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Chip Amps Amplifiers based on integrated circuits

tda 2050 bridge
tda 2050 bridge
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Old 10th January 2018, 08:36 AM   #1
rahulrahullll is offline rahulrahullll
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Join Date: Dec 2014
Exclamation tda 2050 bridge

i have 2 separate tda 2050 mono boards working separately fine—-but if i bridge them—-huge distortion–slight song coming out——————-c1 cap wrong given—-i have reversed polarity—-i have +/- 22 v dc


---circuit tested-----https://youtu.be/i_HmCorNBi4-----------


https://3.bp.blogspot.com/-dM-f-4sFu.../s1600/BTL.JPG

———-is there anything wrong ?

—-thank you
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Old 10th January 2018, 12:38 PM   #2
palstanturhin is online now palstanturhin  Finland
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Your circuit seems to be OK.
You might get 80W into 8ohms, after that it begins to distort quite heavily.
With 4ohms it will probably blow up.
Are the chips authentic or from China? Most of the TDA2050 from China are rebadged 2030.
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Old 10th January 2018, 04:14 PM   #3
rahulrahullll is offline rahulrahullll
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actually---i am using 3 way passive crossover 4 ohms---chips are china but work fine---using 6 mono boards -----------

---actually i was previously using 6 mono for 5.1-----enough power --no bridge required


i made 2 --3 way tower speaker---using 8 inch woofer tweeter----local cheap written---

4 ohm--woofer 40 w

tweeter--eastech philips--12 ohm--30 w---new tweeter--6 ohms--tried to make 12 ohm--no bass increase---

passive crossover 4 ohms

-----i sold the tower ---now buyed the same woofer driver brand--but getting---20% of previous bass effect---thats why bridging---i dont like bass increasing equilizer sound------only like bass without any boosting effect applied-----

earlier and now both woofer magnet everything same except looks---------


earlier pic--------example type not actual----- http://www.mavin.com/sc_images/produ...-sca1-1000.jpg

new one only top cone change shape-pushed inside--pic--example type not actual--- https://www.parts-express.com/Data/D...0-334_HR_0.jpg

--------could not understand how same woofer same ohm,wattage,price---only top cone change shape-pushed inside-----------performing different----using same amplifier--crossover--same brand ???

----------ANY IDEA WHAT IS HAPPENING
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Old 12th January 2018, 09:35 PM   #4
FauxFrench is offline FauxFrench  France
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Just some possible inspiration:

Have you checked the DC-offset between the two TDA2050 outputs (no signal at the input)? If there is an important DC-offset, your speaker may be pushed out of its mechanically safe movement range and you will have distortion.

IF it would be re-marked TDA2030s sold as TDA2050s, +/- 22V supply is too high. Is it possible to reduce the supply voltage below +/-18V, at least until you know what is wrong?

A way to get valuable information is to use a double-beam oscilloscope and put the two ground wires of the probes to supply "-" with each of the probe tips to the two TDA2050 output pins. When you increase the amplitude of an input sinewave (around 1KHz) you can see when the two TDA2050 starts distorting.
Without a load (speaker or dummy load) connected, do both outputs remain sine-wave close to the clipping amplitude?
With a load at the output, do the TDA2050s distort at any amplitude level?
Do both TDA2050 outputs distort at the same time (with a load)?
At which AC output level (the threshold level)?
Does the amplifier play well below that amplitude threshold level?
If you insert a DC blocking capacitor (two 4700uF capacitors connected back-to-back), does it then work without obvious distortion?
Is the supply voltage(s) stable and more or less constant?

For a start it is important to know if there is a circuit mistake that introduces distortion even without a load or the distortion is related to the loading.

Last edited by FauxFrench; 12th January 2018 at 09:46 PM.
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Old 13th January 2018, 06:27 PM   #5
rahulrahullll is offline rahulrahullll
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thank you--------

will check dc offset

dont have oscilloscope

ics cannot be tda 2030 because when +-22 v dc applied separate boards works nice no noise

made earlier 6 tda 2050 mono no issues

my best guess its oscillating ---but how ?---made exact circuit ---

tight soldering in pcb board




checked resistors by multimeter

changed ics

----------If you insert a DC blocking capacitor (two 4700uF capacitors connected back-to-back), does it then work without obvious distortion?----------

---i guess i put caps in series to speaker ?


tried 5 days no improvement---------frustrated------

----------if there is dc offset--------what should i do ?
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Old 14th January 2018, 02:55 PM   #6
FauxFrench is offline FauxFrench  France
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Suggestion:

Without input signal, measure the DC voltage between the two outputs. If more than 1 volt, you for sure have a problem.

Make a bipolar capacitor from two 4700uF capacitors connected "back-to-back".

With this bipolar capacitor in series with the speaker, connect the series coupling between a first TDA2050 output and ground. Does it sound well with input signal?

With this bipolar capacitor in series with the speaker, connect the series coupling between the second TDA2050 output and ground. Does it sound well with input signal?

With this bipolar capacitor in series with the speaker, connect the series coupling between the first TDA2050 output and the second TDA2050 output. Does it sound well with input signal?
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Old 14th January 2018, 04:38 PM   #7
Fast Eddie D is offline Fast Eddie D  United States
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Location: Skokie Il
Good advice given here about checking DC voltages. This is first and foremost and must be done before hooking up any speakers.

There are two flaws with your circuit. First and foremost U2 is a slave to U1. This means that any distortion produced by U1 will be amplified by U2 and added to the distortion produced by U2. This includes any clipping by U1. This master slave setup is OK for ultra low distortion op amp circuits that never clip. It is not OK for a power amplifier like this. However it should work well enough to verify operation.

Second, low distortion operation of a bridge amplifier depends on close matching of each leg of the bridge. This means that resistors must match closely between the two legs. R2, R9, and R6 must closely match, R3 must closely match R7, R1 must closely match R5. Evan a mismatch between C2 and C4 can introduce distortion unless you make the C1/R1pole dominant. You have this pole set at 3.3 Hz while your feedback pole is 10.6 Hz. This is very poorly thought out and should be addressed. Making C2 220 uF would lower this pole to 1.1 Hz; which is much better. Did you think about that?

Finally, if you want the best performance out of your bridge amp, consider this DRV134PA Texas Instruments | Integrated Circuits (ICs) | DigiKey which will add even more precision to your circuit and completely eliminate the first problem I cited.

Hope this helps.
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Old 14th January 2018, 06:11 PM   #8
Fast Eddie D is offline Fast Eddie D  United States
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A word on the resistors. I've seen circuits for bridge amps that specify 0.1 % resistors. The bottom line is that the closer each leg matches, the lower the distortion will be. It's not just a matter of extracting maximum power from the circuit.

These are the resistors I buy for audio use. Through Hole Resistors | DigiKey I typically buy in quantities of 10, 1% tolerance. As you see, 0.1% resistors are pricey. But you can buy 10 1% of each value ( a good deal if you're going to use them) and match them up by hand. You can get much closer than 1% out of any batch. In fact, they typically match much closer than 1% anyway.

I prototyped a bridge amp using some TDA chips I took out of a boombox. I built two amplifiers and verified they worked, then used an inverting amplifier to drive one. This is not ideal but I was just doing a feasibility study anyway. I got around 100 watts continuous into 8 ohms (my dummy load was smoking) and it was a very nice amplifier (one channel only). I think it's worth building - lots of clean power for cheap!
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