bourns potentiometer), there's no active circuitry adding noise or distortion. It's fully balanced and transparent, with near-zero insertion loss at maximum volume, ensuring the signal path stays clean.
- Practical Outcome: You can turn down the volume for comfortable listening without compromising the audio's inherent resolution. This is especially useful in professional monitoring setups where you want to evaluate mixes at various levels without fidelity loss.
4. Caveats and Limitations
- While analog controls preserve digital resolution, they aren't immune to all issues. For instance:
- Long cable runs or impedance mismatches can introduce high-frequency roll-off or noise pickup in passive analog setups (though the Level Pilot X includes a short, high-quality quad-core cable to minimize this).
- If your source signal is already low-resolution or noisy, analog attenuation won't magically improve it - it just doesn't degrade it further.
- In very low-volume scenarios, the analog noise floor (from cables, pots, or amps) might become audible, but this is separate from digital resolution loss.
- This advantage assumes your system is set up correctly: Keep digital levels hot (close to 0 dBFS without clipping) to maximize DAC performance, then use the analog control for final volume adjustment.
Analog volume controls like this one shift attenuation to the post-DAC stage, ensuring the digital signal is converted at full resolution before being scaled down continuously in analog. This contrasts with digital attenuation, which can inherently reduce effective bit depth. It's a straightforward engineering principle that makes these devices popular in pro audio for critical listening.
OTHER APPLICATIONS - Volume Fade Out
I usually mix outside the box, the stereo output from my console-system feeds a couple of Tascam recorders. Usually one is set to encode mp3 and the other, a DA3000, is set to 24/192 high resolution. The external recorders are fed from a Coleman TC-4 where various bus processors can be inserted. I have one of these TC Level Pilots in the patch bay so I can put it in the 4th (last place) processor slots on the Coleman. This lets me use the Level Pilot to control the fade out on the way to the stereo recorders. The vintage tube compressors and EQP master equalizers add low level residual noise, I put the Level Pilot after everything else in the signal path and do the final fade out by hand using the Level Pilot. I’ve used the Coleman TC-4 to listen for any degradation caused by the Level Pilot and have not heard any yet.
EPILOGUE
In my studio experience the TC Level Pilot pots have not been long lasting. After one to two years of daily use the pot inside seems to develop a static sort of noise, especially at lower level positions. The complete XLR TC Level Pilot device is priced under $50, I now have a spare in stock so if one goes bad I can swap it with a new one without waiting for a delivery or running into a backorder. $25/year is an acceptable maintenance cost and swapping one of these out is so easy my GF just changed out the one in the bedroom. I have three of these in regular use; in my small studio, the big room and our bedroom where we use a Level Pilot to control the movie screen sound system. I love the analog feel of “The Knob”, it’s smooth, it’s compact, it is fast and easy to use and it works great.
Thanks for reading High on Technology, Good Music To You!
©September 2025 by Mark King, it is not ok to copy or quote without written permission from the author.
Here, we just call it “The Knob”, it is so much smoother than an IR remote for controlling volume. Have you created anything beautiful today. . . . . . . . .
