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Line out from Toy speaker
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author Line out from Toy speaker
HappySampler
Hi,

I’m planning to sample a few of juniors toys and want to create a temporary line out put so I can record without some of the noise (speaker, buttons) issues.

If I remove one end of a TS instrument cable and replace with crocodile clips, attach these to the speaker / wire contacts would that work?

Secondly and more importantly could I do any damage to my audio interface ?

Thanks
infinitemachinery
Output for a speaker is going to be a lot hotter than the line level that your audio interface will expect. You'll need a speaker level to line level conversion.
HappySampler
Thanks, Is there something you’d recommend for this?

Amazon (uk) sell this which appears to be mostly used in cars

https://www.amazon.co.uk/Speaker-Converter-High-Line-Level/dp/B004UA75 3G/ref=mp_s_a_1_4?crid=3KRE4D6YERZUR&keywords=speaker+to+line+level+co nverter&qid=1554755940&s=gateway&sprefix=speaker+to+line+&sr=8-4
memes_33
you're probably not going to get a spec sheet for the toys that identify speaker impedance, but this will probably work pretty well in most cases:

https://www.rdlnet.com/blog/tips/line-level-from-a-4-ohm-or-8-ohm-spea ker-line/
HappySampler
Ouch!!! Pricey
astrosound
Try something like a 10k resistor between the positive speaker terminal and the clip that goes to the cable tip. Cable screen clips directly to the other speaker terminal.

If these are just small battery powered toys you might not even need the resistor, but it doesn't hurt to play it safe.
HappySampler
Yes, all battery powered toddler toys.

Thanks I’ll give that a try.

Just don’t want to risk damaging the audio interface
infinitemachinery
Here's are the voltage levels that various audio equipment expect.

https://en.wikipedia.org/wiki/Line_level
NS4W
Just unsolder the speaker and attach your crocodile output jack - voila! You could also solder pot in between to control the volume. Cheap and easy does it!
HappySampler
Surely the signal is amplified before it hits the speaker so desoldering it wouldn’t change the levels problem ?

That aside, these are still toys in use so I don’t imagine desoldeing.
I just need to get a relatively clean recording of them
HappySampler
Found this which is useful and talks about the resistor option

http://www.oscillateur.com/circuitbending/faq
electricanada
Why not just use a mic?
OIP
i've plugged toys straight in before and just adjust the input level to get the cleanest possible signal.

be pretty shocked if you could damage the interface. you could try running it through any sort of pedal for a buffer if you want.
HappySampler
The speakers in these toys are cheapest of the cheap, I believe quality would be improved by using a line out. Besides that the buttons themselves are almost as loud as the volume so mic would pic up that noise too
electricanada
Ah, I would have thought sampling toys was a lofi project. I'd probably record them on my microcassette to make them sound even better.
JimY
If you really wanted to mic them and not pick up handling noise, you might take the speaker out, extend the wires so you can isolate speaker & mic from the noise. As the cheap speaker is a big part of the lo-fi charm, this would be a premium way to record it. That said, the toys casing will have a tuning/resonance effect on the speaker response too so it might sound a bit different out of the case.

The speaker won't have any higher voltage than the total battery does but it is an inductor so could (in theory) produce much higher voltages from the voice coil, but the circumstances to make that happen are unlikely.
Any decent audio interface ought to handle it, but as suggested earlier, a series resistor in line with your clip lead can attenuate it if necessary. An unbalanced line input (check the interface manual) will have an input impedance of 10k, so a 10k clip resistor will attenuate to half. If you have a potentiometer handy (100k would be useful), use it as a variable resistor then you can find an optimum.

To save time, you might record the speaker direct and with a mic to 2 separate tracks so you can pick & mix.
timdrage
electricanada wrote:
Ah, I would have thought sampling toys was a lofi project. I'd probably record them on my microcassette to make them sound even better.


the point of adding line outs to toys (circuit bent or otherwise) is that the 'lo-fi' nature of the sounds is often mostly due to the tiny speaker, you can get all sorts of unexpectedly clear / heavy / electronic /harsh sounds out of them with a line out

if you leave the speaker in place while wiring up a line out it will work but of course will act as a microphone too, which may or may not matter.

I've found that some toys won't work at all without a speaker, often this can be worked around by putting a 8ohm-ish resistor where the speaker was, or on very small plastic cheap speakers you can just carefully snap the glue that holds the magnet in place and remove it smile
Grumble
To make things worse, I tried to get a line-out from a small board with a bluetooth speaker.
It turned out that the speaker was not connected to gnd level, but each side of the speaker was connected to a push-pull output where the signal of one pin of the speaker was inverted to the other, effectively doubling the voltage over the speaker.
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