OS DB7 User Manual

Hide thumbs

Table Of Contents

Table of Contents

Quick Links

Download this manual

User Guide

DB7

Table of Contents

Need help?

Do you have a question about the DB7 and is the answer not in the manual?

Questions and answers

Summary of Contents for OS DB7

Page 1 User Guide...
Page 2: Table Of Contents
Contents Important Safety Instructions ........ Page 3 Introduction .............. Page 5 Operation .............. Page 7 Connectors and Controls .......... Page 8 DSP Presets .............. Page 9 Linear-Phase Time Alignment ........ Page 10 Monitor Placement ............ Page 12 Technical Specifications .......... Page 14 Warranty and Service .......... Page 15 Contact Us .............. Page 16...
Page 3: Important Safety Instructions
Important Safety Instructions • Read and follow these instructions carefully, and retain them for future reference. • The DB7 is heavy (~12kg). Please take care when lifting! • Take care unpacking your new monitors, being careful not to touch the drive units • Please retain the packaging for safe transportation if the need for servicing arises. Ensure packaging is stored or disposed of safely to avoid posing a risk to the young and vulnerable. • Do not use this apparatus near water. • Clean only with a dry cloth. The cabinet finish may be damaged by solvents, abrasives, waxes, or liquids. • Do not install the loudspeaker near any heat sources such as radiators, heat registers, stoves, or other apparatus (including amplifiers) that produce heat. • Do not cover the heatsink on the rear panel, or block any ventilation openings. • Protect the power cord from being walked on, or being pinched or damaged in any other way. • Do not defeat the safety purpose of the polarized or grounding-type plug. A polarized plug has two blades with one wider than the other. A grounding type plug has two blades and a third grounding prong. The wide blade or the third prong is provided for your safety. If the provided plug does not fit into your outlet, consult an electrician to replace the obsolete outlet. • A power switch is located on the rear of the loudspeaker. The mains cord is used as a mains disconnect device and should remain accessible at all times. •...
Page 4 • Make sure that the audio source volume is set to minimum before powering the DB7 to prevent sudden high sound levels. Failure to follow these instructions may result in damage to your hearing or to the DB7.
Page 5: Introduction
Introduction Thank you for choosing OS Acoustics DB7 active reference monitors. The DB7 is constructed using components of the highest quality and, with the right care and attention, your new loudspeakers will provide many years of excellent audio reproduction. A sophisticated digital signal processing (DSP) system is built into the DB7 to provide a new standard in timing coherence and accuracy. Designed with acoustic transparency as a priority, OS Acoustics DB7 faithfully preserves phase relationships to present a three-dimensional soundstage, and reproduces every timbral detail and harmonic nuance with stunning realism. Proprietary UMAC™ Class-D amplifier technology from market-leading manufacturer Pascal Audio offers unparalleled, extreme audiophile sonic performance, and boasts of the best measurable specifications in the market. The DB7 enjoys a total of 650 Watts (RMS) of ultra-low distortion amplification, and its ability to deliver very high short-duration power bursts gives the DB7 an exceptional transient response. To guarantee maximum reliability the DB7 also features a highly efficient switch-mode power supply with UREC™ power-factor correction technology. It supports universal AC mains operation, ensuring consistent, regulated power worldwide, eliminating susceptibility to local power-related reliability issues. Precision Each individual loudspeaker drive unit is measured during production, and any response deviations are corrected by the DSP to a very fine tolerance. This allows an accurate frequency and phase response controlled to a level of precision only obtainable using DSP, providing the DB7 with outstanding linearity. It is essential that loudspeakers have very closely matched frequency responses for accurate and stable imaging in critical stereo and surround sound applications. Matching individual monitors so precisely gives the added advantage of interchangeability so that, in the unlikely case of a monitor breakdown, another DB7 monitor can be substituted with complete confidence.
Page 6 Frequency & Phase Response The powerful digital signal processing built into the DB7 enables an almost perfectly flat on-axis frequency response, as illustrated below (left-hand scale), with an amplitude variation within ±2dB, and matching between any two loudspeakers of better than 0.5dB. Digital signal processing also allows the loudspeaker’s phase response to be maintained within tight tolerances across the entire audio bandwidth, as shown below (right-hand scale). The phase tolerance is maintained within ± 15 degrees between 200Hz and 20kHz.
Page 7: Operation
Operation Your loudspeakers should provide many years of trouble-free operation with normal usage. However, in the unlikely event that you suspect damage or failure has occurred, do not attempt to repair the unit yourself. Opening or removing covers may expose dangerous voltages or other hazards. The amplifier chassis may only be opened by qualified personnel. There are no user-serviceable parts inside. Please contact your dealer for advice and a service return address. Clean the loudspeaker cabinets only with a dry and lint-free cloth. The use of solvents or abrasive cleaners should be avoided as they will damage the finish of the cabinet. Breaking-in Time It takes time for the moving parts of the transducers to relax after manufacture and reach optimum compliance. As a result, you will notice a significant improvement in the sound quality after a period of use of about eight hours, with greater bass extension and a more neutral tonality. Additionally, more subtle enhancements will be noticed during the first week of use. Standby Mode The DB7 will switch to a power-saving standby mode automatically if no signal has been detected for a period of 15 minutes. The standby mode uses less than 0.2 Watts, making it Energy Star compliant and in accordance with the ErP (1275/2008/EC) directive. The system wakes from this standby mode automatically when an audio input signal is detected, typically regaining normal operating status within 660 milliseconds. Depending on the source material, you may find one loudspeaker wakes fractionally before the other, or that slightly more signal level is required to reach the ‘wake-up’ threshold and re-activate the loudspeakers. Limiter The DB7’s DSP system incorporates sophisticated limiters designed to protect the transducers from damage by over-excursion. They also keep the voice-coil travel within the optimum working range, and avoid thermal overload. An LED on the rear panel illuminates when the protective limiter is activated.
Page 8: Connectors And Controls
Connectors and Controls 1. Power – illuminates green when the monitor is receiving mains power. 2. Limit – illuminates orange when the limiter is activated. 3. Signal/Clip – illuminates blue when an audio signal is present and above a preset threshold. The iIllumination changes to red if the input level reaches the clipping point. 4. Input Gain control – Provides an adjustable sensitivity range of -30dBu to 0dBu. It is recommended to operate the loudspeakers with the control at the 0dBu position where possible, controlling the volume from the sound source. 5. Preset Select control – Eight-position rotary switch. See ‘DSP Presets’ for more information. 6. Analogue audio input female XLR connector. 7. Link Output male XLR connector. 8. Dual RJ45 data connectors for manufacturer access only. 9. IEC mains inlet: 85 to 265 VAC, 50/60Hz 10. Power on/off switch. Preset Select Control Summary Preset Response Preset Response Flat Flat Voiced Voiced Flat Flat Voiced Voiced...
Page 9: Dsp Presets
DSP Presets The DB7 can be configured for different installation situations and preferences using any of eight factory-programmed DSP presets. These are recalled using the ‘Preset Select’ rotary switch at the rear of the loudspeaker near the top of the amplifier chassis. Preset 1 provides an optimally ‘Flat’ response (±2dB). This mode is designed for complete accuracy and delivers an incredibly neutral, uniform frequency response. Preset 2 is a ‘Voiced’ setting, which is not as accurate as Preset 1, but delivers a slightly smoother and more relaxed acoustic presentation. Preset 3 is a linear-phase version of Preset 1 (Flat). Preset 4 is a linear-phase version of Preset 2 (Voiced). Loudspeakers are not naturally linear-phase, which means that the reproduction of low frequencies is inherently slightly delayed compared to high frequencies. Presets 3 and 4 impose a linear-phase response to realign the timing coherence between all frequencies. This enhances spacial information, refines transients, and improves the relationship between the fundamentals and harmonics of instruments. The linear-phase mode is configured to work best when listening on the direct axis of the tweeter. NOTE: All of the linear-phase modes impose an additional five-millisecond processing time through the DSP. Preset 5 is the same as Preset 1 (Flat), but with Room Boundary Correction (RBC) applied. RBC can be selected to counter the bass-loading effect on the loudspeaker due to the proximity of one or more local boundaries. Generally speaking, the closer a loudspeaker is to a wall or to the corner of a room the more the low frequencies are boosted. The RBC mode compensates for this effect by reducing the low-frequency output from the loudspeaker. Another factor affecting the choice of whether or not to use RBC could be ‘room modes’ which cause reinforcements and cancellations of the low-end response at different points within the room. All rooms affect the reproduced sound differently, and so RBC might not always be needed even if the monitors are positioned in the corners of a room. Please experiment to see what mode works best in your specific listening environment. Presets 6...
Page 10: Linear-Phase Time Alignment
Linear-Phase Alignment Phase All sound frequencies travel at the same speed through air, maintaining a coherent arrival time at the listening position. Unfortunately, though, the same cannot be said of audio that is played back through a loudspeaker system. Virtually all loudspeakers introduce phase errors, distorting the timing coherence so that some frequencies are smeared across time and delayed compared to others. This can be thought of as a frequency-dependent delay. Accuracy To reproduce a complex waveform precisely, the playback device needs to perform accurately in both the frequency-domain (so that each pitch is recreated at the correct amplitude) and the time-domain (so that each note arrives when it should). The latter requires the loudspeaker to maintain the original phase or time relationships between different sound components as closely as possible. Coherence Correction of these fundamental time-alignment problems in conventional loudspeakers isn’t practical or affordable using analogue techniques. However, the advanced digital signal processing employed in the DB7 allows the phase relationships and timing coherence of the source audio to be properly and precisely restored. A New Standard The time-domain response of a loudspeaker can be understood by examining what happens to a perfect spike-like signal of very short duration, known as a unitary impulse (Dirac delta) which contains all frequencies aligned in a fixed, uniform phase relationship. This is the time-domain equivalent of a perfectly flat frequency response. The measured output from a loudspeaker reproducing this unitary impulse is called its Impulse Response. The left-hand graph (red trace) on the next page shows a loudspeaker’s uncorrected impulse response which has been smeared out in time. In contrast, the right-hand graph (yellow trace) shows the impulse response after phase-correction has been applied. The impulse is offset towards the right-hand side of the graph because of the five millisecond processing latency inher- ent in achieving a linear-phase time-domain response. However, the important point is that the smeared-out characteristic seen in the uncorrected impulse response has been removed, and the corrected time-domain response more accurately represents the unitary impulse input signal.
Page 11 Linear-Phase Alignment A typical loudspeaker impulse response A corrected linear-phase impulse response. The Importance of Time Alignment The sensitivity of the human ear, and the brain’s ability to decode sound information, should not be underestimated. For example, the very small difference in the arrival times of acoustic vibrations at each ear (known as the interaural time difference) is essential for identifying the precise location of a sound source in the space around the listener. These spatial information cues are vastly improved when the DB7 loudspeaker is operated in its linear-phase mode, presenting a much more vivid and life-like soundstage. Timbral information is also more naturally preserved, avoiding the potential situation where harmonics can arrive ahead of the fundamental in time. Chords with short and well-defined start and end points become less blurred. Transients – which are critical for realism and punch – are reproduced more faithfully resulting in a better sense of natural dynamics and musical rhythm. NOTE : The frequency response is not affected by adopting the linear-phase mode, which is why there are different presets for the flat and voiced frequency response options. Not all playback material will emphasise or benefit from the more accurate time-domain characteristics of the linear-phase modes to the same degree.
Page 12: Monitor Placement
Monitor Placement Both the monitor placement and the room acoustics have a significant influence on perceived sound quality of the loudspeakers. Please read the sections below which will assist in realising the best possible performance from your monitor loudspeakers. Room Acoustics Loudspeakers typically radiate low frequencies omnidirectionally. As a general rule of thumb the closer the speakers are positioned to reflective surfaces, like a wall (one boundary) or in a corner (two or three boundaries), the more the bass is reinforced and amplified. The OS Acoustics DB7 loudspeakers are front-ported and can be placed right up against a wall, if necessary, providing sufficient space is available for the power and audio cables to be connected. However, if the bass reproduction becomes too powerful with this kind of placement, there are a few options. Ideally, the loudspeakers could be moved away from the reflective surface, but if that’s not possible one of the RBC modes could be selected (see DSP Presets for more information) which will reduce the bass response of the loudspeaker. The professional studio solution would be to install more acoustic treatment – specifically more bass traps. Positioning When moving the loudspeaker away from a wall boundary it is recommended that the front baffle should either remain within one metre of the back wall, or be more than four metres away in larger rooms. These dimensions are necessary to reduce the effects of destructive comb- filtering or speaker/boundary interference of the low-frequency response. For optimum results it is recommended that the monitors are positioned equidistant from the listening position, meaning the distances to the left and the right monitors is identical and – for proper stereo monitoring – the monitors should also be that same distance apart from each other. This means they will subtend an angle of approximately ±30 degrees either side of the listening position. A stable stereo image is helped by good left-right symmetry within the room, and this applies to both a stereo setup and for the left-right front monitors in a multi-channel setup. Ideally, the loudspeaker height should be such that the tweeters are close to ear height or, in situations where this is not possible, the loudspeaker should be tilted so that the tweeter is pointing directly towards the ear position.
Page 13 Monitor Placement Orientation It is recommended to use the loudspeakers in their vertical orientation. This provides the largest ‘sweet spot’ area where the stereo image is stable and the frequency response is accurate. If vertical orientation is not possible or is impractical, the loudspeakers can be used horizontally. However, the ‘sweet spot’ is much smaller in this configuration and frequency response cancellations around the crossover frequency can occur the more you move off axis (left and right). Stands The structure supporting a loudspeaker forms part of the complete loudspeaker system, and the sound from a loudspeaker is never independent of its mounting conditions. Therefore, heavy-duty stands which hold the loudspeaker stable in space are recommended. Desktops As sound radiates from the loudspeaker, the early- or first-reflections from any nearby surfaces will negatively impact both the sound quality and your enjoyment. If the monitor speakers are placed directly on a workstation, the first reflections are usually from the desk surface directly in front of the loudspeaker. In this situation, it is highly recommended that desk stands be used to both raise the height of the loudspeakers and to acoustically decouple them from the desk structure. As a result, the destructive first-reflections will be reduced, as will any sympathetic resonances within the desk, significantly improving tonality and the accuracy of the loudspeakers.
Page 14: Technical Specifications
Specifications Frequency Response 40 Hz - 20 kHz (±2 dB above 65 Hz) DB7 Performance Consistency Matched to within 0.5dB Design Principle 2-Way Front-Ported Reflex Tweeter 1” Ceramic Coated Magnesium Woofer 6.5” Aluminium Crossover 2.1kHz Phase Tolerances ± 15 degrees (200Hz - 20kHz) THD (90dB at 1m) Less than 1% (75Hz - 20 kHz) Max SPL 105 dB SPL Dimensions (HxWxD) 403 x 208 x 437 mm Weight 11.80 kg Amplifier: Class-D UMAC™ with ultra-low distortion Power 500W RMS (woofer) + 150W RMS (Tweeter) Signal-to-Noise Ratio >120 dB (A-weighted, 20 Hz - 20 kHz) THD+N (typical use) <0.05 % (20 Hz - 20 kHz, 3 dB below rated power) Power Supply UREC™ Universal mains switch-mode with Power Factor Correction Operating Mains Voltage Universal Mains: 85-265V IEC C14 inlet Standby Mode Energy Star and ErP compliant Digital Conversion...
Page 15: Warranty And Service
Warranty And Service OS Acoustics products are built to very high standards and, under normal operation, will provide many years of excellent performance. OS Acoustics products are warranted to be free from defects in components and factory workmanship for a period of two (2) years. In the unlikely event of a monitor breakdown please contact your local authorised OS Acoustics dealer/distributor. If you do not have a local representative please visit www.os-acoustics.co.uk and click on ‘Contact’ to message OS Acoustics directly. OS Acoustics shall not be responsible for any incidental or consequential damages. OS Acoustics’responsibility is limited to the product itself. OS Acoustics assumes no responsibility for any loss due to cancellation of any events, or rent of replacement equipment, or costs due to third party’s or customers’ loss of profit, or any other indirect cost or losses however incurred. OS Acoustics reserves the right to make changes or improvements in design or manufacturing without assuming any obligation to change or improve products previously manufactured and/or sold. Units on which the serial number has been removed or defaced may not eligible for warranty service. This warranty shall be null and void if the product is subjected to repair work or alteration by a person or facility other than those authorised by OS Acoustics.
Page 16: Contact Us
Contact Us OS Acoustics Ltd, Bournemouth International Airport, 4 Brackley Close, Bournemouth BH23 6SE Tel: 0845 299 0213 info@os-acoustics.co.uk www.os-acoustics.co.uk www.facebook.com/osacoustics www.instagram.com/osacoustics...
Page 18 O.S Acoustics DB7 Manual Version 1.2 February 2020...