How to power a speaker on and off

Ian0

Joined Aug 7, 2020
1,929
A speaker that is idling (i.e. the amplifier is powered, but there is no signal across the speaker) is no more likely to fail than a disconnected speaker. At a guess, if you integrated the cone excursion over time, that would be proportional to how long it would last.
2500 hours is probably more than the life of the electrolytic capacitors in the amplifiers. My guess is that the product would be obsolete first, its amplifier would fail next, and the loudspeaker itself, if kept dry, and away from pets and small children armed with sharp objects, would outlast both the amplifier and the product's useful life.
After all, there is a good market on Ebay for products like this, https://ebay.us/1aOrZF which worked hard in their early life for 3 decades in cinemas, and then became collectors' items and are still going after 60 years.

Anyone with any concerns for the environment should be using 1960's stereos - not only does it reduce waste, but loudspeakers of that era were at least an order of magnitude more efficient than it is these days. (though if you're still using valve amplifiers, that might not be entirely true)
 

Thread Starter

Raptorist

Joined Apr 6, 2021
6
So many messages to reply to! Let's get to it :D


Don't know where you heard this. I have never heard this one before.
In general, electronics will last longer if left powered on 24/7.
I just googled the matter and this is what a few people agreed on. I don't have any reputable source to back this claim.

If you want to turn off electrical/electronic devices the usual methods are:
  1. turn off the power switch
This was my initial idea, to be able to press the power button on the powered speakers via software, while leaving them plugged in.

I don’t think so. When there is no sound, the speaker - the sound producing transponder or component - has 0V across it. You don’t have to do anything. It just is 0V.

In a powered speaker, there are components to interface with the (3.5mm) audio and a small amplifier. But keeping power to those components won’t shorten their life. There is a chance that capacitors might age but that’s a common problem and would happen regardless of power applied. Plus, we’re talking decades of use. By then, the powered speaker would be obsolete. Or do you still have an 8-track?
Thanks for the clarification. Decades of use would be perfectly fine for me, I just don't want it to be a couple of months.
Also, I have never seen an 8-track :D

Well, here's a very quick and dirty version:

Get this:

https://www.amazon.com/dp/B01MYTZGYM/

It uses this chip:

https://www.digikey.com/htmldatasheets/production/1282043/0/0/1/PAM8403.pdf

Pin 12 on it is SHDN (shutdown), it is "active low" meaning you have to pull it to ground to shut down the chip.

You can use one of the RPi's GPIO pins to do this, and just have to modify the code for Mycroft, which is open source, to bring the pin high before it speaks.

Whatever value the exercise has, it will be a full stack learning experience.
Thanks a lot, that's very helpful! I read the material in the link you left, and I also found a video showing how to connect it to other components, soldering etcetera. Only one thing wasn't addressed: how do I connect to Pin 12? It doesn't go into the silicon board, does it? Do I just connect a wire to it? Solder it?

A powered speaker that is not playing sounds is costing money by the electricity its idling amplifier is using.
This was another concern of mine, although secondary.
The small "salt and pepper shaker" speakers you have might be made very cheaply "over there" and not last long even if they are not powered all the time.
This might very well be the case, these speakers were a present, and they're definitely on the cheap side.
I have a cheap Japanese Name-Brand clock radio that is always powered for 35 years and it still works.
Is it possible that the loudspeaker is, in fact, not powered for the whole time, but only when you actually use it?

2500 hours is probably more than the life of the electrolytic capacitors in the amplifiers. My guess is that the product would be obsolete first, its amplifier would fail next, and the loudspeaker itself, if kept dry, and away from pets and small children armed with sharp objects, would outlast both the amplifier and the product's useful life.
2500 hours of 24/7 use is three and a half months, whereas 2500 hours of 10 minutes use per day is 41 years, so the loudspeakers becoming obsolete strongly depends on how much I use them.
Distinguishing between these two cases is the point of this thread.
 

BobTPH

Joined Jun 5, 2013
3,129
Unfortunately, people are talking about 2 different things here, without making the proper distinctions.

You have a set of powered speakers. These consist of electronics (the power supply and amplifier) and an electro-mechanical device I will call the loudspeaker.

If you leave your powered speakers on, you are powering the electronics. The loudspeaker itself sees no voltage unless it is actually making sound in all but the stupidest amateur circuit, which might apply a DC voltage to the speaker when idling. I think we can rule that out in any commercial product.

So, leaving them on might affect the electronics, whether it will shorten their life is debatable, but it is certainly not as bad as an MTBF of 2500 hours, as attested to by the fact that many of us leave such things powered continuously for years.

The loudspeaker, on the other hand, will see no excess wear as long as it is quiet. But even then, think about malls, stores, restaurants etc. that are playing music continuously during operating hours. Do you think they need to replace the loudspeakers every 2500 hours? Some of them have probably been operating for a decade or more.

Bob
 

wayneh

Joined Sep 9, 2010
17,152
This was my initial idea, to be able to press the power button on the powered speakers via software, while leaving them plugged in.
Are you still wanting to do that? I mentioned one way in #3, a MOSFET switch under control of your Pi. Very simple and a good technique to learn for future projects.

Here's a generic diagram. Your speaker set would replace the lightbulb.

1618068952532.png

Basically the same thing, maybe easier to understand.

1618069218671.png
 
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