VPD variable inline attenuator
The VPD variable inline attenuator can be configured as one of the following:
- XLR-F to XLR-M, 6dB to 30dB balanced microphone level attenuator, in eight 3-4dB steps.
- XLR-F to XLR-M, 6dB to 48dB balanced line-level attenuator, in eight 6dB steps.
- 1/4″ TRS to 1/4″ TRS, 6dB to 48dB balanced mono line-level attenuator, in eight 6dB steps.
- 1/4″ TS to 1/4″ TS, 6dB to 48dB unbalanced mono line-level attenuator, in eight 6dB steps.
- 1/4″ TRS to 1/4″ TRS, 12dB to 48dB unbalanced stereo line-level attenuator, in four 12dB steps.
- XLR-F to XLR-M, passive shelving (max -12dB) low cut filter for microphones, 50Hz to 160Hz in four 2/3 octave steps.
- XLR-F to XLR-M, passive balanced line-level low cut filter, 50Hz to 160Hz in four 2/3 octave steps.
- 1/4″ TRS to 1/4″ TRS, passive balanced line-level low cut filter, 50Hz to 160Hz in four 2/3 octave steps.
- 1/4″ TRS to 1/4″ TRS, passive unbalanced stereo line-level low cut filter, 50Hz to 160Hz in four 2/3 octave steps.
- 1/4″ TS to 1/4″ TS, passive unbalanced mono line-level low cut filter, 20Hz to 500Hz in eight 2/3 octave steps.
- XLR-F to XLR-M, passive notch filter, -7dB at 250Hz to 6kHz in eight 2/3 octave steps. (coming soon)
Custom values for attenuation and input impedance are available on request.
Microphone level attenuators are intended for use with condenser microphones on loud sources. Microphone level attenuators have an input impedance of approximately 2KΩ and will thus pass phantom power with minimum voltage drop. Maximum input level is +20dBV.
Line level attenuators have input impedance of 7KΩ or higher and are thus not intended for use between microphone and amplifiers, but rather between line level outputs and inputs. Maximum input level is +30dBV.
The passive low-cut filters must be specified for the input impedance of the following device; between 600Ω and 3KΩ for the microphone filter, and between 10KΩ and 50KΩ for the line-level filter. The stated frequency range will only be accurate for the specified impedance. The microphone filter is a shelving type in order to pass phantom power to connected microphones. The maximum cut is -12dB, which will be achieved at no lower than 10Hz.
The line-level filter will vary between first- and second-order across its range (higher slope at lower frequency corners). The line-level filter has input impedance of 3.3KΩ. The TS and TRS versions of the line-level filter are directional, in order to achieve second-order response. If only first-order is required, the filter may be built as symmetrical.
Please specify required input impedance of connecting device in order comments; otherwise, filters will be built for 1.5KΩ microphone or 10KΩ line impedance. The frequency range of the low-cut filters may be customized on request.
The passive notch filter is designed for feedback rejection in live sound applications. The 2/3 octave bands are designed to cover the midrange frequencies where feedback typically occurs. It is especially useful as an inline microphone filter where a parametric or graphic EQ is not otherwise available, as with certain instrument amplifiers. The notch filter has input impedance of 1.2KΩ and insertion loss of -3dB. The passive notch filter will pass phantom power with minimal voltage drop.
All VPD XLR inline attenuators/filters are directional balanced (“U” pads); the TRS attenuators are symmetrical balanced or unbalanced (“H” or “T” pads). The VPD attenuators use precision 1% tolerance resistors, so matching between units and channels in stereo units will typically be within 0.1dB.
|Dimensions||5 x 3 x 2 in|
XLR microphone attenuator, XLR line-level attenuator, TRS balanced line-level attenuator, TS mono unbalanced line-level attenuator, TRS stereo unbalanced line-level attenuator, XLR low-cut microphone filter, XLR low-cut line-level filter, TRS balanced low-cut line-level filter, TRS stereo low-cut line-level filter, TS low-cut line-level filter