My topic title may be misleading as I’m not an audio expert (as you’ll be able to tell from this post!). I have an audio source (toy sound effect unit) currently feeding a small passive (i.e. no amplification) 8 ohm speaker (unknown power rating but it's going to be low).
I want to retain that arrangement, but be able to switch the output to feed a better quality speaker via an LM386 amp.
Many questions, but here are the main ones:
Can I common one side of each speaker together as the attached sketch**?
Can I use a SPDT switch on the other side, or should I use a DPDT switch and if so, why?
Have I got it all wrong because of my lack of knowledge?
Yes, a schematic will better explain what you are talking about.
Normally a speaker can maintain a common GND connection; only the top () speaker lead needs switching.
You can do it but I do not know if the hardware will survive. In audio you know that you do not unhook or connect loudspeakers when the sound system is active.
There is an auto amp somewhere in the circuit or you would get nothing out of the speaker. I assume by active speaker you are indicating it has some sort of amplification and passive has none, just two wires connected to the voice coil.
Notice the 8 ohm speaker! You need to match that 8 Ohms to a high impedance input of your amplifier, which will likely be in the thousand of Ohms. The usual way is a transformer. For a test, keep the speaker connected and connect the amplifier input to the speaker wiring. What is the result?
As I intend using a GS26347 LM386 Amp Board (which has the capacitor C1 onboard), and a separate speaker for the amp output, do you think my original sketch will still hold up? The source and amp board would be unpowered during the changeover.
Just to clarify the whole idea, basically the existing sound source and small speaker are located inside a model vehicle, but due to the size of the speaker (dictated by the space available in the model) the sound quality is fairly poor and volume is low. My intention is to have the model displayed in a case at which time I would switch over to the amp and larger speaker. However, I would like to retain the original installation for when the model is removed from it’s case.
The LM386 is an old inefficient chip from the seventies.
Class-D amplifiers are smaller, have a higher efficiency and deliver more volume on a 5volt supply. The only problem is that these chips usually have ballanced outputs (needing a DPDT speaker switch). An examples is the PAM range (PAM8403 etc.)
Leo..
I’m using the LM386 board (GS26347) because I have a couple of them in my spares box and I will only need a mono output. I’m not really looking for top end quality, just something better (and higher volume!) than the existing speaker on it’s own can deliver.
The amplified output will be for when the model is in it’s display case and I’ll make do with the original setup (small speaker only) for when I’m demo’ing the model outside of it’s case.
) speaker lead needs switching.
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