DIY TDA2050 IC Hi-Fi Chip Amplifier
DIY TDA2050 IC Hi-Fi Chip Amplifier
This project which I call a "Mini Gainclone" is a stereo amplifier with an added headphone output. The amplifier is built around a single integrated circuit (IC), the TDA2050V which is produced by STMicroelectronics. From the data sheet, the TDA2050V is intended for use as a Class-AB hi-fi audio amplifier. The chip will operate within a supply voltage range of +/-4.5V to +/-25V. At about 25W of power output the efficiency is about 65%. One thing to note is that the gain of the circuit needs to be at least 24dB to maintain stability.
The amplifier was built to drive a pair of my friends Klipsch RB-51 Bookshelf speakers. The speakers are 8 ohms and have a sensitivity of 92dB @ 2.83V / 1m, so it does not take much power to get high SPL which makes the TDA2050 a nice match. The amplifier can be driven by most line-level sources such as an mp3 player, cd player, tuner and so on. The small TDA2050V chip can sound very well, similar to the popular ICs from National Semiconductor.
Construction - DIY TDA2050 Amplifier
Before we get started, I suggest you take a look at the TDA2050 Data sheet - (PDF 2.25MB), particularly if you want to make some changes to match your stereo setup. Figure 1 below is from the data sheet and shows the typical application using a split supply.
Figure 1: TDA2050 Typical Hi-Fi Amplifier Schematic
The data sheet also includes a PCB design (shown in Figure 2) that one can use. I used a protoboard for my amplifier (details below).
Figure 2: TDA2050 Hi-Fi Amplifier PCB Design
A schematic of the amplifier I built is shown below (Figure 3). Only one channel is shown. A double pole, double throw (DPDT) switch is shared between both channels and this allows switching the output between speakers output or headphone output. If you do not need a headphone output, you can eliminate the DPDT switch and the resistors after the switch. The headphone adapter is from the Rod Elliott (ESP) site which you can reference for more details.
The gain of the circuit is 33 (30 dB) which should work well for most line level sources. You can adjust the gain, but note that note that the minimum gain for stability is 16 (24dB)
Figure 3: DIY TDA2050 Hi-Fi Amplifier Schematic
The circuit has been constructed on a protoboard (perfboard) and the general layout follows the PCB design shown in Figure 2. For the input DC blocking capacitor I used a 1uF Audyn MKP (metalized polypropylene film) capacitor. Use your personal preference of capacitor here. Most film type capacitors (polypropylene, polyester, mylar ...) should be a large improvement over electrolytic caps which I don't recommended.
Photograph 1: TDA2050 Hi-Fi Amplifier ProtoBoard - Top View
Photograph 2: TDA2050 Hi-Fi Amplifier ProtoBoard - Bottom View
It is fairly simple to construct the circuit on a variety of protoboards. Here are some additional construction tips that I hope you find useful.
- A proper grounding scheme is important to obtain low noise. The best approach is to use a star grounding technique. You will want two star ground points - one for the signal and one for the power. The two ground points should then be connected together through a single connection.
- Try keep the signal wiring as short as possible. Also, the signal wires should be tightly twisted together. You will also want to keep them away from any AC sources like the mains power cord and the transformer. Keeping the wires as close as possible to the chassis also helps.
- Use separate power supply wiring to each channel.
DIY Chip Amplifier Power Supply
Before I describe the power supply, I want to say a few things about safety. This project requires a mains wiring connection (120 or 220V) which you do not want to get in between. Faulty or incorrect mains wiring can result in death or serious injury! Please refer to your local electrical code for the mains connection requirements. Use appropriate fuses and connect the chassis to the mains "earth".
The power supply generally follows the "snubberized" Gainclone PSU design Carlos Filipe (CarlosFM). A torroidal transformer with dual 18 Volt secondaries and rated at 120VA (3.3A per secondary) is used. For the rectifiers I used 35A rectifier bridges (15-25A bridges should also work). In the original PS schematic by Carlos Filipe ultra-fast MUR860 diodes are used. Discrete ultra-fast rectifiers can also be used at an increased cost. I found no need to use them. Each power supply rail has a 10,000uF capacitor which is shared between the channels. The supply has only very slight hum which can only be heard with my AKG headphones when I turn the volume to max and no signal connected.
Figure 4: TDA2050 Chipamp Power Supply Schematic
Photograph 3: TDA2050 Hi-Fi Chip Amplifier and Power Supply
DIY TDA2050 Chip Amplifier Enclosure
For the enclosure I used a satin black steel 12" x 8" x 3" chassis from Hammond (Model 1441-24). The transformer and circuit boards are hung from the top of the enclosure. The power switch, volume control and headphone socket are on the front of the enclosure for easy access.
Photograph 4: TDA2050 Hi-Fi Chip Amplifier Enclosure
For input, standard gold plated RCA jacks are used. The speaker output plugs are standard three-way binding posts that will accept a 4 mm banana plug, a spade connector or bare wire. Note that the input jacks and speaker binding posts are insulated from the chassis using the supplied nylon spacers.
The heat sinks are placed on the back of the chassis. For the heat sinks I used a pair that each measured 50 mm x 88 mm with 35 mm fins and rated at 2.9 C/W. Additional details to determine an appropriate size of heat sink are described in the data sheet. A hole was cut in the chassis so that the TDA2050 package could be mounted directly on the heat sink. Note that the TDA2050 IC must be isolated from ground (the chassis) as the negative potential resides on the metal tab of the TO-220 package. Failing to do so will destroy the chip once power is applied. For isolation you can use silicon pads or mica and don't forget a spacer for the mounting screw that will secure the chip to the heat sink. Once installed check to make sure there is no continuity between the tab of the chip and the heat sink / chassis / ground. Also, to ensure good thermal contact I used some thermal grease on the back of the chip prior to mounting.
Photograph 5: TDA2050 Hi-Fi Chip Amplifier Enclosure - Rear View
Sound - TDA2050 Hi-Fi Chip Amplifier
I will not make too many comments on the sound as it is ultimately up to the individual listener to decide. To my ears the small TDA2050 chip produces a very good sound which can hold it own against various high quality amplifiers I have used. The amp has the ability to produce deep bass, clear mids with a wide sound stage and crisp highs that are not too sharp.
Have fun building this one! If you do build one, I would be happy to see some photos of your TDA2050 amps. Most importantly, have a lot of fun by listening to your work. If you need help building this project or if you have any questions, you may direct them to the TDA2050 Hi-Fi Chip Amplifier Project (Support) thread on the forum.
DIY PCB for TDA2050 Hi-Fi Chip Amplifier
UPDATE - 16 April 2012
Here is a little update for the TDA2050 Hi-Fi Chip Amplifier project. I have made a PCB design for the amplifier circuit. The photos below show my DIY PCB for the TDA2050 amplifier circuit.
Photograph 6: DIY PCB Boards for TDA2050 Chip Amplifier
Photograph 7: DIY PCB Boards for TDA2050 Chip Amplifier
The PCB layout easily fits on a standard copper clad board or photo PCBs (160 x 100mm). A PDF of the PCB Images is attached below. Don't scale or rescale. The PCB layout must be mirorred to expose the copper. Flip the exposure film to the left. Direct Toner: The text must be readable. Also below is an updated list of components for the new PCB.
- TDA2050 PCB Images - (PDF 42kB)
- TDA2050 PCB Components Layout - (PDF 19kB)
- Updated List of Components for TDA2050 PCB - (PDF 17kB)
DIY Power Supply PCB for TDA2050 Amp
UPDATE - 16 April 2012
Here is a little update. I've made a layout for a proper and juicy new Power Supply Unit for use with the TDA2050 amplifier project (and the LM1875 which can be used in place of the TDA2050). The complete PSU project should explain itself. It's a no brainer - also for beginners.
The PCB layout for the power supply can be used with standard copper clad board or photo PCB. A PDF of the PCB Image with two boards on one page is attached below. Flip the exposure film to the left. Direct Toner: The text must be readable. A list of materials and component layout for the new power supply PCB is also attached.
- Power Supply PCB Images - (PDF 23kB)
- Power Supply PCB Component Layout - (PDF 19kB)
- Updated List of Components for Power Supply PCB - (PDF 17kB)
Wiring information: Use a transformer as suggested on the project page. One dual secondary (2 x 18VAC / about 160VA) is your friend. The two wires from one secondary winding (= 2 x one pair) connects to one pair of AC inputs on the rectifier diode section. One secondary pair to the upper section (+), one secondary pair to the lower section (-). Please feel free to comment or to ask any questions that you may have about this amplifier project on the TDA2050 Hi-Fi Chip Amplifier Project (Support) thread.
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