73 EQ JR - Audio Equalizer Heritage Audio - Free user manual and instructions

Product Type	500 Series Equalizer Module
Brand	Heritage Audio
Model	73 EQ JR
Category	Uncategorized
Form Factor	500 Series single slot
Dimensions (W x H x D)	38 mm x 135 mm x 150 mm
Weight	Approx. 0.45 kg (estimated)
Power Supply	±16 V DC via 500 series edge connector
Power Consumption	Less than 85 mA per rail @ ±16 V DC
Input Impedance	10 kΩ bridging, transformer balanced and floating
Output Impedance	Less than 75 Ω, transformer balanced and floating
Maximum Output Level	Greater than +26 dBu into 600 Ω
THD	<0.025% @ 1 kHz, <0.05% @ 100 Hz
Frequency Response	Not specified; typical 20 Hz – 20 kHz
Equalizer Type	3-band (shelving high/low, peaking mid) with Baxandall topology
High Shelf Frequencies	10, 12, 16, 20 kHz
High Shelf Gain Range	±16 dB
Mid Peak Frequencies	0.36, 0.7, 1.6, 3.2, 4.8, 7.2 kHz
Mid Peak Gain Range	±18 dB
Low Shelf Frequencies	30, 60, 110, 220 Hz
Low Shelf Gain Range	±16 dB
Line Gain Range	+6 dB to -20 dB (continuous)
Equalizer Bypass	Yes (EQL button)
Internal Power Regulation	+24 V slow turn-on (approx. 20 seconds)
Connector	Gold-plated 500 series edge connector (15-pin)
Warranty	2 years limited to original purchaser
Country of Manufacture	Spain

Frequently Asked Questions - 73 EQ JR Heritage Audio

How do I power the 73 EQ JR?

The module is powered through the 500 series rack's edge connector. It requires ±16 V DC supplies (less than 85 mA per rail). The internal +24 V slow turn-on regulation takes about 20 seconds to reach full voltage, protecting the unit.

What is the line gain range and how do I adjust it?

The LINE GAIN knob adjusts from +6 dB to -20 dB. Use it to set the input level appropriately. Note: the knob must be turned from the 'OFF' position to engage the module.

How do I activate the equalizer?

Press the EQL button on the front panel to toggle the EQ on/off. When the button is out, the EQ is bypassed.

What frequencies are available for each EQ band?

High shelf: 10, 12, 16, 20 kHz. Mid peak: 0.36, 0.7, 1.6, 3.2, 4.8, 7.2 kHz. Low shelf: 30, 60, 110, 220 Hz. Each band has its own frequency selector switch.

What are the gain ranges for the EQ bands?

High and low shelves: ±16 dB. Mid peak: ±18 dB.

Why is there no sound or no tonal change?

Ensure the LINE GAIN knob is not set to 'OFF'. Also check that the EQL button is pressed in (EQ active). If still no change, verify signal routing and that the module is properly seated in the rack.

What is the maximum output level?

Greater than +26 dBu into a 600 Ω load, transformer balanced.

How should I clean the module?

Use a dry, lint-free cloth to clean the front panel and enclosure. Do not use solvents, abrasive cleaners, or spray liquids directly onto the module.

What is the warranty coverage?

The 73 EQ JR is covered by a 2-year limited warranty to the original purchaser against defects in materials and workmanship. It excludes normal wear, abuse, shipping damage, or misuse. Contact Heritage Audio for service.

Can I use the 73 EQ JR as a standalone line preamp without EQ?

Yes, you can bypass the EQ by pressing the EQL button out. The transformer-coupled line preamp remains active, providing gain from +6 to -20 dB for clean level matching.

USER MANUAL 73 EQ JR Heritage Audio

Thank you for choosing the 73 EQ JR. Heritage Audio is dedicated to bringing you 'the sound of yesterday for tomorrow'. We specialize in capturing that unique, enticing sound that everybody has fallen in love with. For years engineers, producers and musicians have been yearning for that classic vibe. Usually the only option is to search for old, used original equipment that is almost always in a questionable state of operation. This brings with it a whole lot of other issues, making the experience less than desirable. Not to mention the very high prices asked for this equipment, which makes them virtually unobtainable for the great majority. Now it's possible to obtain that same sound with a brand new piece that will give you all the problem-free, heavy-duty use you'll need for years of music making history.

Peter Rodriguez

CEO

Heritage Audio - Madrid, Spain

© 2022 Heritage Audio S.L. is the sole owner of the copyright of all information and drawings contained in this manual which are not to be copied or reproduced by any means or disclosed in part or whole to any third party without written permission.

Heritage Audio reserves the right to alter specifications without notice. The information in this manual has been carefully checked and is believed to be accurate at the time of publication. However, no responsibility is taken by us for inaccuracies, errors or omissions nor any liability assumed for any loss or damage resulting either directly or indirectly from use of the information contained within it.

TABLE OF CONTENTS

INTRODUCTION	2
CONTENTS	2
DESCRIPTION	3
GETTING STARTED	4
APPLICATIONS	5
SPECIFICATIONS	6
SIGNAL FLOW	6
TROUBLE SHOOTING	7
WARRANTY STATEMENT	8
REGISTRATION	8
RECALL SHEETS	9

All the EQ you should ever need

The 73 EQ JR is a fully featured Line Input module for the 500 Series.

It not only shares the 3-band Equalizer with his big brother, the Heritage Audio 73 80 Series, but also shares the same transformer coupled line preamp and Class A transformer balanced output stage.

These facts make the 73EQ JR unique on its class, being able to capture a full transformer based, Class A sound without relying on external preamps.

The Equalizer features the same Baxandall type High and Low shelf found in the HA73 80 Series, with the addition of a high frequency selector switch. 4 different frequencies are possible instead of the fixed 12kHz one.

The mid band is the same exact dual inductor one, thick low and sweet high midrange boosts without becoming muddy or brittle.

The line preamp has a range of +6 to -20 dB, allowing heavy eq boosts without overloading A/D converters.

Finally, special care has been taken with power handling, implementing internal +24 V slow turn on regulation (about 20 seconds to reach full voltage). This makes your 73 EQ JR independent of the rest of the slots and makes your lunchbox's PSU happier.

FRONT

1	2	3	4	5
LINE INPUT GAINFrom +6 to -20 dB	HIGH SHELFFrequency Selector: 10, 12, 16, 20 kHz	MID PEAK BANDFrequency Selector: 0.36, 0.7, 1.6, 3.2, 4.8, 7.2 kHz	LOW SHELFFrequency Selector: 30, 60, 110, 220 Hz	EQLActivates Equalizer
	6	7	8
	HIGH SHELF GAIN±16 dB	MID PEAK BAND GAIN±18 dB	LOW SHELF GAIN±16 dB

REAR

500 SERIES CONNECTOR

Interior view of an electronic device showing internal components and a blue connector with red connectors (no text or symbols visible)

1

SLOT CONNECTOR Gold Plated

500 SERIES EDGE CONNECTOR PIN OUT

TERMINAL	FUNCTION
1	CHASSIS GROUND
2	OUTPUT + (4 LEVEL)
3	NOT USED
4	OUTPUT - (4 LEVEL)
5	COMMON
6	NOT USED
7	NOT USED
8	INPUT - (4 LEVEL)
9	NOT USED
10	INPUT + (4 LEVEL)
11	NOT USED
12	+16VCD
13	GND
14	-16VCD
15	NOT USED

graph TD
    A["CONDenser MIC"] -->|ACTIVATE +48V FOR CONDENSER MIC| B["HERITAGE AUDIO"]
    B --> C["OUTPUT 2"]
    C --> D["LINE INPUT - AUDIO INTERFACE"]
    D --> E["USB - COMPUTER"]
    E --> F["OUTPUT 1"]
    F --> G["Line INPUT - Audio Interface"]
    G --> H["ACTIVATE LINK SWITCH (SLOT 1)"]
    H --> I["OUTPUT 2"]
    I --> J["Line INPUT - Audio Interface"]
    J --> K["73 EQ JR SLOT 2"]
    J --> L["73 JR II SLOT 1"]
    K --> M["Line INPUT - Audio Interface"]
    L --> N["Line INPUT - Audio Interface"]
    M --> O["OUTPUT 4"]
    N --> P["OUTPUT 3"]
    O --> Q["OUTPUT 2"]
    P --> R["OUTPUT 1"]
    Q --> S["OUTPUT 1"]
    R --> T["OUTPUT 1"]
    S --> U["OUTPUT 1"]
    T --> V["OUTPUT 1"]
    U --> W["OUTPUT 1"]
    V --> X["OUTPUT 1"]
    W --> Y["OUTPUT 1"]
    X --> Z["OUTPUT 1"]
    Y --> AA["OUTPUT 1"]
    Z --> AB["OUTPUT 1"]

graph TD
    A["INSERT SETUP"] --> B["Recommended setup to insert EQ processing on individual tracks."]
    B --> C["Line OUTPUTS"]
    B --> D["Line INPUTS"]
    C --> E["MONITOR SPEAKERS"]
    D --> E
    E --> F["THUNDERBOLT COMPUTER"]
    G["OUTPUT 4 V 2.0"] --> H["Output 3"]
    G --> I["Output 2"]
    G --> J["Output 1"]
    H --> K["Output 4"]
    I --> L["Output 3"]
    J --> M["Output 2"]
    K --> N["Output 1"]
    L --> N
    M --> N
    N --> O["Output 4"]
    style A fill:#f9f,stroke:#333
    style G fill:#bbf,stroke:#333
    style B fill:#fff,stroke:#333
    style C fill:#fff,stroke:#333
    style D fill:#fff,stroke:#333
    style E fill:#fff,stroke:#333
    style F fill:#fff,stroke:#333
    style G fill:#fff,stroke:#333
    style H fill:#fff,stroke:#333
    style I fill:#fff,stroke:#333
    style J fill:#fff,stroke:#333
    style K fill:#fff,stroke:#333
    style L fill:#fff,stroke:#333
    style M fill:#fff,stroke:#333
    style N fill:#fff,stroke:#333

• Input impedance: 10 kΩ bridging, transformer balanced and floating.
• Output impedance: Less than 75 Ω, transformer balanced and floating, to drive a load of 600 Ω load.
  • Maximum output: Greater than +26 dBu into 600 Ω.
  • THD: Less than 0,025 % at 1 kHz, Less than 0,05 % at 100 Hz.
  • Maximum Gain: 6 dB.
  • Power consumption: Less than 85 mA per rail @ ±16 V DC.
• Dimensions (W x H x L): 38 mm x 135 mm x 150 mm.

SIGNAL FLOW

graph LR
    A["LINE INPUT"] --> B["CARNHILL TRANSFORMERS"]
    B --> C["INPUT AMP"]
    C --> D["EQUALIZER"]
    D --> E["OUTPUT AMP"]
    E --> F["LINE OUTPUT"]
    G["Heritage Audio"] --> F

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Illustration of a glowing incandescent light bulb with a white H-shaped symbol on its side (no text or labels)

PROBLEMS	SOLUTIONS
There doesn’t appear to be any tonal change at all from the 73 EQ JR.	Make sure the GAIN knob is not in the ‘Off’ position.
There still doesn’t appear to be any tonal change at a from the 73 EQ JR.	Check to see if the EQL button has been pushed to activate it.
Even at the lowest position on the LINE GAIN knob I still have too much gain.	You will have to reduce the signal level being sent to the 73 EQ JR.
There seems to be a very high output from the unit.	Adjust the LINE GAIN knob to compensate for any ton adjustments made that raise the signal too much.
There seems to be a very low output from the unit.	Adjust the LINE GAIN knob to compensate for any ton adjustments made that lower the signal too much.

* For any further doubts or questions please get in contact with us at: [e-mail]

LIMITED 2 YEAR WARRANTY

Heritage Audio 73 EQ JR is warranted by Heritage Audio SL to be free from defects in materials and workmanship for the period of 2 years to the original purchaser. In the event of such defects, the product will be repaired without charge or, at our option, replaced with a new one if delivered to Heritage Audio prepaid, together with a copy of the sales slip or other proof of purchase date. The warranty excludes problems due to normal wear, abuse, shipping damage or failure to use the product in accordance with the specifications.

Heritage Audio shall not be liable for damages based upon inconvenience, loss of use of the product, loss of time, interrupted operation or commercial loss or any other damages, whether incidental, consequential or otherwise.

This warranty is not transferable.

Interior view of a vintage audio workstation with multiple tuning knobs and a 73EQ JR audio jack (no visible text or symbols on the main subject)

REGISTRATION

Please visit our website: https://heritageaudio.com/registration/

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www.heritageaudio.com

HERITAGE AUDIO. C/ Alfonso Gómez, 38, 3C. 28037 Madrid – Spain. Tel: [phone]

[e-mail]