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DI box

Most common application for DI boxe is to connect equipment with high-impedance outputs (such as synths and guitars) to a mixer’s low-impedance inputs using long cables. If you were to run a long cable from a guitar to an amp, it would completely load the guitar; you’d lose high-frequency end and add a lot of noise.

However, if you connect the guitar to a DI box close to your instrument, you can then run the signal through long mic cable to a mic preamp or mixer board.

The electrical isolation between the input and output is provided by the transformer and a switch linking the input ground to the output ground can be set to provide a ground-lift.

The balanced output from this DI box is at microphone level so it can be connected to the mic input of a mixing console.

The input is directly wired to a Thru socket. This enables the DI box to be inserted between an instrument and its amplifier without interfering with the normal signal flow.

Compact case of black anodised extruded aluminium with plastic end bezels which guard lockable Neutrik connectors and switches for ground lift.

Customize your DI box by choosing the transformer with adequate ratio:

  • LL1530 features 3,5:1 and 7:1 ratios

  • LL1935 features 5:1 and 10:1 ratios

Product Features:

  • High quality Lundahl transformer.
  • Neutrik Combo connectors on Input and Thru, accepts both male XLR and 1/4'' phono.
  • Neutrik male XLR on Out
  • Ground lift switch with distinct marking when on or off.
  • Level pad -12dB.

We guarantee that this device will survive fall from one meter high and operate correctly afterwards. Damages on the box like deformations and scratches are to expect and we can not take answer for them.

Important note:

Electric guitars and basses with passive piezo pickup systems need to work into a fairly high input impedance to avoid loading the pickups and compromising the tonality. Typically, an impedance between 1MOhm and 5MOhm is required. That's why we do not rocomend use of this DI box with the piezo pickups.

Analog Impedance Match

When connecting a low-Z (low impedance) source to a high-Z load, there is no distortion or frequency-response change caused by this connection. But if high-Z source connected to a low-Z load, you will get distortion or altered response.

For example, suppose you connect an electric bass guitar (a high-Z output) into an XLR-type mic input (low-Z). The low frequencies in the signal will roll off, so the bass will sound thin. Bass guitar has to be loaded by high impedance, and the mic input fed by a low-Z signal. Our impedance matching adapter fix this for you.

It is made on high quality 2:1 ratio transformer in rugged and compact package, still weighting only 100grams. Adapter has a ¼' female jack on one end and a male XLR connector on the other. Primary winding is high impedance, wired to the female jack. The transformer's secondary winding is low impedance, wired to the XLR. You plug the guitar cord into the phone jack, and plug the XLR into a mic input in a snake or mixer. Use it with a bass guitar, electric guitar, synth, etc.

For other transformer ratios please contact us.

Note: XLR-s pin Nr.1 is connected to housing.





Analog Level Match 221

Balanced to Unbalanced interface, called "balun" is often find in antenna circuits. But balun's are needed in audio too.

This one is made in 2:1 ratio in rugged and compact package (weighting only 100grams).

This is high quality interface for connecting professional to semiprofessional standard equipment. In other words connects balanced signal sources to unbalanced inputs without impedance drop and no overload on semiprofessional input side. Both level and impedance are transformed through for this application specially adapted transformer. Transformer is made by Lundahl based on their LL1532.

Connections schematic shown above (XLR-s pin Nr.1 is connected to housing).

Dimensions: height=31mm, width=26mm and length=74,4mm. Weight 100gr.

Digital Impedance Match

110-75 ohm and 75-100 ohm Digital Audio Impedance Adapters

Digital Audio Impedance Adapter allows 75 ohm coaxial transmission of AES/EBU Digital Audio signals. Adapters are designed to convert all standard AES/EBU digital audio signals from 110 ohm/XLR3 Output (@ 4.5 Volts) to a 75 ohm BNC coaxial cable and back again to a 110 ohm/XLR3 Input (200mV min). They also provide excellent rejection against hum and RF noise.

Key Features:

  • SMPTE 276M and AES3 Transmission Standard
  • Coaxial transmission of 2 Channel Digital Audio
  • Allows longer cable runs than 110 ohm twisted pair

Digi BalUn is made in two versions:

75 ohms BNC to 110 ohms male XLR               110 ohms female XLR to 75 ohms BNC

NOTE: The AES signal at 1V is the same voltage as the analog video signal. Instead of discarding old patch panels for analog video, they can be used for patching AES in the coax format. Check in the service manual or with the manufacturer to see if your distribution amplifier have enough bandwidth and a good squarewave response to handle digital audio signals.

M-S to Stereo matrix

M-S to stereo matrixes are made with Lundahl transformers as a reference design!

Customizations are possible besides our two recommended versions.

The recommended versions:

MSS7 uses LL1527 which is the optimal solution for "normal" signal levels.

MSS8 uses LL1588 which handles high signal levels in modern music studios.

Two Combo connectors (female XLR and 1/4'' jack combined) on inputs and two male XLR's on outputs.

It is a passive matrix which can be used in both directions, M-S to Stereo or Stereo to M-S.

Monitor controller

The MM3S Monitor Controller offers source selecting, volume control, as well as muting and stereo to mono summing. This unit invites possible use not only in pro audio applications but as an audio controller for a more advanced home stereo system, as well.

There is no active circuitry that can interfere with the signals feed through. This allows you to keep your software volume masters at unity to preserve bit-depth, resulting in pure and transparent sound with no degradation.

The MM3S has one large, robust and high precision volume control knob with ALPS potentiometer, one source selector switch with 3 inputs and a stereo/mono/mute switch on the front panel for quick and easy control.

The MM3S uses passive mono summing made with 0,1% tolerance metal film resistors.

There is one headphone output on the back side, which mutes speakers when headphone jack plugged in.


1 x Volume knob

1 x Input selector switch

1 x Stereo/Mono/Mute switch

Main features:

  • High quality ALPS potentiometer with robust aluminium knob for lasting durability.
  • All wiring is done by hand.
  • All inputs and outputs are balanced.
  • Completely passive, no batteries or power needed.
  • Input Source Select switch with 3 inputs.
  • Stereo, Mono and Mute monitoring mode switch.


  • Inputs: 3
  • Outputs: 1
  • Operating level: no limitations
  • Input Connections, by order: XLR/Jack 6,5mm/Phono (Neutrik)
  • Output Connections, by order: XLR/Jack 6,5mm/Phono(Neutrik)