Will an inrush current limiter on the power in and/or X2 cap across the power switch on the SMPS eliminate or decrease the startup pop that seems prevalent on so many of the Class D/SMPS setups?
In almost all cases - no. A well developed amplifier does not do that since practically all recent amp ICs support soft start or mute on start and shutdown. If your amp does that, you need to implement (better) mute-function, add an external delayed relay for power on or change the (maybe too big) input capacitor.
Some TA2020 amps (DIY Paradise Charlize II ?)eliminated the turn on pop by modifying the grounding with what was called the "bias cap mod" because this eliminated the input coupling caps - no caps, no pop. I seem to remember the turn off pop can be minimised by trimming the output offset voltage. I don't have details - Google it? Or maybe someone who did this mod will give more details...?
Not only on class D amps. Most amplifiers exhibit power on effects on the output. Good designs protect the loudspeakers with delayed switching and/or switching off when an error occurs like sudden DC on the output.
So regardless of topology it is necessary to look careful how protection is done. If it is lacking better not buy that amplifier no matter how cheap it is. Most of us ignore that at first but wisdom comes with the first burnt woofer. Despite all semiconductor tricks designers may have designed, it is always better to trust an external circuit that does not rely on that same chip that can exhibit a severe error. In general this is called a muting/protection circuit.
An inrush current limiter won't help much as that is not the problem. The problem is a short moment of DC at the outputs while the amplifier settles and idle DC output voltage goes to 0 V. Larger destructive pops occur when the chip itself decides to go to semiconductor heaven and puts out rail voltage. A good protection circuit will then protect the expensive woofers.
So regardless of topology it is necessary to look careful how protection is done. If it is lacking better not buy that amplifier no matter how cheap it is. Most of us ignore that at first but wisdom comes with the first burnt woofer. Despite all semiconductor tricks designers may have designed, it is always better to trust an external circuit that does not rely on that same chip that can exhibit a severe error. In general this is called a muting/protection circuit.
An inrush current limiter won't help much as that is not the problem. The problem is a short moment of DC at the outputs while the amplifier settles and idle DC output voltage goes to 0 V. Larger destructive pops occur when the chip itself decides to go to semiconductor heaven and puts out rail voltage. A good protection circuit will then protect the expensive woofers.
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Ah, please don't seed the idea once you don't hear a pop anymore it's protected. Or the other way around either, a pop does not mean there's no protection. Ofcourse, a protection can (or even should) prevent the popping noise, one does not guarantee the other.
If you read my post carefully you will see that I did not write what you think I wrote. I don't think I could have written it any clearer.
* just make sure you carefully check how power on anti-plop and protection are done (in 99% of cases that will be combined) in the amp you are going to buy. Without those item it is gambling and hoping it will never break down. People that have tried TA2024/TA2022 amplifiers will know what I mean. Switching on the vacuum cleaner or just one interlink (or speaker cable) not making contact and it is BOOM !!
* IMHO there is a preference for an external circuit as one can rely on the protection of the chip that dies but I would not rely on the protection of a dying chip. Possibly the protection also dies at the same time leaving your nice loudspeakers at rail voltage...
* Checking carefully = making sure by looking at the schematic or the pictures of the PCB if there is any external protection like a speaker relay. As said: in most cases that same circuit will also function as muting circuit at power on (but not always). Listening for plops is NOT the method to check but if you hear a relay switching the loudspeakers with a delay you just know it has anti-plop 😉
* Power on plops may be annoying (I think they are) but they won't cause harm as long as they are not severe. Severe is when you see the woofers go 20 mm forward and backward and you think someone shuts a door with force. It is better to avoid them though, if not for technical reasons then for a better user experience.
* Adding a protection PCB is possible but be careful with symmetrical outputs as many protection circuit are not suitable for that and short one of the outputs.
A + B + C + D = buy or build an amp that has all this. Shortest and least time consuming way to satisfaction.
* just make sure you carefully check how power on anti-plop and protection are done (in 99% of cases that will be combined) in the amp you are going to buy. Without those item it is gambling and hoping it will never break down. People that have tried TA2024/TA2022 amplifiers will know what I mean. Switching on the vacuum cleaner or just one interlink (or speaker cable) not making contact and it is BOOM !!
* IMHO there is a preference for an external circuit as one can rely on the protection of the chip that dies but I would not rely on the protection of a dying chip. Possibly the protection also dies at the same time leaving your nice loudspeakers at rail voltage...
* Checking carefully = making sure by looking at the schematic or the pictures of the PCB if there is any external protection like a speaker relay. As said: in most cases that same circuit will also function as muting circuit at power on (but not always). Listening for plops is NOT the method to check but if you hear a relay switching the loudspeakers with a delay you just know it has anti-plop 😉
* Power on plops may be annoying (I think they are) but they won't cause harm as long as they are not severe. Severe is when you see the woofers go 20 mm forward and backward and you think someone shuts a door with force. It is better to avoid them though, if not for technical reasons then for a better user experience.
* Adding a protection PCB is possible but be careful with symmetrical outputs as many protection circuit are not suitable for that and short one of the outputs.
A + B + C + D = buy or build an amp that has all this. Shortest and least time consuming way to satisfaction.
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I did not think what you think I think you wrote. I thought it would be necessary to mention what I said because others would probably not read the intended meaning out of your post. Thanks for clarification though, I think that should eliminate most (if not all) unclarity.
I only have a problem with initial pop with the TPA3118 boards. TA2024, TDA7498 TPA3110, YDA138 all do not have this pop. The way I want to power up is that the amp and power supply are both switched on simultaneously when I throw the power switch on a power strip. I do not want to have an extra step. It looks like I will need to get a speaker protection relay with a time delay, there are several available for $6-$7 on eBay/Ali.
I had terrible trouble with an irs2092 on power down giving two second siren type noise then a massive thump through speaker !
It turned out I was using too much smoothing and this made the power down discharge too slow and upset the irs2092.
IR suggested a power down detect then hold 2092 in reset if VCC was too low.
I used a small PIC with a2d converter to sense VCC and a opto-isolator to control 2092 reset pin. This worked perfectly.
It turned out I was using too much smoothing and this made the power down discharge too slow and upset the irs2092.
IR suggested a power down detect then hold 2092 in reset if VCC was too low.
I used a small PIC with a2d converter to sense VCC and a opto-isolator to control 2092 reset pin. This worked perfectly.
Well, I don't recall that but I trust you on that. I live in Germany you know 🙂
Of course you need to switch on amp and PSU at the same time otherwise you will need to switch DC and you don't want that for various reasons.
Please watch out when buying a protection/delay circuit from Ebay as you probably need one that can handle symmetric outputs for your TPA3118 amplifier. The "normal" ones will short-circuit your - outputs to GND.
Of course you need to switch on amp and PSU at the same time otherwise you will need to switch DC and you don't want that for various reasons.
Please watch out when buying a protection/delay circuit from Ebay as you probably need one that can handle symmetric outputs for your TPA3118 amplifier. The "normal" ones will short-circuit your - outputs to GND.
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