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STD Op Amp Mixer 2.1 version 1

Op Amp Mixer 2.1 version 1

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License

Public Domain

License: Public Domain

Mode:

Mode

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Cloned from Op Amp Mixer

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Update time: 2024-09-29 15:01:26
Creation time: 2024-05-05 05:43:21
Description

Description

2.1 mixer preamp board that allows two inputs mixed to a single Stereo output and Subwoofer output. For example, great for computer audio input. Has sub output and bass and treble boost cut. I have now tested the sub output and have added that video to this project and my SqueezLite Rover project here. Based on TI OPA1654 op amp but should work with any good opamp. Overall, I am happy with this project result! However, improvements are always welcome. Oh, and video's may be LOUD so turn down your sound before playing!

 

Also, I am using PTD902 and PTD901 series potentiometers.

J1 and J2 are 50k such as PTD902-2015K-B503. Also, you can just use PTD902-2015K-B103 if your inputs can tollerate a 10k load and most things are just fine with 10k loads. 

VR1 is 100k PTD902 such as PTD902-2215K-B104 with Detent.

VR2 is 10k PTD902 such as PTD902-2015K-B103 

VR3 is 200k PTD902 such as PTD902-2215K-B204 with Detent.

VR6 is 20k PTD902 such as PTD902-2215K-B203 with Detent.

VR7 is 10k PTK901 as it only has one output such as PTD901-1015K-B103.

VR8 is 50k 4 gang pot PTD904-1215K-B503 with Detent.

I think I have completed this project now.

The good: it works and has really good sound.

The bad: After many attempts to isolate digital noise crated by the ESP32 I have decided that DAC onboard of the pre-amp creates some digital noise that is picked up by the preamp opamps. So, after many attempts to clean this up I have decided to remove the DAC and place it on the ESP32 board directly. I have updated the schematics design to reflect this change. Also, I have found that even powering the DAC via this preamp introduces to much noise into these sensitive preamps.

I would go as far to say do not even attempt to run an ESP32 via the same power supply. I have spent hours of time redesigning the power supply of this board and nothing has been able to prevent the ESP32 from injecting digital noise into the preamp. So, this works great for very small and simple I2S micro controllers. However, if you plan on using with an ESP32 wait until I provide the ESP32 Rover and DAC on my Squeeze Rover DAC project I will be posting by Friday of this week. I have spent much time on both of these already and am waiting for the final boad designs on both of these to give an overall review of a really capable preamp with SqueezeLite cababilities. That project is awsome so go check it out here. Also, check out my blog here there is also a post on this project there and another more simple project based on ESPHome here

 

Overall, I am almost done with this project. I am proud of how far I have taken it to get to this point. I know I called it a simple preamp but after much testing it has grown into this project. I concider it a well rounded project that delivers excellent sound when you take into concideration about power supplies and isolation of digital from the sensitive analog preamp stage. So, with proper power supply conciderations this delivers very high quality sound with very little background noise or distortion. 

 

I have also added this project here for the ESP32 SqueezeLite client. This project adds Bluetooth and SquezeLite to this preamp project. I have also added this post to my alshowto.com site.

 

Added Extra Features

So, this addition allows one to add other outputs that get the same feed as the final output stage. This allows one to do things like add midrange controls as the overall board is as big as I really want to make it. For example, I am working on a center channel element that will allow center midrange speakers to be added. This is also a great spot to add future filtering or further sub woofer outputs tuned to specific amps and speakers. Very much control can be had with this and I will also be adding input 

modules in the future. For now I am testing the center channel concept out and will add that to the project list once I have ironed out all the bugs.

  • GRD - of coarse this is ground for the extra features.
  • 15+ - Positive 15 volts to power extra features.
  • 15- - Negative 15 volts to power extra features.
  • LP - Left Pre Output. This is right before output of final stage that is the final HP filter AKA: LPre in schematic. 
  • RP - Right Pre Output. THis is right before output of final stage that is the final HP filter AKA: RPre in schematic.

 

 

Design Drawing

Design Drawing

schematic diagram
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PCB
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ID Name Designator Footprint Quantity Manufacturer Part Manufacturer Supplier
1 270nF C2,C3,C9,C10 C0603 4 CC0603KRX7R7BB274 YAGEO(国巨) LCSC C519443
2 5.6nF C5,C12 C0402 2 C0402X7R562K500NTB EYANG(宇阳科技) LCSC C115688
3 2.21kΩ R1,R2,R4,R12,R13,R16 R0402 6 CR0402FF2211G LIZ(丽智电子) LCSC C100313
4 2.71kΩ R8,R9,R20,R21 R0402 4 RC0402FR-072K71L YAGEO(国巨) LCSC C477660
5 20k VR1,VR4 RES-ADJ-TH_PTD902 2 PTD902-2215K-B203 Bourns Mouser 652-PTD902-2215KB203
6 100k VR3 RES-ADJ-TH_PTD902 1 PTD902-2215K-B104 Bourns Mouser 652-PTD902-2215KB104
7 22uF C22,C23 C2220 2 FS55X226K500EHG PSA(信昌电陶) LCSC C784103
8 2.54mm 1*2P P1 HDR-TH_2P-P2.54-V-M 1 2.54mm 1*2P null LCSC C36717
9 2.54-1*3P CN5,CN2,CN3,CN4 CONN-TH_C722693 4 2.54-1*3P CAX(创都) LCSC C722693
10 XH-4A-A CN6 CONN-TH_XH-4A-A 1 XH-4A红色 null LCSC C9900016113
11 HX 2.54MM-5P ZZ CN7 CONN-TH_5P-P2.50_HX-2.54MM-5P-ZZ 1 HX 2.54mm-5P ZZ hanxia(韩下) LCSC C7543434
12 560Ω R26,R31 R0603 2 0603WAF5600T5E UNI-ROYAL(厚声) LCSC C23204
13 51kΩ R27,R29,R34,R35 R0603 4 0603WAF5102T5E UNI-ROYAL(厚声) LCSC C23196
14 57.6kΩ R28 R0603 1 RC0603FR-0757K6L YAGEO(国巨) LCSC C245983
15 15kΩ R30,R23 R0603 2 0603WAF1502T5E UNI-ROYAL(厚声) LCSC C22809
16 100Ω R32,R40,R45,R47,R48,R6,R18 R0603 7 0603WAF1000T5E UNI-ROYAL(厚声) LCSC C22775
17 33kΩ R33,R36,R11,R22 R0603 4 0603WAF3302T5E UNI-ROYAL(厚声) LCSC C4216
18 5.6kΩ R37,R38,R42,R43 R0603 4 0603WAF5601T5E UNI-ROYAL(厚声) LCSC C23189
19 1kΩ R39,R44,R10,R14,R19,R3 R0603 6 0603WAF1001T5E UNI-ROYAL(厚声) LCSC C21190
20 1.74kΩ R41,R46 R0603 2 0603WAF1741T5E UNI-ROYAL(厚声) LCSC C22848
21 4.7uF C45,C46,C41,C44,C15,C16,C32,C33,C36 C0603 9 CL10A475KO8NNNC SAMSUNG(三星) LCSC C19666
22 100nF C47,C48,C42,C43,C17,C18,C30,C31,C34,C35 C0603 10 CC0603KRX7R9BB104 YAGEO(国巨) LCSC C14663
23 OPA1652AIDR U5 SOIC-8_L5.0-W4.0-P1.27-LS6.0-BL 1 OPA1652AIDR TI(德州仪器) LCSC C30025
24 WAFER-XH2.54-2PZZ CN1 CONN-TH_XH2.54-2P_1 1 WAFER-XH2.54-2PZZ XUNPU(讯普) LCSC C5359631
25 10k VR5 PTD901-1015K-B103 1 PTD901-1015K-B103 Bourns Mouser 652-PTD901-1015KB103
26 50k VR6 BOURNS_PTD904 1 PTD904-1215K-B503 Bourns Mouser 652-PTD9041215KB503
27 OPA1654AIPWR U4,U3,U1 TSSOP-14_L5.0-W4.4-P0.65-LS6.4-BL 3 OPA1654AIPWR TI(德州仪器) LCSC C544430
28 3.3nF C1,C7,C8,C14 C0603 4 CL10B332KB8NNNC SAMSUNG(三星) LCSC C1613
29 10uF C11,C13,C4,C6 C0603 4 CL10A106MA8NRNC SAMSUNG(三星) LCSC C96446
30 150nF C37,C38,C39,C40 C0603 4 0603B154K500NT FH(风华) LCSC C1597
31 220uF C19,C24,C28 CAP-SMD_BD10.0-L10.3-W10.3-LS11.0-FD 3 RVT220UF50V67RV0021 KNSCHA(科尼盛) LCSC C2887271
32 4.7uF C20,C25,C27 C1206 3 1206B475K500NT FH(风华) LCSC C29823
33 1uF C21,C26,C29 C0603 3 CL10A105KB8NNNC SAMSUNG(三星) LCSC C15849
34 2kΩ R25 R0603 1 0603WAF2001T5E UNI-ROYAL(厚声) LCSC C22975
35 10k J1,J2 PTD9022015KA503 2 PTD902-2015F-B103 Bourns Mouser 652-PTD902-2015FB103
36 SS310F D1,D2,D3 SMAF_L3.5-W2.6-LS4.7-RD 3 SS310F 晶导微电子 LCSC C116123
37 LESD8D24CT5G D4 SOD-882_L1.0-W0.6-BI 1 LESD8D24CT5G LRC(乐山无线电) LCSC C2912020
38 TLC-LSMD050/50 F1 F2920 1 TLC-LSMD050/50 TLC(竞沃) LCSC C506870
39 2.2uH L1,L5 IND-SMD_L3.5-W3.0_SLF0302 2 CD32YP0302-2R2M YJYCOIN(益嘉源) LCSC C492258
40 33uH L2,L3,L4 IND-SMD_L7.2-W6.6_GPSR0730 3 CYA0650-33UH SHOU HAN(首韩) LCSC C5189937
41 22kΩ R24 R0603 1 0603WAF2202T5E UNI-ROYAL(厚声) LCSC C31850
42 XL6007E1_C5240411 U2 SOIC-8_L4.9-W3.8-P1.27-LS6.0-BL 1 XL6007E1 XLSEMI(芯龙) LCSC C5240411
43 24v V1 R0805 1 SDV2012E260C800NPTF Sunlord(顺络) LCSC C882642
44 18kΩ R15,R17,R5,R7 R0603 4 0603WAF1802T5E UNI-ROYAL(厚声) LCSC C25810
45 10k VR2 RES-ADJ-TH_PTD902 1 PTD902-2015F-B103 Bourns Mouser 652-PTD902-2015FB103

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Project Attachments

Project Attachments

Order File name Download times
1

12cDacDemo.mp4

2
2

ESP32Playing.mp4

2
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