Mapletree Phono 3E User manual

Phono 3E Phono Preamplifier
User’s Manual
Revised Dec 24/19
Mapletree Audio Design
Lloyd Peppard
R. R. 1, Seeley s Bay, Ontario, Canada, K0H 2N0
[phone]
hollowstate.netfirms.com
[email protected]
© Copyright Lloyd Peppard 2013-19
5751
5751
12SN7
5751 5751
ON
Power

Introduction _
The Mapletree Audio Design Phono 3E Phono Preamplifier is the companion phono
preamplifier to the Line 2 family of line preamplifiers. The features of the Phono 3E
include:
Compact chassis layout with separate PSX power supply, or designed to share the
Line 2 power supply (PS 2D).
Low output impedance (<2.5K).
RIAA equalization within 0.5 dB, 20 Hz – 20000 Hz.
Use of polypropylene film signal coupling capacitors.
40 dB gain suitable for all MM cartridges when used in conjunction with a line
preamp with at least 10 dB gain.
Selector switch for two separate phono inputs.
Power Supply Connections_______
For operation with a separate line preamp other than the Line 2 family, a headphone
amplifier or an integrated amplifier, the Phono 3E can be supplied with the PSX power
supply, which provides high voltage (B+) and DC heater voltage (A+) for the preamp.
The physical separation of amplification and power supply units eliminates induced hum
originating from power supply circuitry and components. The PSX provides 12 VDC at
0.6 A for the tube heaters and 200 VDC at 15 mA for the B+ plate voltage. A power
interconnect cable provides power from the PSX to the Phono 3E chassis (“Power In”
jack). The power switch on the Phono 3E should remain in the ON position when using
the PSX power supply.
PSX Power Supply
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Phono 3E connection to PSX Power Supply
For use with a Line 2CRM/PS 2D line preamp/power supply, a power interconnect cable
is connected from the Phono 3E to the PS 2D power supply and a separate power
interconnect cable is connected from the power supply to the Line 2CRM preamp power
input jack. The connections are shown below. When using the Phono 3E, the power
switch on the front panel should be turned ON; otherwise, it should be turned OFF.
Phono 3E connection to PS 2D Power Supply
The PSX and PS 2D power supply chassis are connected to the AC line ground but are
otherwise isolated from the preamp chassis, which is connected to the signal ground. This
eliminates the possibility of ground loops between the two chassis, through the signal
interconnect shield and the AC line ground circuit, which can produce hum.
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CAUTION: Do not operate a power supply when it is not connected to a preamp.
Damage to components may result rom operating the power supply with no load.
Once the interconnecting power cable(s) are securely attached (use of the locking rings is
recommended) between the power supply and the preamp(s), and the line cord is plugged
in, the power supply AC power switch may be turned on.
The pilot lamps on the power supply and the Phono 3E chassis indicate that the power
supply is on and the preamp is active. It takes about 30 seconds for the tubes to reach
operating temperature ready for use. During operation, is it normal for the power supply
chassis to become quite warm to the touch.
The PSX and Line 2D power supplies are protected by 20mm, 1 A, 250 V fast-acting
fuses that can be accessed by removing the fuse drawer from the AC receptacle after
disconnecting the AC line cord. Under normal conditions, it should not be necessary to
replace the fuse. If power fails to come on, you can check the fuse and replace with a
spare if necessary. A spare fuse is also located within the fuse drawer. If the fuse blows a
second time, you should not try to operate the unit. Contact Mapletree Audio Design for
information regarding service.
Input/Output Connections______
RCA jacks are provided for two stereo phono inputs, selectable using the toggle switch
located between them, and one stereo output. The same ground binding post is used for
both inputs. Left channel jacks (white) are uppermost.
Tubes____
The vacuum tubes supplied are new or new-old stock (NOS) and have been pre-tested. A
burn-in period of several hours may be needed to achieve the best sonic performance.
Tube life should be thousands of hours. Aging tubes may result in a reduced gain in one
or both channels or an increase in noise levels. Infrequently, a heater may burn out which
is indicated by total loss of sound. Replacement tubes can be obtained from several
suppliers in the U. S. and Canada.
Some listeners enjoy trying different brands and variants of tubes. The highly regarded
12SX7GT is equivalent to the 12SN7GT.
The choice of driver tubes is largely up to the owner, based on experience with the sonic
character of the brand and type variant. Lacking such direction, it is recommended that
the listener try currently manufactured tubes such as Russian and Slovakian 12AX7,
ECC83, and 5751. The 12AY7, which is a low noise version with slightly less gain, is
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also recommended. All these types are also available as NOS but at significantly higher
prices.
Warranty___
Mapletree Audio Design warrants the materials and workmanship (parts and labor) for a period of 2 years
to the original purchaser. Tubes are warranted for 90 days. Electrolytic capacitors are heat sensitive with
lifetimes that vary with usage and are not covered by the warranty. Warranty service does not include
shipping costs.
Phono 3E Specifications______
RIAA equalization: 20 Hz–20 kHz  0.5 dB (typically  0.3 dB)
Gain: 40 dB  0.5 dB with 470K load (connected to Line 2CRM)
Output impedance (1 kHz): 2.5 k
Input impedance: 47 kfor both inputs
Hum and noise at output: less than 2 mV rms
Phase: inverting
Power requirements: 30 W (12 [email protected] A; 200 VDC@10 mA)
Phono 3 Equalization (average of L and R)
Gain = 4 dB +/- .5 dB
Hum and Noise: < 2 mV
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Frequency (Hz)
dB
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