Hello,
I'm working on the HP amplifier which has a TPA1620 on the output as a buffer. It has 1k ohm on the inverted feedback. I use it as a non-inverting amp.
There is also switching psu for +-15V, after that have a positive and negative LDO with 47u tantal.
Pos and Neg voltage increases simultaneously 30ms, 0 to 15V. On the 32ohm output I have measured two picks that made a click, one is positive 3.4V that last 3ms and 2nd is negative after that pos -4.4V and decreases much longer.
I found from some articles that it is expected, isnt it? If so, I want to decrease it. On the HP I hear it but not too much (not high-end result) but on the iEM it is very unpleasant.
I don't have any DC offset on the input/output of the amp, and don't use capacitor at the output.
That pop is heard just when PSU is enabled, after that it works good.
Does anyone has similar experience and what could be the solution?
I'm working on the HP amplifier which has a TPA1620 on the output as a buffer. It has 1k ohm on the inverted feedback. I use it as a non-inverting amp.
There is also switching psu for +-15V, after that have a positive and negative LDO with 47u tantal.
Pos and Neg voltage increases simultaneously 30ms, 0 to 15V. On the 32ohm output I have measured two picks that made a click, one is positive 3.4V that last 3ms and 2nd is negative after that pos -4.4V and decreases much longer.
I found from some articles that it is expected, isnt it? If so, I want to decrease it. On the HP I hear it but not too much (not high-end result) but on the iEM it is very unpleasant.
I don't have any DC offset on the input/output of the amp, and don't use capacitor at the output.
That pop is heard just when PSU is enabled, after that it works good.
Does anyone has similar experience and what could be the solution?
What you want is probably a relay that connects the headphones with a litte bit of delay on power-up but with almost no delay on power-down. You could look at some headphone amp DC protection boards posted here in the past, a few or even most of them also have a startup delay function. I remember there is one from Xen and from AMB. But I am sure there are others as well.
A speaker protector would do the job.
They come in various flavours.
Some have a relay with a few second power up delay.
Others also monitor power supply or mains and turn off relay before power dies.
You can also get DC detect versions that will protect your speakers in case of DC fault.
They come in various flavours.
Some have a relay with a few second power up delay.
Others also monitor power supply or mains and turn off relay before power dies.
You can also get DC detect versions that will protect your speakers in case of DC fault.
Thank you for the answer, I was thinking about a relay, but I don't know if it's the best solution because I'm working on a battery-powered portable device. The biggest problem is the size of the relay, I did not find a mini / micro relay that works with 5V.
I have not used any protector and I have no experience with it, I need something that will not affect the output. Don't know is there any circuit that can help?
I have not used any protector and I have no experience with it, I need something that will not affect the output. Don't know is there any circuit that can help?
For a miniature relay which works with 5V look at Omron G6K series. Those are available in 3V, 4.5V and 5V versions.
There are plenty of 5V mini relays, but check few things first.. I experimented with this chip and the click on power up, with 50 ohms headphones connected, was very low, not worthy of implementing turn on delay circuit. I guess you are talking about TPA6120, not 1620? Do you have pot on the input, and what is the pot value?
The schematic would be most easy way to figure out what's going on..
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I assume your worries are about a relay have to do with the current "wasted" on the coil. You might look into
these switches from Analog Devices.
https://www.analog.com/media/en/technical-documentation/data-sheets/ADG1401_1402.pdf
They aren't cheap but at $4 per channel they aren't prohibitive. On resistance is 1 ohm. Power supply current in
microamps. It's a definite possibility. If it was my project I would use them.
G²
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You could also use a MOSFET transmission gate on the output. That would consume lower power than a relay. Just be careful that you don't exceed the max Vgs for the devices.
You could also explore a latching relay. Those types only consume power when they're switching.
Tom
You could also explore a latching relay. Those types only consume power when they're switching.
Tom
Some inspiration.
Positive rail detection(could detect negative rail as well, but positive rail collapses first due to higher current draw), DC offset detection for each channel, Turn on delay circuit, Solid state output relay.
It works, no turn on/turn off thump, pop or plop.
You wont hear anything at all when turning your amp ON or OFF, providing you have no sound playing, just silence.
Solidstate relay is the way to go.
To make it simple, drop the DC offset protection and just go with the Positive rail detection, Delay circuit and Solidstate output relay.
Positive rail detection(could detect negative rail as well, but positive rail collapses first due to higher current draw), DC offset detection for each channel, Turn on delay circuit, Solid state output relay.
It works, no turn on/turn off thump, pop or plop.
You wont hear anything at all when turning your amp ON or OFF, providing you have no sound playing, just silence.
Solidstate relay is the way to go.
To make it simple, drop the DC offset protection and just go with the Positive rail detection, Delay circuit and Solidstate output relay.
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