Poll for Topping PA5 owners only please.

[pkane]

My defective units used balanced connections, and were always left on. First few weeks, no problems, then static problem started to manifest. I posted video in the “main” PA5 thread.

At least in your case, it sounds like the two proposed explanations are not valid, then.

 

[pma]

I agree. It would need an expert analysis to come to a useful conclusion. Long distance second guessing cannot be a substitute.

 

[andrewjohn007]

Normally designed and produced electrical equipment cannot have failures when switched on/off several times a day. I cannot recall a single failure of any of my audio components in such conditions over decades. If it has issues, there must be a serious design flaw. I am speaking about normal components, excluding toys like A07.

Curious - Why would you consider the A07 a "toy" and not the PA5?

 

[pma]

Curious - Why would you consider the A07 a "toy" and not the PA5?

Correct, both . Worse, PA5 is overpriced. A07 is cheap, at least, and to me more acceptable for this reason. I mentioned A07 because I own it. I do not own PA5.

 

[Deleted member 46664]

I don't know why people keep saying the amp power supply voltage is out of the recommended range. It is right in the table you show that 38V is within the recommended range. All the graphs in the data sheet go up to 38V as well.

Yes it is ... it is the maximum recommended voltage. This is not where you want to run things, it leaves no overhead. It's like smashing the gas pedal in your car right to the floor at every intersection... how long before you break something?

Also consider that if you are using 38 volts and a startup spike of +6 volts occurs... now you are at 44, which is not within the recommendations...

Like your car... if you want things to last you don't drive the snot out of them...

 

[pjug]

Yes it is ... it is the maximum recommended voltage. This is not where you want to run things, it leaves no overhead. It's like smashing the gas pedal in your car right to the floor at every intersection... how long before you break something?

Also consider that if you are using 38 volts and a startup spike of +6 volts occurs... now you are at 44, which is not within the recommendations...

Like your car... if you want things to last you don't drive the snot out of them...

The overhead should be considered by TI and built into the spec, and it looks like it is. They specify 50V as absolute maximum although the amplifier will be stressed if the voltage is above recommended.

 

[antcollinet]

The overhead should be considered by TI and built into the spec, and it looks like it is. They specify 50V as absolute maximum although the amplifier will be stressed if the voltage is above recommended.

Exactly - and that is where the headroom comes from for startup spikes also (if they even exist). 38V is an absolutely acceptable operating voltage.

 

[Deleted member 46664]

WOW ... I am really glad neither of you two (tonycollinet or pjug) are working for me.

That's some of the worst advice I've ever seen. You are literally justifying reckless design practices.

 

[antcollinet]

WOW ... I am really glad neither of you two (tonycollinet or pjug) are working for me.

That's some of the worst advice I've ever seen. You are literally justifying reckless design practices.

Not as glad as we are

 

[jmillar]

Fine... ignore the obvious evidence of proper use (cords, switches, modes, etc) and ignore information about previous rectifier failures in SMPS devices that are far more sophisticated than these little bricks and ignore my 40 years in the industry .... advise this person to go ahead and blow up another amp.... Be my guest!

Like it or not basic inexpensive consumer grade switching power supplies don't really "like" this very much. When I was told this decades ago my computing (and other electronic) devices were left idling/sleeping when not in use. I didn't like the trickle of power drawn, but the argument made sense.
This debate began in earnest with the first PC's. The "chink in the armor" is the PSU (and HD's of course).

 

[Deleted member 46664]

Like it or not basic inexpensive consumer grade switching power supplies don't really "like" this very much. When I was told this decades ago my computing (and other electronic) devices were left idling/sleeping when not in use. I didn't like the trickle of power drawn, but the argument made sense.
This debate began in earnest with the first PC's. The "chink in the armor" is the PSU (and HD's of course).

The key phrase being "like it or not" ... You are exactly correct. We cant deal with this stuff as "what we want it to be" or "to do"... we are stuck dealing with it as it is.

Same thing with the voltage on the TPA3251 chip ... they recommend 36 volts as the ideal operating point. We can't simply decide that something else is okay ... we need to deal with the chip as it is and use it as intended.

I mean really ... some people's kids!

 

[Deleted member 46664]

At least in your case, it sounds like the two proposed explanations are not valid, then.

But there is still the issue of 38 volts on a 36 volt chip.

 

[IPunchCholla]

The manual does explicitly say to turn the amp off before unplugging the supply, so if you are running it from an auto-off/anti-vampire strip, I would make sure to turn it off manually before the strip does. Since I forget all the time, I plugged the power supply into an always on outlet.

 

[Deleted member 46664]

The manual does explicitly say to turn the amp off before unplugging the supply, so if you are running it from an auto-off/anti-vampire strip, I would make sure to turn it off manually before the strip does. Since I forget all the time, I plugged the power supply into an always on outlet.

That does not avoid the current inrush when you turn the AC back on.
The "power" switch in the amp is merely a "standby" switch that turns off the outputs ... everything else is still live.

 

[pma]

Sorry but every "normal" amplifier has to work reliably without need for the owner to take special care of when and where to turn on/off the switch. It must survive possible removal of mains cord or plug, it must survive home breaker failure. It is ridiculous to prepare clinical conditions for a mere consumer product like this one. The cults are created based on some parameter number and that is neither good, nor scientific.

 

[Deleted member 46664]

Sorry but every "normal" amplifier has to work reliably without need for the owner to take special care of when and where to turn on/off the switch. It must survive possible removal of mains cord or plug, it must survive home breaker failure. It is ridiculous to prepare clinical conditions for a mere consumer product like this one. The cults are created based on some parameter number and that is neither good, nor scientific.

Yes, I agree ... these power bricks (the part that dies most often) are under built. And yes, they do not like being AC cycled all the time.

But it is what it is ... and we gotta deal with that.

 

[IPunchCholla]

Sorry but every "normal" amplifier has to work reliably without need for the owner to take special care of when and where to turn on/off the switch. It must survive possible removal of mains cord or plug, it must survive home breaker failure. It is ridiculous to prepare clinical conditions for a mere consumer product like this one. The cults are created based on some parameter number and that is neither good, nor scientific.

I’m not disagreeing with your main point, but mine has survived a minimum of 60 cycles of being cut off at the source. Nor do we have any evidence that current onrush is the failure mechanism for those who are having issues, nor do we know if failure rates are elevated compared to other amps. So let’s not slip from a proposed failure mode to implying that people buying the PA5 are SINAD cultists. Most of us aren’t. We just want a transparent amp. This one costs significantly less than the Hypex 125 builds I have seen and measures better. So it is a good buy, if reliable, which we still don’t know if it is or isn’t.

 

[Nzama]

I’m not disagreeing with your main point, but mine has survived a minimum of 60 cycles of being cut off at the source. Nor do we have any evidence that current onrush is the failure mechanism for those who are having issues, nor do we know if failure rates are elevated compared to other amps. So let’s not slip from a proposed failure mode to implying that people buying the PA5 are SINAD cultists. Most of us aren’t. We just want a transparent amp. This one costs significantly less than the Hypex 125 builds I have seen and measures better. So it is a good buy, if reliable, which we still don’t know if it is or isn’t.

If I can post an example to counterfair this theory mine has never been disconnected from mains and suffered the issue. So if this was supposed to be 100%of failure mode it clearly isn't.

 

[Nzama]

Yes, I agree ... these power bricks (the part that dies most often) are under built. And yes, they do not like being AC cycled all the time.

But it is what it is ... and we gotta deal with that.

Btw, i generally very much appreciate your point Blake. You seems to be very knowledgeable.
Sometimes I have the feeling you use autoritas arguments that shall have no place in (?) in ASR.

Cheers

 

[Deleted member 46664]

If I can post an example to counterfair this theory mine has never been disconnected from mains and suffered the issue. So if this was supposed to be 100%of failure mode it clearly isn't.

It is a possiblity. We don't actually know what's causing it yet.

I’m not disagreeing with your main point, but mine has survived a minimum of 60 cycles of being cut off at the source. Nor do we have any evidence that current onrush is the failure mechanism for those who are having issues, nor do we know if failure rates are elevated compared to other amps. So let’s not slip from a proposed failure mode to implying that people buying the PA5 are SINAD cultists. Most of us aren’t. We just want a transparent amp. This one costs significantly less than the Hypex 125 builds I have seen and measures better. So it is a good buy, if reliable, which we still don’t know if it is or isn’t.

The thing is that we do know that repeatedly power cycling these little brick supplies will eventually kill them. You just need to take one apart and see the rectifier diodes to know that it's not going to live forever if you're turning the AC on and off all the time. We aren't talking about instant death ... it generally reduces the brick's lifetime from 5 or 6 years to something like a year.

This is not specific to the PA5 .... this is a well known issue with ALL power bricks.