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Preamps for home hi-fi and musical instruments

3 - Preamplifiers for musical instruments and home hi-fi

Document last modified and saved: 19 October 2011 7:39 PM

Schematics and Bill of materials for instrument preamplifiersSchematic and BOM of cheap microphone preamp

Schematics and Bill of Materials for audio

preamplifiers projects

Schematics and Bill of Materials for audio preamplifiers projects . . . . . . . . . . . . . . . . . . . . . . .2Schematic and BOM of cheap microphone preamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3Stereo jFET guitar (instrument, effect) preamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4Stereo dual OpAmp instrument or audio preamplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5Stereo circuit with 2 single OpAmp, instrument and audio preamplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6Stereo low noise 2 single OpAmp instrument preamplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7Schematic and BOM of power supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

Printed Circuit Boards for instrument preamps project . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9Top and bottom PCBs and overlay of INA217 microphone preamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10Top and bottom PCBs and overlay of stereo jFET preamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12Top and bottom PCBs and overlay of simple dual OpAmp preamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13Top and bottom PCBs and overlay of power filters (ver .3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14Top and bottom PCBs and overlay of power filters (ver .2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15Top and bottom PCBs and overlay of power filters (ver .1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16Two single OpAmp - stereo universal preamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17Two single OpAmp - stereo low noise universal preamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18Switch module for preamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19The PCB of power supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20

Images and Picasa galleries about the prototype of preamps . . . . . . . . . . . . . . . . . . . . . . . 22The selectable prototype of jFEt and OpAmp projects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23Audio mixer with jFET and OpAmp preamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24Microphone preamp with INA217 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25

This project made for testing and building the best simple solutions for instrument and audio preamplifiers for home users . Microphone preamp with cheap instrument ampli-fier INA217, noiseless solution with jFET for guitarists, and very simple but hi-gained

audio circuits with OpAmps for audio solutions for home hi-fi . The next project is to make audio mixer with these preamplifier circuits .

Read details, updates, advices on the page of schematics and notes . PCB-s and more notes, pictures, advices about this project are available on the author’s blog and web-

sites:

English blog and PCB order: http://custompcb.blogspot.com/Hungarian blog and PCB order: http://diyguitarpa.blogspot.com/

The Youtube Channel • Picasa gallery • Email: [email protected]

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26

74

U3OPA137

1MR10

100nFC14

Q2

BC560C

Q1

BC548C12K

R2

12K

R3

V_OUT 6

REF5

RG_28

V-

4

V_IN-2

RG_11

V+

7

V_IN+3

INA217 AIP

U1

47uF 60V

C3

47uF 60V

C4

47nFC1 47nFC2

100nFC8

100nFC6 10uF

C9 10uFC7

GND

Q3BC560C

Q4

BC548C12K

R17

12K

R16 47uF 60V

C21

47uF 60V

C20

47nFC23

47nFC22

100nFC18

100nF

C16

10uFC17

10uFC19

GND

GND

8R8

2.2KR13

2.2KR14

GND GND

D31N4148

D11N4148 D4

1N4148

D21N4148

47uF 60VC12

47uF 60VC13

6.8K

R6

6.8K

R9

47KR1

GND47uF 60V

C5

GND

GND

+15V

-15V

-15V a2

+15V a2

-15V a1

+15V a1

1.6kAP1

47kBP2

GND

1

2

H4

1

2

H5

1 2 3

H2

1 2 3

H1

+48V

1 2 3

H3

GND

3

26

74

U2OPA137

470

R7

10uFC11

100KR15

100KR11

10uFC15

470R12

GND GND

1KR5

1KR4

GND

GNDOutput

Bal In 1

Bal In 2

0 1 2 3 4 5

J1Input Jack 6.3

10uFC10

123456

789101112

P3Header 6X2A

Mic and instrument preamp with assimatrical/simmetrical inputs

http://diyguitarpa.blogspot.com/http://custompcb.blogspot.com/

Description Comment ValueQuanti

ty Designator Footprint Model:Footprint

Capacitor Cap 47nF 4 C1, C2, C22, C23 RAD-0.3 Capacitor; 2 Leads

Polarized Capacitor (Radial) Cap Pol1 47uF 60V 7C3, C4, C5, C12, C13,C20, C21

Elco 12 mm, 2mil pins

Capacitor Cap 100nF 5 C6, C8, C14, C16, C18 RAD-0.3 Capacitor; 2 Leads

Polarized Capacitor (Radial) Cap Pol1 10uF 7C7, C9, C10, C11, C15,C17, C19 Cap, Tantal, 1mil

High Conductance FastDiode 1N4148 1N4148 4 D1, D2, D3, D4 DO-35

Diode, Axial; Body 3.8 x 1.9 mm (LxDia. max), LeadDia. 0.53 mm (max)

Connector, 3 pin, 2 mil Connector 3 H1, H2, H3Panel Connector3 input Small

Connector, 2 pin, 2 mil Connector 2 H4, H5Panel Connector2 input Small

Input Jack6.3 1 J1 Jack input 6.3

Resistor Pot Mono 1.6kA 1 P1Pot MonoMetalCase 3 pin mono metal case pot, 2 mil

Resistor Pot Mono 47kB 1 P2Pot MonoMetalCase 3 pin mono metal case pot, 2 mil

Header, 6-Pin, Dual rowHeader6X2A 1 P3 HDR2X6_CEN Connector; Header; 6x2 Position

Amplifier Transistor NPNSilicon BC548C 2 Q1, Q4 29-04

TO, Flat Index; 3 In-Line, Axial Leads; Body Dia.4.8mm; Leads 0.48 x 0.5 mm (max)

Low Noise Transistor PNPSilicon BC560C 2 Q2, Q3 29-04


Resistor Res2 47K 1 R1 AXIAL-0.4 Resistor; 2 Leads

Resistor Res2 12K 4 R2, R3, R16, R17 AXIAL-0.4 Resistor; 2 Leads

Resistor Res2 1K 2 R4, R5 AXIAL-0.4Axial Device, Thru-Hole; 2 Leads; 0.4 in PinSpacing

Resistor Res2 6.8K 2 R6, R9 AXIAL-0.4 Resistor; 2 Leads

Resistor Res2 470 2 R7, R12 AXIAL-0.4Axial Device, Thru-Hole; 2 Leads; 0.4 in PinSpacing

Resistor Res2 8 1 R8 AXIAL-0.4 Resistor; 2 Leads

Resistor Res2 1M 1 R10 AXIAL-0.4 Resistor; 2 Leads

Resistor Res2 100K 2 R11, R15 AXIAL-0.4Axial Device, Thru-Hole; 2 Leads; 0.4 in PinSpacing

Resistor Res2 2.2K 2 R13, R14 AXIAL-0.4 Resistor; 2 Leads

Instrument AmpINA217AIP INA217 AIP 1 U1 DIP-8 DIP, 8-Pin, Row Spacing 7.62 mm, Pitch 2.54 mm

General Purpose FET-InputOperational Amplifiers OPA137 1 U2 006E

DIP; 8 Leads; Row Spacing 7.62 mm; Pitch 2.54mm

FET-Input Operational AmplifiersOPA137 OPA137 1 U3 006E DIP; 8 Leads; Row Spacing 7.62 mm; Pitch 2.54 mm

Notes

This circuit made for mono microphone inputs only . The input is mono, jack in-serted directly to the board with asymmetrical/sym-metrical converter, and 3 inputs header inserted for symmetrical phones with XLR output . Switch module required to select between two inputs (asymmetrical jack or symmetrical XLR) . The amplifier of this circuit is INA217 . This instrument amp is very cheap, and noiseless . Volume and gain potentiometers included .

The Picasa album about prototype testing

http://custompcb.blogspot.com/

http://diyguitarpa.blogspot.com/

http://www.youtube.com/playlist?list=PLDBAFF83D547F7EB7&feature=viewall

http://picasaweb.google.com/gitarfogas

mailto:gitarfogas%40gmail.com?subject=PDF%20Message%20-%20EQ%20Project

https://picasaweb.google.com/105028544937175433650/MicPreampTesting

Preamplifiers for musical instruments and home hi-fi - 4 5 - Preamplifiers for musical instruments and home hi-fi


Schematics and Bill of materials for instrument preamplifiersStereo jFET guitar (instrument, effect) preamp

Schematics and Bill of materials for instrument preamplifiersStereo dual OpAmp instrument or audio preamplifier

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Q2BC548C

12K

R10 47uF 60V

C747nFC8

100nF

C5

10uFC6

GND

+15V Stage

012345

J1

Input Jack 6.3

GND

GND

1

2

3

H1

GND

1

3

2

Q1A2N3958

57

6Q1B2N3958

1

2

H2

1

2

H3

10MR2

10MR8

5.1KR6

5.1KR1

5kA

P2

Pot stereo

47kB

P1

Pot stereo

10uFC2

10uFC3GND

GND

220R9

220R5

GND

10uFC1

10uF

C4

GND51KR3

51KR4

GND GND

22KR7

GND

+15V Input

Out 1

Out 2

12

P3

Header 2


Stereo Dual jFET preamp


ty Footprint Designator Model:Footprint

Polarized Capacitor (Radial) Cap Pol1 10uF 5 Cap, Tantal, 1mil C1, C2, C3, C4, C6

Capacitor Cap 100nF 1 RAD-0.3 C5 Capacitor; 2 Leads

Polarized Capacitor (Radial) Cap Pol1 47uF 60V 1Elco 6mm, 1 milpins C7

Capacitor Cap 47nF 1 RAD-0.3 C8 Capacitor; 2 Leads

Connector 1Panel Connector3 input Small H1 3 pin, 2 mil connector

Connector 2Panel Connector2 input Small H2, H3 2 pin, 2 mil connector

Input Jack6.3 1 Jack input 6.3 J1

Resistor Pot stereo 47kB 1Pots PlasticStereo P1

Resistor Pot stereo 5kA 1Pots PlasticStereo P2

Header, 2-Pin Header 2 1 HDR1X2 P3 Connector; Header; 2 PositionN-Channel Dual JFET (GeneralPurpose) 2N3958 1 TO-71 Q1

Can; 7 Leads (1 Absent); Pin Circle Dia. 2.54 mm;Lead Dia. 0.48 mm (max)

Amplifier Transistor NPN Silicon BC548C 1 29-04 Q2TO, Flat Index; 3 In-Line, Axial Leads; Body Dia.4.8mm; Leads 0.48 x 0.5 mm (max)

Resistor Res2 5.1K 2 AXIAL-0.4 R1, R6Axial Device, Thru-Hole; 2 Leads; 0.4 in PinSpacing

Resistor Res2 10M 2 AXIAL-0.4 R2, R8Axial Device, Thru-Hole; 2 Leads; 0.4 in PinSpacing

Resistor Res2 51K 2 AXIAL-0.4 R3, R4Axial Device, Thru-Hole; 2 Leads; 0.4 in PinSpacing

Resistor Res2 220 2 AXIAL-0.4 R5, R9Axial Device, Thru-Hole; 2 Leads; 0.4 in PinSpacing

Resistor Res2 22K 1 AXIAL-0.4 R7Axial Device, Thru-Hole; 2 Leads; 0.4 in PinSpacing

Resistor Res2 12K 1 AXIAL-0.4 R10 Resistor; 2 Leads

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B B

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012345

J1

Input Jack 6.3

47kB

P2Pot stereo

100kA

P3Pot stereo

1

2

3

H3

1

2

3

H2

1

2

3

H1

84

5

67B

U1B

TL072ACN

2

31A

U1A

TL072ACN

12

P1

Header 2

10uFC3

10uFC4

GND GND

GND

22KR3

Q2

BC560C

Q1

BC548C12K

R8

12K

R9

47uF 60V

C9

47uF 60V

C10

47nFC7 47nFC8

100nFC13

100nFC11 10uF

C14 10uFC12 GND

GND

1MR7

1MR2

GND

GND

100k

R1

100k

R468p

C5

68p

C1

10uF

C6

10uF

C2

GND

GND

4.7kR5

4.7kR6

-15V

+15V

+15V Clean

-15V Clean

123456

789101112

P4

Header 6X2A

Dual stereo OpAmp w. power filter



ty Footprint Designator Model:Footprint

Capacitor Cap 68p 2 RAD-0.3 C1, C5 Capacitor; 2 Leads

Polarized Capacitor (Radial) Cap Pol1 10uF 6 Cap, Tantal, 1milC2, C3, C4, C6, C12,C14

Capacitor Cap 47nF 2 RAD-0.3 C7, C8 Capacitor; 2 Leads

Polarized Capacitor (Radial) Cap Pol1 47uF 60V 2Elco 12 mm, 2mil pins C9, C10

Capacitor Cap 100nF 2 RAD-0.3 C11, C13 Capacitor; 2 Leads

Connector 3Panel Connector3 input Small H1, H2, H3 3 pin, 2 mil connector

Input Jack6.3 1 Jack input 6.3 J1

Header, 2-Pin Header 2 1 HDR1X2 P1 Connector; Header; 2 Position

Resistor Pot stereo 47kB 1Pots PlasticStereo P2

Resistor Pot stereo 100kA 1Pots PlasticStereo P3

Header, 6-Pin, Dual rowHeader6X2A 1 HDR2X6_CEN P4 Connector; Header; 6x2 Position

Amplifier Transistor NPN Silicon BC548C 1 29-04 Q1TO, Flat Index; 3 In-Line, Axial Leads; Body Dia.4.8mm; Leads 0.48 x 0.5 mm (max)

Low Noise Transistor PNPSilicon BC560C 1 29-04 Q2


Resistor Res2 100k 2 AXIAL-0.4 R1, R4Axial Device, Thru-Hole; 2 Leads; 0.4 in PinSpacing

Resistor Res2 1M 2 AXIAL-0.4 R2, R7Axial Device, Thru-Hole; 2 Leads; 0.4 in PinSpacing

Resistor Res2 22K 1 AXIAL-0.4 R3Axial Device, Thru-Hole; 2 Leads; 0.4 in PinSpacing

Resistor Res2 4.7k 2 AXIAL-0.4 R5, R6Axial Device, Thru-Hole; 2 Leads; 0.4 in PinSpacing

Resistor Res2 12K 2 AXIAL-0.4 R8, R9 Resistor; 2 Leads

Low-Noise J-FET Dual Operational AmplifierTL072ACN 1 dip-8 U1 DIP; 8 Leads; Row Spacing 7.62 mm; Pitch 2.54 mm

Notes

This very simple, small, cheap and noiseless preamp made for musical instruments with ste-reo (or mono) input . The main part of this circuit is 2N3958 dual jFET . Ideal for stereo or mono guitar effects, key-boards, or to connect another devices with stereo outputs like audio mixers . Stereo jack, gain and volume adjustable resistors are inserted to the PCB . Very cheap and very good quality for guitars . The possible gain is not too high of this circuit, but enough for guitars and guitar ef-fects with very warm sound .

Notes

This is another really simple, good quality and cheap preamplifier with stereo jack input for guitar effects or keyboards . The possible gain is much higher than jFET circuit, and the sound is better for keyboards or mixers than the guitars or guitar effects . The dual OpAmp must be compat-ible with TL072 . Gain and volume pots has inserted to the PCB board .

The Picasa album about jFET amplifier

The Picasa album about OpAmp amplifier

https://picasaweb.google.com/105028544937175433650/JFETGuitarPreamp




Schematics and Bill of materials for instrument preamplifiersStereo circuit with 2 single OpAmp, instrument and audio preamplifier

Schematics and Bill of materials for instrument preamplifiersStereo low noise 2 single OpAmp instrument preamplifier

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B B

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J1

Input Jack 6.3

47kB

P2Pot stereo

100kA

P3Pot stereo

1

2

3

H3

1

2

3

H2

1

2

3

H1

12

P1

Header 2

10uFC3

10uFC4

GND GND

GND

22KR3

Q2

BC560C

Q1

BC548C12K

R8

12K

R9

47uF 60V

C9

47uF 60V

C10

47nFC7 47nFC8

100nFC13

100nFC11 10uF

C14 10uFC12 GND

GND

1MR7

1MR2

GND

GND

100kR1

100k

R468p

C5

68p

C1

10uF

C6

10uF

C2

GND

GND

4.7kR5

4.7kR6

-15V

+15V

+15V Clean

-15V Clean

8

53

26

741

U3

LF356D

8

53

26

741

U4

LF356D

123456

789101112

P5

Header 6X2A


Stereo single OpAmp preamp w. power filter

Description ValueQuanti

ty Comment Footprint Designator Model:Footprint

Capacitor 68p 2 Cap RAD-0.3 C1, C5 Capacitor; 2 Leads

Polarized Capacitor (Radial) 10uF 6 Cap Pol1 Cap, Tantal, 1milC2, C3, C4, C6, C12,C14

Capacitor 47nF 2 Cap RAD-0.3 C7, C8 Capacitor; 2 Leads

Polarized Capacitor (Radial) 47uF 60V 2 Cap Pol1Elco 12 mm, 2mil pins C9, C10

Capacitor 100nF 2 Cap RAD-0.3 C11, C13 Capacitor; 2 Leads

3 ConnectorPanel Connector3 input Small H1, H2, H3 3 pin, 2 mil connector

1Input Jack6.3 Jack input 6.3 J1

Header, 2-Pin 1 Header 2 HDR1X2 P1 Connector; Header; 2 Position

Resistor 47kB 1 Pot stereoPots PlasticStereo P2

Resistor 100kA 1 Pot stereoPots PlasticStereo P3

Header, 6-Pin, Dual row 1Header6X2A HDR2X6_CEN P5 Connector; Header; 6x2 Position

Amplifier Transistor NPN Silicon 1 BC548C 29-04 Q1TO, Flat Index; 3 In-Line, Axial Leads; Body Dia.4.8mm; Leads 0.48 x 0.5 mm (max)

Low Noise Transistor PNPSilicon 1 BC560C 29-04 Q2


Resistor 100k 2 Res2 AXIAL-0.4 R1, R4Axial Device, Thru-Hole; 2 Leads; 0.4 in PinSpacing

Resistor 1M 2 Res2 AXIAL-0.4 R2, R7Axial Device, Thru-Hole; 2 Leads; 0.4 in PinSpacing

Resistor 22K 1 Res2 AXIAL-0.4 R3Axial Device, Thru-Hole; 2 Leads; 0.4 in PinSpacing

Resistor 4.7k 2 Res2 AXIAL-0.4 R5, R6Axial Device, Thru-Hole; 2 Leads; 0.4 in PinSpacing

Resistor 12K 2 Res2 AXIAL-0.4 R8, R9 Resistor; 2 Leads

Wide-Bandwidth Single J-FET Operational Amplifier2 LF356D dip-8 U3, U4 DIP; 8 Leads; Row Spacing 7.62 mm; Pitch 2.54 mm

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B B

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J1

Input Jack 6.3

47kB

P2Pot stereo

100kA

P3Pot stereo

1

2

3

H3

1

2

3

H2

1

2

3

H1

12

P1

Header 2

10uFC3

10uFC4

GND GND

GND

22KR3

Q2

BC560C

Q1

BC548C12K

R8

12K

R9

47uF 60V

C10

47uF 60V

C11

47nFC7 47nFC8

100nFC13

100nF

C9

10uF

C14 10uFC12 GND

GND

1MR7

1MR2

GND

GND

100kR1

100k

R468p

C5

68p

C1

10uF

C6

10uF

C2

GND

GND

4.7kR5

4.7kR6+15V Clean

-15V Clean

52

3

4

6

7

18

U1

LT1028CN8

52

3

4

6

7

18

U2

LT1028CN8

Q4

BC560C

Q3

BC548C12K

R10

12K

R11

47uF 60V

C18

47uF 60V

C19

47nFC15 47nFC16

100nFC21

100nF

C17

10uF

C22 10uFC20

+15V Clean 1

-15V Clean 1

-15V

+15V

123456

789101112

P4

Header 6X2A


Stereo preamp w. 2 single OpAmp and 2 power filtersGND

Description ValueQuanti

ty Comment Footprint Designator Model:Footprint

Capacitor 68p 2 Cap RAD-0.3 C1, C5 Capacitor; 2 Leads

Polarized Capacitor (Radial) 10uF 8 Cap Pol1 Cap, Tantal, 1milC2, C3, C4, C6, C12,C14, C20, C22

Capacitor 47nF 4 Cap RAD-0.3 C7, C8, C15, C16 Capacitor; 2 Leads

Capacitor 100nF 4 Cap RAD-0.3 C9, C13, C17, C21 Capacitor; 2 Leads

Polarized Capacitor (Radial) 47uF 60V 4 Cap Pol1Elco 12 mm, 2mil pins C10, C11, C18, C19

3 ConnectorPanel Connector3 input Small H1, H2, H3 3 pin, 2 mil connector

1Input Jack6.3 Jack input 6.3 J1

Header, 2-Pin 1 Header 2 HDR1X2 P1 Connector; Header; 2 Position

Resistor 47kB 1 Pot stereoPots PlasticStereo P2

Resistor 100kA 1 Pot stereoPots PlasticStereo P3

Header, 6-Pin, Dual row 1Header6X2A HDR2X6_CEN P4 Connector; Header; 6x2 Position

Amplifier Transistor NPN Silicon 2 BC548C 29-04 Q1, Q3TO, Flat Index; 3 In-Line, Axial Leads; Body Dia.4.8mm; Leads 0.48 x 0.5 mm (max)

Low Noise Transistor PNPSilicon 2 BC560C 29-04 Q2, Q4


Resistor 100k 2 Res2 AXIAL-0.4 R1, R4Axial Device, Thru-Hole; 2 Leads; 0.4 in PinSpacing

Resistor 1M 2 Res2 AXIAL-0.4 R2, R7Axial Device, Thru-Hole; 2 Leads; 0.4 in PinSpacing

Resistor 22K 1 Res2 AXIAL-0.4 R3Axial Device, Thru-Hole; 2 Leads; 0.4 in PinSpacing

Resistor 4.7k 2 Res2 AXIAL-0.4 R5, R6Axial Device, Thru-Hole; 2 Leads; 0.4 in PinSpacing

Resistor 12K 4 Res2 AXIAL-0.4 R8, R9, R10, R11 Resistor; 2 Leads

Ultra Low Noise Precision High-Speed Operational Amplifier2 LT1028CN8 dip-8 U1, U2 DIP; 8 Leads; Row Spacing 7.62 mm; Pitch 2.54 mm

Notes

This circuit looks like the previous version of TL072 compatible OpAmp pre-amplifier, but for this, two single OpAmp device required, instead of one dual . The reason of this so-lution is the better quality, if you want to use for exam-ple really noiseless single LF or LT serial integrated circuits instead of relative noisy one dual TL072 .

This solution is really cheap, against the noise one pow-erfilter circuit included (for both OpAmps) . Stereo jack input, stereo/mono and bypass switch, gain and volume potentiometers inserted to the board .

Because the circuit noise, distortion (and the gain) depending on the included single OpAmp, the solution recommended for all non-guitar instrument, and au-dio amplifiers for home hi-fi solutions .

Notes

This is the last version of OpAmp preamplifiers . This have best quality . This is the reason why two single OpAmp included instead of one dual . LT1115 or LT1028 recommended for best result, maybe one of LF or NE serial OpAmps .

The difference between this and the previous version of board, here we have two power filter, one filter for one OpAmp for the best re-sult of really low noise and distortion . The cir-cuit recommended for home hi-fi and instru-ments, included instru-ment effects .

Gain and volume po-tentiometers, bypass and stereo/mono switches included to the board with stereo jack input .



Printed Circuit

Boards for

instrument preamps

project

Schematics and Bill of materials for instrument preamplifiersSchematic and BOM of power supply

1

1

2

2

3

3

4

4

5

5

6

6

D D

C C

B B

A A

Title

Number RevisionSize

A

Date: 10/17/2011 Sheet ofFile: D:\!Works\..\Power supply.SchDoc Drawn By:

1

2

3

H1

1

2

3

H2

D1 KBL04

47nC6

47nC8

47nC9

47nC7

GND

2200uC1

2200uC10

10 1W

R1

10 1W

R2

2200uC2

2200uC11

GND

100nC4

100nC13

IN3

1

OUT 2

ADJ

U1LM317BT

IN2

1

OUT 3ADJ

U2LM337BT

D216V Zener

D316V Zener

47uC3

47uC12

100nC5

100nC14

15V AC - 1

15V AC - 2

+15V In

-15V In

+15V Out

-15V Out


Power supply

Description CommentQuanti

ty Value Footprint Designator Model:Footprint

Polarized Capacitor (Radial) Cap Pol1 4 2200uELCO 22 MM 4MIL C1, C2, C10, C11

Polarized Capacitor (Radial) Cap Pol1 2 47uElco 12 mm, 2mil pins C3, C12

Capacitor Cap 4 100n RAD-0.3 C4, C5, C13, C14Radial Cap, Thru-Hole; 2 Leads; 0.3 in PinSpacing

Capacitor Cap 4 47n RAD-0.3 C6, C7, C8, C9Radial Cap, Thru-Hole; 2 Leads; 0.3 in PinSpacing

Full Wave Diode Bridge KBL04 1 Bridge hor. D1

Zener Diode 16V Zener 2 DIODE-0.7 D2, D3 Diode, Thru-Hole; 2 Leads; 0.7 in Pin Spacing

Connector 2panel connector3 input big H1, H2 3 pin, 3 mil connector

Resistor Res2 2 10 1W AXIAL-0.4 R1, R2Axial Device, Thru-Hole; 2 Leads; 0.4 in PinSpacing

3-Terminal Adjustable PositiveVoltage Regulator LM317BT 1 221A-04 U1

TO, Thru-Hole, Vertical, Heatsink Mounted; 3 In-Line Leads; Pitch 2.54 mm

3-Terminal Adjustable Negative Voltage RegulatorLM337BT 1 221A-04 U2 TO, Thru-Hole, Vertical, Heatsink Mounted; 3 In-Line Leads; Pitch 2.54 mm

Notes

This is the power supply . Very simple and good quality low power circuit . Two adjustable regulators can be fixed to the heatsink . The adjustable regulator with Zener diode have cleaner output than simple 7815 and 7915 regulators .



PCB for the instrument preampsTop and bottom PCBs and overlay of INA217 microphone preamp

1

13

3

1

C5

Q2

1 R3

C16

D2

R4

Q1

Q3

C3

C1

R7 R5R6

R1

D4

C9

R15

C6

C8

C15

R13

R12R14

R10

J1

P1

P2

Q4

C4

R8R9

R17

U2

D1

H4 H5

R11

C17

C19

C10

C2R16

R2

C23

C14

C21U1

C11D3

C7

C20

H2

3

3H1 H3

U3

C22

C13

C12

C18

1

13

3

1

C5

Q2

1 R3

C16

D2

R4

Q1

Q3

C3

C1

R7 R5R6

R1

D4

C9

R15

C6

C8

C15

R13

R12R14

R10

J1

P1

P2

Q4

C4

R8R9

R17

U2

D1

H4 H5

R11

C17

C19

C10

C2R16

R2

C23

C14

C21U1

C11D3

C7

C20

H2

3

3

H1 H3

U3

C22

C13

C12

C18

TO

P LA

YE

RB

OT

TO

M LA

YE

R

PCB TOP OVERLAYT

OP

OV

ER

LAY

ON

TO

P LA

YE

R



PCB for the instrument preampsTop and bottom PCBs and overlay of stereo jFET preamp

TO

P LA

YE

R

BO

TT

OM

LA

YE

R

PCB TOP OVERLAY

TOP OVERLAY ON TOP LAYER

51

H2

H3

R9

3

Q1

C3

7

R2

P1

1

P2

J1

3Q2

C6

C5

R6

R7

R1

R4

R3

H1

R10

C1 C2C4

C8

C7

R5

R8

P3

51

H2

H3

R9

3

Q1

C3

7

R2

P1

1

P2

J1

3Q2

C6

C5

R6

R7

R1

R4

R3

H1

R10

C1 C2C4

C8

C7

R5

R8

P3

TOP LAYER BOTTOM LAYER

PCB OVERLAY

OVERLAY ON TOP LAYER

PCB for the instrument preampsTop and bottom PCBs and overlay of simple dual OpAmp preamp

1

C14

H2

R8

1

3

Q2

Q1

R9

C7

C8

C1

H1

C2

C6

C5

R5

P1

R6

P3

P2

C4 J1

C3

C11

3

R4

C12

H3

C9

R1U1

R2

R7

C10

C13

R3

1

C14

H2

R8

1

3

Q2

Q1

R9

C7

C8

C1

H1

C2

C6

C5

R5

P1

R6

P3

P2

C4 J1

C3

C11

3

R4

C12

H3

C9

R1U1

R2

R7

C10

C13

R3



PCB for the instrument preampsTop and bottom PCBs and overlay of power filters (ver .3)

TO

P LA

YE

R

BO

TT

OM

LA

YE

R

PC

B O

VE

RLA

Y

1

1 6P17 12

3

R2

Q1

C4C5

R1

C6

3

1

C7

Q2

C8

C1

C3 C2

1

1 6P17 12

3

R2

Q1

C4C5

R1

C6

3

1C7

Q2

C8

C1

C3 C2

OV

ER

LAY

ON

TO

P L

AY

ER

TO

P LA

YE

R

BO

TT

OM

LA

YE

R

PCB OVERLAY



1 67 12P1

C3

C2

C8

C6

1

Q1

C1

3 R1

3R2

1

Q2C7

C5 C

41 67 12P1

C3

C2

C8

C6

1

Q1

C1

3 R1

3R2

1

Q2C7

C5 C

4

Notes

We have 3 versions of power filter PCB . No dif-ference between schematics, the one of them is landscape, the another 2 is portrait .

Notes

We have 3 versions of power filter PCB . No difference between schematics, the one of them is landscape, the another 2 is portrait .



1 6

3

7 12

C6 C2

P1

Q2

13

1

C3 C8

C5

R2

C1 C4

R1Q1

C7

1 6

3

7 12

C6 C2

P1

Q2

13

1

C3 C8

C5

R2

C1 C4

R1Q1

C7


TOP LAYER

BOTTOM LAYER

PCB OVERLAY


Notes

We have 3 versions of power filter PCB . No dif-ference between schematics, the one of them is landscape, the another 2 is portrait .

PCB for the instrument or hi-fi preampsTwo single OpAmp - stereo universal preamp

31

C1

C8

H1

H3

H2

C10

1

Q1

R9

C2

R7 C9

R5

R3

U4

C11

J1

3

C3

R1 C5U3

C13

R2

Q2 R6

C14

C4C7

R8

P1

C6

P2

R4

C12

P3

31

C1

C8

H1

H3

H2

C10

1

Q1

R9

C2

R7 C9

R5

R3

U4

C11

J1

3

C3

R1 C5U3

C13

R2

Q2 R6

C14

C4C7

R8

P1

C6

P2

R4

C12

P3

TOP LAYER BOTTOM LAYER

PCB OVERLAY




PCB for the instrument or hi-fi preampsTwo single OpAmp - stereo low noise universal preamp

PCB for the instrument or hi-fi preampsSwitch module for preamps

TOP LAYER

TOP LAYER

BOTTOM LAYER

BO

TT

OM

LAY

ER

PCB OVERLAY

PC

B O

VE

RLA

Y


1 1

1

Q3

Q4

H3

C1

C5

C9

U1

3

Q2

H2

3

Q1C7

R4R3

R7

R1

R5

R2

R6

H1

C3

P3

P2

J1

C8

1

C15

R10

C16

C4

C18

C6

R9

C2

P1

C10

C11

3C17

C20

U2

3

R11C22 C21

R8C14 C13

C12

C19

1 1

1

Q3

Q4

H3

C1

C5

C9

U1

3

Q2

H2

3

Q1C7

R4R3

R7

R1

R5

R2

R6

H1

C3

P3

P2

J1

C8

1

C15

R10

C16

C4

C18

C6

R9

C2

P1

C10

C11

3C17

C20

U2

3

R11C22 C21

R8C14 C13

C12

C19

1

1

2

2

3

3

4

4

5

5

6

6

D D

C C

B B

A A

Title

Number RevisionSize

A

Date: 10/18/2011 Sheet ofFile: D:\!Works\..\Switches.SchDoc Drawn By:

123456

789101112

P5

Header 6X2A

123

654SW

2

A/B Switc

h

123

654

SW1A/B Switch

1 2 3

6 5 4

SW3

A/B Switc

h


Switch module

71

71




PCB for the instrument or hi-fi preampsThe PCB of power supply

TOP LAYER

BOTTOM LAYER

1 2 1

C13

C4

R2

C7

C6

C8

C9

R1

C10

C12

D2

3C5

U2

3C14

H1

C1 C2

H2

C11

U1

2D1

C3

D3

1 2 1

C13

C4

R2

C7

C6

C8

C9

R1

C10

C12

D2

3C5

U2

3C14

H1

C1 C2

H2

C11

U1

2D1

C3

D3


PCB OVERLAY



Images and Picasa

galleries about the

prototype of preamps

Images about the prototypes of this preamp projectThe selectable prototype of jFEt and OpAmp projects

The Picasa gallery about this circuit




Images about the prototypes of this preamp projectAudio mixer with jFET and OpAmp preamps

Images about the prototypes of this preamp projectMicrophone preamp with INA217

The Picasa gallery about this circuit The Picasa galleries about this circuit:

• Planning and collecting parts• Images about the prototype• Testing the INA217 board

http://lh5.ggpht.com/-rwWJfEoHk1Q/Sg1v6dzLaqE/AAAAAAAAB04/PDEijSzfo4s/s144-c/MixerWithPreampms.jpg


https://picasaweb.google.com/105028544937175433650/MicPreampTervek

https://picasaweb.google.com/105028544937175433650/Ina217MicPreamp

https://picasaweb.google.com/105028544937175433650/MicPreampTesting

English blog and PCB order: http://custompcb.blogspot.com/Hungarian blog and PCB order: http://diyguitarpa.blogspot.com/

The Youtube Channel • Picasa gallery • Email: [email protected]

http://custompcb.blogspot.com/

http://diyguitarpa.blogspot.com/

http://www.youtube.com/playlist?list=PLDBAFF83D547F7EB7&feature=viewall

http://picasaweb.google.com/gitarfogas

mailto:gitarfogas%40gmail.com?subject=PDF%20Message%20-%20EQ%20Project

preamps public doc

Documents

opamp preamps

stereo dual opamp instrument

overlay of stereo jfet

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