• Cost-effective, multi-channel noise removal.
• Eliminates 50Hz/60Hz mains & harmonics.
• 2, 4 or 8* channel versions.
• Easy to use, portable & standalone.
• Analogue signal path with no degradation.


The NEW D400 Multi-channel 50Hz/60Hz Mains Noise Eliminator is a standalone instrument designed for real-time removal of 50Hz or 60Hz mains noise interference, including harmonics, from amplified biological and other signals prior to acquisition by digital data recording systems. Unlike 50Hz/60Hz notch filters, the D400 noise eliminator can remove mains noise without degrading the signal of interest, even if it overlaps with the mains frequency.

Rapidly evolving multi-channel mains noise removal

The D400 is unique as a multi-channel, standalone mains noise eliminator, which is not incorporated within and does not have to be used in conjunction with any specific electrophysiology data acquisition system. While the method of noise removal follows the principles of other single channel devices, such as the Quest Scientific Humbug Noise Eliminator, the hardware and software algorithms used by the D400 have been developed wholly by Digitimer and are unique to this device. For those unfamiliar with the concept of operation, the D400 receives amplified analogue voltage signals (AC or DC coupled) from an amplifier via its inputs and as these signals pass through the D400 noise eliminator remaining in the analogue domain, it rapidly constructs a phase-locked “mains noise template” and subtracts this from the original signal. Noise removal occurs in real-time and the noise template evolves constantly, so that any changes in the amplitude or other characteristics of the noise are corrected for.


• There are many other 50/60Hz notch filters available, what makes the Digitimer D400 so special?

The Digitimer D400 is NOT a mains noise filter, making this the main reason it is a special, and unique as a standalone multi-channel device. Filtering often results in phase shifts, frequency loss, amplitude errors, DC shifts, time delays or digital distortion, but the D400 will eliminate 50/60Hz electrical interference (and harmonics) without altering your signal of interest.

• I am particularly interested in measuring brain activity in the gamma frequency range – won’t the D400 distort my data?

No, absolutely not. This is one of the key features of active noise cancellation devices, in that they synchronize with the local mains frequency whether it is 50Hz or 60Hz and will ignore components of the input waveform even if they overlap with these mains frequencies. As a result, many researchers interested in signals within the gamma band will opt for devices like the D400.

• I understand that the D400 constructs a noise template which is subtracts from the signal, but is the same template used for all channels?

No, the D400 has a distinct noise template for each channel. This means that it is theoretically possible to share one D400 across more than one electrophysiology rig, although there may be issues when any of the function buttons need to be used, as their actions are applied globally to all channels.

• I see that you now have some software to control the D400 – what is the benefit of using this?

The obvious benefit is that the user can control the D400 without having to look away from or move from their computer screen when using the clear, hold or bypass controls. However, the other advantage is that individual channels can be controlled separately from the software. This may be of use in a rig that has 4 parallel brain slice recordings and the operator only wants to make adjustments to one of them, without affecting the other electrophysiological recordings.

The D400 software also allows the user to visualize the noise template rather than the cleaned output signal, in order to verify exactly what is being subtracted from the amplified signal of interest.

Manufacturer: Digitimer
Catalog number: Di-D400-4
Parent Category: Noise Eliminators
Application: Amplifiers & Stimulators


Number of Channels:
2 (D400-2), 4 (D400-4) or 8 (D400-8)* Input voltage range: ±10V

Output Voltage Range: ±10V

Frequency Response: DC to 1MHz

Front Panel Controls:
• Clear – Erases existing noise templates
• Pause – Freezes existing noise templates
• Bypass – Pass-through of raw signals to outputs

Front Panel Indicators:
• Power (Green)
• Signal (Green) & Template (bi-color Red or Amber)

• BNC input and output sockets (one pair per channel)
• Combined signal inputs/outputs via pair of 9-way “D” connectors
• Equipotentiality Connector
• USB socket for connection to host PC
• Mains power inlet socket

Supplied Accessories:
• Mains Lead
• Windows Software supplied on USB flash drive
• 9-way “D” to multiple BNC input cable
• 9-way “D” to multiple BNC output cable
• USB cable

Operating Voltage Range:
100V – 240V

200mm (W) x 275mm (D) x 110mm (H) Weight: 2.5kg