Aphex AURAL EXCITER III Operating Manual & Service Manual
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Aphex AURAL EXCITER III Operating Manual & Service Manual

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AURAL EXCITER® TYPE III
MODEL 250
OPERATING GUIDE
&
S E R V IC E MANUAL
APHEX SYSTEMS LTD.

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Summary of Contents for Aphex AURAL EXCITER III

  • Page 1 AURAL EXCITER® TYPE III MODEL 250 OPERATING GUIDE & S E R V IC E MANUAL APHEX SYSTEMS LTD.
  • Page 2 WARNING TO REDUCE THE RISKS OF FIRE OR ELECTRIC SHOCK, DO NOT EXPOSE THIS APPLIANCE TO RAIN OR MOISTURE...

  • Page 3: Table Of Contents

    TABLE OF CONTENTS INTRODUCTION OPERATIONAL CHARACTERISTICS New Features Typical Applications Specifications Warranty and Service Information INSTALLATION Unpacking Setting Input Sensitivity Audio I/O (Input/Output) Connectors I/O Connection Considerations AC Line Connection Remote Control Connection Installing the Type III in an Equipment Rack Applying Power and Initial Checkout FRONT PANEL CONTROLS...
  • Page 4 TABLE OF CONTENTS APPLICATIONS (continued) Exciting FM Audio for Television and Radio Exciting AM Broadcast Audio User Templates CIRCUIT DESCRIPTION Main Audio Path Ax Sidechain Path Power Supply TEST AND NULLING PROCEDURES Main Audio Board Control Boards PARTS LIST Main Audio Board Control Board Power Supply SCHEMATICS...

  • Page 5: Introduction

    The new Aural Exciter III The beginning of 1989 marks the introduction of the latest generation Aphex Aural Exciter III. The slimmer and more powerful Model 250 is the latest successor to the premium product in the field of Aural Excitement. As you read the following sections you will find information on Operational Char­...

  • Page 6: Operational Characteristics

    2.0 OPERATIONAL CHARACTERISTICS Special features... The Aphex Aural Exciter Type III, Model 250, is the latest generation, fully - professional Aural Exciter, loaded with powerful new processing features and improved circuitry. The dual-channel Type III adds thrilling new dimensions to Aural Excitement. Noise and distortion are virtually elimi­...
  • Page 7 Mode B is a revolutionary new noise reduction technique which operates to actually "erase" source audio noise while the Type III enhances the signal. This feature allows you to restore brightness and intelligibility to noisy recorded tracks or other noisy sources and improve the signal-to-noise ratio! Both modes are fast and easy to use, and effective in any application from live sound to broadcasting and recording.

  • Page 8: Typical Applications

    2.1.6 Null Fill Phase Nulling... NULL FILL is a new and useful tuning adjustment introduced for the first time with the Aural Exdter Type III. The addition of NULL FILL to the PEAKING and TUNE controls gives the Type III more power and flexibility to enhance all types of audio sources.

  • Page 9: Specifications

    2.2.2 Tape Duplication Pre-process recordings The Aural Exciter may be used to "pre-process" recordings to anticipate the audio degradation in the medium or during subsequent reproduction. Much of the detail added by the Aural Exciter will survive filtering and distortion of the reproduction equipment and provide a better quality audio playback.
  • Page 10 As a result of these efforts, modifications may be made from time to time to existing products without prior notice. Specifications and appearance may differ from those listed or shown. Aphex and Aural Exciter are registered trademarks of Aphex Systems, Ltd.

  • Page 11: Warranty And Service Information

    Warranty and Service Inform ation Aphex Systems, Ltd. warrants parts and labor for the Aural Exciter Type ID for a period of one year from the date of purchase. If it becomes necessary to return a unit for repair, repack it in the original carton and packing material, if possible.

  • Page 12: Installation

    3.0 INSTALLATION To install the Aphex Aural Exciter Type III for use with your system, per­ form the instructions described in the following sections. CAUTION... H Id Thoroughly read Section 3.5 before you apply power to the unit. An incorrect line voltage setting can damage the unit.

  • Page 13: I/O Connection Considerations

    I/O Connection Considerations Prior to installing the Aural Exciter Type III into your system, take note of the following considerations for 1/O impedance matching and system wiring. 3.4.1 Impedances The input is of high (19.5 kOhms) impedance and may be easily driven by any output source.
  • Page 14 3.5.1 AC Voltage Selection As shipped, the Aural Exciter Type III is set for 120 VAC operation, but you can change your unit to match any standard AC line voltage simply by reprogramming the voltage programming card in the fuse holder in the following way: Remove the power cord from the chassis receptacle.

  • Page 15: Remote Control Connection

    Remote Control Connector The Aural Exciter Type Etl can be set up for remote bypass control use via the REMOTE CONTROL connector, as shown in Fig. 3-4. This four-pin, modular telephone-type jack (Fig. 3-1) provides the follow­ ing control signals: Pin 1 - Logic Ground Pin 2 - Channel 2 Relay Control Pin 3 - Channel 3 Relay Control...

  • Page 16: Applying Power And Initial Checkout

    Applying Power and Initial Checkout After you have completed the previous instructions, apply power to the unit by depressing the POWER switch (located on the front panel). If none of the indicator LED's light, check fuse and power cord installation before proceeding with the remaining checks.

  • Page 17: Front Panel Controls

    FRONT PANEL CONTROLS The front panel layout of the Aphex Aural Exciter III provides identical sets of controls for two independent channels of Aural Excitement, as shown in Fig. 4-1. Each channel contains six rotary controls (located left to right), for setting NR THRESHOLD, TUNE, PEAKING, NULL FILL, HARMONICS, TIMBRE, and MIX parameters.

  • Page 18: Nr Mode Switch

    Notice that the signal coming from the input is divided into two paths, known as the "Main Path" and "Ax Sidechain". The "Main Path" contains very little processing and basically serves as a signal tap and summing point for the Excitement circuits. In the "Ax Sidechain", the signal tap is altered and enhanced via the rotary controls, and then is added back to the original signal on the way to the output connector.
  • Page 19 4.1.2 NR MODE B When selected, the NR MODE B is a variable shelving equalization circuit that also controls the "Ax Sidechain" signal. The associated red, yellow, and green LED's correspond directly to a -, 0, or + change in a variable high pass shelving circuit when you set the NR THRESHOLD Control.
  • Page 20 NR THRESHOLD Control This rotary control provides a threshold setting range from +30 dB to -60 dB for a chosen NR MODE (described in section 4.1). When audio program is present at the channel input, the NR MODE LED's provide an indication of noise reduction action for a given threshold setting.

  • Page 21: Tune Control

    TUNE Control The TUNE Control sets the frequency of the second-order high pass filter in "Ax Sidechain" that establishes the frequency domain for the Aural Excite­ ment effect. The control range extends from 700 Hz to 7 kHz and is similar to all other TUNE Controls found on other Aural Exciter models.

  • Page 22: Peaking Control

    PEAKING Control The PEAKING control provides a damping effect on the leading frequency edge of the high pass filter controlled by TUNE. As you vary this control from minimum to maximum, the TUNE frequency will become more accen­ tuated, as demonstrated in Fig. 4-6. However, at that same time, a dip is created just before the accentuated TUNE frequency.
  • Page 23 a "dip" or "null" also occurs in the output equalization curve at the TUNE frequency. As a result, the "null" frequencies are de-empasized, thus giving even more empasis to the higher frequencies. Although this often is a desir­ able effect, the NULL FILL Control was created to allow the user to "fill-in" the "nuU”...

  • Page 24: Harmonics Control

    4.6 HARMONICS Control The HARMONICS Control replaces the original DRIVE control that varied the density of harmonics created by earlier Aural Exciter models. With this new control, harmonics are generated directly through a VCA modulation process with no effect on the signal level in the sidechain. The internal harmonic generator produces harmonic components according to a complex set of laws, including considerations for transient and steady-state qualities, as well as relative amplitude of the original audio signal.

  • Page 25: Solo Switch

    Unlike the BYPASS Mode, the audio signal from the input does travel through active circuits on the way to the output whenever Ax is Off. When Ax is Off, SPR (section 4.11) is still operational. 4.10 SOLO Switch The SOLO Switch gives you a choice of auditioning the Aural Excitement signal alone without the main audio, whenever youpress the button in.

  • Page 26: Relay Switch

    4.12 RELAY Switch The RELAY switch, located in the center of the front panel, provides an internal, two-channel (hard-wire) bypass of the Aural Exciter III circuitry. In the normal mode of operation, the RELAY Bypass is "Off" (button Out), and the CHI and CH2 indicators, located to the right of each individual channel MIX Control, are "On".

  • Page 27: Applications

    APPLICATIONS In this section, we will first review setting the Aphex Aural Exciter Type III for initial operation (as mentioned in Section 3.8 - Initial Checks). Then, a series of illustrated applications will provide you a look at some typical settings for the Model 250.
  • Page 28 Press SPR to indicate in (LED on). Make sure that RELAY is not active (no indicator - button out). Set all Control knobs to the 12 o'clock position. Connect an audio program to one channel and monitor the results by alternately pressing the RELAY button. Experiment with the following controls and buttons to hear how each feature enhances the original audio signal: Alternately press SOLO button to hear the pure excitement...

  • Page 29: Exciting A Recorded Tom Or Kick Drum

    Exciting a Recorded Tom or Kick Drum After you have set the console gain structure and applied equalization, try the following settings, as shown in Fig. 5-3, to Excite the tom or kick drum sound: Press NR MODE to indicate B, and Ax to indicate in (LED on).

  • Page 30: Recording A Snare Drum With Excitement

    Recording a Snare Drum with Excitement To add Aural Excitement to the sound of a snare drum, perform the follow­ ing steps after you are satisfied with the audio balance of level and equaliza­ tion: Press NR MODE to indicate A, Ax to indicate on (LED on), and SPR to indicate on (LEDon).

  • Page 31: Exciting Fm Audio For Television And Radio

    Exciting FM Audio for Television and Radio To improve the sound of television and FM radio broadcast audio, place the Aural Exciter Type III in-line between the studio feed and the transmitter limiter, as shown in Fig. 5-5. Set the controls as follows: MODE to indicate A, Ax to indicate on (LED on), and SPR to indicate on (LED on).

  • Page 32: Exciting Am Broadcast Audio

    Adjust the NR THRESHOLD control so that the "0" (green) LED is flashing a majority of the time. The NR THRESHOLD setting is dependent upon program material content. For example, classical music programming would require a lower dB setting to accommodate the wider dynamic excursions in the music. Exciting AM Broadcast Audio To improve the broadcast sound of AM radio, place the Aural Exciter Type III in-line between the studio feed and the transmitter limiter.

  • Page 33: User Templates

    User Templates A set of Front Panel drawings without knob indicators are provided for your use in Fig. 5-8. Feel free to reproduce the page so you can mark and include custom settings with your project documentation. Fig. 5-8. User templates. Applications...

  • Page 34: Circuit Description

    CIRCUIT DESCRIPTION The circuits that make up the Aphex Aural Exciter Type III are grouped onto several boards, including: one Main Audio Board (two channels), two Control Boards (one for each channel), and a Power Supply Board for AC to DC voltage conversion via the separate AC line transformer.

  • Page 35: Main Audio Path

    NOTE... For the sake of brevity, only channel 1 components are mentioned in the following discussion. Main Audio Path Channel 1 audio enters the Model 250 through the INPUT XLR connector to a Servo Balanced Input Stage. Then the audio signal is routed to the Spectral Phase Refractor (SPR) and through some electronic switching circuits on to the Summing Stage, where it is combined with the signal from the Ax Sidechain.
  • Page 36 6.1.2 Spectral Phase Refractor (SPR) The SPR circuit, U102A and U102B, is designed as two identical all-pass filters that act as delay circuits on the overall audio signal. A greater time delay occurs for signals above 150 Hz according to the time constant product of C110 and R109.
  • Page 37 CMOS switches U103B and U103C, also working in tandem, route the Ax Sidechain signal to Summing Stage whenever the Ax IN/OUT button is pressed IN. Logic ground is routed via SW402 (see Control Board schematic) to H101 pin 6 causing U103C's switch to open and U103B's switch to close through the use of logic invertor U301 A.

  • Page 38: Ax Sidechain Path

    One signal from the state variable filter reaches VR405, a variable HAR­ MONICS Control. The potentionometer wiper feeds a chosen amount of signal to an Aphex MAX 1502 integrated circuit for transient processing of fast attack signals. Transient processing helps produce more harmonics in the attack, rather than the sustain, portion of the incoming signal.
  • Page 39 are used in the feedback loop to define the logarithmic function. The output from the logarithmic amplifier stage feeds a full wave rectifier circuit made up of U401B and U401C, which produces a positive-going signal at pin 8 of U401C. The THRESHOLD Control imparts a DC bias voltage onto this rectified signal prior to feeding a peak-hold filter made up of U401A circuitry.

  • Page 40: Power Supply

    the VCAtt integrated circuit. OUT 1 and OUT 2 (from VCAtt) feed U405B where they are combined into single-ended signal feeding the MIX Control VR407 through capacitor C417. The VCAtt output is controlled by the type and amount of voltage present on the VC terminal.

  • Page 41: Test And Nulling Procedures

    7.0 TEST AND NULLING PROCEDURES The listed test procedures require the use of the following test equipment: 1. Audio Analyzer (Sound Technology 1710 or equivalent) 2. Spectrum Analyzer (Tektronics 5L4N or equivalent) 3. Sweep Function generator (B&K 3025 or equivalent) 4.

  • Page 42: Control Boards

    5. Verify output distortion less than .01 7.1.6 Noise 1. Short the inputs. 2. Output should be better than -86dBu. 7.1.7 Input Loads 1. Turn loads off. 2. Set input signal equal to 1kHz at +20dBu, NORMAL MODE. 3. Turn on one load at a time. 4.
  • Page 43 7.2.1 Beginning Setup 1. Make sure all boards are connected. 2. Verify Ax, SOLO, and SPR are all "OFF". 3. Verify RELAY (Bypass) is "OFF". 4. Set NR THRESHOLD to -60. 7.2.2 Tune Check 1. Set input signal to audio sweep. 2.
  • Page 44 7.2.6 NR Mode A 7.2.6.1 Threshold Check 1. Set input signal equal to lk H z a t +26dBu. 2. Set NR MODE switch to A. 3. Set NR THRESHOLD to +30. 4. Place an osilloscope probe on D409’s anode. 5.
  • Page 45 7.2.8 Transient Processor 1. Set input signal to 5 kHz at OdBu. 2. Set TUNE to 700Hz. 3. Set PEAKING and NULL FILL to 12 o ’clock positions. 4. Place an oscilloscope probe on pin 16 of U407. 5. Vary HARMONICS control end to end. 6.

  • Page 46: Parts List

    PARTS LIST The following items are sub-assemblies and assorted parts that make up a complete Model 250 Aural Exciter III. QUANTITY DESCRIPTION PART# © CORCOMPWR CONN 42-013 (7) PIN MOLEX 43-059 MOLEX PINS 49-016 US POWER CORD 54-013 GROUND LUG 60-028 8-32X5/8"...
  • Page 47 PART# VALUE TOLERANCE STYLE STOCK# R133 10K0 FILM 92-1002 R134 10K0 FILM 92-1002 R135 332K FILM 92-3323 R136 56 OHM FILM 92-0560 R137 10 MEG FILM 92-1005 R138 150 OHM FILM 92-1500 R139 150 OHM FILM 92-1500 R140 20K0 FILM 92-2002 R141 20K0...
  • Page 48 8.1.2 Variable Resistors STOCK# PART# VALUE STYLE VR101 PIHER LAYDOWN TRIMMER 22-008 VR102 PIHER LAYDOWN TRIMMER 22-003 22-008 VR201 PIHER LAYDOWN TRIMMER 22-003 VR202 PIHER LAYDOWN TRIMMER 8.1.3 Capacitors STOCK# PART# VALUE STYLE ClOl 470 PF CERAMIC DISC 80-015 C102 470 PF 80-015 CERAMIC DISC...
  • Page 49 8.1.4 Semiconductors PART# DESCRIPTION FUNCTION STOCK# U101 LF353N DUALOP AMP 32-007 U102 LF353N DUAL OP AMP 32-007 U103 CD4016BE QUAD ANALOG SWITCH 38-003 U104 LE353N DUAL OP AMP 32-007 U10S LF353N DUAL OP AMP 32-007 U106 NE5532N DUAL OP AMP LOW NOISE 32-028 U201 LF353N...
  • Page 50 8.1.6 Hardware STOCK# PART# DESCRIPTION/FUNCTION 11-009 ALPS BUTTON CAPS 20-031 SW101 2PDT SW 600 OHM IN MTK2UEE 20-031 2PDT SW -10/+4 MTK2UEE SW102 20-031 SW201 2PDT SW 600 OHM IN MTK2UEE 20-031 SW202 2PDT SW-10/+4 MTK2UEE 43-003 (10) 8 PIN IC SOCKETS 43-004 14 PIN IC SOCKETS 43-074...
  • Page 51 PART# VALUE TOLERANCE STYLE STOCK# R423 11K0 FILM 92-1102 R424 11KO FILM 92-1102 R425 10K0 FILM 92-1002 R426 10K0 92-1002 FILM R427 2K49 FILM 92-2491 R428 24K3 FILM 92-2432 R429 20K0 FILM 92-2002 R430 2K40 FILM 92-2491 R431 10K0 FILM 92-1002 R432 10K0...
  • Page 52 LF347 QUAD OP AMP 32-048 U402 LE347 QUAD OP AMP 32-048 U403 LE353N DUAL OP AMP 32-007 U404 VCA1001 APHEX 33-052 U405 NE5532N DUAL OP AMP LOW NOISE 32-028 U406 LF347 QUAD OP AMP 32-048 U407 MAX 1502 ENHANCEMENT GEN.
  • Page 53 8.2.5 Hardware PART# DESCRIPTION/ FUNCTION STOC1 ALPS BUTTON CAPS (9 PER UNIT) 11-009 KNOBS 12-004 KNOBS CAPS 14-003 SW401 4PDTSW MTK4UEE 20-030 SW402 2PDTSW MTK2UEE 20-031 SW403 4PDTSW MTK4UEE 20-030 SW404 2PDTSW MTK2UEE 20-031 SW40S 2PDTSW MTK2UEE 20-031 H401 (4) PIN RT ANGL MOLEX CONNECTOR 43-NEW H402 (9) PIN RT ANGL MOLEX CONNECTOR...
  • Page 54 8.3.3 Hardware PART# DESCRIPTION STOCK# H501 (7) COND LOCKING MOLEX HEADER 43-062 H502 (3) COND LOCKING MOLEX HEADER 43-093 H503 (4) COND LOCKING MOLEX HEADER 43-113 H504 (4) COND LOCKING MOLEX HEADER 43-113 H505 (4) COND LOCKING MOLEX HEADER 43-113 #4-40 X 1/4"...

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