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:
I just recently added U4 and U6, along with most of the parts on the lower part of the schematic.
Here is the PCB:
Thanks in advance!
Not even sure if that's possible.
Audio signals are typically mixed in a pre-amp and the mixed
signal used as the amp inputs. Mixing amplifier outputs is something
I've never heard of. Not saying it can't be done but I have no clue
how that would be done. For starters shorting the outputs together
doesn't sound like a good idea.
That is what I figured, so I didn't even try because I didn't want to damage anything.
I don't really mean mixing, really bridging / combining.
FYI, there's no preamp.
I know that some amplifiers have that as an option in the data sheet, such as the TPA3116.
Well there's this
Your question begs the question: "Why are four 40W outputs not equal to one 160W output ?"
Meaning (if you read between the lines) if sound is by definition sound pressure and you have
4 sound pressure sources each 40W, is not the combined sound pressure equal to one 160W
sound pressure source ?
I'm not an audio engineer but this certainly sounds like an excellent question for an
electronics test. I submit you should just use 4 speakers and be done with it.
The 7836 already is a bridge type amp so the speakers dont have a common ground.
"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?"
Why do you need to - what are you trying to achieve?
I am trying to temporarily run a subwoofer on this circuit. 160W max is much better than only 40W max.
That begs the question:
"If you knew from the beginning that the subwoofer needed 160W , WHY did you build a
circuit that only has 40W outputs ? If you were planning to combine them, wouldn't it
have made more sense to post your question BEFORE you proceeded to build
your circuit ?
You state here : "I have a 4x 40W audio amplifier based on the E-TDA7386" , meaning
you ALREADY built the circuit. WHEN (EXACTLY) did you decide you wanted to combine
the 4 outputs, BEFORE or AFTER you built it ?
Sounds like a classic case of "cart before the horse" if you ask me.
1: you cant.
2: how is this an arduino question?
That was my first thought...
I didn't know that my subwoofer was going to be needing 160 watts. I originally planned on having this amplifier run 4x 30W mid range speakers. I built it 2 years ago, and it is not being used right now, so I was wondering if I could bridge the outputs to have it run a 160W subwoofer.
If you are building your own subwoofer you could use 4 (probably smaller) drivers. And with 4 drivers they could be re-wired in series-parallel for the same impedance as one driver in case you wanted a more "traditional" setup in the future...
Or buy a powered subwoofer?
Bridging means each amp sees half the load impedance or double the current it has to drive. So bridging into 4 ohms means each amp channel sees a 2 ohms load. Unless each is built to work into 2 ohms, bridging into 4 ohms risks damaging both the amp and the speaker.
I can you can cross that bridge when you get to it...
I know you can run MOSFETs in parallel to (mostly) double their switching capacity. This is not "wrong" and in fact can be seen in numerous designs.
Running amps in parallel? Depend on the circuitry, I guess. TDA7386 is effectively 4 power FET packed into one, so I guess "yes". But the input pins must also be tied together (with wires soldered to jump across, and even that might be considered too flimsy). HOWEVER, you should note that despite it claiming to be able to drive 4*45W, the maximum heat dissipation for it is 80W.
I'm sure you have seen the datasheet, but there's some more stuff beside pinout.
I also know that you can run speakers below their rated voltage/watt by powering them with lower voltages. V (voltage)= I(current)*R(resistance), huh. And 1V * 1A = 1W.
You can measure the resistance of the speaker and figure out what's a comfortable voltage to supply it at so your FETs will not blow up
Sorry, what exactly does that mean? Does that mean I can only use 80W at one time because of the heat?
FYI, I do have a large heatsink on it.
Someone else said that the outputs CANNOT be bridged, because they are already bridged.
Referring to the schematic the out+ and out- pins represent bridge-mode output (for channels 1-4). And its probably already specified for the minimum load impedance (maximum load current). The only way to get more power (if at all possible) is to either use a smaller impedance speaker or increase the supply voltage (and gain or the input signal). However both would be ill-advised.
This might be a really bad idea, but could I maybe attach one side of the speaker to GND (instead of the amp), and the other side through a single MOSFET configured so as to amplify, with the GATE to the MOSFET attached to the audio output on the amp?
Just brainstorming.
