replace speaker with audio jack

[redepoch7]

I am going to replace a speaker in a toy with a 1/4 inch jack.

The speaker is 8 ohm.
Do I need to put some resistance in series or in parallel with the jack or can I just connect the jack?

I thought maybe I heard somewhere that it can be bad to just substitute a speaker for a jack... is that right?

Thanks for the help!

N

 

[MikeMl]

It is common practise to use a jack that has a "normally closed" set of contacts, wired so that when no plug is inserted into the jack, the audio is connected to the built-in speaker. With the plug inserted, the internal speaker is disconnected, and the audio is fed to the plug, and the other end of the plug's cord is hooked to either an external speaker or headphones or whatever...

For solid-state appliances, no terminating resistor is needed.

 

[redepoch7]

Oh cool.
I have seen this in action. Is the "normally closed" set of contacts plug a special item or do you wire it up in a certain way?

In my case, I want to delete the speaker all together because I need the space inside the toy case.

If I did just take the speaker out and put a 1/4 inch jack, would it cause any damage to the toy or to my guitar amp if I just plugged it strait in?

 

[MikeMl]

Oh cool.
I have seen this in action. Is the "normally closed" set of contacts plug a special item or do you wire it up in a certain way?
...

**broken link removed** (mono), or item 1 (stereo)

 

[redepoch7]

And again,

If I did just take the speaker out and put a 1/4 inch jack, would it cause any damage to the toy or to my guitar amp if I just plugged it strait in?

 

[MikeMl]

Is the input to the Guitar Amp LINE level (~1V) or PICKUP level (a few mV)? If the second, then the Speaker level out of the toy will greatly overdrive the guitar amp and sound horribly distorted. Wont hurt anything, but it will sound awful.

 

[redepoch7]

I would have to guess that it's PICKUP level. It's just a little compact amp.

If it won't hurt anything then I'll try it out and see what happens.

Now, if it is horribly distorted... What do I do then?

 

[redepoch7]

I just tried it... not terribly distorted but it doesn't sound good.

Do I put a potentiometer in series (just guessing) to bring the distortion down???

 

[crutschow]

Try an attenuator consisting of a 1kΩ and a 100Ω resistor in series, with the speaker signal to the 1k and the 100Ω going to ground. Connect the amp input between the junction of the two resistors and ground.

Edit: Or connect the CW terminal of a 1kΩ pot to the speaker signal and the pot CCW terminal to ground. Connect the amp input between the pot wiper output and ground.