Ultra 4B SE phono/line preamplifier
Contents
1. connected to pin 2 insulated from chassis 4 8 Mounting tab 102. AUDIO DESIGN Ultra 4B SE Special Edition Stereo Phono Line Preamplifier User s Manual i ls PHONO LINE LINE2 BALANCE VOLUME e Audio Design Ultra 4B SE Stereo Pre Rev Feb 22 13 Mapletree Audio Design Lloyd Peppard R R 1 Seeley s Bay Ontario Canada KOH 2NO 613 387 3830 www mapletreeaudio com info mapletreeaudio com Copyright Lloyd Peppard 2002 2013 Specifications are subject to change without notice Introduction The Mapletree Audio Design Ultra 4B SE Stereo Phono Line Preamplifier offers the audiophile a number of desirable features Compact chassis layout for use with separate power supply for low noise Exclusive use of NOS octal tubes known for low distortion and musicality Switchable for use with 12SN7GT or 6SN7GT tubes Precise RIAA equalization 20 5 dB using non interacting passive and active filters High input impedance and low output impedance Parallel output jacks for bi amp or headphone amplifier applications Phono gain of 48 dB suitable for all moving magnet MM and high output moving coil MC phono cartridges Audio grade polypropylene and polystyrene film capacitors in signal path Power Supply Connections The Mapletree Audio Design PS 2 power supply provides 12 VDC regulated heater supply voltage and 200 VDC B plate supply voltage at a current of 15 mA see specifications It utilizes a slow start cathode type rectifie
3. 1 R15b 3 3 3M 1 Dib Ww 1K 19 R17b 3M UR R9b redLED 1M 196 221K N 51 8 V l 1 gt R16b 10K 1 277 c B A 144 V 172 V 200 V R18 R19 22K 2W 5 5 1K2W5 ANN AAA C12 C11 100 400 100 400 WEN O1 12 VDC Os 3 7 d J6 P 125075 A 12V o sw2 12SN7s Heater Voltage Parts List Reference No C1a b C2a b C4a b C8a b C3a b C5a b C7a b C9a b C11a b C12a b Dia b J1a b J5a b J6 J7 P1a b P2a b Ria b R11a b R2a b R4a b R3a b R7a b R9a b R5a b R6a b R8a b R14a b R15a b R16a b R17a b R18 R19 R20a b R21a b SW1 SW2 V1a b V2a b Description 0 012uF 160V 2 polystyrene capacitor 0 1uF 400 V polypropylene film capacitor 820pF 630V 2 596 polystyrene capacitor 0 001uF 100 V 5 polypropylene capacitor 1uF 200 V polypropylene film capacitor 100uF 400V electrolytic capacitor 10 mA red LED RCA gold plated phono jack 4 pin chassis jack power in Ground binding post 100K dual audio taper potentiometer 100K linear potentiometer 47 5K 0 5W 196 metal film resistor 3 3M 1W 10 carbon film resistor 332K 0 6W 196 metal film resistor 221K 0 6W 196 metal film resistor 432K 0 6W 196 metal film resistor 100K 0 5W 196 metal film resistor 511K 0 6W 1 metal film resistor 1K 0 6W 196 metal film resistor 10K 0 6W 196 metal film resistor 1M 0 5W 1 metal film resistor 22K 2W 5 metal oxide resistor 5 1K 2W 5 metal oxide resistor 475K 0 6W 1 meta
4. cost Service including parts and labor but excluding shipping is free within the warranty period MAD Ultra 4B SE Phono Line Preamplifier Copyright Lloyd Peppard 2002 2013 Rev Jan 21 13 J3a 2 O L Line inputs SWia B A 1 t O Source J2a c 0 4 L gt E R21a mE HOUR sk da V2a 475K 1 s 2m c 125 7 E C3a 11200 332k 1G 12507 03 12210 2 Pla 5 0 1 400 R o j 100K 1 100K 0 1 400 Cia E iK ANN L outputs 5 Jia 012 2 432K Um 0 1 400 PK Gee C9a J4a L Phono input Ic b 3 P2 6 1 200 IX 1 R5a R9a 0 001 5 Balance J5a 432K 1 221K 106 ie chassis io R4a 1 511K R17a 1 R2a gt Ms 41 R15a im 1 3M 1 SM1 W K 1 redLED N l R16a 10K 196 l J7 Gnd O Ground Bus 5 OD SW1b R Line inputs Source B A 1 172 7 200 V J2b C oa E R11b R20b 475K 1 144 V 475K 196 T surat 1 7 R3b Vib gt R7b 1 200 A C3b 2221K 1 71V 332K 1 A 12SC7 DE ox S ab 2 C 1 oe 2763 0 0909 190K 196 4 0 1 400 oH Cib C R6b 5 Sab A E R outputs Jib 0 012 2 432K 1 0 1 400 5b ez Volume C9b J4b i f 4 3 6 1 200 R Phono input O 1 P ET 0 001 5 PEU Rib 6 432K 1 R14b J6b 47 5 511K Lr R2b R4b
5. l film resistor 3 position 4 pole rotary switch 2 poles used DPDT heater voltage selector switch 12SC7 tube 12SN7GT tube Circuit Operation Referring to the schematic diagram both channels are identical The following description refers to either channel unless otherwise noted The phono input signal is applied to input jack J1 loaded by resistor R1 then capacitor coupled to the grid of the first section of the 12SC7 which is configured as a common cathode voltage amplifier Capacitor sets the low frequency breakpoint in the RIAA equalization curve at 50 Hz The negative grid bias is obtained through the grid resistor R2 The output from this stage is capacitor coupled through C2 to the second stage which uses the second section of the 12SC7 also configured as a common cathode voltage amplifier The feedback network consisting of R5 R6 and C3 implements the turnover frequency of the RIAA curve at 500 Hz Bias is again obtained through the leakage grid current flowing through the 3 3 M resistor R4 The signal is then capacitor coupled through C4 to the phono terminal of the source selector switch SW1 The passive network comprised of R8 and C5 implements the roll off frequency of the RIAA curve at 2130 Hz The selector switch is used to steer either the amplified phono signal or one of two line input signals jacks J2 and J3 to the third stage which utilizes the first section of the 12SN7GT in a common cathode voltage amplifier co
6. nfiguration giving a gain of around 22 dB This stage is biased by a light emitting diode LED which provides the required dc bias voltage while presenting a low resistance to signals This eliminates the necessity of an electrolytic cathode resistor bypass capacitor The output of this stage is capacitor coupled through C7 to the volume control potentiometer P1 and to the balance control potentiometer P2 The wiper of the level control is capacitor coupled through C8 to the grid of the output stage which employs the second section of the 12SN7GT configured as a cathode follower This stage has a voltage gain of less than unity but provides a low output impedance suitable for driving cable capacitance without loss of high frequencies Grid bias is obtained by resistors R14 and R15 while R16 establishes the plate voltage and current to provide maximum output voltage swing The output voltage is taken from the cathode of the output stage capacitor coupled to the output jacks J4 and J5 through capacitor C9 MAD Ultra 4B Specifications Phono Section 100 k load Max RIAA error 0 5 dB 30 20 kHz Maximum Gain 50 dB Noise less than 3mV for gain of 48 dB less than 1 mV for gain of 40 dB Input resistance at 1 KHz 47 k Line Section 100 k load Frequency response 1 V output 100K load 20 Hz 20 kHz 0 5 dB any volume control setting Max output voltage 100K load 15 V rms Gain 18 dB Channel balance 0 5 dB Hum and noise les
7. o right the 3 position Source selector switch Phono Linel Line2 the Balance control and the Volume control which adjusts the gain of both channels simultaneously you find that you hear pops from your speakers when switching between sources turn down the volume control before switching Tubes 12SC7 L 12SC7 R 12SN7GT L 12SN7GT R Vacuum tube socket locations are shown in the diagram on p 6 The 12SC7s are toward the rear of the chassis The 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 Mapletree Audio Design will attempt to provide replacement tubes to customers at cost plus shipping Some listeners enjoy trying different brands and variants of tubes The heater voltage selector switch permits the use of 6SN7GT or the 5692 special red version tubes of NOS or current manufacture The highly regarded 12SX7GT is equivalent to the 12SN7GT Warranty Assembled components are warranted for 2 years to the original purchaser for failure of parts excluding tubes and workmanship Tubes are warranted for 90 days exclusive of shipping
8. on regarding service Signal I O Connections Obi OO IE 0000 The signal input output jacks are located on the rear panel of the preamplifier chassis RCA jacks are provided for phono input two line inputs and two line outputs Left channel jacks are at the top and right channel jacks are at the bottom A binding post is provided for phono ground The phono input resistance is 47 k which matches standard MM phono cartridge loading requirements The input capacitance is approximately 50 pF The line input impedance is 470 k Wwhich provides minimal loading of any line source such as CD DVD player tape deck tuner or PC sound card The line output impedance is less than 500 which is suitable for connection to a power amplifier through cables up to 10 ft in length The ground wire from the turntable should be connected to the ground binding post to minimize hum pickup The heater voltage switch located next to the power input jack allows you to accommodate either 12SN7GT supplied or 6SN7GT tubes in your Ultra 4A Note that the switch does not affect the heater voltage for the 12SC7 tubes While it will do no damage to switch to 6SN7 position with 12SN7 tubes installed operation in the 12SN7 position with 6SN7 tubes may damage the tubes Front Panel Controls PHONO LINE2 BALANCE VOLUME Mapletree Audio Design Ultra 4B SE Stereo Preamplifier The front panel controls are left t
9. r tube 6X5GT in conjunction with low noise ultra high speed diodes to achieve all the advantages of tube rectification low noise soft startup with the high efficiency of a bridge rectifier topology The separate power supply eliminates induced hum originating from power supply circuitry and components The power connections to the preamplifier chassis are made through a special 3 conductor power cord that plugs into jacks located on the rear panels of the power supply and preamplifier chassis CAUTION Do not operate the power supply when it is not connected to the preamp Damage of components may result Once the interconnecting power cord is securely attached between the two chassis and the line cord is plugged in the power supply can be turned on The pilot lamp on the power supply chassis indicates that the unit is on 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 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 chassis cover after the unit has been unplugged 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 informati
10. s than 150 V at full gain input shorted Input impedance 1 kHz 475 Output impedance 1 kHz 450 9 Power requirements 12 VDC 1A 4180 250 VDC 14 mA ground is common to both supplies FU1 0 5A 250V Power Supply Parts List Reference No Description BR1 6A 200V diode bridge C1a b Dual 50uF 50uF 500V electrolytic capacitor C2 10000uF 16V electrolytic capacitor D1 1N4007 diode D2 10 mA LED D3 D4 MUR180 high speed diode 800 V FU1 Ve A 250 V fast action fuse J1 4 pin chassis jack J2 IEC ac line receptacle IC1 IC2 7812 voltage regulator R1 6 8K 5W 596 wire wound resistor R2 220K 1W 596 metal film resistor R3 1 8K 1W 596 carbon film resistor Swi SPST power switch 250 V rated TR1 230 VAC 25 mA power transformer TR2 14 VAC 1 4 A filament transformer TR3 6 3 VAC 0 9 A filament transformer V1 6X5GT rectifier tube Mapletree Audio Design Preamplifier Power Supply PS 2 Copyright Lloyd Peppard 2003 13 Rev Feb 17 13 SWI D3 D4 V1 Power TR muriso 6X5GT R1 1 5 3 6 8K 5W A 115 115 VAC 8 ieee Bane J2 VAC 25 mA o gt ls Cla Cib j 120AC 60 Hz Z 5 M 50 500 NS N p e Power Out Chassis R2 NS Rear View 220K 1W R3 TR2 E j 6 14 VAC m Su d x D2 A LED 6 VAC 0 9A
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