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So I have some nice headphones and what has been a very nice sounding amp.
Today the left speaker of the headphones was really warm, the sound was low and distorted. Called the place where I bought them, they suggested letting them cool and trying again. This time no sound, heating up, electrical burning smell. Turn off amp, take them out, contact the manufacturer.
They suspect DC got into the output, fried the headphone, and they say this is a risk with any solid state headphone amp that's not DC coupled. I've never heard this before, but I have to say I don't give any attention to technical aspects of headphones, or much of anything technical related to high end audio for that matter.
So anyway, my question is, was the manufacturer correct that any solid state amp not DC coupled runs the risk of frying your amp like this?
If so, could I have a bit more of an explanation and also are there any steps to prevent it?
Thanks!
Robert
fight the good fight
Follow Ups:
You have your information a little bit backwards.
A headphone amp with a directly coupled output can do this. A capacitively coupled or transformer coupled amplifier is very, very unlikely to have a problem like this.
If the headphone amp is in warranty, you should consider talking to the manufacturer about repair as well as repairing your headphones.
Any thoughts on what might cause this to happen, or is it just a random event that can damage headphones?
fight the good fight
A shorted transistor can cause this pretty easily. An open resistor in the DC feedback network might do the same, as would a shorted coupling cap where that feedback was being applied.
Sometimes you will see people talk about modding amps by removing the coupling caps they find unnecessary, and events like this can be an unintended consequence.
I hadn't done any mods on the amp. I'll send it back. And maybe try to use a safer design in the future.
fight the good fight
If an amp is DC coupled (meaning it has no output coupling capacitor) you run the risk of a possible failure in the amp's output stage and DC being applied to the output. And you can get what you have experienced.
What a manufacturer is trying to accomplish by making it DC coupled is they want to avoid coupling capacitors, especially at the output. The reason for this is that all capacitors have a "sound" and to make the amp as transparent and neutral as possible they make it DC coupled.
When you read an amp is DC coupled throughout, they are saying there are no coupling capacitors anywhere in the circuit. This is a wanted feature but if the amp is DC coupled it must also have some sort of protection circuitry to avoid what happened to you.
The protection circuit that I mentioned should have monitored that there was DC in the output and shut down the amp to prevent the damage.
I would contact the amp's manufacturer and ask what happened.
Ed
We don't shush around here!
Life is analog...digital is just samples thereof
That's what the manufacturer said
fight the good fight
My experience is that it is recommended get everything ready, but turn the amp on, wait 10 seconds before plugging the phones in. I don't recall anyone making a differentiation between SS and tubes.
Thanks!
fight the good fight
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