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Questions and Answers
What is the primary function of a DI box in audio engineering?
What is the primary function of a DI box in audio engineering?
- To convert high impedance, unbalanced signals to low impedance, balanced signals. (correct)
- To reduce noise by summing stereo signals to mono.
- To convert low impedance, balanced signals to high impedance, unbalanced signals.
- To amplify low-level signals to line level.
Which of the following is a characteristic of high-impedance headphones?
Which of the following is a characteristic of high-impedance headphones?
- They are best suited for on-the-go use.
- They typically have an impedance of 32 ohms or lower.
- They require dedicated amplification for optimal performance. (correct)
- They are easily driven by portable devices.
What benefit does a DI box provide in terms of signal transmission?
What benefit does a DI box provide in terms of signal transmission?
- Reduces signal strength over long distances.
- Enables the use of unbalanced cables for longer runs.
- Offers immunity to noise and interference over long cable runs. (correct)
- Increases susceptibility to electrical interference.
What is the purpose of the 'THRU' output found on many DI boxes?
What is the purpose of the 'THRU' output found on many DI boxes?
Which of these is a common feature found on DI boxes that helps prevent ground loops?
Which of these is a common feature found on DI boxes that helps prevent ground loops?
What distinguishes a passive DI box from an active DI box?
What distinguishes a passive DI box from an active DI box?
Which type of instrument is generally better suited for use with a passive DI box?
Which type of instrument is generally better suited for use with a passive DI box?
Why might an audio engineer choose to use an active DI box over a passive DI box?
Why might an audio engineer choose to use an active DI box over a passive DI box?
Which scenario would most benefit from using the pad (attenuator) feature on a DI box?
Which scenario would most benefit from using the pad (attenuator) feature on a DI box?
In a typical signal chain using a DI box with a bass guitar, where is the DI box placed?
In a typical signal chain using a DI box with a bass guitar, where is the DI box placed?
Flashcards
What does a DI box do?
What does a DI box do?
Converts a High Impedance, Unbalanced Line Level audio signal to Low Impedance, Balanced, typically via a 6.5mm TS connector.
Primary Use of DI Boxes
Primary Use of DI Boxes
Integrates signals from instruments like bass guitar and keyboards into a mixing console, connecting them to a microphone input or pre-amplifier.
Benefit of DI Box Output
Benefit of DI Box Output
A unified input signal (XLR) that provides immunity to noise and interference, electrical isolation, and the ability to resolve ground loops.
DI Box 'THRU' Output
DI Box 'THRU' Output
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PAD (Attenuator)
PAD (Attenuator)
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GROUND (Earth) LIFT
GROUND (Earth) LIFT
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Passive DI
Passive DI
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Active DI
Active DI
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Passive DI Ideal For
Passive DI Ideal For
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Active DI Ideal for
Active DI Ideal for
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Study Notes
- Introduction to DI Boxes produced by Mark Kelson
Direct Injection/Input
- Converts a high impedance, unbalanced line level audio signal via a 6.5mm TS connector to a low impedance, balanced signal
- The difference between high and low impedance audio gear lies in electrical impedance, measured in ohms
- High-impedance headphones, typically 100 ohms or more, need dedicated amplification for optimal performance
- Low-impedance headphones, 32 ohms or lower, can be easily driven by portable devices but may sacrifice audio fidelity compared to their high-impedance counterparts
- Used to integrate the signal from bass guitar & keyboards to the microphone input of a mixing console, but can be used for any line level source that requires connection to a microphone pre-amplifier
- Results in a unified input signal (XLR) that is immune to noise & interference and benefits from electrical isolation, ability to resolve hums and buzzes, and offers additional user-optional features All DIs offer a loop-through split of the unbalanced input signal labelled ‘THRU’, typically used to send the source signal from the DI to the instrument amplifier when working with a bass guitar
Typical DI features include:
- PAD (attenuator) e.g. -15dB or -20dB attenuation
- GROUND (Earth) LIFT
Additional feature sets may include:
- Phase REVERSE
- LOW PASS FILTER
Passive DI
- Has no powered components
- Uses an audio transformer to reduce voltage and impedance, providing electrical isolation between input and output
- Does not require power to operate (no battery, no phantom +48v)
- Matches high output instruments such as active pickups and modern keyboards/synths/samplers resulting in minimal distortion
- Can be used in reverse from low to high (re-amping)
- RMIT examples: Radial JDI and Pro2
Active DI
- Has powered components
- Features an amplifier to perform level change
- Requires power to operate (+48v, battery, 240v depending on DI)
- Popular for higher headroom and transfer of a natural sound
- Ideally matched to lower level instruments such as passive pickups (Fender P-bass), older keys (Fender Rhodes, Wurlitzer), and acoustic instruments
- RMIT examples: Radial J48, Avalon U5
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