Can a PTC thermistor prevent overheating in a DIY speaker heater?

In summary: Might be worth trying that.In summary, my brother's logitech pure fi anytime alarm clock radio does not work properly in cold weather, but a bank of resistors can be used to heat the speakers so they work normally.
  • #1

My brother has a logitech pure fi anytime alarm clock radio. The problem with it is that when it is cold the speakers do not work properly distorting the sound. This is not very useful as it is cold in the mornings when the alarm goes off (playing a song from the ipod).

Now I had an idea that I could use a bank of resistors to heat the speakers so that they would operate normally all the time. I have basically used the same idea as a dew heater for a telescope ( ).

this is my idea


I am just a bit worried that the resistors would end up overheating. My question is would it be possible to use a PTC thermistor in the circuit to prevent overheating?
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  • #2
It is unlikely to be the speakers themselves that cause distortion.
It would possibly be something in the amplifier driving the speakers.

Easy to check. Just plug another set of speakers in one cold morning.
Or use a hair dryer to warm up just the speakers or just the amplifier.
If a warm amplifier gives clean sound into cold speakers this means the amplifier is at fault.

Or put the amplifier in the fridge for a while and see if it is distorted after that.

So, having worked out where the distortion is coming from, you need to fix it.

Assuming it is the amplifer, you could open it up when it is warm and working OK and get a can of freezer spray and try to identify which part you spray that makes it get distorted again.

But look for obvious faults like burnt resistors.

Forget about heating it up with resistors etc. It needs to be fixed because whatever is faulty now will probably get worse.
You really need some test equipment and a schematic diagram to be sure of fixing it, but you might be able to get lucky and fix it just by having a look.

Also look at the power pack if it has one that plugs into a wall socket. It could give low voltage if it is cold.
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  • #3
Good points to think about. I will give it a try. Thanks!
  • #4
I had never considered the possibility of building my own dew heater - thanks for that!

Unrelated aside: I had my telescope outside last night and based on dewpoint and predicted low temperature, didn't expect to need my dew heater. But the absolute humidity ended up rising through the night in advance of a new weather pattern and I found when I woke up this morning I had lost 2 hours of exposure to dew. :cry: Clear weather is so rare here I need to make a policy of using the dew heater even if I think I won't need it.
  • #5
One passing thought. I once had problems with the speaker coil in a sagging speaker cone rubbing against the magnet. I turned the speaker upside down and the problem went away.

1. What causes distorted sound when it's cold?

Distorted sound when cold is typically caused by the contraction of materials in audio equipment in response to cold temperatures. This can lead to changes in the electrical resistance of components, causing changes in the signal and resulting in distorted sound.

2. Can cold weather permanently damage audio equipment?

In some cases, prolonged exposure to cold temperatures can cause permanent damage to audio equipment, particularly if the equipment is not designed to withstand cold temperatures. It is important to check the operating temperature range of your equipment and take precautions to keep it within that range.

3. How can I prevent distorted sound when it's cold?

One way to prevent distorted sound when it's cold is to keep your audio equipment in a temperature-controlled environment. If that is not possible, you can also try to warm up the equipment gradually before use, or use insulation materials to protect it from extreme cold.

4. Does the type of audio equipment affect its sensitivity to cold temperatures?

Yes, the type of audio equipment can affect its sensitivity to cold temperatures. For example, analog equipment is generally more sensitive to cold temperatures compared to digital equipment. Additionally, equipment with higher quality components may be less affected by cold temperatures.

5. Can distorted sound when cold be fixed?

In some cases, distorted sound when cold can be fixed by allowing the equipment to warm up to room temperature or by adjusting the settings on the equipment. However, if the distortion is caused by permanent damage, it may not be fixable and the equipment may need to be replaced.

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