PrismSound MEA-2 User Manual

Download

Page 1

MASELEC MASTER SERIES

MEA-2 Precision Stereo Equalizer

Operation Manual

Issue 1.2 17 January 2000

Page 2

Prism Media Products Limited Operation Manual MASELEC MASTER SERIES MEA-2 Precision Stereo Equalizer

CONTENTS

1. INTRODUCTION ..............................................4

2. SUMMARY OF MEA-2 FEATURES ................................4

3. GETTING STARTED ...........................................5

3.1. Unpacking your MEA-2 ....................................5

3.2. Using the MEA-2 for the first time ............................5

3.3. MEA-2 product concept and capabilities .......................6

4. OPERATION .................................................7

4.1. Shelf/bandwidth and boost/cut settings ........................8

4.2. Frequency selections by Eq band ............................9

5. CONNECTORS ..............................................10

5.1. Input connections .......................................10

5.2. Output connections ......................................11

5.3. Rear panel connectors ...................................12

6. SPECIFICATION .............................................12

6.1. Analogue inputs ........................................12

6.2. Analogue outputs .......................................12

6.3. Performance specification .................................13

6.4. Servicing and repair .....................................13

6.5. Mains transformer voltage selection .........................13

6.6. Fuse .................................................14

6.7. Earthing ...............................................14

6.8. Physical dimensions .....................................14

7. EQUALIZER RESPONSE CURVES ..............................15

7.1. Range of cut/boost for 60Hz shelf on LF1 .....................15

7.2. Range of cut/boost for 60Hz bell curve on LF1 .................15

7.3. Range of frequency for +8dB shelf on LF1 ....................16

7.4. Range of bandwidths for +8dB 530Hz bell on LF1 ..............16

7.5. Range of bandwidth and shelf curve at 435Hz on LF1 ...........17

Issue 1.2 © Prism Media Products Limited 17 January 2000 Page 2 of 20

Page 3

Prism Media Products Limited Operation Manual MASELEC MASTER SERIES MEA-2 Precision Stereo Equalizer

7.6. Range of bandwidth and shelf curve at 108Hz on LF2 ...........17

7.7. Range of boost/cut for 617Hz shelf on HF1 ...................18

7.8. Range of boost/cut for 3300Hz shelf on HF1 ..................18

7.9. Range of bandwidth plus shelf curve at 617Hz on HF1 ..........19

7.10. Range of bandwidth plus shelf curve at 9000Hz on HF1 .........19

8. ELECTROMAGNETIC COMPATIBILITY ...........................20

9. REFERENCES ..............................................20

Manual Revision History

Issue 1.0; 23 October 1997 Issue 1.1; 8 January 1998 Issue 1.2; 17 January 2000 Detail changes only; email addr; Layout;

Product Revision History

This manual is for use with MEA-2 units having serial numbers beginning with ‘4' (or higher number) thus : MEA-2-4-xx-xxxx

Issue 1.2 © Prism Media Products Limited 17 January 2000 Page 3 of 20

Page 4

Prism Media Products Limited Operation Manual MASELEC MASTER SERIES MEA-2 Precision Stereo Equalizer

1. INTRODUCTION

The MEA-2 Precision Stereo Equalizer is intended for professional audio use in recording , mixing and mastering applications where high performance is required.

The MEA-2 provides a unique set of tools, carefully crafted to provide an equalizer whose sonic character was the most important design objective.

The unique character of the device is evident in the response curves included at the end of this manual.

The MEA-2 employs state-of-the art analogue electronics and provides a perfect solution to analogue mastering needs, especially used in conjunction with Prism Sound A/D and D/A converters.

Also available in the MASELEC MASTER SERIES is the MLA-2 compressor.

2. SUMMARY OF MEA-2 FEATURES

Operational:

C Four separate equalizer sections per channel C EQ in/out for each channel C All sections switchable between shelving & five different peaking responses C Precision stepped controls C Overlapping frequency ranges in each pair (LF1&2 and HF1&2) C 84 frequency settings per channel

Technical:

C Low noise C Extended headroom with maximum input amplitude of +28dBu C Extended frequency response C Low distortion C Electronically balanced inputs and outputs

Issue 1.2 © Prism Media Products Limited 17 January 2000 Page 4 of 20

Page 5

Prism Media Products Limited Operation Manual MASELEC MASTER SERIES MEA-2 Precision Stereo Equalizer

3. GETTING STARTED

It is not necessary to read all the manual before being able to use the MEA-2 Precision Stereo Equalizer. This section contains all the information required for you to get going straight away.

3.1. Unpacking your MEA-2

Check that you have the following items and that they are undamaged:

" MEA-2 Precision Stereo Equalizer unit " MEA-2 Precision Stereo Equalizer operation manual (this book) " IEC320 type mains lead with appropriate plug for your supply

Check that the slide switch mounted on the rear panel is set to the correct mains voltag e range (‘120' setting : 90V-130Vac 50-60Hz; ‘240' setting : 180-260Vac 50-60Hz) and that the plug fitted to the mains lead is of the correct type. If not, DO NOT CONNECT THE MAINS SUPPLY, but contact your distributor.

Please keep the packaging for re-use in the event that the unit should be shipped to another location or in the event that it should ever need to be returned to the manufacturer for repair or upgrade.

3.2. Using the MEA-2 for the first time

Connect a source of balanced audio to the input connectors on the MEA-2. Refer to section 10 for details of how to wire up interconnecting cables for the MEA-2.

Connect the output of the MEA-2 to a monitoring system or to a tape recorder input. Connect the mains supply to the MEA-2 unit. There is a main power switch on the rear of

the unit and an auxiliary switch on the front which is more convenient to use if the equipment is rack mounted and the rear panel is inaccessible. It is necessary for the rearmounted mains switch to be in the ‘ON’ position before the front panel switch will operate. The front panel switch operates a relay within the unit.

The indicator lamp integral in the rear-mounted mains switch should illuminate when switched on. If it fails to light the power may be absent or the unit may be faulty. Check the mains supply, and try again. If the problem is still evident contact your distributor.

Issue 1.2 © Prism Media Products Limited 17 January 2000 Page 5 of 20

Page 6

Prism Media Products Limited Operation Manual MASELEC MASTER SERIES MEA-2 Precision Stereo Equalizer

Switch the secondary power switch on the front of the MEA-2 to 'ON'. Press and release the 'In/Out' push buttons for the left and right channels on the front of the unit. When the equalizer for each channel is in-circuit, the button will be illuminated a soft green colour.

Switch the monitor selection to monitor the MEA-2 output. The unit is now ready to use.

3.3. MEA-2 product concept and capabilities

The MEA-2 Precision Stereo Equalizer is designed to provide very high quality signal processing for the most demanding professional applications. It has been carefully developed in conjunction with balance engineers, producers and mastering engineers to provide a natural and warm sound. Samples of the unique response curves of the MEA-2 are reproduced in section 7 of this manual.

The presentation of the controls is designed to be clear and intuitive.

Issue 1.2 © Prism Media Products Limited 17 January 2000 Page 6 of 20

Page 7

Prism Media Products Limited Operation Manual MASELEC MASTER SERIES MEA-2 Precision Stereo Equalizer

4. OPERATION

The unit is designed for either stereo or 2-channel operation and each channel is controlled independently by an identical set of controls.

Each channel has four equalizer sections, denoted in this manual as LF1, LF2, HF1 & HF2. These are presented on the front panel in the same order as above with LF1 being on the left.

Each section has controls for

C Response/Q C Frequency C Cut/Boost

These parameter adjustments are interactive to a degree; for example filter bandwidth is adjusted automatically while adjusting the cut/boost control. For further information see the sample curves in section 7.

For reference, the settings available on the unit are reproduced here:

Issue 1.2 © Prism Media Products Limited 17 January 2000 Page 7 of 20

Page 8

Prism Media Products Limited Operation Manual MASELEC MASTER SERIES MEA-2 Precision Stereo Equalizer

4.1. Shelf/bandwidth and boost/cut settings

The numerical bandwidth settings relate to the Q factor or sharpness of the peaking filters. As a result of the asymmetric shape of the MEA-2 Equalizer curves it becomes difficult to define Q factor in a meaningful way. These settings should therefore be regarded as indicating the relative bandwidths with 4 being the broadest and 20 the narrowest. For more detail, see section 15.

All sections shelf/bandwidth settings:

Shelf, 4, 6, 9, 14, 20

All sections cut/boost settings (dB):

Boost (dB) Cut (dB)

+8.0 -8.0 +6.0 -6.0 +5.0 -5.0 +4.0 -4.0 +3.0 -3.0 +2.5 -2.5 +2.0 -2.0 +1.5 -1.5 +1.0 -1.0 +0.5 -0.5

0.0

Issue 1.2 © Prism Media Products Limited 17 January 2000 Page 8 of 20

Page 9

Prism Media Products Limited Operation Manual MASELEC MASTER SERIES MEA-2 Precision Stereo Equalizer

4.2. Frequency selections by Eq band

LF1 (Hz) LF2 (Hz) HF1 (Hz) HF2 (Hz)

19 21 617 665 22 24 727 787 26 29 862 937 31 34 1k 1k1 37 41 1k2 1k3 43 48 1k4 1k5 51 57 1k7 1k8 60 67 2k0 2k2 71 79 2k4 2k6 84 92 2k8 3k0

98 108 3k3 3k6 114 126 3k9 4k2 134 148 4k6 5k0 158 173 5k4 5k9 185 203 6k4 7k0 218 240 7k6 8k2 258 280 9k0 9k7 305 332 11k 12k 364 400 13k 14k 435 477 17k 19k 530 572 24k 27k

Issue 1.2 © Prism Media Products Limited 17 January 2000 Page 9 of 20

Page 10

Prism Media Products Limited Operation Manual MASELEC MASTER SERIES MEA-2 Precision Stereo Equalizer

5. CONNECTORS

For this equipment, the convention for balanced XLR connections pin 2 is 'hot' or '+' and pin 3 'cold' or '-'. Some users and equipment implement the opposite. This should not be problematic providing a consistent implementation is used throughout.

Note: When interfacing to other devices such as A/D and D/A converters it may be necessary to check the manufacturers polarity convention if the correct absolute phase is to be maintained. However, this does not affect use of the MEA-2 with either polarity convention.

Balanced analogue audio connections should use a good-quality screened twisted-pair lead. Unbalanced connections must also be screened.

5.1. Input connections

The following diagrams illustrate correct connection for balanced and unbalanced sources:

Using the above method when driving the MEA-2 with unbalanced sources should provide best results.

Note: The maximum input amplitude is reduced by approximately 6dB from the nominal +28dBu when driving the MEA-2 from an unbalanced source.

Issue 1.2 © Prism Media Products Limited 17 January 2000 Page 10 of 20

Page 11

Prism Media Products Limited Operation Manual MASELEC MASTER SERIES MEA-2 Precision Stereo Equalizer

5.2. Output connections

The following diagrams illustrate correct connection for balanced and unbalanced sources:

Using the above method for driving unbalanced loads should provide best results. It employs ‘Ground Loop Compensation’ and the signal level remains unchanged compared to balanced operation.

Note: When driving unbalanced loads with the MEA-2 the maximum output level is reduced by approximately 6dB from the nominal +28dBu.

Issue 1.2 © Prism Media Products Limited 17 January 2000 Page 11 of 20

Page 12

Prism Media Products Limited Operation Manual MASELEC MASTER SERIES MEA-2 Precision Stereo Equalizer

5.3. Rear panel connectors

A. Audio I/O

C Left Channel Input C Left Channel Output

C Right Channel Input C Right Channel Output

B. Earthing Stud - Link to a good-quality ground connection by the most direct route. C. IEC Mains Inlet (Switched).

6. SPECIFICATION

6.1. Analogue inputs

The analogue inputs are on a three pin XLR connector with positive and negative signal polarities on pins 2 and 3 respectively, and screen on pin 1. Pins 2 & 3 have a high impedance path to the chassis earth.

Differential input impedance: 27 kS(*) (pin 2 to pin 3) Single-ended input impedance: 27 kS(*) (pin 1 to 2 or 3) Coupling impedance to chassis: 1.0 MS (chassis/pin 1 to 2 or 3) Common-mode range: 20 Vrms

* Note : Some earlier units are 38.4 kS

6.2. Analogue outputs

The analogue outputs are on a three pin XLR connector with positive and negative signal polarities on pins 2 and 3 respectively, and the mid-point on pin 1.

Differential output impedance: 62 S (pin 2 to pin 3, balanced) Single-ended output impedance: 31 S (pin 1 to 2 or 3, unbalanced)

Issue 1.2 © Prism Media Products Limited 17 January 2000 Page 12 of 20

Page 13

Prism Media Products Limited Operation Manual MASELEC MASTER SERIES MEA-2 Precision Stereo Equalizer

6.3. Performance specification

Specifications quoted in this section are to AES17-1991 (ANSI S4.51-1991) [Ref. 1], with input level set to +22dBu except where stated. For ‘EQ in’ measurements, the CH1/CH2 ‘In’ buttons are illuminated and other settings are : LF1 - Shelf, LF2 - Bell, slope 9, HF1 Bell, slope 9, HF2 Shelf. Gain for each section is set to 0dB.

Maximum input amplitude : +28dBu Output noise : EQ out < -97dBu

EQ in < -89dBu Frequency response : + 0.1, -0.4dB, <1Hz to > 50 kHz Crosstalk : less than -100 dB, 20 Hz to 20 kHz

Un-driven input terminated 150R

Harmonic distortion and noise, EQ in : <-105dB (<0.0006%), 997 Hz Dynamic range : (Measured at -32dBu) EQ out > 125dB

EQ in > 117dB

6.4. Servicing and repair

There are no user serviceable parts inside this unit. Repairs should only be undertaken by qualified electronics technicians or engineers.

6.5. Mains transformer voltage selection

The mains transformer has a tapped primary to allow operation at nominal voltages of 120V or 240V. A rear-panel slide switch selects the mains voltage range. Ensure that the correct voltage range is selected before using the MEA-2.

6.5.1. Mains voltage range : 90-130V (nominally 120V) or 180-260V

(nominally 240V) operation. The selected supply voltage range is indicated on the rear panel slide switch.

6.5.2. Power consumption : 15W max.

Page 14

Prism Media Products Limited Operation Manual MASELEC MASTER SERIES MEA-2 Precision Stereo Equalizer

6.6. Fuse

There is one mains fuse, accessible externally in the IEC320 mains inlet. If this fuse is blown it should be replaced by an identical value and type. (20x5mm 250V 315mAT (anti-surge, slow)).

6.7. Earthing

The unit has an internal link connecting the audio ground to the chassis. A chassis earth stud is provided on the rear of the unit.

6.8. Physical dimensions

Weight : 11 lb (5 kg) Width : 19 inch (483mm) (rack-mountable) Height : 3U (77mm) Depth : 10.5 inches (267mm) front face to rear face. (Add clearance for

connectors)

Page 15

Prism Media Products Limited Operation Manual MASELEC MASTER SERIES MEA-2 Precision Stereo Equalizer

7. EQUALIZER RESPONSE CURVES

The following plots are samples of the responses of the MEA-2 equalizer. All section types are represented, but for brevity only a small selection of the total number of possible settings are included.

7.1. Range of cut/boost for 60Hz shelf on LF1

AUDIO PRECISION MEA_2GB1 vs 09 JUN 97 13:35:04

7.2. Range of cut/boost for 60Hz bell curve on LF1

AUDIO PRECISION MEA_2GB1 vs 09 JUN 97 13:35:04

Page 16

Prism Media Products Limited Operation Manual MASELEC MASTER SERIES MEA-2 Precision Stereo Equalizer

7.3. Range of frequency for +8dB shelf on LF1

AUDIO PRECISION MEA_2GB1 vs 09 JUN 97 13:35:04

7.4. Range of bandwidths for +8dB 530Hz bell on LF1

AUDIO PRECISION MEA_2GB1 vs 09 JUN 97 13:35:04

Page 17

Prism Media Products Limited Operation Manual MASELEC MASTER SERIES MEA-2 Precision Stereo Equalizer

7.5. Range of bandwidth and shelf curve at 435Hz on LF1

AUDIO PRECISION MEA_2GB1 vs 09 JUN 97 13:35:04

7.6. Range of bandwidth and shelf curve at 108Hz on LF2

AUDIO PRECISION MEA_2GB1 vs 09 JUN 97 13:35:04

Page 18

Prism Media Products Limited Operation Manual MASELEC MASTER SERIES MEA-2 Precision Stereo Equalizer

7.7. Range of boost/cut for 617Hz shelf on HF1

AUDIO PRECISION MEA_2GB1 vs 09 JUN 97 13:35:04

7.8. Range of boost/cut for 3300Hz shelf on HF1

AUDIO PRECISION MEA_2GB1 vs 09 JUN 97 13:35:04

Page 19

Prism Media Products Limited Operation Manual MASELEC MASTER SERIES MEA-2 Precision Stereo Equalizer

7.9. Range of bandwidth plus shelf curve at 617Hz on HF1

AUDIO PRECISION MEA_2GB1 vs 09 JUN 97 13:35:04

7.10. Range of bandwidth plus shelf curve at 9000Hz on HF1

AUDIO PRECISION MEA_2GB1 vs 09 JUN 97 13:35:04

Page 20

Prism Media Products Limited Operation Manual MASELEC MASTER SERIES MEA-2 Precision Stereo Equalizer

8. ELECTROMAGNETIC COMPATIBILITY

This equipment is intended for use in an electromagnetically controlled environment. To maintain the performance specification it should not be subject to strong magnetic fields (such as in the immediate vicinity of a power amplifier or cathode ray tube) and all connections should be terminated as described below. This equipment does not include digital circuitry or generate high-frequencies that could be radiated or conducted from the unit.

All XLR connections should use a screened twisted pair cable with the screen connected to pin 1 of the XLR connector at both ends.

9. REFERENCES

[1] AES17-1991 - `AES Standard Method for Digital Audio Engineering - Measurement of Digital Audio Equipment' J.

Audio Eng. Soc., Vol. 39 No. 12, pp 961-975 (December 1991)

FURTHER INFORMATION Enquiries about this product should be addressed to :

Prism Media Products Limited

William James House

Cowley Road

Cambridge

Phone: +44-(0)1223-424 988

Fax: +44-(0)1223-425 023

Email : [email protected],

[email protected]

Web : www.prismsound.com

CB4 0WX