A Dual Channel passive DI is now available.
Same specs and size as the single channel DI below
Suitable for the most demanding of situations in both live and recording
A no-compromise audio isolation transformer designed by The Leon Audio
Company provides very high sound quality and the maximum possible rejection
of external electrical interference, such as dimmer buzz.
The transformer also provides excellent isolation of high common mode
(earth) voltages, well above the level that an active D.I. box could handle
without destruction. Optimised internal design of the isolation transformer
provides earth isolation performance approaching the theoretical maximum.
This translates into excellent performance when isolating input and output
An optimally balanced output, provided by the transformer, is ideal
for driving long balanced cables, such as multicores. The output can also
be connected to unbalanced circuits.
The fully floating balanced input and output are able to accept either
3 conductor balanced circuits or 2 conductor unbalanced circuits, providing
an ideal unbalanced/balanced or balanced/unbalanced interface.
An input impedance several times higher than many commercial units ensures
accurate reproduction of a musical instrument by providing minimal electrical
loading on the source, which could otherwise result in degraded performance.
Effective screening against hum pickup from nearby transformers, such
as those in power amplifiers, is provided by a MU metal shield which totally
encloses the transformer.
High signal level handling ability means that no pad or attenuator switch
is required. A totally passive design means that no batteries or phantom
||20Hz - 20kHz ±0.1dB
||-10° at 10KHz
|Nominal Input Impedance
||Greater than 300K ohms
|Recommended Load Impedance
||2000 ohms or greater
|Maximum Input Level
||-22dBu (0dBu input)
|Total Harmonic Distortion (T.H.D.)
||<0.1% 30Hz - 20KHz up to +22dBu
||Powder coated die cast aluminium
||440 grams net.
||W 95mm H 120mm D 67mm
D.I. Boxes are constructed using one of two common techniques.
A D.I. box is required to perform three separate basic tasks:-
The first type uses electronic circuitry and are known as active D.I. Boxes.
They require either Phantom Power or a battery supply.
The second type uses an audio transformer and are known as either transformer
or passive D.I. Boxes. They require no power supply.
1. Impedance Conversion.
2. Unbalanced to balanced conversion.
3. Earth isolation.
1. Impedance Conversion.
The medium or high impedance of a signal source is converted to a low
impedance suitable for feeding down a long multicore to a mixing desk’s
microphone input. A low impedance enables long cable runs with very little
quality loss, with low susceptibility to external electrical interference
(hum and buzzes). A D.I. box provides a high input impedance for connection
to a signal source, and a low output impedance for connection to a microphone
input of a mixing desk.
2. Unbalanced To Balanced Conversion.
The unbalanced (2 conductor) wiring of a signal source is converted
to the balanced (3 conductor) wiring of a mixing desk.. A balanced cable
provides good rejection of electrical interference. An unbalanced cable
does not. Active D.I. Boxes are potentially capable of providing excellent
unbalanced to balanced conversion, but due to cost restrictions, many are
poor performers in this area. Transformer D.I. Boxes provide excellent
unbalanced to balanced conversion.
3. Earth Isolation.
A D.I. Box provides isolation between the earth wiring of a signal
source (e.g. musical instrument) and the sound system being connected together.
This prevents earth loops which cause hum and buzzes.
An earth loop occurs when a device, such as a keyboard, is connected
to the mains earth via more than one path. The first path is via the instrument's
own power cable to the mains earth. The second path is via the interconnecting
audio cable to the sound system, then via the sound system's power cable
to the main's earth. The resultant circulating earth current is amplified
and is often heard as a hum or buzz. Active D.I. Boxes are usually very
poor at providing good earth isolation between an instrument and a sound
system because there is a direct electrical path between the instrument
and the sound system. There is not isolating device such as a transformer,
as there is in a passive D.I.
Earth Lift Switches.
D.I. boxes have an earth lift switch to allow the input and output
earths of the D.I. box to be disconnected, so that earth loops can be broken.
Disconnecting the signal (audio) earth is not a safety issue, as the Protective
Earths in all the mains cables are still connected and fully functional.
This assumes that the sound system or mixer is connected to the mains earth,
as it should be.
If the instrument is connected to the mains earth, open the Earth Lift
If there is no mains earth connected to the instrument, close the Earth
The Passive D.I. Boxes are guaranteed for two years from date of original
purchase against defects in workmanship and materials.
If such malfunction occurs, the item will be repaired or replaced (at
our option) without charge for materials or labour if delivered prepaid
to THE LEON AUDIO COMPANY. Unit will
be returned prepaid. Warranty does not cover finish or malfunction due
to abuse or operation at other than specified conditions. Repairs by other
than THE LEON AUDIO COMPANY or authorised agents will void this guarantee
|| Download brochure for the Passive D.I. Box.
PDIB2a.pdf (120Kb) in Adobe Acrobat
Adobe Acrobat Reader
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