6673 - Uncategorized Heritage Audio - Free user manual and instructions

Product Type	80 Series Microphone Preamplifier and Equalizer Module
Dimensions (W x H x D)	45 mm x 224 mm x 304 mm (Standard Series 80 Module)
Power Consumption	< 110 mA @ 24V DC (supplied by 80 Series chassis)
Mic Preamp Gain	20 dB to 80 dB in 5 dB steps (Class A)
Line Amplifier Gain	-20 dB to +10 dB (Class A)
Equalizer Type	4-Band: Baxandall High Shelf, Two Peak Mids, Baxandall Low Shelf
High Shelf Frequencies	10 kHz, 12 kHz, 16 kHz
High Mid Peak Frequencies	10 selectable frequencies + OFF
Low Mid Peak Frequencies	10 selectable frequencies + OFF
Low Shelf Frequencies	35 Hz, 60 Hz, 110 Hz, 220 Hz
High Pass Filter	50 Hz, 80 Hz, or 300 Hz (both buttons pressed)
Phase	180° Flip
Phantom Power	+48V (supplied by chassis)
Input Impedance	1200 Ω or 300 Ω (switchable on rear)
Maximum Output	> +26 dBu into 600 Ω
Total Harmonic Distortion	< 0.025% at 1 kHz, < 0.05% at 100 Hz
Frequency Response	20 Hz (+0.3 dB) to 20 kHz (-0.2 dB)
Noise	< -100 dBu
Transformers	Carnhill input and output (hand-wound, Oxford)
Construction	Handmade in Madrid, Spain; hand-wired on 5 plug-in cards
Warranty	Limited 2 years (original purchaser)

Frequently Asked Questions - 6673 Heritage Audio

How do I activate the 300 Hz high-pass filter?

Press both the 50 Hz and 80 Hz high-pass filter buttons simultaneously. This engages a 300 Hz low-cut filter.

Can I use the 6673 with a guitar or bass directly?

Yes, if you have the RACK 2 enclosure, it provides two DI inputs on the front panel. For other enclosures, use an external DI box ahead of the module.

How do I change the input impedance?

The impedance switch is on the rear of the module. You need to pull the module out of the enclosure to access it. It switches between 1200 Ω and 300 Ω.

Why is there no signal from the 6673?

Check that the GAIN knob is not in an OFF position (between steps), and ensure the OUTPUT knob on your rack enclosure (e.g., RACK 2 or FRAME 8) is turned up.

Does the 6673 provide phantom power?

The 6673 does not generate phantom power itself, but it passes +48V from the 80 Series chassis to the microphone input when the chassis phantom power is activated.

Can I use only the high shelf EQ without the other bands?

Yes. Set the mid peak and low shelf bands to the OFF position, and they will be removed from the signal path, leaving only the high shelf active.

What is the maximum gain of the mic preamp?

The mic preamp provides up to 80 dB of gain, adjustable in 5 dB steps from 20 dB to 80 dB.

What type of transformers does the 6673 use?

The 6673 uses custom Carnhill input and output transformers, hand-wound at the Oxford factory exclusively for Heritage Audio, housed in vintage-correct green metal cases.

How do I reset the unit if it malfunctions?

Ensure proper power and connections. If issues persist, contact Heritage Audio support at [e-mail]. Do not attempt internal repairs; the unit has no user-serviceable parts.

What is the warranty period for the 6673?

The Heritage Audio 6673 is covered by a limited 2-year warranty for the original purchaser against defects in materials and workmanship. Proof of purchase is required.

USER MANUAL 6673 Heritage Audio

Thank you for choosing the 6673 Module. 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

© 2023 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

A great 80 Series tool for the ultimate control

Leverage your 80 Series's investment with the Heritage Audio 6673.

The 6673 module is a Heritage Audio unique design, which has been engineered to fill input module slots in the restoration process of vintage 80 Series sound mixing consoles. It is also compatible with the Heritage Audio FRAME 8 and RACK 2 powered enclosures, and with any other rack, console or enclosure that follows the same mechanical and electrical protocol.

The 6673 offers what the vintage modules do plus much, much more

The 6673 has a Class A Mic preamp with 80 dB of gain to make sure you're never lacking for more. This gives you more than enough even for demanding ribbon mics and older dynamic mics, which are often low output. With the 6673 your mic collection has never sounded better.

There is also a Class A line-level amplifier with 10 dB of additional gain as well as -20 dB for when you need to reduce a very high signal coming into the unit before EQing it. Both the Mic preamp and the Line amplifier have their own separate exclusive Carnhill transformers to guarantee solid, professional results.

The 6673 is a 73-sized module, adding the 1066 mid bands to the 73 classic design, creating an equalizer that is really hard to beat. It features a Baxandall type high shelf band, but with the addition of a high frequency selector switch offering 3 different frequencies instead of the fixed one at 12 kHz. There are also two Mid peak bands (Hi & Low) with 10 selectable frequencies to choose from each in addition to the OFF position that removes the filter from the signal path. Then you have a Low Shelf band, also of the Baxandall type, with 4 selectable frequencies available for some incredible low end shaping. The result is a 4-band tone monster that combines the best features of the vintage modules in a smart and tasteful way, at a price lower than most current offerings. And not to be overlooked, the 6673 has a Class A High Pass Filter with 3 frequencies to choose from to make you can clean up the very low end allowing more room to achieve the sound you want.

Vintage connoisseurs and plug-in users already know how cool the 1066 mid bands are for sculpting sounds in a musical way. This level of flexibility has never been present in a 73 style module and will certainly make finding that elusive sound much easier.

Using the right components is necessary to achieve desired sound

Special care has been taken in sourcing the correct components that not only ensure that performance will be as close to a 1970's unit as possible, but also gives your top-class studio the look and feel it deserves to help enhance the overall experience.

Custom polystyrene and film capacitors have been developed to closely match the Siemens styroflex and Mullard Mustard types of the late 60s and early 70s. This attention to detail is reflected in the unit's performance and is appreciated by the end user.

Carnhill input transformers are hand wound at its Oxford factory exclusively for Heritage Audio, enclosed in vintage correct green metal cases for the ultimate in detail nailing. The vintage character is indeed guaranteed and you won't find them in any other brand's products.

A solid, thick output is guaranteed with the use of another Carnhill transformer on the fully balanced output. The RACK 2 and FRAME 8 contain output pots to control the exact level required.

The Heritage Audio 6673 is entirely handmade and hand wired by our most experienced technicians in our facilities in Madrid, Spain, employing the same wiring and soldering techniques of the 70s. All its circuitry is conveniently held on 5 plug-in cards.

Interior view of an electronic control panel with exposed wiring, capacitors, and modules (no visible text or labels)

FRONT

1	2	3	4	5
INPUT GAIN SWITCH5 dB Steps From 20 to 80 dB in MIC mode and -20 dB to 10 dB in LINE mode	HIGH SHELF BOOST/CUT+/- 15 dB at Selected Frequency	HIGH SHELF FREQUENCY10, 12 and 16 kHz Options	HIGH MID BOOST/CUT+/- 15 dB at Selected Frequency	HiGH MID PEAK FREQUENCYMid Band Frequency Selection
6	7	8	9	10
LOW MID BOOST/CUT+/- 15 dB at Selected Frequency	LOW MID PEAK FREQUENCYLow Band Frequency Selection	BASS SHELF BOOST/CUT+/- 15 dB at Selected Frequency	BASS SHELF FREQUENCY220, 110, 60 and 35 Hz	HIGH PASS FILTER50 Hz
11	12	13	14	15
HIGH PASS FILTER80 Hz	HIGH PASS FILTERPressing both buttons gives a 300 Hz cut	EQLTurns Equalizer On	PHASEFlips phase 180°	FASTENING SCREWTo secure 80 Series module in enclosure

graph TD
    A["REAR"] --> B["1 MIC INPUT IMPEDANCE 1200 Ω or 300 Ω when pressed"]
    A --> C["80 SERIES EDGE CONNECTOR PIN OUT"]
    B --> D["1: To Pin V, Hi: Mic I/P, Lo: -20 dBu"]
    B --> E["2: 0V, Hi: Line I/P, Lo: 0 dBu"]
    B --> F["3: 0V, Hi: Line I/P, Lo: 0 dBu"]
    B --> G["4: 0V, Hi: Line I/P, Lo: 0 dBu"]
    B --> H["5: 0V, Hi: Line I/P, Lo: 0 dBu"]
    B --> I["6: 0V, Hi: Line I/P, Lo: 0 dBu"]
    B --> J["7: 0V, Hi: Line I/P, Lo: 0 dBu"]
    B --> K["8: 0V, Hi: Line I/P, Lo: 0 dBu"]
    B --> L["9: 0V, LiNK"]
    B --> M["10: 0V, LiNK"]
    B --> N["11: 0V, LiNK"]
    B --> O["12: 0V, LiNK"]
    B --> P["13: Unbalanced O/P, Hi: BAL O/P, Lo: +24 V at 106 mA"]
    B --> Q["14: Unbalanced O/P, Hi: BAL O/P, Lo: +24 V at 106 mA"]
    B --> R["15: Unbalanced O/P, Hi: BAL O/P, Lo: +24 V at 106 mA"]
    B --> S["16: Unbalanced O/P, Hi: BAL O/P, Lo: +24 V at 106 mA"]
    B --> T["17: Unbalanced O/P, Hi: BAL O/P, Lo: +24 V at 106 mA"]
    B --> U["18: Unbalanced O/P, Hi: BAL O/P, Lo: +24 V at 106 mA"]

graph TD
    A["CONDENSER MIC - L"] -->|Rack 2 Not included| B["RACK 3"]
    B --> C["ACTIVATE +48V FOR CONDENSER"]
    C --> D["MIC INPUT 1"]
    D --> E["OUTPUT -1"]
    E --> F["LINE INPUTS - AUDIO INTERFACE"]
    F --> G["USB - COMPUTER"]
    G --> H["Line Inputs - Audio Interface"]
    H --> I["OUTPUT -2"]
    I --> J["MIC INPUT 2"]
    J --> K["OUTPUT 1"]
    K --> L["LINE INPUTS - Audio Interface"]
    L --> M["CONDENSER MIC - R"]
    M --> N["CONDENSER MIC - L"]

graph TD
    A["Guitar FX PEDAL"] -->|D.I. INPUT 2| B["Heritage Audio RACK 2"]
    B -->|D.I. INPUT 1| C["Rack 2 Not included"]
    C --> D["Line Inputs - AUDIO INTERFACE"]
    D -->|OUTPUT - 1| E["Output - 2"]
    E --> F["USB - COMPUTER"]
    F --> G["Line Inputs - AUDIO INTERFACE"]
    G --> H["Line Inputs - LINE DATA"]
    H --> I["Output - 1"]
    I --> J["Line Inputs - LINE DATA"]
    J --> K["Output - 2"]
    K --> L["Line Inputs - LINE DATA"]
    L --> M["Output - 1"]
    M --> N["Line Inputs - LINE DATA"]
    N --> O["Output - 2"]
    O --> P["Line Inputs - Line DATA"]
    P --> Q["Output - 1"]
    Q --> R["Line Inputs - Line DATA"]
    R --> S["Output - 2"]
    S --> T["Line Inputs - Line DATA"]
    T --> U["Output - 1"]
    U --> V["Line Inputs - Line DATA"]
    V --> W["Output - 2"]
    W --> X["Line Inputs - Line DATA"]
    X --> Y["Output - 1"]
    Y --> Z["Line Inputs - Line DATA"]
    Z --> AA["Output - 2"]
    AA --> AB["Line Inputs - Line DATA"]
    AB --> AC["Output - 1"]
    AC --> AD["Line Inputs - Line DATA"]
    AD --> AE["Output - 2"]
    AE --> AF["Line Inputs - Line DATA"]
    AF --> AG["Output - 1"]
    AG --> AH["Line Inputs - Line DATA"]
    AH --> AI["Output - 2"]
    AI --> AJ["Line Inputs - Line DATA"]
    AJ --> AK["Output - 1"]
    AK --> AL["Line Inputs - Line DATA"]
    AL --> AM["Output - 2"]
    AM --> AN["Line Inputs - Line DATA"]
    AN --> AO["Output - 1"]
    AO --> AP["Line Inputs - Line DATA"]
    AP --> AQ["Output - 2"]
    AQ --> AR["Line Inputs - Line DATA"]
    AR --> AS["Output - 1"]
    AS --> AT["Line Inputs - Line DATA"]
    AT --> AU["Output - 2"]
    AU --> AV["Line Inputs - Line DATA"]
    AV --> AW["Output - 1"]
    AW --> AX["Line Inputs - Line DATA"]
    AX --> AY["Output - 2"]
    AY --> AZ["Line Inputs - Line DATA"]
    AZ --> BA["Output - 1"]
    BA --> BB["Line Inputs - Line DATA"]
    BB --> BC["Output - 2"]
    BC --> BD["Line Inputs - Line DATA"]
    BD --> BE["Output - 1"]
    BE --> BF["Line Inputs - Line DATA"]
    BF --> BG["Output - 2"]
    BG --> BH["Line Inputs - Line DATA"]
    BH --> BI["Output - 1"]
    BI --> BJ["Line Inputs - Line DATA"]
    BJ --> BK["Output - 2"]
    BK --> BL["Line Inputs - Line DATA"]
    BL --> BM["Output - 1"]

graph TD
    A["You need to be in the LINE GAIN section to use the LINE Inputs"] --> B["LINE"]
    B --> C["RACK 2"]
    C --> D["Line INPUT -1"]
    D --> E["Line INPUT -2"]
    E --> F["Line OUTPUTS - KEYBOARD"]
    F --> G["Line INPUT -2"]
    G --> H["Line OUTPUTS - KEYBOARD"]
    H --> I["Line INPUT -2"]
    I --> J["Line INPUT -1"]
    J --> K["Output -1"]
    K --> L["Line INPUTS - AUDIO INTERFACE"]
    L --> M["USB - COMPUTER"]
    M --> N["Line INPUTS - AUDIO INTERFACE"]
    N --> O["Output -2"]
    O --> P["Line INPUTS - AUDIO INTERFACE"]

• Class A mic preamp with 80 dB of gain, plus a sweet-sounding 4-band EQ.
• Class A line-level amplifier with 10 dB of gain.
- Equalizer's mid-bands cover nearly the entire audible frequency range.
- Low and high shelving EQs with Baxandall curves for smooth, natural-sounding response.
• High-pass filter, switchable between 50 Hz, 80 Hz, and 300 Hz.
• +48 V phantom power is supplied by your 80 Series chassis.
• Maximum output: Greater than +26 dBu into 600 Ω.
• THD: Less than 0.025 % at 1 kHz, Less than 0.05 % at 100 Hz.
• Frequency response: 20 Hz (+0.3 dB) to 20 kHz (-0.2 dB).
• Maximum Gain: Slightly greater than 80 dB.
- Noise: Less than -100 dBu.
• Power consumption: Less than 110 mA @ 24V DC.
- Dimensions (W x H x L): 45 mm x 224 mm x 304 mm. (Standard Series 80 Module)

SIGNAL FLOW

graph TD
    A["MIC INPUT"] --> B["LOZ"]
    C["LINE INPUT"] --> D["CARNHILL TRANSFORMER LDC"]
    D --> E["INPUT AMP"]
    E --> F["EQ"]
    F --> G["HPF"]
    G --> H["OUTPUT AMP"]
    H --> I["CARNHILL"]
    I --> J["LINE OUTPUT"]
    K["D.I. Input accessible on the front panel of the RACK 2."] --> L["D.I."]
    M["PHASE"] --> H

Abstract black-and-white graphic of a question mark with a human profile silhouette and a small 'H' symbol below (no text or symbols present)

Illustration of a glowing light bulb with a black circular symbol containing the letter 'H' (no text or labels)

PROBLEMS	SOLUTIONS
I can’t seem to get any signal out of the 6673.	Check to make sure you have not left the GAIN knob in an ‘OFF’ position.
I still can’t seem to get any signal out of the 6673.	Check to make sure you have not left the OUTPUT knob turned all the way down on your rack enclosure.
Is it possible to use a bass or electric guitar with the 6673.	It certainly is. There are two convenient DI inputs on the RACK 2 enclosure and with the FRAME 8 or any other setups you could simply use a DI box ahead of the 6673.
How do I activate the 300 Hz low cut filter?	You must push both of the buttons, the 50 Hz and 80 Hz buttons to access the 300 Hz cut.
I can’t figure out how to change the impedance.	There is a switch on the backside of the module. It does require pulling the module out of the RACK 2 or SESSION 8 to access the switch. It switches between 1200 ohm and 300 Ω.
Can I simply use the Hi Shelf on the EQ without using the other bands?	Yes, of course. You simply leave the other bands in the ‘OFF’ position and they will not be in the signal path.

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

LIMITED 2 YEAR WARRANTY

Heritage Audio 6673 Module 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.

Heritage Audio and the Heritage Audio "H" logos are registered Trademarks owned and/or licensed by Heritage Audio.

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]