Phono 3 Phono Preamplifier
Contents
1. AUDIO DESIGN Phono 3 Phono Preamplifier User s Manual Revised Dec 22 13 Mapletree Audio Design Lloyd Peppard R R 1 Seeley s Bay Ontario Canada KOH 2N0 613 387 3830 hollowstate netfirms com info mapletreeaudio com Copyright Lloyd Peppard 2013 Introduction The Mapletree Audio Design Phono 3 Phono Preamplifier is part of the modular series of components that includes the Line 2B line preamp the Ultra 4B phono line preamp the LR 1 line router and the PS 2 2a X power supplies The features of the Phono 3 include Compact chassis layout and separate power supply for low noise The Phono 3 can share one PS 2a power supply with the Line 2B preamp if desired Exclusive use of New Old Stock NOS 12SN7 and 12SC7 octal tubes known for low distortion and musicality Low output impedance 2 5K RIAA equalization within 0 5 dB 50 Hz 20000 Hz Use of polypropylene film signal coupling capacitors 38 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 PSX Power Supply Connections PSX Power Supply For operation with a separate line preamp or integrated amplifier the Phono 3 is supplied with the PSX power supply which provides high voltage B and heater voltage A for the preamp The physical separation of amplification and power supply units el2. n e EE 1 R Output a ton may 432K 1 e Wu 6 47 5K SCH 1 6 8n chassis in I v 1 3 3M 1 I AM I 1 I I I Gnd Bus Hammond 1A 250V Power si 6 8K 5W 5 230 VAC 115 113 25 mA if OF VAC VAG MUR180 3 Si 120AC 60 Hz 100 400 100 400 330K 1W Chassis VAC VAC e W ki LED e e Power Ou e SZ PN rear view 1 8K Ge 10 10 VAC i VAC VAC HA 100 V e E 115 10 10000 16 VAC VAC H e i 7 Triad FS20 300 Mapletree Audio Design Preamplifier Power Supply PS 2a Copyright Lloyd Peppard 2012 13 Rev Nov 4 13 1a 250v Power muriso 6X5GT E 3 E 6 8K 5W L e e S 115 115 0 ver l VAC VAC E o 120VAC 60 Hz 25 oc 5 IT 50 500 150 500 N wm mmm emm d 330K 1W 77 A 115 115 Chassis M VAC Line 2 Power Out o Rear View R 12 1W 14VAC 1N4007 115 VAC 14VAC its 1 4A Lx 115 14VAC 10000 25 AC l e e Phono 3 Power Out e Rear View 9 31 7 115 VAC 6 3 VAC 2 6X5 0 9A 115 VAC
3. ic 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 3 Specifications RIAA equalization 50 Hz 20 kHz 0 5 dB typically 0 3 dB Gain 38 dB 1 dB with 30k load Output impedance 1 kHz 2 5 k Input impedance 47 k Yor both inputs Hum and noise at output less than 2 mV rms Phase inverting Power requirements PS 2a or PSX power supply 30 W 12 VDC 0 6 A 200 VDC 10 mA Copyright Lloyd Peppard 2009 13 Mapletree Audio Design Phono 3 Preamplifier Rev Dec 22 13 47 5K re VV 4166 V Va 12SN7 o SKEW uge 125C7 ZE 2 1900 m 100u 400V 332K 1 196 S 400V 820p A de se 0 1u 400V M SCH to CA 2 432K UE 5 d L Phong aks 4 input 3 e e ose iu 400Y L Output da 432K 6 Gnd O 3 3M 1 D n chassi To in Y m o 45 3 3M 1 I RM 1M s M Power In I 1 N u e I I Gain 38 dB 1kHz with 33K load Gnd Bus Noise lt 2 mV Output impedance lt 2 5K k Va 12SN7 lt 47 5k 1 332K 1 12SC7 221K1 S 0 1u 221K 820p 400V 1 0 1u 400V i T R Phono x Z zu LS 2 1M 1u 400V A 4 9 K input A cone
4. iminates 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 The preamp and power supply are connected by a special interconnect cable that plugs into the 4 pin sockets on the rear of the two chassis as shown below The power supply chassis is connected to the AC line ground but is otherwise isolated from the preamp chassis which is connected to the signal ground This eliminates the possibility of ground loops forming between the two chassis through the signal interconnect shield and the ac line ground circuit which can produce hum PSX Power Supply Power interconnect cable AC Line cord PS 2a Power Supply Connections If you purchased your Phono 3 with the Line 2B SE line preamp and are sharing a common power supply you will be provided with the PS 2a power supply The PS 2a power supply provides high voltage B and heater voltage A for both the Line 2B and Phono 3 preamps It differs from the PS 2 only in providing two power output jacks The physical separation of amplification and power supply units eliminates induced hum originating from power supply circuitry and components The PS 2a provides 12 VDC regulated at 1 2 A for the tube heaters and 200 VDC at 20 mA for the B plate voltage Separate 4 pin jacks are provided for the Line 2B and Phono 3 power connections via special 4 cond
5. pply Remove this cover only after powering down for at least 60 sec 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 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 centre position of the source selector switch is a mute position The same ground binding post is used for both inputs Left channel jacks are uppermost Tubes The vacuum tubes supplied are 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 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 Electrolyt
6. uctor cables Pin assignments are as follows Pin 1 B Pin 2 B Pin 3 A Pin 4 A In order to prevent a ground loop from forming through the common B connections signal ground the B feed for the Phono 3 is isolated from that for the Line 2 by a series 12 Ohm resistor in the power supply In practice either power output jack can be used with either preamp Power interconnect cable AC Line cord Power interconnect cable to Line 2B Power Supply Operation CAUTION Do not operate a power supply when it is not connected to a preamp Damage to components may result from operating the power supply with no load Once the interconnecting power cable s are securely attached between the power supply and Phono 3 and the line cord is plugged in the ac power switch may be turned on A separate power switch is located on the rear panel of the Phono 3 adjacent to the power input jack The Phono 3 can be powered off with this switch which disables both the plate and heater voltages Pilot lamps on both the power supply and Phono 3 chassis indicate that the power supply is on and when power is being supplied to the Phono 3 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 power supply is protected by a 1 A 250 V fast acting fuse which can be accessed by removing the bottom cover of the power su
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