Heritage Audio Herchild 660 User manual
INTRODUCTION
CONTENTS
DESCRIPTION
GETTING STARTED
DC THRESHOLD SETTINGS
TIME CONSTANT SETTINGS
APPLICATIONS!
SPECIFICATIONS!
SIGNAL FLOW
TROUBLE SHOOTING
REGISTRATION
WARRANTY STATEMENT!
RECALL SHEETS
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TABLE OF CONTENTS
Thank you for choosing the HERCHILD Model 660. 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
INTRODUCTION
© 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.
HERCHILD 660
AC POWER CORD EU & US
2
DESCRIPTION
The HERCHILD Model 660 is our newest release and one of the products we are proudest of. A tube-based audio
compressor with a striking resemblance to one of the most famous compressors of all time, the Fairchild 660.After years of
research, development and new designs we are finally ready to release this beast to the public. While making sure to
capture all the lush sound and mystique of the original we were able to improve on several aspects and offer a more
reliable, more durable, modern version that will last you for decades to come.
The HERCHILD Model 660 contains nothing less that 11 valves and 5 transformers to achieve that indistinguishable,
classic, triumphant sound that we all know and love. The original intention of the his historical compressor was to be used
in the cutting of lacquer masters for vinyl albums, but it soon became an industry standard for getting that all enveloping
sound that takes us to another level.
The Fairchild 660 is found on almost all of the classic releases in the 60´s and 70´s, defining the sound of a generation…or
two.
The grandaddy of all tube-based compressors had a relatively limited amount produced, somewhere between 500 and
1,000 units.Therefore, some 60 years later there are only a small amount that remain today. There are even fewer that are
totally usable as years have gone by since it´s late 1950´s introduction so many units aren´t exactly as they once
were.Maintenance is obligatory on a high-end piece like this and unfortunately, too many of them have simply been
neglected and aren´t up to their optimal specifications. This means an alternative is needed.And this is where the
HERCHILD Model 660 comes in, to once again offer that magic that only this compressor design can.
Our HERCHILD Model 660 offers a couple of new and ever so helpful features. The user now has immediate access to the
all important DC THRESHOLD.This control basically combines adjustments to the progressively developing curved RATIO
and the KNEE simultaneously through 4 different settings varying from a gentle slope to a more pronounced and
aggressive slope.This control really does put sound manipulation right at your finger tips as opposed to the original´s out of
reach and inconvenient screw adjuster. The other main addition is something no modern day studio can be without, a side
chain filter.With the SC FILTER on the HERCHILD Model 660 you have 4 different frequencies to choose from: 50, 100,
200 and 350Hz.Using this feature you now have lots more control over just how much compression will be applied as you
can make it less sensitive to the lower frequencies therefore allowing more compression where you need it and for the track
to stay powerful.
3
GETTING STARTED
4
FRONT
1
2
3
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12
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4
5
9
11
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1-METER ADJUSTMENT SCREW: This is not meant to be user adjustable. We recommend not adjusting this and to
contact an official repair service.
2-RED JEWEL INDICATOR LIGHT: Simply indicates that the equipment is ´On´.
3-POWER SWITCH: Turns the unit on or off.
4-ZERO ADJUSTMENT SCREW: Use this screw to set the meters to 0dB on the VU meter when there is no
compression happening. It is normal for this setting to drift for the first 30 minutes of operation.
5-BALANCE ADJUSTMENT SCREW: Use this screw to balance the circuit for optimum performance based on the
particular set of tubes installed.
6-VU METER: Indicates GAIN REDUCTION.
7-METERING: Knob to choose the readout of the VU meter, either for adjusting the balance of the valves or the gain
reduction being applied.
8- INPUT GAIN CONTROL: This knob is used to control the amount of input gain applied. This is actually an
attenuator that reduces the the input by up to -20dB.
9- AC THRESHOLD: The threshold knob determines when the compression begins. It’s used to decide when and
how much gain reduction takes place. When in the fully counter-clockwise position, the HERCHILD Model 660 will not
compress at all. As the threshold control is turned clockwise, the amount of compression will progressively increase.
10- DC THRESHOLD: Here you decide what kind of curve will be applied to the compression. It is similar to a knee
and ratio effect combined. So at the most counter-clockwise position the HERCHILD Model 660 responds like a
limiter with immediate and aggressive action happening as soon as the AC THRESHOLD is passed. While as you
turn it clockwise more of gradual, progressive effect occurs until you have a very slight compression happening at all
times.
11-TIME CONST: Here you have 6 options for the attack and release timings giving you combinations for fast and
slow timings. (Please see the TIME CONSTANT Section for exact timings.)
12-SC FILTER: This is a side chain filter applied only to the control signal to decide if and where the HERCHILD
Model 660 will be less sensitive to certain frequencies. There are 5 choices available: 50, 100, 200, 350Hz and OFF.
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REAR
1
2
4
3
5
1-LINE INPUT: Female Gold Plated XLR Connector.
2-LINE OUTPUT: Male Gold Plated XLR Connector.
3-VALVES: (11) User changeable valves with easy access.
4-POWER INPUT: IEC standard power input connector.
5-VOLTAGE SELECTOR: Here you can select the correct voltage input according to the country you are in.
All XLRs are:
Pin 1: GND!
Pin 2: Hot!
Pin 3: Cold
1
2
3
3
2
1
GND!
Hot (+)!
Cold (-)
MALE XLR
FEMALE XLR
DC THRESHOLD
SETTINGS
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MEDIUM KNEE & PROGRESSIVE
HIGHER RATIO
.3 Seconds for individual peaks
10 Seconds for multiple peaks
25 Seconds for consistently high program level
RELEASE
.2 ms
.2 ms
.4 ms
.4 ms
.4 ms
.2 ms
2 Seconds for individual peaks
10 Seconds for multiple peaks
5 Seconds
2 Seconds
.8 Seconds
.3 Seconds
ATTACK
1
2
3
4
5
6
TIME CONSTANT
SETTINGS
MEDIUM KNEE & PROGRESSIVE
LOWER RATIO
HARD KNEE
HIGH RATIO (LIMITING)
SOFT KNEE & VERY PROGRESSIVE
MEDIUM RATIO
The HERCHILD
Model 660, just like
the original, uses a
progressively
developing ratio
curve so it is not
possible to describe
the ratio as 2:1, 10:1
or anything so exact.
VOICE
TRACK INSERT
APPLICATIONS
BASS
RECORDING
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MONITOR
SPEAKERS
THUNDERBOLT
COMPUTER
OUTPUT
AUDIO INTERFACE
LINE INPUT
AUDIO INTERFACE
MONITOR
SPEAKERS
THUNDERBOLT
COMPUTER
LINE INPUT
AUDIO INTERFACE
D.I. INPUT
PREAMP TT-73
OUTPUT
PREAMP TT-73
SPECIFICATIONS
•Input Impedance: 2K Ω
•Output Impedance: 600 Ω
•Output Level: +4 or +8 VU (+30dBu clipping point)
•Frequency Response: 40Hz to 15kHz +/- 1db
•Self Noise: Less than -82dBu
•Harmonic Distortion: Less than 1% at any level up to +18dBu output (no limiting)
• Dimensions (W x H x L): 482mm x 134mm (3 Rack units) x 200mm
•Weight: 7.365 Kg
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SIGNAL FLOW
LINE INPUT
LINE OUTPUT
CLASS A !
VALVE AMPLIFIER
INPUT
TRANSFORMER
OUTPUT
TRANSFORMER
TROUBLE SHOOTING
PROBLEMS
SOLUTIONS
There is almost no sound coming from the HERCHILD
Model 660.
Make sure you have raised the INPUT GAIN to a sufficient
level.
There doesn´t seem to be any compression taking place.
Make sure you have adjusted the AC THRESHOLD level
to a reasonable setting.
I´m getting way too much compression for what I need.
Try lowering the AC THRESHOLD.
I´m still getting way too much compression for what I
need.
Try adjusting the SC FILTER to make the HERCHILD
Model 660 less sensitive to the lower frequencies.
The HERCHILD Model 660 does not seem to be reacting
as it should.
Have you allowed the recommend 30 minutes for the unit
to warm up?
The readings on the VU meter don´t seem to correspond
with what is actually happening.
Sounds like it´s time for some calibrating.
The compression I am getting is altogether too aggressive
for what I am looking for.
Try a different setting on the DC THRESHOLD to alter the
Ratio/Knee.
The compression I am getting is still altogether too
aggressive for what I am looking for.
Try a different setting on the TIME CONST selector to
ease the attack and release controls. (See Time Constant
Settings for exact timings).
The compressor seems to be heating up excessively.
Have you installed a blank rack panel above and below
the unit to assure proper ventilation?
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LIMITED 2 YEAR WARRANTY
Heritage Audio HERCHILD Model 660 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
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Please visit our website:
WARRANTY STATEMENT
https://heritageaudio.net/registration/
RECALL SHEETS
11
Session / Title: Track: Connected Equipment: !
Date: Instrument: Notes:
Session / Title: Track: Connected Equipment: !
Date: Instrument: Notes:
www.heritageaudio.com
HERITAGE AUDIO. C/ Alfonso Gómez, 38, 3C. 28037 Madrid – Spain. Tel: +34 917 266 189
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