zesto Andros 1.2 User manual

Zesto Audio 2016 Page #1
Andros 1.2
Vacuum Tube Phonostage Preamplifier
Owner’s Manual
Please read carefully before
installing and operating this equipment
Zesto Audio
3138 Calle Estepa
Thousand Oa s, California 91360
805-807-1840
www.zestoaudio.com
[e-mail]
Made in the U A
Using U and Imported Parts

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Dear Music Lover,
I wanted to personally than you for your purchase of my Andros 1.2 Phonostage.
I have loved music all my life – as a musician, record producer and audio engineer. That ma es me fussy about sound.
That’s a good thing.
Each unit is built by hand with precision and pride to produce the most enjoyable listening experience for you.
I am proud to put my name on it and honored to share this with you.
Wishing you many happy years of listening!
Sincerely,
-- George Counnas, President of Zesto Audio
FYI:
Zesto is Gree for hot
Andros is a Gree island and the home of my grandmother’s family.
Table of Contents
Thank You …………………………………….. Page 2
Table of Contents……………………………… Page 2
What’s in the box……………………………… Page 2
Warning and Caution…………………………. Page 3 & 4
Parts and Controls……………………………. Page 5
pecifications ……………………………..…. Page 6
Tube Layout………………………………….. Page 7
Hookup, ettings and Adjustments……….. Page 7 & 8
Tips and Tricks ………………………………. Page 8 - 10
Warranty Information……………………….. Page 11
What’s in the box?
Andros 1.2 Phonostage
4 Vacuum Tubes
White glove for handling tubes
IEC power cable 6’
Optional ground wire for turntable
Not Included: Interconnect cables

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Warning and Caution
WARNING: The triangle with the lightning flash symbol displayed on the unit advises the user of dangerous uninsulated
voltage inside the product’s enclosure.
CAUTION: To reduce the ris of electric shoc , do not remove the cover. There are no user-serviceable parts inside; it is
recommended that only qualified personnel service this component.
1. OWNER’ MANUAL: Before powering up the equipment, read all safety and operating instructions and follow them as
instructed. Retain the safety and operating instructions for future reference.
2. ATTACHMENT : Use only those attachments recommended by the unit manufacturer, as others may cause hazards.
3. ACCE ORIE : Do not place the unit on an unstable cart, stand, tripod, brac et, or table. The unit may fall, causing
injury to a person or damage to the unit. Mount the unit according to the manufacturer’s instructions with the
suggested mounting accessory.
4. WALL OR CEILING MOUNTING: Do not mount the unit on a wall or ceiling.
5. WATER AND MOI TURE: Do not use the unit near water (for example, near a swimming pool, bath tub, wash bowl,
itchen sin , or laundry tub) or in a damp environment (li e a basement or outside in the rain).
6. OBJECT AND LIQUID ENTRY: Do not push objects of any ind into the unit through openings as they could touch
dangerous voltage points and short-out parts, possibly resulting in a fire or electric shoc . Do not spill liquid of any
ind on the unit. If water or any metal object (such as a paper clip, coin, or staple) accidentally falls inside the unit,
disconnect it from the AC power source immediately and contact Zesto Audio for further instructions.
7. HEAT: Position the unit away from heat sources such as radiators, heat registers, stoves, or other units (including
amplifiers) that produce heat.
8. VENTILATION: Slots and openings in the enclosure create ventilation to protect the component from overheating. All of
these openings must remain unobstructed. Allow at least six inches of clearance above the unit, 0.5 inch below and
an opening behind the unit for airflow. Do not place the unit on a bed, sofa, rug, built-in boo case, or rac without
adequate ventilation.
9. GROUNDING OR POLARIZATION: As a safety feature, the unit may be equipped with a polarized alternating current
line plug in which one blade is wider than the other and has an additional grounding blade. This plug will fit into the
power outlet only one way. If you cannot insert the plug fully into the outlet, try reversing the plug. If the plug still will
not fit, contact a licensed electrician to update your outlet. Do not defeat the safety purpose of the polarized plug.
10. POWER OURCE : Operate the unit only from the power source indicated on the mar ing label on the bac of the
unit. If you are unsure of the type of power supplied to your home, consult your unit dealer or local power company.
11. POWER CORD PROTECTION: Arrange power supply cords so that they do not suffer from foot traffic or pinching by
items placed on or against them. Pay close attention to cords where plugs enter the AC outlet and where they exit
from the unit.
12. LIGHTNING: For added protection during a lightning storm or when the component is idle for long periods of time,
unplug the unit from the wall outlet. This will help protect the unit from lightning and power line surge damage.

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13. POWER LINE : Do not locate an outside antenna system in the vicinity of overhead power lines or other electric light
or power circuits. When installing an outside antenna system, ta e extreme care to avoid touching the power lines or
circuits; contact with them could be fatal.
14. OVERLOADING: Do not overload wall outlets, extension cords, or integral convenience receptacles as this increases
the ris of fire or electric shoc .
15. REPLACEMENT PART : When replacement parts are required, be sure the service technician has used
replacement parts specified by the manufacturer or those having the same characteristics as the original parts.
Unauthorized substitutions may result in fire, electric shoc or other hazards.
16. AFETY CHECK: Upon completion of any service or repairs to the unit, as the service technician to perform safety
chec s to ensure the unit is in proper operating condition.
17. IMPORTANT AFETY NOTE:
• Before connecting a new product such as the Andros 1.2 Phonostage to your audio or home theater system, turn off
all other equipment (preferably unplugging them from the AC power source). Many audio components feature
automatic turn-on circuits that may activate during an installation, potentially causing damage to electronic
components or spea ers. This type of damage is not covered by product warranties, and Zesto Audio specifically
disclaims responsibility for any such damage.
• Power Cord: The removable IEC power cord provided with your unit was specifically designed for use with this
product, but other AC cords may be used. Consult your dealer for advice on AC power cords and high quality wire
in your system.
• AC Fuse: The fuse is located inside the IEC power entry connector. If the unit does not power up, contact an
authorized service representative.
• Wiring: Cables running inside walls should have the appropriate mar ings to indicate compliance and listing by the
UL, CSA or other standards required by the UL, CSA, NEC, or your local building code. Questions about cables
inside of walls should be directed to a qualified custom installer, licensed electrician, or low-voltage contractor.
18. RECORDING COPYRIGHT: Recording of copyrighted material for other than personal use is illegal without
permission of the copyright holder.
19. FCC INFORMATION FOR U ER:
• CAUTION: Any changes or modifications not expressly approved by Zesto Audio could void the user's authority to
operate the equipment.
• These limits are designed to provide reasonable protection against harmful interference in a residential installation.
This equipment generates and can radiate radio frequency energy, and if not installed and used in accordance
with the instructions it may cause harmful interference to radio communications. However, there is no guarantee
that interference will not occur in a particular installation. If this equipment does cause harmful interference to
radio or television reception, which can be determined by turning the equipment off and on, the user is
encouraged to try to correct the interference by one or more of the following measures:
• Reorient or relocate the equipment.
• Increase the separation between the equipment and receiver.
• Connect the equipment into an outlet on a circuit different from where the receiver is connected.

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Rear Panel Inputs and Controls
Power ON/OFF switch …………………………………………… Turns the unit ON/OFF (located on side panel).
IEC Power entry connector …………………………………………… 110/120V or 220/230/240V AC power input.
Ground binding post/banana soc et …………………………………. The main ground point for turntable.
RCA Output (Left and Right) …………………………………………. The main output going to your system.
RCA Moving Magnet (MM) Input (Left and Right) …………………… A possible turntable input.
RCA Moving Coil (MC) Input (Left and Right) ……………………….. A possible turntable input.
XLR3 Balanced MC Input (Left and Right) …………………………… A possible turntable input.
MM/MC selection switch (Left and Right) …………………………….. Selects between the MM/MC inputs.
MC High/Low Output switch (Left and Right) ………………………… Selects the gain for MC cartridges.
Ground ON/OFF switch (Left and Right) ……………………………… Connects or disconnects the ground to
the MC input.
MC Load rotary switch (Left and Right) ……………………………… Correctly tunes your MC cartridge.
MM Load switch (Left and Right) ……………………………………… Correctly tunes your MM cartridge.

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pecifications
Inputs per channel
• Separate MM and MC inputs
• MM/MC switch
• MM impedance switch 47K or 15K Ohms
• MM capacitance 200pf
• MC Single Ended RCA with isolated ground or transformer Balanced XLR3F
• MC ground on/off switch
• MC load impedance adjustable 1000, 800, 600, 500, 400, 300, 200, 100, 50, 20 Ohms
• MC Internal step up transformers
• MC High/Low switch with ~ – 3dB gain for high output MC
cartridges
Outputs per channel
• Impedance 10K ohms
• +6V max output level
Power
• Ground binding post
• Power consumption 27W , 0 drain when off
• Voltage 110/120V AC 60Hz
(optional factory installed 220V or 230/240V AC 50/60Hz)
• Standard 3 pin IEC power connector
• ON/OFF power switch conveniently located on the front side
• Two internal high quality linear regulated power supplies
250V and 12V
Active Components
• Four (4) Gold pin ECC83S vacuum tubes
• High quality Gold pin ceramic soc ets
Detailed pecifications
• Gain MM input 47dB
• Gain MC input 67dB
• Noise -75dBu below max output
• Frequency response complies to RIAA curve within +or- 0.5 dB
• RIAA curve is achieved using a passive filter
• 1% metal film resisters throughout
• Polypropylene capacitors throughout the audio path
Other Features
• Each unit is made by hand
• 50 hour factory burn in on all circuits and vacuum tubes
• Dimensions 17" W X 12" D X 5" H
• Weight 20 lbs.

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Hookup, ettings and Adjustments
Before you start you will need:
1. RCA Interconnect cables to your system
2. Turntable cables, RCA or XLR
3. Manufacturer specs on your Phono cartridge
• Is your cartridge MM or MC?
• Is your MC cartridge high or low output?
• What is the recommended Ohms load for MC cartridge?
Proper Care of your Vacuum Tube Phonostage
Very Important Read First
The simple rule to remember is “Turn on first, Turn off last”.
It is customary for vacuum tube equipment, as it is first turned on, while the unit is powering up, to have a brief initial
“hum” coming from the unit, not from the spea ers.
It is very important that all of your audio equipment is turned off or unplugged from the main power before attempting to
install this unit.
It is recommended that during normal operation this unit is turned on first for at least 5 minutes before turning on the rest
of your system to prevent damage to your equipment and to get the best performance from the phonostage.
You should also turn off your power amplifiers before ma ing any adjustments to the phonostage.
In addition it is also strongly recommended that this unit is turned off last after the rest of your system has been turned
off to prevent damage to your equipment. Remember “Turn on first, Turn off last”.
Not doing so may create a very loud noise that could damage your spea ers or other equipment.

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Hookup, ettings and Adjustments
Burn-in
Li e all high end audio equipment, this Vacuum Tube Phonostage can ta e 100 hours to break in. For circuit testing and
quality assurance, Zesto Audio ships all their Phonostage units with at least 50 hours of burn-in.
Vacuum Tubes
Using the glove provided, unpac and carefully plug in the four vacuum tubes ma ing sure they are firmly pushed in all the
way in their soc ets. They can only go in one way.
Output
Using interconnect cables connect both the left and right color coded RCA outputs to an auxiliary or equivalent input on
your system.
Ground Wire
Attach the Spade Lug to both the Turntable and Phonostage binding post ground. This wire is included.
Input
Before connecting your turntable to the phonostage please determine if your cartridge is MM or MC high output or an MC
Low output. Also what is the recommended loading for your cartridge? This information is usually in the cartridge
documentation or can be found on the manufacturer’s web site.
The left and right signal paths (inputs, switches and outputs) are completely independent of each other. So any
adjustments or connections must be applied to both left and right.
The turn table signal cables attach to the left and right inputs of the phonostage. Either MM-RCA, MC-RCA or MC-XLR.
Cartridge et up
Select MM or MC on the switch.
If using an MC cartridge select the ground ON position to start with.
If using an MC cartridge select Low output on the phonostage to start with.
If using an MM cartridge select either 47K or 15K.
Feet
Your unit is installed with four feet using #8-32 screws.
Power
Carefully plug in the AC power cable to the phonostage first then to your main power.
Turn it on
Caution: Tube electronics should not be turned ON, then OFF, then ON again quic ly. This could blow a fuse or create a
hum. Once the unit is ON, it is safe to wait a minute before switching OFF. If you do get a hum, leave the unit off for 15
minutes.
Turn on the phonostage using the ON/OFF switch located on the front left side. After a short time (about two minutes) the
four tubes should start glowing. The amber glow will be the only visible indication that the unit is turned on.
If the tubes do not light up, turn off the unit at the power switch and unplug the power cord. After waiting a few minutes
unplug each vacuum tube in turn (using the glove provided) and ma e sure that none of the pins are bent. If they are
please contact Zesto Audio for instructions.
Enjoy the music!

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Tips and Tricks
Grounding
• Important! It is necessary to have your Phonostage plugged into a proper three pin electrical grounded outlet.
Grounding is a safety issue as well as a potential source of noise problems.
• Although all the other switches on the bac panel should be in the same position for the left and right channels,
the ground switches wor independently. You can adjust them for the least amount of noise.
• Start with both ground switches up. Then try any combination that sounds good.
• The ground switches are designed to isolate the grounds between the turntable and the phonostage.
• They affect only the input and not the output of the phonostage.
• Ground switches wor independently and are designed to brea ground loops.
• Example: Some tone arms have all their grounds wired together.
• Start with both ground switches up. Then try any combination that sounds good.
• Throw switches independently until you get the lowest noise.
MC Load Adjustments
• The range is 1000 to 20 Ohms in ten steps. Find the setting that sounds best in your system. Don’t go below the
cartridge manufacturer’s recommended settings, but experiment with any setting above. Load settings can be
done while the unit is Turned On so you can hear the difference. Keep the volume low, while carefully ma ing
these adjustments.
• Unli e most Phonostages, the loading on the Andros is different because it loads on the secondary of the step-up
transformer. This method transfers the entire signal from the cartridge to the primary side of the transformer
without any interference from other components li e resistors.
• It is recommended that you adjust the MC loading for the highest amount of dynamic range. Tip: You can adjust
on the “Fly” while the unit is on without clic s or pops, so you can hear what sounds best.
• Loading Example: For the Dynavector XXII MK2, they recommend a 30 Ohm load and I set mine at 300 Ohms.
You can hear when you’ve gone too far, usually in the mid-range.
• You may find a need to adjust the loading as your Cartridge brea s in.
• You may also want to revisit the load settings after any adjustments to your turntable/tone arm.
MM Load Adjustments
• Start with 47K Ohms on the switch then try the 15K Ohms.
High/Low MC etting
• The labeling of the High/Low MC switch was intended to match the specifications of the cartridge.
• Example: For Low MC output cartridges, set the switch to Low MC, High MC cartridges set to high MC.
• Technically this is a high/low gain switch; however it’s labeled to match a High/Low MC cartridge.
• The Low MC switch setting means the unit is set to high gain of 67dB.
• The High MC setting means the unit is set to low gain of 61dB.
• The unit is designed to wor best in the Low MC setting and the majority of the time this setting will sound better.
Even if the cartridge is on the higher output side, I would recommend trying it on the Low MC setting first and if
you hear distortion then switch to the High MC setting.

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Volume
• If the volume is louder on one channel then the other, you may want to try switching the bac tubes around with
the unit Turned Off. Use the white glove provided and switch the bac tubes only left to right, not the front tubes.
Tube Rolling (The port of Audiophile Kings)
• The 12AX7 input tubes closest to the bac /curve are the most sensitive and effective to tube roll.
• Only a 12AX7/ECC83s type will wor and we recommend that it is high gain/ low noise tube.
• The unit is designed around the JJ ECC83s because they are neutral, consistent and are high gain/low noise.
• If your tastes are warmer, you may want to try Mullard’s and if you li e it brighter try GE.
• We cannot recommend any specific NOS tubes, as no 2 are the same. We prefer to encourage personal taste,
trusting your ears and enjoying the sport.
• Any damage caused by tube rolling will not be covered under the warranty.
Tube Rush Noise
• If you are hearing this noise it is most li ely a gain setting is too high on the input of the Line Amp.
Power cord
• The Andros is not particularly sensitive to power cords.
No Balanced outputs
• The decision was based purely on cost not to include balanced outputs, as there is not enough sonic
difference between single ended and balanced in this application to warrant the increased cost. As a
manufacturer, balanced outputs would require 2 more transformers, 2 more tubes, all the associated
circuitry and a change to the design and size of the case, which would increase the cost of this
phonostage significantly.
Balanced-in verses single ended inputs
• The Andros has a built in step up transformer, so it’s a very nice option to provide both balanced and
single ended inputs. In this particular application there is no sonic difference, but a high convenience
factor.
Leaving the equipment on
• The filament on the tube will burn out quic er if switched on and off more often.
• The tube will wear out quic er if it’s left on all the time. There is no clear choice which is preferred.