Manual

Volume 8

Model 2608

Analog Eight-Channel Volume Controller
Manual Volume 8, Model 2608
Version 1.0 5/2006 Designer: Wolfgang Neumann This user's guide contains a description of the product. It in no way represents a guarantee of particular characteristics or results of use. The information in this document has been carefully compiled and veried and, unless otherwise stated or agreed upon, correctly describes the product at the time of packaging with this document. 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 manner, in part or fully, without prior authorization by SPL.
SPL electronics GmbH Sohlweg Niederkruechten Germany Tel. +49 (0)40 Fax +49 (0)420 Email: info@soundperformancelab.com www.soundperformancelab.com
2006 SPL electronics GmbH. All rights reserved. Names of other companies and their products are trademarks of their respective owners.

Contents

Introduction.... 4 Installation and Security Advices.. 5 Power Supply.... 5 Rear Panel... 6 Power Supply, ON/Off Switching... 6 Rear Panel Graphic, Signal Connections, DB 25 Pin Wiring. 6 Operation.... Volume Control... Calibrating the Monitoring System... Mute.... 7 7
Specications.... 8 Measurements... 9 Guarantee & Product Registration... 11

Introduction

The Volume Controller Volume 8 serves as a system-independent analog volume regulator in all areas of audio processing and playback, including Stereo and surround music production Movie and video post production, video computer games production Demanding hi-delity/home cinema applications Complementing the fully equipped SPL Surround Monitoring Controller (SMC 2489), the Volume 8 focuses exclusively on the highest quality in active volume control. Users who do not need additional monitoring functionality provided by the SMC 2489 will nd the Volume 8 an cost-effective solution without compromises. The Volume 8s design is based on active switching to avoid nonlinear frequency response introduced by impedance changes with passive designs when changing levels.
Who needs analog level control?
Simply putmost DAW (Digital Audio Workstation) users. A majority of D/A converters and sound cards provide nothing in the way of analog level monitoring control, and this means the necessity of varying signal levels at the converter outputs. The result is a lowered bit rate in the monitoring signal, which leads to commensurate loss of audio quality. A further, very interesting application area is in the construction of a straight multi-channel playback chain, where the Volume 8 is situated between the playback machine and either power amp and speakers or simply active speaker systems. In such cases, the playback machine must offer analog outputs. This provides for minimal nancial and electronic efforts through the most direct possible playback path.
Additional Reasons for employing the Volume 8
High quality balancing stages with extremely good common mode rejection (minimize interferences and disturbances in the signal paths) The mute switch allows for very fast reaction times in cases where loud speakers or ears should be protected (for example, with computer crashes) Users of analog summing without monitoring facilities can cost effectively improve their systems

Special Features

The Volume 8 is built only with analog circuitry and performance, and its high quality parts in sophisticated circuitry design are prerequisites to superior audio quality: Custom designed, high end, eight-ganged potentiometer with invariable precision at each and every gain level Illuminated passive mute switches from ALPS, relay switching for all channels A high quality power supply with toroidal transformer Input and outputs over DB-25 connectors (to multicore XLR or 1/4-inch TRS) Massive, 45 mm/1.78-inch diameter aluminum knob ensure consistent, rened handling The elegant, compact format housing (215 x 80 mm or 8.5 x 3.1 inch) allows for exible desktop positioning near or below a computer monitor or generally saving space in positioning
Installation and Security Advices
Please Read this Important Note:
Be very careful to check that the rear chassis power selection switch is set to the correct local line voltage position (either 230 or 115 volts) before using your machine! Before connecting any equipment make sure that any machine to be connected is turned off (on the Volume2 rear panel the power switch must be pushed down). Turning the Volume 8 on and off: The Volume 8 should always be the rst to be turned on before either power amp or active loudspeaker. In powering down the reverse should take place (rst turn off amps/speakers followed by the Volume 8). In connecting any cables be sure that the Volume 8 and all machines affected are turned off. It makes good sense to think about where you place the unit before connecting it. It should be positioned so that you can easily reach it, but there are other considerations. Try not to place it near heat sources or in direct sunlight, and avoid exposure to excessive vibrations, dust, heat, cold or moisture. It should also be kept away from transformers, motors, power ampliers and digital processors. Do not open the case. You may risk electric shock and damage to your equipment. Leave repairs and maintenance to a qualied service technician. Should foreign objects fall inside the case, contact your authorized dealer or support person. To avoid electric shock or re hazards, do not expose your unit to rain or moisture. If the danger of lightning is foreseeable, unplug the unit. Never touch a power cable during a thunderstormdanger of life! Always unplug the cable by pulling on the plug only; never pull on the cable. Never force a switch or knob. Use a soft, lint-free cloth to clean the case. Avoid cleaning agents as they may damage the unit. If necessary, use an acid-free cleaning oil instead. The power supply was carefully engineered to provide clean and consistent current an important prerequisite for excellent audio. Built around a toroidal transformer, the power supply generates a minimal electromagnetic eld with no hum or mechanical noise. The output side is ltered by an RC circuit to extract noise and hums inherent in commercial AC power. All audio-related components are fed by two separate voltage regulators to minimize disturbance from other components. An AC power cord is included for connection to the standard 3-prong IEC connector. The transformer, power cord and IEC connector are VDE, UL and CSA approved. The AC fuse is rated at 250 mA (230 V version) or 500 mA (115 V version).

Power Supply

Rear Panel
Power Supply, On/Off Switching
Be sure before connecting the Volume 8 to power that the rear-chassis voltage supply is switched to the proper local rating (either 230 or 115 volts). Above all, before connecting any machines, take additional care to power down all those to be used (and move the rear-chassis power supply switch of the Volume 8 to the down position). Finally, always use the following procedure in powering up your assembly: Always power on your Volume 8 rst before the power amp or active speakers. When powering down, always power off the power amp or active speakers before your Volume 8. Not following this sequence can result in ear or speaker damage from high level discharges. The Volume 8 comes with a standardized 3-pole (grounded) IEC power cord which is connected to the main power input socket (Mains Input).
The electrical pin conguration of the balanced DB 25 input and output sockets comply with the TASCAM standard (see graphic below). The nominal input level is +4 dB, other levels are transmitted 1:1. DB 25 to XLR, TRS or RCA multicore cables are required for connection of input and output signals. The eight channels of the DB 25 connector at one side are routed to eight single XLR, TRS or RCA connectors on the other side. The channel conguration is free (input = output). Here are some common multichannel congurations: SMPTE/ITU: L/R/C/LFE/LS/RS/L(t/o)/R(t/0) DTS: L/R/LS/RS/C/LFE/L(t/o)/R(t/0) Film: L/LS/C/RS/R/LFE/L(t/o)/R(t/0) SDDS: L/LC/C/RC/R/LFE/LS/RS

Operation

Volume Control
The single volume potentiometer controls volume for all eight channels. The audio signal is controlled directly by the potentiometerthus no VCA or DAC regulators in the paths which tend to produce bigger tolerances and distortions. The scale of this control has been purposely marked in percentage rather than in dB values. A dB scale would not make too much sense because we cannot plan for absolute values in signal level reproduced by individual systems and in playback rooms.
Calibrating the Monitoring System
Both the signal level which is send to the Volume 8 controller as well as the input sensitivity of the power amps or active speakers should be matched to ensure a proper overall gaining. An inappropriate adjustment might happen when, for example, a (fairly small) 10% setting in level might already result in an extremely high playback level. Important: You can encounter very loud signals during calibration, so be sure to keep your ear protection on. For calibration we recommend measurement with a Real Time Analyzer (RTA) or a SPL Meter (in this case, SPL translates to Sound Pressure Level). First the measuring machine and microphone are set up at the listening position. Then one produces in the DAW a sound le with pink noise, which is played back and measured. Each measurement should be done through one channel and loudspeaker at a time. A recommendable calibration is the playback of a 83 dB SPL reference signal at the playback locationa common reference volume level. The DAW output level should be adjusted to 0 dB, and next, the power amps or active speakers input level should also be set to 0 dB. Now the Volume 8 level control is adjusted until the RTA or SPL Meter measures 83 dB with the pink noise playback. For a perfectly matched gaining the Volume control would now be set above a 50% scale position. At this point one can record or note the exact value for 83 dB. Should this 83 dB SPL occur markedly above a 6080% scale position, one should lower the power amps/active speakers input sensitivity (=higher dB value). On the other hand, the power amps/active speakers input sensitivity should be raised if the 83 dB SPL point is reached far before the 60% control level. In cases where regulating power amp/active speaker input is not enough, one may reach good values by changing the D/A converter output level (for example from +4 dB to 0 or -10 dB in cases where this switch option may exist). In any case, the converters should always be driven at full scale from the DAW.

You guessed it. this switch mutes all speaker outputs. It is particularly valuable in panic situations, for example, if the computer crashes and its converters suddenly output uncontrolled high level noise. It is also very useful in any case where one simply wants silence without changing the Volume settingse. g. to answer the telephone. IMPORTANT: When making any cable connection changes, you should not only activate the mute switch, but follow the On/Off powering procedures noted on p. 6.

Specications

Inputs/Outputs Instrumentational amplier, electronically balanced (differential), transformerless Nominal Input Level Input Impedance Output Impedance Max. Input Level Volume Gain Measurements Frequency Range (100 kHz = -3 dB) CMRR THD & N (@ +15 dBu Input Level) S/N A-weighted Crosstalk L/R (@ 1 kHz) Dynamic Range Power Supply Toroidal transformator Fuse Voltage Selector Power Consumption Dimensions & Weight Housing +4 dBu =22 kOhm 600 Ohm +20 dBu bis -4 dB

10 Hz-100 kHz

60 dBu@1 kHz -100 dBu -102 dBu -80 dBu 120 dB
15 VA 250 mA/230 V, 500 mA/115 V 230/50 Hz 115 V/60 Hz ca. 15 W
215 x 80 x 220 mm/ 8.5 x 3.1 x 8.8 inches Depth incl. Potentiometer & Sockets 245 mm/9.8 inches Weight 1.9 kg/4.18 lb
Notes: 0 dBu = 0.775 V Subject to change without notice.

Audio Precision

Volume 8 FREQUENCY RESPONSE

04/27/06 11:37:24

100 Hz

FREQ RESP only On.at2c

-1k 2k

Measurements

+0 -20 -40 -60 d B -80 -100 -120 -28.100
Crosstalk Volume 8 CH 1-2 und 1-8

04/27/06 11:41:36

dx=-.96722 kHz

500 Hz

.995319k 1k

CROSSTALK VS FREQ.at2c

Volume 8 THD+N vs AMPLITUDE

04/27/06 11:43:05

+20 +0 -20 -40 d B -60 -80 -100 -120 -40

-10 dBu

THD+N VS AMPL 2CH.at2c
Guarantee & Product Registration
All SPL products come with a two-year manufacturers guarantee again defects in material or assembly from the date of purchase. Tubes have a guarantee of three months. End users are supported in the two-year guarantee through their distributor. In such cases, please contact your dealer for full guarantee conditions and service. Direct SPL product support requires product registration. Please ll out the guarantee card enclosed in the package legibly in printed letters and send it directly to SPL. Or use the online registration form that may be reached at www.soundperformancelab.com (international clients) or www.spl-usa.com (US clients).