Failure in the official datasheet of TDA7293

The original datasheet of TDA7293 is not correct. The 10th page for parallel module is wrong on the first version created at 1999. If you seek the datasheet by google, you may find this older version first. You have to use new datasheet created at 2003. Here is an article about this problem (and my own paralleled TDA amplifier by the datasheet 1999 was wrong like in the article):

"Make sure to use the schematic from the datasheet from 2003. Slave mode is activated by pulling IN+, IN- and SGND to -Vs, the negative supply! In older versions of the schematic slave mode is NOT activated properly, which may lead according to reports on the internet to the destruction of the chip."

About these datasheets:

On the first version created at 1999 the inputs of slave chip is grounded:


In the new datasheet from 2003 this is changed to "-" power voltage:


This change is very important for parallel design. Against chip destruction and high value of distortion use the second version of the official datasheet.

See also:

• TDA7293 for more than 300W
• New PWM Fan controller with speaker protection
• Modular TDA7293 bridge/parallel amplifier
• PDF manual for TDA7293 amplifiers
  

TDA7293 for more than 300W (500-600-700W)

My previous post, where I wrote about the TDA7294 and 7293 modular amplifier design, I uploaded a table about the output powers:



By this table, for the maximum 300W amplifier required:

• 1 Main module
  
• 2 Parallel module
  
• 1 Bridge module
  
• 2 Parallel module
  
• Speaker protection with FAN controller
  

This amplifier required 6 pcs TDA7293, but for stereo device 12 pcs needed. The "chip" is really low cost, not too much for 300W amplifier.

But not only 2 parallel chips can be inserted after the main and bridged module. Schematics with 3 parallel modules (after main and bridged modules too) may possible. If the possible output current of one chip is 2.5A, with 4 chips (one main or bridged, and 3-3 paralleled modules after main and bridge circuits) is 4x2.5=10A. With +-40V (80V) the result is 800W like in this schematic. But this is not true. One chip is 75W, 8x75=600W maximum output power.

The official guitar amplifiers (Marshall, Carlsbro, ...) using one TDA729x chips always says 100W output powers what is not true. But for high output power around 550...600W not impossible. For this amplifier required good speaker protection and fan controller and very good power supply with kW-s of transformer and high values of capacitors.

See also:

• Failure in the official datasheet of TDA7293
• New PWM Fan controller with speaker protection
• Modular TDA7293 bridge/parallel amplifier
• PDF manual for TDA7293 amplifiers

PCB sales of this project Module name Size (mm) Area (cm2) PDF SCH PCB image Tested Price (US$) Des. Sim.1 Full2 Sim.1 Full2 Man3 TDA 7293 main module 59x65 38 Yes Yes Yes - - No 7 15 Ask TDA 7293 bridge module 44x50 22 Yes Yes Yes - - No 5 12 Ask TDA 7293 parallel module 41x47 19 Yes Yes Yes - - No 5 12 Ask Dual speaker protection 51x42 21 Yes Yes Yes - - No 5 12 Ask PWM Fan controller V:1 70x57 40 Yes Yes Yes - - No 7 15 Ask PWM Fan controller V:2 56x57 32 Yes Yes Yes - - No 6 14 Ask Stereo bridged TDA7294 amp (2x200W + speaker protection) 77x184 142 Yes Yes Yes Yes - Yes 21 - Ask Power supply for poweramps 135x98 132 Yes Yes Yes Yes - Yes 19 - Ask Soft start for toroid transformers 67x67 45 Yes Yes Yes Yes - Yes 8 - Ask How to order? Please read the rules carefully!

New PWM FAN controlers with speaker protection module

On the previous post I wrote about modular amplifier, can be connected to single, parallelled, and bridged mode (here is the PDF manual). The single amplifier is about 75-100W, bit with parallel and bridged mode the full poweramp maybe 700-800W (with bridged mode, but with 3 paralleled module). The original design contains one module for speaker protection with UPC1237 chip, which is very cheap and good solution. But the FAN controller for thermal protection is missing.

The thermal protection included to all TDA7293 chip, but no fan controller. The benefit of PWM FAN controller is the control sign is depend on the heatsink heat. I re-designed the PCB of speaker protection with PWM Fan controll circuit, but I made two versions. The first working with 4 OpAmps, and controls 3 fans with 10A output current:



The fan controller starts with 12V regulator, and the end of this circuit the 200V 10A MOSFET before fans. Paralleled with fans I have LED to display the "heat" of the system because the LED controlled with same same output like the fans.

Here is the PCB for this new module which compatible with the original speaker protection module:


This have PCB 7cm width, which is too much, so I looking for smaller and simpler fan controller circuit. Lot of solutions available on the NET with 555 and 556 timer IC, but I made something with MIC502 fan controller circuit. This circuit is simple and "vintage" DIL8 package, not the cheapest solution, but small, and not too much other parts required. The benefit of this solution, that the "sleep mode" setting. This is the threshold while the FANs not working (if not required).



with this simplest circuit I can design smaller PCB:


The width of this PCB is 55 mm instead of 70, what is good result. The speaker protection without PWM fan controller is 51 mm. This module now 4 mm wider.

I have one more choice to made PWM controller. The AMC6821 chip is really good solution. The chip made for computer mainboards, so the size is really small which is not really good for home designers, but maybe more smaller solution is good news for industrial designs.

The AMC6821 PWM Temp monitor and FAN controller chip:


The application of this is really easy and simple. The original module, contains speaker protection only is available if the single version of TDA729x modular amplifier required. But if using more modules for paralleled and bridged application, maybe for real instrument amplifications, the good heating system with temperature monitored FAN controller required.

See also:

• Failure in the official datasheet of TDA7293
• TDA7293 for more than 300W
• Modular TDA7293 bridge/parallel amplifier
• PDF manual for TDA7293 amplifiers

PCB sales of this project Module name Size (mm) Area (cm2) PDF SCH PCB image Tested Price (US$) Des. Sim.1 Full2 Sim.1 Full2 Man3 PWM Fan controller V:1 70x57 40 Yes Yes Yes - - No 7 15 Ask PWM Fan controller V:2 56x57 32 Yes Yes Yes - - No 6 14 Ask How to order? Please read the rules carefully!

Modular TDA7293 bridge/parallel amplifier

I finished the project of the most simplest and cheaper modular instrument amplifier. The final amplifier have output power between 70W and 300W for 4 and 8 ohm speakers. Three several modules required for this project if bridged and paralleled modes required. The 4th module is the speaker protection. The amplifier can be built as:

• Single amplifier with only one module with 1 TDA7293 or TDA7294 / channel
  
• Bridged amplifier with 2 modules / channel
  
• Paralleled amplifier with 2 modules / channel
  
• Combined bridged and paralleled with 4 modules / channel
  
• Paralleled simple or bridged amplifier, but with 2 paralleled module
  

The modules can be connected with 15 pin connectors instead of wires. The single, bridged, and paralleled amplifier modules are not same, one for the first and the most important "main" module, one for bridge connection, and one for parallel connection what can be used for both main and bridged modules. The last 4th module is the speaker protection, must be placed to the middle of stereo configuration between left and right channels.

The official datasheet contains all modes of TDA729x circuits. The TDA7294 is very cheap, but cannot use for paralleled mode, and no clipping led output. The recommended max. power supply voltage is +-40V. The TDA7293 have paralleled mode (where only the power stage works, the preamp stages off), the max. power supply voltage is +-47V, and clipping led output available. The maximum output power of one circuit is 70-75W of TDA7294, and about 80-100W of TDA7293.

The possible output powers of bridged application:


The V column is the power supply voltage, 1 means: 1 IC paralleled, 2 means: 2 IC paralleled with all others. Without superscripted number have no parallel connections, this is only bridged.

The possible output power with single (non bridged) application:

The V is the power supply voltage, 1 means: 1 IC paralleled, 2 means: 2 IC paralleled. Without superscripted number have no parallel connections.

The bridged or single version is very popular on "official" instrument amplifiers. Carlsbro GLX100, Marshall MG, and Marshall Mode Four contains TDA7293/7294 circuits. I using bridged application long time ago for stereo guitar amplifications and for microphones. This is more than enough for small rooms or rock clubs for live sessions with very good (for example Eminence) speakers.

The four modules (including speaker protection) can be connected by the 15 pin connectors soldered to the edge of the PCB. This is the method to build single, bridged, paralelled, bridged+paralleled, bridged+duble-paralleled, mono or stereo applications with very simple easy to build PCBs.

The first and the most important circuit is complete 70-75W amplifier:

This circuit always be the first of the complete amplifier configuration, which can be continued with parallel, bridge, or speaker protection module.

The PCB of main TDA module:


To the Conn2 on right edge can be connected another module for bridged or parallel application. It this one main module required (for 75W output power) then Conn2 can be used for speaker protection, but this is not required. The nother side have Conn4 connector for the second (right) channel is the setup is stereo. This Conn4 connector can be connected the speaker protection only. For example the simplest stereo setup is: 1 main module for left channel, 1 speaker protection, 1 main module for the right channel. Examples are on the PDF manual. The speaker protection will be protected bot left and right channels.

On this first PCB the Conn5 connector is the stereo audio level inputs, the right channel wired to the input of another main module on the right side of speaker protection. The output connector Conn6 is not stereo. This connector can be user for one channel only (the another output is on the second main module). The single setup uses Out+ and GND, the bridged setup uses Out+ and Out- for speaker connection.

The second circuit for bridge configuration:


And the bridge PCB:


The Conn4 connector of this bridge PCB can be used for the connection of first main circuit. This module can be continued by Conn5 connector with speaker protection (if the channel finalized) or with parallel module if more output current needed.

If the setup must be continued with parallel mode, here is the schematic:


PCB for parallel mode:


This is the simplest module, because the premaplifiers are off within the circuit, only the power FETs working. This mode controlled by Buffer Driver and Slave mode pins of TDA circuit. This module can be connected to the right side of main module, bridge module, or if required can be connected to the parallel module to duplicate the paralleled circuits within the application. The second parallel modules can be continued with speaker protection or with nothing only. The another edge of the speaker protection (if used) can be restart the full setup with main module for right channel.

The speaker protection:


And the PCB:


Here are the examples how to build complete amplifiers with several output powers with these four modules. The "Module 1" is always the first and always required main module, the "Module 2" is the optional bridge module, "Module 3" is the optional parallel module can be duplicated within the setup, and the 4th is the speaker protection.

The simplest mono setup (75W on 4 Ohm, with 8 Ohm about half):

1. Module 1
   
2. Speaker protection (optional)
   

Simple stereo setup (2x 75W on 4 Ohm, with 8 Ohm about half):

1. Module 1
   
2. Speaker protection (required)
   
3. Module 1

Mono bridged application (8 Ohm only, about 150W):

1. Module 1
   
2. Module 2
   
3. Speaker protection (optional)
   

Bridged stereo setup (8 Ohm only 2x150W)

1. Module 1
   
2. Module 2
   
3. Speaker protection
   
4. Module 1
   
5. Module 2
   

Mono paralleled setup (4 Ohm about 100W):

1. Module 1
   
2. Module 3
   
3. Speaker protection (optional)
   

Stereo paralleled setup (2 x 100W on 4 Ohm):

1. Module 1
2. Module 3
3. Speaker protection (required)
   
4. Module 1
   
5. Module 3
   

Mono bridged and paralleled (4 Ohm - 300W, 8 Ohm 200W):

1. Module 1
   
2. Module 3
3. Module 2
4. Module 3
   
5. Speaker protection (optional)
   

Stereo bridged + paralleled setup (About 2 x 300W on 4 Ohm):

1. Module 1
   
2. Module 3
   
3. Module 2
   
4. Module 3
   
5. Speaker protection
   
6. Module 1
   
7. Module 3
   
8. Module 2
   
9. Module 3
   

The parallel module can be connected to the first parallel module for duplication. This increases the maximum current, maybe smaller output impedance possible.

Doubled parallel bridge setup:

1. Module 1
   
2. Module 3
   
3. Module 3
   
4. Module 2
   
5. Module 3
   
6. Module 3
   

and the upper setup can be continued with speaker protection and the another edge of speaker protection can be repeated the same setup for right channel is stereo application required.

See also:

• Failure in the official datasheet of TDA7293
• TDA7293 for more than 300W
• New PWM Fan controller with speaker protection
• PDF manual for TDA7293 amplifiers
  

PCB sales of this project Module name Size (mm) Area (cm2) PDF SCH PCB image Tested Price (US$) Des. Sim.1 Full2 Sim.1 Full2 Man3 TDA 7293 main module 59x65 38 Yes Yes Yes - - No 7 15 Ask TDA 7293 bridge module 44x50 22 Yes Yes Yes - - No 5 12 Ask TDA 7293 parallel module 41x47 19 Yes Yes Yes - - No 5 12 Ask Dual speaker protection 51x42 21 Yes Yes Yes - - No 5 12 Ask PWM Fan controller V:1 70x57 40 Yes Yes Yes - - No 7 15 Ask PWM Fan controller V:2 56x57 32 Yes Yes Yes - - No 6 14 Ask Stereo bridged TDA7294 amp (2x200W + speaker protection) 77x184 142 Yes Yes Yes Yes - Yes 21 - Ask Power supply for poweramps 135x98 132 Yes Yes Yes Yes - Yes 19 - Ask Soft start for toroid transformers 67x67 45 Yes Yes Yes Yes - Yes 8 - Ask How to order? Please read the rules carefully!

2 input headphone amplifier with TPA6120

I already designed circuit and 3 versions of PCB with TPA6120. I heard only good reviews about this circuit, this is the reason why I made new version again. In this board I want to use all features of this circuit with 2 inputs and one outputs placed to the PCB, with transformer. I want to use this device for my computer sound-card what is EMU1212m, this card shipped without headphone output (and without microphone input). But have very good sound quality, therefore I need this headphone amp.

Because I would like to use all possible features with all-in-one PCB:

• Small transformer placed to the PCB, with 2 independent symmetrical +/-15V outputs. This is because separated power possible for left and right channels.
  
• 2 inputs on the PCB with volume control and jack or RCA inputs.
• Master volume and output jack.
  
• Mini audio mixer after inputs.
• After the mixer, unbalanced/balanced converter.
  

With this board I can use the features of TPA6120.

The new schematic:


The transformer and the voltage regulators placed to the PCB, with two independent outputs with 4 regulator devices. With inputs, you can choose what you like, 2 pcs 6 .3mm jack, or stereo RCA. Maybe 1 jack and 1 RCA. The balanced converter make better quality and more volume.

This is the PCB:


The longer side of PCB is about 15cm. Around the inputs have something "chaos". You can choose between RCA and Jack inputs this is the reason why 2 footprints on one place, but the inputs have to be placed to the bottom side (must be soldered on the top) and the volume potentiometers placed to the top layer (must be soldered on the bottom). But I think this is no problem on assembly. Because the transformer is on the board, 230V must be connected to the header called "Conn2". The regulators on the edge of the board can be screw to the wall of case or to heatsink. 3 "power filter" circuits required as module for this board, one for mixer, 1-1 for left/right unbalanced/balanced converter.

See also:

• 4 input headphone amplifier with line output
• More unbalanced to balanced converters
• Simulation of unbalanced-balanced converter
• Headphone amplifier with TPA6120
  

PCB sales of this project Module name Size (mm) Area (cm2) PDF SCH PCB image Tested Price (US$) Des. Sim.1 Full2 Sim.1 Full2 Man3 2 input headphone amplifier 90x160 144 Yes Yes Yes - - No 21 31 Ask How to order? Please read the rules carefully!

New power supply with 48V phantom power and 24V for relays

I have simple power supply for my preamplifiers (and all other) projects, but the 48V phantom power is missing from this device. This required for micrphone premplifier only, if the source is condenser microphone instead of dynamic microphone. Condenser mic source is useful on studios, for live singing, home amplification the simplest and cheaper dynamic microphones more useful. I searched some good solution, but the circuit which convert 48V from 30V AC is not simple enough. IT is true, one transformer not required with this circuit, but I think small PCB transformer with 48V (or 2x24V) is good and cheap solution. This is the reason why 2 transformers inserted to my design. The another thing with this new power supply, that I like relays to switch something if required, therefore I made one more output for 24V for relays (for example switching audio input, or switching speaker protection).

In current design the AC input is for 230V, because the PCB transformers soldered to the board. I like LM317/337 pair of adjustable regulator, the result is much better for me like 78xx/79xx circuits. The output voltage depend on the zener diode connected to the adjust of regulators. All regulators placed to the edge of board, if heatsink required.

The simple schematic:


The PCB:


If 24V for relays not required:


The original PCB for +/- 15V only without transformers:

PCB sales of this project Module name Size (mm) Area (cm2) PDF SCH PCB image Tested Price (US$) Des. Sim.1 Full2 Sim.1 Full2 Man3 Power supply for preamplifiers 168x89 150 No Yes Yes - - No 22 32 Ask How to order? Please read the rules carefully!

Modified microphone preamplifier with INA217

I really like the microphone preamplifier with INA217. No noise, very good sound and dynamic, no feedback, very high (max 10.000x) gain, very simple application. Lot of websites testing and comparing this design with another industrial devices. The article, when this is the best mic preamp and the cost is USD5 only, maybe not true. Not only the INA217 required, you need PCB, transformer, 2 potentiometers, input and output connectors, power supply.

I modified the original design recommended on the datasheet. The original application circuit on datasheet is really simple and very good microphone preamplifier. I added a better unbalanced/balanced converter after unbalanced jack input. I have this feature before, but now I have better circuit. The another modification is the output. Because this preamp is mono, the simple connection to stereo system is not the best. The result may increase the crosstalk between left and right channels. This is the reason why I included two line driver circuits to separate left and right channels. Finally because this new design contains 3 integrated circuit, I inserted 3 "power filter" for less noise.

The modified preamp design with input unbalanced/balanced converter and output line drivers:


The PCB with simple connectors:


The same design without connectors, because this PCB can be inserted to the mainboards of modular mixers. The connectors changed to P4 header:


Now here is the list of features:

• Balanced input
  
• 6.3 jack as Unbalanced input, but with unbalanced/balanced converter
  
• Gain adjustment
• Volume adjustment
• Connector for 48V phantom power
  
• Switch for 48V phantom power
  
• Switch between unbalanced jack and balanced XLR input
  
• Divided line driver inputs connect to stereo systems
  
• Power filter circuits for all 3 integrated circuits for less noise
  

PCB sales of this project Module name Size (mm) Area (cm2) PDF SCH PCB image Tested Price (US$) Des. Sim.1 Full2 Sim.1 Full2 Man3 Mic preamp pro with connectors 79x104 82 Yes Yes Yes - - No 13 21 Ask Mic preamp pro as mixer module 67x103 69 Yes Yes Yes - - No 11 19 Ask How to order? Please read the rules carefully!

Expandable, modular audio mixer for any number of channels

This is my second audio mixer project. The difference between current and previous design is, that this design can be expandable to any number of channels, the previous is made for 4 or 8 input channels only. At the end of the PDF manual of this project I inserted examples how to build audio mixer for any number of input and output channels.

I made paper models of my design to check how possible to build the complex device:



This gallery is funny, but very cheap to find mechanical problems before manufacturing the PCBs. With this test, I detected the problem, that the PCBs of "power filter" circuits are too big, have to be smaller than 25mm. This is the reason why I have 5 several power filter PCBs, and here is the smallest, with 22mm height, and 25mm width for the modular mixers:



The schematic of power filter module to decrease the preamplifier's noise and the crosstalk between left and right channels:


This PCB is very small, much harder to build....

The required preamplifiers for input channels are exactly same as than my simplest mixer project. The new on this design, that the small mainboards can be expanded with female/male connectors to build bigger than 8 channel audio mixer.

The first module of expandable mainboard:


...and the PCB for the first mainboard module:


This design is simple 4 channel audio mixer. Possible to finalize with 4 several preamplifiers. The blue potentiometers on the bottom of PCB is the L/R balance adjustment, but these parts are ignorable if not important. These potentiometers have blue color, because must be soldered to the bottom layer. There are mono, metal case parts. The first mainboard contains connectors for powers, phantom powers, line outputs, and balanced microphone input for all channels if mic preamp inserted. The main difference is the P1 female connector. This is the part where possible to connect another mixer mainboard to make more input or output channels. This first 4 channel module working without another connected boards, but on this one no connectors for outputs, only one stereo line output on the PCB via H5 connector.

For more inputs, here is the required module can be connected to the right edge of the first board to the connector P1:


and the really small PCB with P21 male connector:


This is an input channel for 2 arbitrary preamplifiers. Upper left is the male connector can be connected to the first, to the same, or to the output boards too. Here is the reason why expandable this device to any input or output channels.

If output channels required, here is the new schematic:


And I have 2 PCB design for upper schematic:


The difference between two PCBs is the L/R balance potentiometer only. This mainboard-module made for output circuits. The board can be connected to anywhere and anytime within the whole system. I offer several output modules:

The line outputs with master volume adjustment:


...and the PCB:


The difference between this, and the previous version of line output board, that this board contains line driver circuits, not the mixer's mainboard. This board contains adjustable master output of mixer with volume potentiometer with following variations:

• 2 6.3mm jack
• 1 6.3mm and 1 3.2mm jack
• 1 6.3mm jack and 1 stereo RCA
• 1 3.2mm jack and 1 stereo RCA

This board contains only one stereo volume adjustment, but possible to soldering to the board with L/R balance potentiometer if this feature required.

Another output circuit:

This is headphone amplifier with TPA6120. I modified my previous design of this module.

The PCB:

This is the simplest application of this really good IC with 6.3mm jack output and volume adjustment feature.

I made another version of this output for my audio mixer. The difference, here is an unbalanced/balanced converter for less noise, higher dynamics, higher possible volume. The official 120dB dynamics range is really high quality.


The required PCB is bigger, with two power filter module on P3 and P4 connectors:

• PDF manual of expandable mixer with examples.

PCB sales of this project Module name Size (mm) Area (cm2) PDF SCH PCB image Tested Price (US$) Des. Sim.1 Full2 Sim.1 Full2 Man3 Power filter module 17x25 4 Yes Yes Yes - - No 3 11 Ask 1st mixer module 103x95 98 Yes Yes Yes - - No 15 24 Ask 2nd mixer module 51x93 47 Yes Yes Yes - - No 8 16 Ask 3rd mixer module 26x93 24 Yes Yes Yes - - No 5 13 Ask Line outout board 65x76 49 Yes Yes Yes - - No 9 16 Ask Headphone output board 56x71 40 Yes Yes Yes - - No 7 15 Ask Balanced headphone output board 58x105 61 Yes Yes Yes - - No 10 18 Ask Microphone preamp module V2 67x103 69 Yes Yes Yes Yes - No 11 19 Ask Microphone preamp module V3 67x103 69 Yes Yes Yes - - No 11 19 Ask 1 dual opamp preamp module 61x103 63 Yes Yes Yes - - No 10 18 Ask 2 single opamp preamp module 64x103 66 Yes Yes Yes Yes - No 11 19 Ask HQ 2 single opamp module 67x103 69 Yes Yes Yes - - No 11 19 Ask jFET guitar preamp module 65x102 66 Yes Yes Yes - - No 11 19 Ask Switch module 18x34 6 Yes Yes Yes Yes - No 3 11 Ask Simple Power supply 121x57 69 Yes Yes Yes Yes - No 11 20 Ask Power supply with 48V phantom 168x89 150 Yes Yes Yes - - No 22 32 Ask How to order? Please read the rules carefully!