Pi-Amp Rev. 6

Amplifier


Pi-Amp Rev. 6 Leach Amp V4.5 PCB Amplifier Complete

Leach Amp V4.5 PCB component layout:

Pi-Amp Rev. 6 Leach Amp V4.5 PCB Component Layout

Download Leach Amp V4.5 Component Layout.

Leach Amp V4.5 PCB bill of material:

Schematic Reference Description Quantity Manufacturer Stock Number USD ea. Total
Q1, Q2, Q5, Q7, Q9, Q10 TRANS NPN MPSA06 12 ON Semiconductor DK MPSA06 0.50 6.00
Q3, Q4, Q6, Q8, Q11 TRANS PNP MPSA56 10 ON Semiconductor DK MPSA56 0.50 5.00
Q13, Q14 TRANS NPN 2N3439 4 STMicroelectronics DK 497-2576-5-ND 2.00 8.00
Q12, Q15 TRANS PNP 2N5416 4 STMicroelectronics DK 497-2596-5-ND 2.25 9.00
Q16 TRANS PWR NPN MJE15030 2 ON Semiconductor DK MJE15030GOS-ND 1.50 3.00
Q17 TRANS PWR PNP MJE15031 2 ON Semiconductor DK MJE15031GOS-ND 1.50 3.00
Q18, Q20 TRANS PWR NPN MJ15003 4 ON Semiconductor DK MJ15003GOS-ND 4.25 17.00
Q19, Q21 TRANS PWR PNP MJ15004 4 ON Semiconductor DK MJ15004GOS-ND 4.25 17.00
Heat Sink for Q16, Q17 HEATSINK TO-220 CLIP-ON BLK 4 Aavid DK HS111-ND 0.40 1.60
Q18-21 Socket SOCKET FOR .090" TO-3 CASE 8 Keystone Electronics DK 4601K-ND 2.40 19.20
Q18-21 Wafer THERMAL PAD TO-3 8 Bergquist DK BER100-ND 0.75 6.00
D1, D2, D3, D4, D11, D12 DIODE GP 400V 1A DO204AL 12 Vishay DK 1N4004-E3/54GICT-ND 0.50 6.00
D5, D6, D7, D8, D9, D10 DIODE SS FAST 100V 200MA DO35 12 Fairchild Semiconductor DK 1N4148TACT-ND 0.15 1.80
D13, D14, D15, D16 DIODE ZENER 20V 500MW DO35 8 Fairchild Semiconductor DK 1N5250B-ND 0.15 1.20
C1 CAP 390PF 500V MICA RADIAL 2 Cornell Dubilier DK 338-1057-ND 2.90 5.80
C2, C3, C15, C16, C23, C24 CAP FILM 0.1UF 100VDC RADIAL 12 EPCOS DK 495-1149-ND 0.60 7.20
C7, C12, C17, C18 CAP FILM 0.1UF 100VDC RADIAL 8 EPCOS DK 495-1147-ND 0.30 2.40
C4, C5, C13, C14, C21, C22 CAP 100UF 63V ELECT FC RADIAL 12 Panasonic DK P10343-ND 0.60 7.20
C6 CAP ELECT 220UF 16V SU NON-POLAR 2 Panasonic DK P1168-ND 0.75 1.50
C6 a/b (alt. to C6) CAP 330UF 16V ELECT FC RADIAL 4 Panasonic DK P10246-ND 0.50 2.00
C8 CAP 180PF 500V MICA RADIAL 2 Cornell Dubilier DK 338-1082-ND 1.90 3.80
C9 CAP 47PF 300V MICA RADIAL 2 Cornell Dubilier DK 338-1084-ND 2.40 4.80
C10, C11 CAP 10PF 500V MICA RADIAL 4 Cornell Dubilier DK 338-1068-ND 1.50 6.00
C19, C20 CAP .01UF 50V STACK METAL FILM 4 Panasonic DK P4513-ND 0.30 1.20
P1 POT 2.0K OHM 3/8" SQ CERM SL ST 2 Bourns DK 3386P-202LF-ND 1.25 2.50
R1 RES METAL FILM 20.0K OHM 1/4W 1% 10 Yageo DK 20.0KXBK-ND 0.15 1.50
R2 RES 2.00K OHM 1/4W 1% METAL FILM 10 Yageo DK 2.00KXBK-ND 0.15 1.50
R3-R10 RES 301 OHM 1/4W 1% METAL FILM 20 Yageo DK 301XBK-ND 0.15 3.00
R11, R12, R27 RES 1.21K OHM 1/4W 1% METAL FILM 10 Yageo DK 1.21KXBK-ND 0.15 1.50
R13, R14 RES 2.21K OHM 1/4W 1% METAL FILM 10 Yageo DK 2.21KXBK-ND 0.15 1.50
R15, R16 RES 12.1K OHM 1/4W 1% METAL FILM 10 Yageo DK 12.1KXBK-ND 0.15 1.50
R17, R18 RES 11.0K OHM 1/4W 1% METAL FILM 10 Yageo DK 11.0KXBK-ND 0.15 1.50
R19 RES 1.10K OHM 1/4W 1% METAL FILM 10 Yageo DK 1.10KXBK-ND 0.15 1.50
R20 RES 22.1K OHM 1/4W 1% METAL FILM 10 Yageo DK 22.1KXBK-ND 0.15 1.50
R21, R22 RES 29.4 OHM 1/4W 1% METAL FILM 10 Yageo DK 29.4XBK-ND 0.15 1.50
R23, R24 RES 365 OHM 1/4W 1% METAL FILM 10 Yageo DK 365XBK-ND 0.15 1.50
R25, R26 RES 1.00K OHM 1/4W 1% METAL FILM 10 Yageo DK 1.00KXBK-ND 0.15 1.50
R28, R29 RES 274 OHM 1/4W 1% METAL FILM 10 Yageo DK 274XBK-ND 0.15 1.50
R30, R31 RES 3.92K OHM METAL FILM .50W 1% 10 Vishay DK PPC3.92KXCT-ND 0.25 2.50
R32, R33, R51 RES 82.5 OHM 1/4W 1% METAL FILM 10 Yageo DK 82.5XBK-ND 0.15 1.50
R34, R35 RES 332 OHM 1/4W 1% METAL FILM 10 Yageo DK 332XTR-ND 0.15 1.50
R36 RES 221 OHM METAL FILM .50W 1% 10 Vishay DK PPC221XCT-ND 0.25 2.50
R37-R40 RES 681 OHM 1/4W 1% METAL FILM 10 Yageo DK 681XBK-ND 0.15 1.50
R41-R44 RES 10.0 OHM METAL FILM .50W 1% 10 Vishay DK PPC10.0XCT-ND 0.25 2.50
R45-R48 RES .33 OHM 5W 5% WIREWOUND 8 Yageo DK 0.33W-5-ND 0.50 4.00
R49 RES 10 OHM 1% WW AXIAL 2 Vishay DK ALSR5F-10-ND 1.75 3.50
PCB Marshal Leach V4.5 2 Pi-Amp.com 25.00 50.00
Total NA NA NA NA NA 238.70

Download Leach Amp V4.5 PCB Bill of Materials.


Pi-Amp Rev. 6 Chassis Wiring and Controls Schematic:

Pi-Amp Rev. 6 Amplifier Wiring Schematic

Download Pi-Amp Rev. 6 Chassis Wiring and Controls Schematic.

Pi-Amp Rev. 6 Chassis Wiring and Controls bill of materials:

Schematic Reference Description Quantity Manufacturer Stock Number USD ea. Total
S1 SWITCH TOGGLE DP3T On-On-On 6A 1 NKK DK 360-2082-ND 13.70 13.70
S2 SWITCH TOGGLE DPDT On-On 5A 1 NKK DK 360-1843-ND 4.70 4.70
S3 (See PC) SWITCH TOGGLE DPDT MOM 6A 1 NKK DK 360-2078-ND 6.30 6.30
P1 ALPS RK27 Dual 100K 1 ALPS RK27112A00AK 13.00 13.00
J1, J2 STEREO JACK PHONE 1/4" 3POS OPEN 2 Switchcraft DK SC1094-ND 2.70 5.40
J3 RCA Jacks, Insulated, Panel Mount 2 Parts Express PA 091-1120 3.45 6.90
J4 (See PC) Front Panel USB Port 1 Switchcraft Panel Mount USB A to B 6.60 6.60
Speaker Binding Posts Bindng Posts, Insulated 4 Parts Express PA 320-3375 2.50 10.00
R1 RES 470 OHM 5% WW 2 Vishay Dale DK ALSR5J-470-ND 1.60 3.20
R2 RES 25 OHM 5W 1% WW 2 Vishay Dale DK RSC-25RCT-ND 1.50 3.00
R3 RES 120 OHM 2W 5% METAL FILM 2 Yegeo DK 120ZCT-ND 0.20 0.40
R4 RES 10 OHM 1% WW AXIAL 2 Vishay Dale DK ALSR5F-10-ND 1.75 3.50
C1 CAP FILM 0.1UF 400VDC AXIAL 2 Cornell Dubilier DK 338-3278-ND 1.85 3.70
Total NA NA NA NA NA 80.40

Download Pi-Amp Rev. 6 Chassis Wiring and Controls Bill of Materials.


  1. Installed the amplifier controls and Leach Amplifier PCB's on the face plate. The leads between the face plate and the other chassis components are long enough to allow wiring with the face plate folded flat. The leads connecting the power transistors to the amp PCB's are soldered to the component side of the PCB's.
    • 1 and 2, right and left amp PCB's, respectively.
    • S3, PC power and reset, not wired at this stage. Start or reboot the PC.
    • S2, speaker / headphone selector switch. Amplifier output to speakers or face plate phono jack.
    • P1, volume control. Adjust the line level signal from the PC sound card, face plate 1/4" phono jack, and rear panel RCA jacks.

      Note: Threaded portion of volume control shaft not long enough to penetrate 3/16" face plate. Machined 1" x 1" x 3/32" recess using a 1/4" spiral "O" single flute solid carbide bit mounted in a plunge cutting router.
    • S1, Three position audio source selector switch. Select line level audio source from PC sound card, face plate 1/4" phono jack, or rear panel RCA jacks.
    • J1, 1/4" phono output jack. Listen to audio using headphones with 1/4" or 1/8" male phono plug.
    • J2, 1/4" phono input jack. Connect mp3 player or other device to the amplifiers using 1/8" or 1/4" male phono plug.
    • J4, front panel USB port. Transfer audio and video files to and from the PC hard drives.
    • R1, R2, R3, headphone attenuator circuit. Reduces 30 V peak amplifier output to 1.5V peak.


    Pi-Amp Rev. 6 Amplifier Face Plate Open
  2. Wired rear panel speaker binding posts, Zobel bridge (R4, C1), and RCA jacks (J3)

    Pi-Amp Rev. 6 Amplifier Rear Panel Wiring
  3. Joined the face plate to the chassis base.

    Pi-Amp Rev. 6 Amplifier Face Plate Joined to Chassis Base Rear View
    Pi-Amp Rev. 6 Amplifier Face Plate Joined to Chassis Base Front View
    Pi-Amp Rev. 6 Amplifier Face Plate Controls Rear
    Pi-Amp Rev. 6 Amplifier Face Plate
  4. Removed "ON Semiconductor" logo from the power transistors for aesthetics. Marked transistor type on back of each transistor case. Transistor order, left to right, as viewed from the front is: MJ15003, MJ15003, Bias Diodes, MJ15004, MJ15004.

    Pi-Amp Rev. 6 Amplifier Face Plate Controls Front
  5. Replaced stock transformer mounting bolt with modified carriage bolt for maximum clearance between bolt head and sound card.

    Pi-Amp Rev. 6 Amplifier Face Plate Joined to Chassis Base Rear View
    Pi-Amp Rev. 6 Amplifier Rear Panel Joined to Chassis Base Rear View
  6. Prepared chassis feet from hard maple. Attached to the chassis using 3M double sided tape (better than screws).

    Pi-Amp Rev. 6 Hard Maple Chassis Feet and Double Sided Tape

    Pi-Amp Rev. 6 Hard Maple Chassis Feet Installed
  7. Cleaned up the chassis with #0000 steel wool and isopropyl alcohol.

    Pi-Amp Rev. 6 Amplifier Complete
  8. Scope and sound checked the amplifier - excellent!
    Signal 20KHz, 2V peak to peak, square wave.
    Output 40V peak to peak, no load.

    Pi-Amp Rev. 6 Amplifier Complete

    Amplifier Complete.