Go Down

Topic: 4 pins on a Speaker? (Read 1 time) previous topic - next topic

dhenry

Quote
I don't understand why they are here


Read the "Polarity Test" section of the datasheet and  take a closer look at the drawing.

Quote
the tech drawing says "Speaker & Receiver", so perhaps there are two coils?


Speakers are necessarily receivers, particularly for piezo.

retrolefty



Hi,

I have just bought a little piezo speaker like that : http://www.newark.com/pdfs/datasheets/spc/25R0936.pdf
The problem is there are 4 pins to connect at the back of the speaker, and I don't understand why they are here... is it not just Gnd and V+ usually?

Thank you.


It is not a piezo speaker as with 8 ohms of impedance it can only be a dynamic speaker, that is simply a 8 ohm coil driven speaker. Piezo elements are high impedance devices. I can't make out the contact arrangement very well, but if there are four pins it's probably just for better mechanical stability for mounting to the PCB. Simply take your ohm meter and identify two terminals that read out a nominal 8 ohms and use them, and ignore the other two. Also there is no + and ground for a speaker as it's designed as a AC device so is polarity insensitive, there are just two signal terminals, and you are free to ground either one if required to be ground based.

Lefty

Cow faith


it's probably just for better mechanical stability for mounting to the PCB


Yes you were right, I have just test the 4 pins with the multimeter and they are connected by pairs. So just Gnd and Signal! I thought it was more complicated....
Thank you very much!

fungus



Hi,

I have just bought a little piezo speaker like that : http://www.newark.com/pdfs/datasheets/spc/25R0936.pdf
The problem is there are 4 pins to connect at the back of the speaker, and I don't understand why they are here... is it not just Gnd and V+ usually?

Thank you.


Stereo?
No, I don't answer questions sent in private messages (but I do accept thank-you notes...)

kf2qd

"+" and "-" on a speaker are there for phasing purposes. On a speaker this small it wouldn't really make much difference, but on large speakers where they are not phased properly makes for a big loss in bass.

A way to test the the result of phasing is to take and drive 2 speakers, side by side, from the same source and reverse the phasing on one and listen for the difference in the quality of the sound. One effect from 2 speakers that are closely spaced but different in phase is that the sound will be quieter at a distance as when on speaker is pushing air, the other is pulling and thus they will tend to cancel out.

Go Up