Possibly the 2ohm load to the sub. Try disconnecting that or rewire to 8ohm then crank up the volume to test?
Probably over-current or over-temperature protection kicking in.
If the protective shutdowns are due to excessive current, it could be either the amp, or the power supply feeding it, that's shutting down.
-Gnobuddy
If you are looking for ear-drum-removing SPL's from 5.25" speakers and an 87dB/W.m sub, you are in for a learning experience. (from the subs website)
If you actually get 50W into the sub, you will have an ear splitting 100 odd dB SPL in bass...
And at 93dB/w for the POLK units, a claimed 106dB in mid/high.
Not only a mismatch, but ultimately only moderately loud. That said, whilst you should not be expecting to remove paint from the walls with pure audio power alone, it should be annoyingly loud.
To compound the potential for mismatch, you may find that the performance of the polk speaker is not exactly what the simple "93dB/W" suggests. It is likely "louder" in midrange than the low end.
Questions:
- What boxes do you have these in? If the answer is either "none" or "random" boxes, then there is your problem.
- How are you matching the levels? If the answer is "I am not" then you need to fix this. Mismatched levels have an incredible capacity to make things sound rubbish.
- How are you crossing over between these? And at what frequency? If the answer is anything other than "Electronic crossover" and "At XXX Hz because I set it to that" then you probably want to look into how the crossover works.
If you actually get 50W into the sub, you will have an ear splitting 100 odd dB SPL in bass...
And at 93dB/w for the POLK units, a claimed 106dB in mid/high.
Not only a mismatch, but ultimately only moderately loud. That said, whilst you should not be expecting to remove paint from the walls with pure audio power alone, it should be annoyingly loud.
To compound the potential for mismatch, you may find that the performance of the polk speaker is not exactly what the simple "93dB/W" suggests. It is likely "louder" in midrange than the low end.
Questions:
- What boxes do you have these in? If the answer is either "none" or "random" boxes, then there is your problem.
- How are you matching the levels? If the answer is "I am not" then you need to fix this. Mismatched levels have an incredible capacity to make things sound rubbish.
- How are you crossing over between these? And at what frequency? If the answer is anything other than "Electronic crossover" and "At XXX Hz because I set it to that" then you probably want to look into how the crossover works.
I guess over-temperature protection, the heatsink is even tinier than that one in this video:
SKU216059 - TPA3116D2 Class D amplifier board measurements - China reviews
If you are looking for ear-drum-removing SPL's from 5.25" speakers and an 87dB/W.m sub, you are in for a learning experience. (from the subs website)
I definitely have my expectations set lower than tectonic effect.
If you actually get 50W into the sub, you will have an ear splitting 100 odd dB SPL in bass...
And at 93dB/w for the POLK units, a claimed 106dB in mid/high.
Not only a mismatch, but ultimately only moderately loud. That said, whilst you should not be expecting to remove paint from the walls with pure audio power alone, it should be annoyingly loud.
It is, in fact getting annoyingly loud, now that I wired the DVC sub in parallel and down to 2 ohms.
To compound the potential for mismatch, you may find that the performance of the polk speaker is not exactly what the simple "93dB/W" suggests. It is likely "louder" in midrange than the low end.
This is true, however, I have been able to overcome this with the wealth of volume controls in this little Franken-amp.
BTW, I am totally willing to rip the amp out and put something else in.
Questions:
- What boxes do you have these in? If the answer is either "none" or "random" boxes, then there is your problem.
Well.... here is where I shouldn't really be complaining yet since I have not put the drivers in the enclosure yet. If I didn't mention it above, I am putting this all into an old, hard-sided suitcase. 21in x 7in x 14 in.
- How are you matching the levels? If the answer is "I am not" then you need to fix this. Mismatched levels have an incredible capacity to make things sound rubbish.
The amp is a 2.1 50w x 50w x 100w
There are four controls, one controls the crossover frequency, then there are three volume pots. one for L+R stereo, one for the Sub, and one "Master" volume control. So, I have been able to balance things out.
- How are you crossing over between these? And at what frequency? If the answer is anything other than "Electronic crossover" and "At XXX Hz because I set it to that" then you probably want to look into how the crossover works.
So as to this, I am using the crossover frequency pot. So... I don't know the values, but I can control it.
The next question is, is it the amp or the power supply that's cutting out?
I took a look at the datasheet, and the TPA3116D2 isn't rated for 2-ohm loads: http://www.ti.com/lit/ds/symlink/tpa3116d2.pdf
So my first guess is that the chip driving the subwoofer is the one that's causing the shutdowns, because it can't cope with the 2 ohm speaker load.
-Gnobuddy
All loudness, balance, and sound-quality bets are off, then. With no enclosure, the speakers are working into an acoustic short-circuit until they get up to very high frequencies, at which point the cone is big enough to act as it's own baffle.
With your 5" speakers, I would estimate that this will only happen somewhere around 3 kHz or higher. So a thin shriek is all you can expect from them for now...
Is the subwoofer really sitting out in free air with no enclosure? If so, I'm amazed you can hear anything at all from it. Low frequencies are critically dependent on the speaker enclosure.
-Gnobuddy
The TPA3116D2 can handle 2 ohm in ptbl mode, there are characteristics for that at page 11, or am I missing something?
But the chip produces 12W max. heat in this configuration, I doubt that the PCB and this freaking tiny heat sink can handle this.
So even if the ocp doesn't trip he will get into thermal problems at higher level.
Anyway as long as the speaker are not in an enclosure this whole thread is pointless.
But the chip produces 12W max. heat in this configuration, I doubt that the PCB and this freaking tiny heat sink can handle this.
So even if the ocp doesn't trip he will get into thermal problems at higher level.
Anyway as long as the speaker are not in an enclosure this whole thread is pointless.
FWIW, I had no intention whatsoever of flaming you. Truthfully, I didn't really see anything that looked like actual hostility from anyone else, either.
Audio electronics is a complex topic, encompassing quite a few different fields of engineering and technology. Everything from carpentry and soldering to electricity, electronics, and the differential equations that describe sound waves traveling through air. I think it just takes a long time to learn enough to make some sense of it. That seems to be true of most things worth learning, actually.
And we often forget this, but the truth is, learning always goes hand in hand with mistakes - there's no other way. Just watch a baby trying to learn to stand up and walk for the first time!
Personally, I had the minor luxury of making most of my initial audio-related learning mistakes in privacy, in the days before there was a publicly accessible Internet. Of course, that also means it took me longer to learn, since I had a lot less access to information than we all do now.
But I'm not done making mistakes, and never will be. To err is human, right? Case in point, I was wrong about the 2 ohm load - I missed the fact that there were two amps in parallel driving the subwoofer. That allows them to cope with a 2 ohm load.
The enclosure thing - I don't want to annoy you by telling you stuff you already know, but, just in case you don't: let's suppose a speaker cone moves forwards at a particular instant in time, compressing the air in front of it. At the same time, it expands the air behind it, making a low-pressure region.
The obvious thing then happens: the high-pressure air from the front rushes around to the back, and fills up the low-pressure region there. Net result, almost no sound is actually radiated from the speaker.
Now, it takes a little bit of time for this to happen. If the speaker is reproducing a high frequency, the speaker reverses direction and starts to move forwards again very quickly, before the air has time to rush around and cancel out the sound from the back. So, at high enough frequencies, the sound cancellation doesn't happen. But, at low frequencies, forget about the speaker making any sound - without an enclosure, virtually all the sound is immediately canceled out.
In practical terms, with speakers of reasonable sizes, you have to get way up into midrange or treble frequencies before the cancellation stops happening. In other words, if you want any bass or low midrange, you pretty much have to have an enclosure of some sort, which contains the pressure waves from the back of the speaker, and keeps them from interacting with the waves from the front.
(There are a small number of masochists who make open-baffle speaker systems, and play complicated electronic tricks to try and get some usable bass from them. That is a different discussion for a different time.)
So, if you want to get any sort of realistic idea about the sound quality from your speaker system, the speakers have to be mounted in the enclosure you're going to use. That heavily emphasized "have" isn't just me being pushy, it's the universe itself being pushy. The laws of sound wave propagation in air are unbending, like that pesky law of gravitation that causes so many falls and injuries every day.
-Gnobuddy
Audio electronics is a complex topic, encompassing quite a few different fields of engineering and technology. Everything from carpentry and soldering to electricity, electronics, and the differential equations that describe sound waves traveling through air. I think it just takes a long time to learn enough to make some sense of it. That seems to be true of most things worth learning, actually.
And we often forget this, but the truth is, learning always goes hand in hand with mistakes - there's no other way. Just watch a baby trying to learn to stand up and walk for the first time!
Personally, I had the minor luxury of making most of my initial audio-related learning mistakes in privacy, in the days before there was a publicly accessible Internet. Of course, that also means it took me longer to learn, since I had a lot less access to information than we all do now.
But I'm not done making mistakes, and never will be. To err is human, right? Case in point, I was wrong about the 2 ohm load - I missed the fact that there were two amps in parallel driving the subwoofer. That allows them to cope with a 2 ohm load.
The enclosure thing - I don't want to annoy you by telling you stuff you already know, but, just in case you don't: let's suppose a speaker cone moves forwards at a particular instant in time, compressing the air in front of it. At the same time, it expands the air behind it, making a low-pressure region.
The obvious thing then happens: the high-pressure air from the front rushes around to the back, and fills up the low-pressure region there. Net result, almost no sound is actually radiated from the speaker.
Now, it takes a little bit of time for this to happen. If the speaker is reproducing a high frequency, the speaker reverses direction and starts to move forwards again very quickly, before the air has time to rush around and cancel out the sound from the back. So, at high enough frequencies, the sound cancellation doesn't happen. But, at low frequencies, forget about the speaker making any sound - without an enclosure, virtually all the sound is immediately canceled out.
In practical terms, with speakers of reasonable sizes, you have to get way up into midrange or treble frequencies before the cancellation stops happening. In other words, if you want any bass or low midrange, you pretty much have to have an enclosure of some sort, which contains the pressure waves from the back of the speaker, and keeps them from interacting with the waves from the front.
(There are a small number of masochists who make open-baffle speaker systems, and play complicated electronic tricks to try and get some usable bass from them. That is a different discussion for a different time.)
So, if you want to get any sort of realistic idea about the sound quality from your speaker system, the speakers have to be mounted in the enclosure you're going to use. That heavily emphasized "have" isn't just me being pushy, it's the universe itself being pushy. The laws of sound wave propagation in air are unbending, like that pesky law of gravitation that causes so many falls and injuries every day.
-Gnobuddy
Do all channels shut down, or only some? If all, then amost surely the PSU is too weak.
Lets calculate: 100+50+50=200WRMS. Peak power is about twice as high. You said PSU is 24V, 5A. 24*5=120W. Get a stronger PSU, or try to attach a very big capacitor (100000 uF at least)! If the PSU can start up with the capacitor, than it will help producing peak power. Or simply get the accumulators (and be very careful, since they can burn everything if you can't handle them well)!
Batteries don't shut down in response to overload, so you may actually have fewer problems than you do now.
(Like Pafi, I think that you need a bigger power supply - 10 amps @ 24V is more like it.)
The issue with batteries is balancing output power against how long a charge will last. The simplest way to estimate this is to find the batteries watt-hour rating, and divide that by the average power consumption of your electronics.
If, say, your batteries hold 15 watt-hours of energy, and your amp draws an average of 10 watts, then you can expect it to run for roughly 1.5 hours on a charge.
-Gnobuddy
I forgot to mention, I like your suitcase-as-enclosure idea. I know the amp-in-a-suitcase has been done before, but some day I might build a little valve guitar amp into a thrift-store suitcase. It just seems like a natural match to put old unwanted $1 valves together with an old unwanted suitcase!
-Gnobuddy
Well...
All the holes are cut drivers mounted and speakers wired up.
Actually sounds pretty good. I had to tweak the crossover setting as well as the relative volumes of the sub and stereo speakers.
It is definitely a bit louder and doesn't cut out nearly as soon as I dial up the volume. But it does eventually trip one of the safety triggers.
FWIW. The amp is rated for 12-24v operation. Just for the sake of experimentation, I hooked up a 12v / 5 amp power supply that I put on the multimeter before testing. The power status LED turned on, but that was it. not a peep. Plugged the 24v back up and we were back to making music.
I ordered a Bluetooth interface/preamp. I am interested to see how that sounds.
Tomorrow I will hook up a line-level source as well to see what difference that makes.
James
All the holes are cut drivers mounted and speakers wired up.
Actually sounds pretty good. I had to tweak the crossover setting as well as the relative volumes of the sub and stereo speakers.
It is definitely a bit louder and doesn't cut out nearly as soon as I dial up the volume. But it does eventually trip one of the safety triggers.
FWIW. The amp is rated for 12-24v operation. Just for the sake of experimentation, I hooked up a 12v / 5 amp power supply that I put on the multimeter before testing. The power status LED turned on, but that was it. not a peep. Plugged the 24v back up and we were back to making music.
I ordered a Bluetooth interface/preamp. I am interested to see how that sounds.
Tomorrow I will hook up a line-level source as well to see what difference that makes.
James
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