Hi all! I have a 4x 40W audio amplifier based on the E-TDA7386. How do I connect all the outputs to get one 160W output? Is that possible? Or maybe could I bridge the right channel, and then the left channel, resulting in 2x 80W? Here is my schematic: [Schematic_TDA7386 Bluetooth Speaker_2022-01-27] I just recently added U4 and U6, along with most of the parts on the lower part of the schematic. Here is the PCB: [Screen Shot 2022-01-27 at 10.23.45 AM] [Screen Shot 2022-01-27 at 10.23.58 AM] Thanks in advance!

@kgray9 If you want to connect your subwoofer just for the sake of connecting it (and have it make noises), you wouldn't have the necessity of supplying the full 160W to it. Especially since you said "temporarily". Since you are not able to run the four channels of TDA7386 in parallel you are limited to only 40W. However, you are able to reduce the power consumption by lowering the voltage so you can run it on a single channel. As I said earlier, V (voltage)= I(current)*R(resistance). And 1V * 1A = 1W. Which means Power = V * V / R. So you can measure the resistance of the speaker and figure out what voltage would cap the max power draw under 40W (to protect from potential thermal meltdowns and/or exploding speaker/power supply) headless assumptions Assume this is a 12V woofer, the resistance will be about 0.9Ohm. To cap the power at 45W, you can supply it with .... eh. 6.3V. If it is a 24V woofer, the resistance would be about 3.6 ohm. To cap the power at 45W you can supply it with 12.7V. Yeah. Half the voltage, 1/4 the power consumption. Interesting. The datasheet for 7498e mentions 36V. If your woofer runs on 36V, the speaker will have a whoppin 8.1 Ohm resistance. In that case you can feed it as high as 19.09V. And if you feed it 24V it would be ... 71.1 watt. Not entirely safe. So yeah. Do you have a multimeter? If you don't ... well, I don't know what to tell you. BUT, The woofer should have the impedance (resistance) listed on the connector/wires/outlet, so that would be very convenient. If you want it to be louder you can simply turn up the input because it will be impossible for the amp to supply more than 45W. If you do want to utilize the full 160W potential (you probably don't need to anyways, since most speakers at full output is more than enough to upset even your most friendly neighbor) I suggest go for something that can handle 160W directly (like this TDA7498e). You CAN build one with a power MOSFET, but you would need to fetch a heatsink and blah blah ...

You probably could do that, but if its higher power you want, its better to go with a circuit that is designed as per that. BPA is best achieved with individual power op-amps, IMO. With full blown amps with their own supplies and all there is every chance of getting something wrong.

[image] rohitbd: its better to go with a circuit that is designed as per that. Yeah I realize that. I did design a 200W HiFi amp, but wanted to look at other possibilities first. Using two amps, do I hook up one terminal of the speaker to one of the outputs on one amp, and the second terminal to one of the outputs on the second amp? Thanks

Have a look at this amp I built for a subwoofer. Its in bridge-parallel mode - not the best, but good enough and will give you an idea of how BPA is done. [image] Rohit Balkishan Dubla - 200W/4Ω power amplifier based on STK4192 Rohit Balkishan Dubla This is a power amplifier based on the (now almost obsolete) STK4192-II stereo power amplifier IC from Sanyo. This amplifier was built to drive my isobaric sub-woofer having a nominal 4Ω impedance (2x 8Ω drivers in parallel),...

Thanks @rohitbd, and by the way, nice website :grinning: I have a couple questions on that: The output power will be 80W total? Or 160W? Do I need to attach the left and right channel audio outputs together, and then to one side of the speaker, as in your circuit?

[image] kgray9: Thanks @rohitbd, and by the way, nice website :grinning: Thank you! As for power, electrical power is simply the arithmetic sum. So if you have one channel putting out 80W into a 4 ohm load, two such channels gives a total of 160W (80W per channel into 4 ohms). If the speakers are 8 ohms, power per channel is halved, as also the total power. Two amps (identical) capable of 80W into 4 ohms (but nothing less than 4 ohms) can be bridged into a single 8 ohms speaker but not into 4 ohms. To calculate power, without bridging, 80W into 4 ohms means 40W into 8 ohms. Now bridging into 8 ohms means 4x the unbridged power into 8 ohms which means 160W bridged mono But dB wise, doubling of electrical power only means a 3dB increase - and acoustically its not that loud. For loudness to be perceived as double the dB change has to be about +10dB - electrically that means almost more than 640W considering 80W as the base. 80W to 160W = +3dB. 160W to 320W = +3dB (+6dB overall) and a further 320W to 640W is another 3dB increase (overall 9dB). It may help to look for speakers (drivers) with better sensitivity rather than just raw power. A driver that is 3dB more sensitive will need half as much power to get to the same loudness. Of course such drivers will be more expensive.

[image] rohitbd: It may help to look for drivers with better sensitivity rather than just raw power. A driver that is 3dB more sensitive will need half as much power to get to the same loudness. Of course such drivers will be more expensive. That makes sense. Thanks @rohitbd for your help! I'll try a BPA :wink: .

One more thing (again :smile:). How is 27db? Good, really bad, etc. etc. That is what the E-TDA7386 has.

27dB of what? Amplifiers typically have that much gain relative to their inputs (line-level) to cater to source variations, volume control, etc.

That's the voltage gain in the data sheet. [Screen Shot 2022-01-29 at 1.20.40 PM] Is that what you meant by dB? Or did I totally butcher that :roll_eyes: EDIT: Now that I think about it, I totally butchered it. What exactly did you mean by dB?

Bridge Outputs on Audio Amp?

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kgray9 January 29, 2022, 6:12pm 28

That makes sense.

Thanks @rohitbd for your help! I'll try a BPA .

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Bridge Outputs on Audio Amp?

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