Build An Audio Signal Tracer

[@AlYoung]

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[@sincerelyyours7538]

I came for the signal tracer probe, stayed for the music. Very fine blues selection there, man. The probe's good too, thanks!

[@anthonyludington8320]

This may sound stupid, but the little flimsy stand that comes with the soldering iron. I never thought of propping the iron on that to use for tinning wires. 🤯 That's so much faster than wrestling them into place in the helping hands. Good video!

[@AlYoung]

Thanks Anthony! I have fairly shaky hands so I find having the iron stationary helps a lot. I appreciate your feedback!

[@tracyaryall]

You are like the Bob Ross of guitars and electronics 🙌

[@cuinoz3569]

Great presentation. Appreciate your time. Thanks for sharing.

[@joemoe1906]

Could I use this for any kind of amps? Say an active speaker/monitor?

[@AlYoung]

@@joemoe1906 hello there! You can definitely use this for that. It works for pedals, tube amps, stereo units, mixers, etc. pretty much anything that has an audio signal.

[@RC-Heli835]

Love them blues man!

[@AlYoung]

Me too Blade!

[@tracyaryall]

Very clear instructions. Love it 😍

[@FulcrumsEdge]

if you are sending audio signal into an amplifier, even if it is line level capable of clipping the signal at the amplifier input stage, isn't it true there is no DC? I've heard of function generators can add dc to create signals with the necessary DC offset to diagnose some device functions, but sending a sinewave signal at any given frequency (the visual representation of alternating current) from a signal generator or a re-amped guitar signal from an audio interface means there should be no DC present. So why the capacitor? To be honest I can't imagine what kind of device or testing equipment you would be sending a test signal from to a guitar amplifier other than a pure sinewave or guitar signal. Is there something I am unaware of that can be used to help diagnose an issue of audio signal loss in an audio amplifier? (genuine question!)

[@AlYoung]

That’s a great question! So the purpose of the capacitor is a safety measure to start. In a tube amp circuit there is potential for high dc voltage in the circuit. When probing around the circuit the cap will prevent shock/damage if you accidentally touch a high voltage solder joint. The other thing is that ac and dc voltage can share the same signal path so the cap will only allow the small ac signal thru while blocking the dc which would likely blow the testing amplifier. It does really matter that much in a pedal as there isn’t that much high voltage but in a tube amp you can have 400-500 dc volts.

[@FulcrumsEdge]

@@AlYoung damn that totally makes sense. learning something new every day! diagnosing means an issue somewhere, and a bad coupling cap means an unkown source of dc leakage into the audio signal, clearly necessitating the cap you put on the signal tracer. I am glad i asked because i have been slowly learning the ins and outs of tube amp circuits, obsessing over learning how to interpret schematics, and understanding electrical fundamentals, and respecting the danger that exists in extremely high voltages. Anything i start to study, I prefer having as much practical knowledge when going into something over taking risks. thanks for giving me a perfect explanation!

[@AlYoung]

@@FulcrumsEdge I also find audio electronics super fascinating!

[@RC-Heli835]

I have a muliti process guitar pedal that went bad after plugging in to a patch with the gain turned up at the sound board. Maybe I could find the problem with this, it powers on but no sound comes out.

[@AlYoung]

I think you could definately trace it to the source with this for sure. Try and find a schematic online and then trace from the input and go down the line. You could also check the power section to make sure it is supplying the proper voltages to the preamp stages with a multimeter.

[@RC-Heli835]

@@AlYoung Ok thanks!

[@mr.selfdestruct2917]

Cool. What's the recommended cap value?

[@AlYoung]

For this probe I used a 0.1uf/600v (104) orange drop capacitor. It has worked well for for all my signal tracing needs.

[@mr.selfdestruct2917]

@@AlYoung thank you

[@Joejoe-nt3gc]

@@AlYoung does it matter where the polarity is pointing towards to??

[@Joejoe-nt3gc]

The capacitor…is it polarized?

[@moonboogien8908]

​@@Joejoe-nt3gcthis cap is not polarized. It can be soldered in either direction.

[@daleburrell6273]

...SIMPLE, BUT EFFECTIVE-(!)

[@AlYoung]

It’s the simple things that make the journey so much easier! I’ve used this tool quite a few times and it’s saved a lot of time and money. Definitely worth the time to build it!