SPL HPM User manual

Content
Manual
HPm
Headphone Monitoring Amp in a Dual Slot 500 Series Rack Module

HPm
Content
Content
Content 2
Version 1.0 – 09/2016 3
Scope of Delivery 4
Measurement & Weight 4
Introduction 5
Welcome 5
Specifications 6
General 6
Input 6
Output 6
Installation 7
Installation into a 500 series rack 7
Control Elements 8
Phase Inversion Ø 9
Crossfeed 10
Speaker Angle 11
Volume 12
Stereo/Mono/Mute 13
Matrix On/Off 14
Center Level 15
Headphone Jacks 16
Phonitor Matrix 17
Basics of stereo listening 17
Stereo listening with an “traditional“ headphone preamplifier 18
How does the Phonitor Matrix work? 19
Setting of Crossfeed and Speaker Angle 20
Symbols 21
Security Advices 22
Declaration of CE Conformity 27
Notes on Environmental Protection 28
Contact 29
Note:
Click on a section or page number to immediately jump to that location.

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Version 1.0 – 09/2016
Developer: Bastian Neu
This manual contains a description of the product. In no way it represents a guarantee
of particular characteristics or results of use.
The information in this document has been carefully compiled and verified and, unless
otherwise stated or agreed upon, correctly describes the product. Sound Performance
Lab (SPL) continuously strives to improve its products and reserves the right to modify
the product described in this manual at any time without prior notice.
This document is the property of SPL and may not be copied or reproduced in any man-
ner, in part or fully, without prior authorization by SPL.

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Scope of Delivery
HPm – 500 Series Rack Module
Quickstart/Product Overview
Measurement & Weight
Dual Slot 500 Series Rack Module
Weight: 1.76 lbs (0.8 kg)
Please keep the original packaging. In a service case the original packaging ensures a safe transport.

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Introduction
Welcome
and thank you for purchasing the Headphone Monitoring Amp HPm. With the HPm the
Phonitor Matrix is making headway into the world of 500 series rack modules.
Each of the two headphone outputs is fed with a separate amplifier to allow independent
operation of two headphones with high-quality amplification.
With the Phonitor Matrix you control Crossfeed, Speaker Angle and Center Level to create
speaker-like listenig and monitoring on headphones.
The HPm can easily be inserted between the DAW and a monitor controller because the
input signals of the HPm are slaved through to the outputs of the 500 series rack.
Phase Inversion of left or right channel as well as a Stereo/Mono/Mute switch round off
the feature set of the HPm.

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Specifications
General
Frequency Response: 10 Hz - ›100 kHz
Noise: -92.3 dBu (A-weighted)
Total Harmonic Distortion: 0,0024% (0dBu output level//600 Ohm)
Current consumption: 260 mA at +/- 16 VoltDC
Input
Electronically balanced
Impedance: approx. 10 kOhm
Max. Input Level: +21dBu
Output
Max. Output Level:
+18 dBu @ 600 Ohm
+15 dBu @ 300 Ohm

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Installation
Installation into a 500 series rack
• Please read the manual that comes with the 500 series rack. You should gain all
information necessary for the installation process.
• Your 500 series rack should be switched off and the power cable should not be
connected.
• Insert the HPm module into two adjacent free slots of your rack. Make sure the con-
nectors of the HPm is precisely aligned with the rack connectors.
• Press the HPm module carefully into the rack connectors and tighten the screws.
• Connect the HPm module with your audio environment using the connections from
your 500 series rack.
• Insert the power cable to the 500 series rack and switch it on.
Note: The HPm can easily be inserted between the DAW and a monitor controller because
the input signals of the HPm are slaved through to the outputs of the 500 series rack.

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Control Elements

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Control Elements
Phase Inversion Ø
With the Phase Inversion switch you invert the phase of the left or the right channel
(180°). In position “L” the phase of the left channel is inverted. In position “R” the phase
of the right channel is inverted.
In position “Off” no channel is phase inverted.
The phase inversion is used to check whether phantom center signals are precisely
positioned in the stereo center. Invert the phase of one channel and engage mono. All
phantom center signals should disappear.

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Control Elements
Crossfeed
The Crossfeed defines the interaural level difference. It approximates the influences of
room size, reflections and absorption characteristics of the room your speakers are in.
The higher the Crossfeed the more the stereo image is shrinking. To mimic a dry room
use lower Crossfeed settings whereas to mimic a wet room the Crossfeed should by set
to higher values.
See also “Phonitor Matrix” on page 17 cont.
Youl’ll find more information about the setting of Crossfeed and Speaker Angle under
“Setting of Crossfeed and Speaker Angle” on page 20.

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Control Elements
Speaker Angle
With the Speaker Angle switch you adjust the interaural time difference which is related
to the placement of the speakers.
You can choose one of three angle values: 20°, 30° and 40°.
See also “Phonitor Matrix” on page 17 cont.
Youl’ll find more information about the setting of Crossfeed and Speaker Angle under
“Setting of Crossfeed and Speaker Angle” on page 20.

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Control Elements
Volume
With these two detended controls you regulate the amplification for each headphone
output individually.

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Control Elements
Stereo/Mono/Mute
The headphone playback can be switched between Stereo and Mono. In the Mute posi-
tion no signal passes through to the headphones.
In Mono position the Mono compatibility can accustically be checked. Voices and instru-
ments which appear quieter or disappear completely in mono have phase problems
within the stereo signals.
The phase inversion is used to check whether phantom center signals are precisely
positioned in the stereo center. Engage mono and invert the phase of one channel. All
phantom center signals should disappear.

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Control Elements
Matrix On/Off
With the Matrix switch you activate or deactivate the Phonitor Matrix (Crossfeed, Speaker
Angle and Center Level).
If switched off the settings of Crossfeed, Speaker Angle and Center Level have no influence
on the headphone playback and the HPm operates as a “normal” headphone amplifier.

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Control Elements
Center Level
With the Center Level you control the monitoring intensity of the signals positioned in
the phantom center.
If the stereo width is narrowed through changes in Crossfeed and Speaker Angle (so as
to correspond to your actual loudspeaker setup), the phantom center may likely sound
too intense while mixing on headphones. You normally would counteract by lowering
the phantom center signals in the mix. When listening to that mix on loudspeakers the
phantom center appear to quiet.
Therefore Center Level gives you the possibility to lower the phantom center playback
level by 0.5, 1.0 or 1.5 dB. The phantom center gains the correct level in relation to the
L/R stereo image on loudspeakers.

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Control Elements
Headphone Jacks
Connect headphones to the standard 1/4” (TRS) stereo jack plugs.
Warning: Never connect a mono jack cable to the headphone output (front
panel stereo jack). Make sure that the stereo jack is fully inserted, otherwise
a short circuit might damage the headphone amplifier!

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Phonitor Matrix
Basics of stereo listening
When listening to speakers sound coming from the right is not only perceived with the
right ear (red line) but it is also perceived with the left ear (green line). The sensation
is time delayed, lower in level and has a reduced frequency range (this applies to the
left speaker accordingly).
Sound from the right side Sound from the left side
It arrives later because the signal travels a distance of approx. 340 meters per second and the distance from the
right speaker to the left ear is longer than it is to the right ear. It is quieter and does not deliver the full frequency
range, because the signal of the right speaker does not directly arrive at the left ear but is partially reflected and
absorbed by the head.

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Phonitor Matrix
Our brain determines the direction of the sound by perceiving the time delay (interaural
time difference) and the level difference (interaural level difference).
Stereo listening with a “traditional“ headphone pre-
amplier
When listening to music with a “traditional” headphone amplifier, the right ear only
perceives the right signal (red line) and the left ear only perceives the left signal (green
line).
In contrast to listening to speakers the delayed and quieter signal of the respective
opposite side is missing.
As a result to this super-stereo-effect reverb and delay effects as well as EQ and pan-
orama adjustments are perceived more intense resulting in an exaggerated playback
on headphones which does not represent the music as approoved by the artist and
producer.

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Phonitor Matrix
How does the Phonitor Matrix work?
The Phonitor Matrix calculates the interaural time difference (Speaker Angle) and inter-
aural level difference (Crossfeed) with their specific frequency responses to deliver a
speaker-like listening experience on headphones.
The super-stereo-effect is eliminated and all reverb and delay effects as well as EQ and
panorama adjustments are perceived correctly on headphones.
The headphone mix therefore translates well to speakers.
An analog filter design creates interaural time and level differences for three different
speaker placements. This analog filter design is controlled by the crossfeed and angle
parameters.

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Phonitor Matrix
Setting of Crossfeed and Speaker Angle
Both parameters (Crossfeed and Speaker Angle) define the interaural level difference
and the interaural time difference.
To reproduce the exact placement of the loudspeakers, first choose the Speaker Angle
parameter representing your real speaker placement.
Then play some audio you know well. Adjust the Crossfeed until the headphone playback
comes closest to your loudspeaker listening experience.
20°20°
30°30°
40°40°