I just Fried fairly expensive AVR which is NOT mine

[thin bLue]

What is critical safety indicator for Amplifier?

It was under 2% of THD+N ratio, stands a few sweeps and Suddenly just popped out and dead with little bit of smoke.
2 Ohm is quite harsh load, but for Over-3500USD-Priced products, I expected non-invasive safety engages.

Now I know THD+N is not significant Safety guideline.


But what should I use..... Kyuuuuuuu

 

[levimax]

View attachment 254292


What is critical safety indicator for Amplifier?

It was under 2% of THD+N ratio, stands a few sweeps and Suddenly just popped out and dead with little bit of smoke.
2 Ohm is quiet harsh load, but for Over-3500USD-Priced products, I expected non-invasive safety engages.

Now I know THD+N is not significant Safety guideline.


But what should I use..... Kyuuuuuuu

Full power 2 ohm sweeps are asking for trouble. For 2 ohm loads there are "burst" tests which are much easier on equipment.

 

[DVDdoug]

2 Ohm is quiet harsh load,

I assume it's not rated for 2 Ohms? And of course, high power test tones are more abusive than normal program material.

 

[Vini darko]

Problem is you dont know what an dut can take till it stops taking it. You're quite right it should have a decent protection circuit at that price.

 

[thin bLue]

Full power 2 ohm sweeps are asking for trouble. For 2 ohm loads there are "burst" tests which are much easier on equipment.

I assume it's not rated for 2 Ohms? And of course, high power test tones are more abusive than normal program material.

But If I Need to test the AMP unknown, what is the way for get power sweep curve as usual with out damage the amp?

 

[thin bLue]

Problem is you dont know what an dut can take till it stops taking it. You're quite right it should have a decent protection circuit at that price.

Problem is I don't know <- 100% right. This is a serious problem. In the case of the Purifi, it would have stopped output immediately and resumed playback as soon as it returned to proper load, but this Class AB amp unfortunately did not work that way.

 

[Doodski]

@thin bLue the lowest you should run some amps at is 4 Ohms but 8 Ohms is a safe common test number for AV receivers. They are simply not built to withstand the current output of a 2 Ohms load never mind a 4 Ohms load. Most likely the output power transistors have been fried and it is possible that peripheral circuitry took some heat and fried too. Don't torture test into 2 Ohms again.

 

[pma]

What is critical safety indicator for Amplifier?

It was under 2% of THD+N ratio, stands a few sweeps and Suddenly just popped out and dead with little bit of smoke.
2 Ohm is quite harsh load, but for Over-3500USD-Priced products, I expected non-invasive safety engages.

Now I know THD+N is not significant Safety guideline.


But what should I use..... Kyuuuuuuu

So it must have been another poorly designed amplifier. Unfortunately we can see many of such products. It should have survived your test. Most usual issues are undersized heatsink, undersized output stage, bad thermal control of idle current. SOA exceeded, second breakdown. Or oscillations. Poor overcurrent protection curve. You name it.

 

[thin bLue]

@thin bLue the lowest you should run some amps at is 4 Ohms but 8 Ohms is a safe common test number for AV receivers. They are simply not built to withstand the current output of a 2 Ohms load never mind a 4 Ohms load. Most likely the output power transistors have been fried and it is possible that peripheral circuitry took some heat and fried too. Don't torture test into 2 Ohms again.

Jesus. AVR....
2 Ohm is Not for AVR that is Really Clear than EVER.

 

[thin bLue]

So it must have been another poorly designed amplifier. Unfortunately we can see many of such products. It should have survived your test. Most usual issues are undersized heatsink, undersized output stage, bad thermal control of idle current. SOA exceeded, second breakdown. Or oscillations. Poor overcurrent protection curve. You name it.

I think I should care way more than I thought.
I became a little philosophical about expensive branded sound industry products.

Thanks for comments.

 

[Doodski]

Jesus. AVR....
2 Ohm is Not for AVR that is Really Clear than EVER.

Huh? I don't understand.

 

[pma]

I think I should care way more than I thought.
I became a little philosophical about expensive branded sound industry products.

Thanks for comments.

Have you checked all fuses? It happened to me few times that fuses have blown during 2 ohm full power sweep.

 

[thin bLue]

Huh? I don't understand.

I mean, I understand what you mean and that brittleness of AVR is way beyond my very expectations for AVRs!

Sorry for confusion!

 

[Doodski]

I mean, I understand what you mean and that brittleness is way beyond my very expectations for AVRs!

Sorry for confusion!

I see. Yes, AVRs are mostly built cheaply and not for sine wave sweeps. In the future if you are torture testing amps with sine waves use a ammeter to monitor the current draw and if you see it increasing when you are testing then that is the time to stop the test before the amplifier goes into thermal runaway.

 

[thin bLue]

Have you checked all fuses? It happened to me few times that fuses have blown during 2 ohm full power sweep.

It seems no user serviceable fuses on back panel. I'll send it to owner today, and owner let them service center. So Unavoidable bleeding of my bank account is now here

 

[Doodski]

It seems no user serviceable fuses on back panel. I'll send it to owner today, and owner let them service center. So Unavoidable bleeding of my bank account is now here

A possibly expensive mistake. It happens. You will know better in the future.

 

[thin bLue]

I see. Yes, AVRs are mostly built cheaply and not for sine wave sweeps. In the future if you are torture testing amps with sine waves use a ammeter to monitor the current draw and if you see it increasing when you are testing then that is the time to stop the test before the amplifier goes into thermal runaway.

THANKS! The Ammeter!
I'll check it out!

 

[thin bLue]

A possibly expensive mistake. It happens. You will know better in the future.

Thank you for your warm hearted comments!

 

[pma]

It seems no user serviceable fuses on back panel. I'll send it to owner today, and owner let them service center. So Unavoidable bleeding of my bank account is now here

They may be placed inside, on the PCB boards. I would try to check it and possibly save the budget.

 

[Doodski]

THANKS! The Ammeter!
I'll check it out!

Over 15 years when I serviced electronics at component level I used the ammeter on maybe 60% of the amps I tested. I blew none up during testing and I got the amps very hot while under test. So the ammeter method is the safest way.