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I already tried it just now. In my setup, it's not a pop, but a tiny tick when TPA3255 tries to start again.
What I did was, While the amp is powered-on, I shorted out pin 3 (GND) and pin 4(MR) for a brief second, a philips screw or any conductive object will do. So the voltage supervisor held the mute/shutdown of TPA3255 for about 1.2 seconds, then when TPA3255 starts up, a faint tick sound is present.
Looks like the loudness of startup tick varies from setup to setup. I will try different cstart, bootstrap caps and voltage supervisor values so that I can get the 'no tick' setting for most systems.
What I did was, While the amp is powered-on, I shorted out pin 3 (GND) and pin 4(MR) for a brief second, a philips screw or any conductive object will do. So the voltage supervisor held the mute/shutdown of TPA3255 for about 1.2 seconds, then when TPA3255 starts up, a faint tick sound is present.
Looks like the loudness of startup tick varies from setup to setup. I will try different cstart, bootstrap caps and voltage supervisor values so that I can get the 'no tick' setting for most systems.
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That's an easy route but it should be solved by changing some values, though soldering is required.
This module has a voltage supervisor to mute the module, so loud turn-on and off pops were avoided. But the problem is when the amp unmutes and tries to start, there is a ticking sound accentuated by 1.2 second delay.
This is the same problem as this one. https://e2e.ti.com/support/audio/f/6/t/889474
I will get back to this issue once I got the suitable values.
This module has a voltage supervisor to mute the module, so loud turn-on and off pops were avoided. But the problem is when the amp unmutes and tries to start, there is a ticking sound accentuated by 1.2 second delay.
This is the same problem as this one. https://e2e.ti.com/support/audio/f/6/t/889474
I will get back to this issue once I got the suitable values.
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https://e2e.ti.com/support/audio/f/6/t/889474 I was wrong, this link has a different issue, his issue is noise when reset is pulled down.
Our issue is when reset is being pulled up, there is an audible tick.
Looks like some EVM has this issue as well except that we are not getting loud pop at shutdown, my voltage supervisor's schematic is wired differently compared to EVM.
TI TPA3255EVM
Our issue is when reset is being pulled up, there is an audible tick.
Looks like some EVM has this issue as well except that we are not getting loud pop at shutdown, my voltage supervisor's schematic is wired differently compared to EVM.
TI TPA3255EVM
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the audible level of pop I am getting is enough to make me worry about my speakers. I have the ncore nc400 which produces a very very gentle tick upon power on. Certainly the tpa3255 noise doesn't motivate me to power it on for fear of damage to my speakers. I will be testing it on my cheap computer speakers from now, till I get a solution.
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Hmm your experiencing a different kind of startup pop. Try to change your opamp, or need to rule out some variables.
I also tried my non PFFB board and it registers a very faint tick, in which I need to put my ear at the surface of the speaker. Thing is it has identical parts with my PFFB module, even the opamp is LME49860. With my PFFB module, the tick sound is more noticeable, I can hear it at 1 meter away from the speaker in silent environment.
I also tried my non PFFB board and it registers a very faint tick, in which I need to put my ear at the surface of the speaker. Thing is it has identical parts with my PFFB module, even the opamp is LME49860. With my PFFB module, the tick sound is more noticeable, I can hear it at 1 meter away from the speaker in silent environment.
My theory is that the character and loudness of that "pop" can be result of different PVDD capacitors you two have. The slower the cap, the less saturated impulse you get. And that is also the reason why it is more audible in the PFFB version.
Or maybe it is because of the phase difference between the PVDD supply pin and AVDD supply pin.
Or maybe it is because of the phase difference between the PVDD supply pin and AVDD supply pin.
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I'm using 4x1200uF for PVDD caps.
I just bought lower value c_start and 10uf Elna Silmic II caps, hopefully they have arrived by weekend.
I looked in the datasheet about the startup sequence and saw that the device also pre-charges the input coupling caps at startup.
Currently I'm using 22uF input coupling caps, I'll check lower value input caps first if it will reduce the startup tick.
I just bought lower value c_start and 10uf Elna Silmic II caps, hopefully they have arrived by weekend.
I looked in the datasheet about the startup sequence and saw that the device also pre-charges the input coupling caps at startup.
Currently I'm using 22uF input coupling caps, I'll check lower value input caps first if it will reduce the startup tick.
i have actually tried without PFFB this morning and the 'pop' is still present. Will have to look at other possiblities.
I am using 4 x 1800uf now.
Someone mentioned in some other discussion that the size of input coupling caps have have a part to play too. I am trying to get hold of 10uf to try, not sure when i could visit the local electronics market; hopefully this week. Thanks for the schematic and startup manual.
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Parts have arrived, I tried the Panasonic FC 1800uF, the tick sound did not change, so it's not affected by the value of the capacitors.
The tick sound is present when the voltage supervisor pulls the !reset up (after 1100ms delay). It can be manually replicated by shorting the shutdown and ground pins. When the voltage supervisor unmutes the amp, the amplifier starts the switching operation, then a tick sound can be heard. Which means startup and shutdown pops and clicks are not present, but muting-unmuting the amp by means of pulling the !reset pin has a small pop/tick which we are currently debugging.
Then I changed c_start to 10nF, the !reset-pullup tick sound became more gentler and non distracting, but the a !reset-pulldown tick has emerged.
So when the amplifier is already running and when I short the shutdown and ground pins, a tick sound can now be heard when the amp mutes the output. When I remove the short, after 1100ms, a tick sound with a gentler sound can be also heard.
Note that the tick/pop sound is not caused by startup / shutdown sequence but by reset/mute functionality.
I will post a video later so that you can hear it.
Next step is I will change the input capacitor's value. Currently it is 22uF
The tick sound is present when the voltage supervisor pulls the !reset up (after 1100ms delay). It can be manually replicated by shorting the shutdown and ground pins. When the voltage supervisor unmutes the amp, the amplifier starts the switching operation, then a tick sound can be heard. Which means startup and shutdown pops and clicks are not present, but muting-unmuting the amp by means of pulling the !reset pin has a small pop/tick which we are currently debugging.
Then I changed c_start to 10nF, the !reset-pullup tick sound became more gentler and non distracting, but the a !reset-pulldown tick has emerged.
So when the amplifier is already running and when I short the shutdown and ground pins, a tick sound can now be heard when the amp mutes the output. When I remove the short, after 1100ms, a tick sound with a gentler sound can be also heard.
Note that the tick/pop sound is not caused by startup / shutdown sequence but by reset/mute functionality.
I will post a video later so that you can hear it.
Next step is I will change the input capacitor's value. Currently it is 22uF
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I'm building an AudioScienceReview entry amp, hopefully my amp gets reviewed even though this is only DIY build. I heard that Amir has lots in queue for review.
I will use LRS-350-36 for the power supply and a TPA3251 PFFB config (since it has a lower 5W at 4 ohms THD+N which is around 0.0017%), for comparison, non-PFFB Minidsp SHD power amplifier which uses TPA3255 chip has an ASR measurement of 0.0039% THD+N (5W at 4 ohms).
I'm only looking for a suitable chassis then after that it will be ready.
I will use LRS-350-36 for the power supply and a TPA3251 PFFB config (since it has a lower 5W at 4 ohms THD+N which is around 0.0017%), for comparison, non-PFFB Minidsp SHD power amplifier which uses TPA3255 chip has an ASR measurement of 0.0039% THD+N (5W at 4 ohms).
I'm only looking for a suitable chassis then after that it will be ready.
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