Hi,
a chipamp is an opamp with a high current output stage that can take ~+-40Vdc on it's supply rails.
As such it is a DC amplifier and can and will output DC, if DC is presented to it's input.
If one chooses a topology and/or protection scheme that allows DC to pass through the amplifier then face the consequences, eventually.
Most builders are looking for a low component count, easy to reproduce amplifier. They generally choose chipamps because they see easy buildability without regard to making any design decisions, for good or bad.
It is not reliability or lack of it in the chipamp that is the problem. It is a designer decision.
a chipamp is an opamp with a high current output stage that can take ~+-40Vdc on it's supply rails.
As such it is a DC amplifier and can and will output DC, if DC is presented to it's input.
If one chooses a topology and/or protection scheme that allows DC to pass through the amplifier then face the consequences, eventually.
Most builders are looking for a low component count, easy to reproduce amplifier. They generally choose chipamps because they see easy buildability without regard to making any design decisions, for good or bad.
It is not reliability or lack of it in the chipamp that is the problem. It is a designer decision.
It's a personal choice really! There have been tales of disaster on this forum but generally, they chips, when properly implemented are as safe as any other type of amplifier.
If you are worried, use one of the speaker protection modules that you can usually buy as kits like this one from Quasar.
If you are worried, use one of the speaker protection modules that you can usually buy as kits like this one from Quasar.
i have made a diligent search thru this forum and it seems like the cause of such disasters had been due to carelessness.Nuuk said:
my actual concern has been on the reliability issues ie. does it known to fail over time, or any other parts of the implementation that fails eg. one half of the PSU failures that may cause the output of the damaging DC.
And I can add that I have never had any speaker damage from a chip failure using the LM3875, LM3886, or OPA541 chips. So yes, rest assured, if you implement a chip amp properly, you shouldn't have any problems.
I think speaker protection is useful though when you are doing a lot of experimentation where you could make a simple mistake, or you are trying something 'new' and untried! Having said that, I now tend to run anything 'new' on old speakers for a few days rather than risk my better speakers!
Nuuk said:
And I can add that I have never had any speaker damage from a chip failure using the LM3875, LM3886, or OPA541 chips. So yes, rest assured, if you implement a chip amp properly, you shouldn't have any problems.
I think speaker protection is useful though when you are doing a lot of experimentation where you could make a simple mistake, or you are trying something 'new' and untried! Having said that, I now tend to run anything 'new' on old speakers for a few days rather than risk my better speakers!
This is certainly very good assurance for me. thanks.
I wonder if a possible compromise is to run amplifiers under test, through some big electrolytics wired back to back.
As for DC protection, I think the answer has to be: How safe do you want to make it? My understanding is that DC protection guards against failures such as an output transistor turning into a short circuit. I would be interested in knowing if the audio power amp chips are either: a) Sufficiently reliable; or, b) internally protected, to the point where external protection is unnecessary. The chip amps do have the advantage of instantaneous temperature monitoring of the output devices.
Thoughts?
As for DC protection, I think the answer has to be: How safe do you want to make it? My understanding is that DC protection guards against failures such as an output transistor turning into a short circuit. I would be interested in knowing if the audio power amp chips are either: a) Sufficiently reliable; or, b) internally protected, to the point where external protection is unnecessary. The chip amps do have the advantage of instantaneous temperature monitoring of the output devices.
Thoughts?
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