Measuring your own electronics

[Jbrunwa]

Ok, I have basic analog electronics theory having been a ham radio operator some years ago, some experience with Room EQ Wizard measuring speakers, a Fluke multimeter, and a Focusrite Scarlett interface. Can someone point me to any tutorials on measuring preamps and AVRs, or is it as simple as gettin my feet wet trying to duplicate the parameter settings, input and output voltages we see on ASR graphs to the best of our ability

 

[Blumlein 88]

The REW forums have some good tutorials for various purposes. With your ham background probably for simpler stuff anyway just as easy as getting your feet wet doing the obvious things.

You also might initially try RMAA Rightmark Audio Analyzer.

RightMark Audio Analyzer. Products. Audio Rightmark

It sort of does it all for you. There are things I don't like about it, and for the most precision I think REW will do you better.

 

[davidandrewmiller10]

The standard units of electrical measurement used for the expression of voltage, current and resistance are the Volt [ V ], Ampere [ A ] and Ohm [ Ω ] respectively.

 

[DVDdoug]

You can make some measurements with an oscilloscope, multimeter, and signal generator (or you can use the computer as an audio generator) but in general it takes specialized equipment to get usable-meaningful results, especially to measure distortion.

Amir uses some kind of Audio Precision analyzer.

The standard units of electrical measurement used for the expression of voltage, current and resistance are the Volt [ V ], Ampere [ A ] and Ohm [ Ω ] respectively.

He has to know that since he had a ham radio license.

 

[AnalogSteph]

Looks like a bot to me.

 

[Lambda]

but in general it takes specialized equipment to get usable-meaningful results, especially to measure distortion.

No absolutely not.
You can do a lot with Just an audio interface. and free software like REW. Baudline and jaaa.

a Fluke multimeter, and a Focusrite Scarlett interface. Can someone point me to any tutorials on measuring preamps and AVRs, or is it as simple as gettin my feet wet trying to duplicate the parameter settings, input and output voltages we see on ASR graphs to the best of our ability

Calibrate your output with your Multi meter.
Calibrate your input with your now calibrated output.

Now have fun with REW. Baudline, jaaa, audacity and maybe Pure data and Gnu radio.
I would recommend to get a view known components. Attenuates and filter.

Easy to make an analog passive notch filter. measure your filter. make an EQ from your filter.

Quick and Simple Notch Filter for THD Measurements – Toli's DIY

So you can measur THD+N well below the limit of your interface.

Distortion Analyser

sound-au.com

THD and THD+N – Similar, but not the same

www.ap.com

 

[Jbrunwa]

For some reason I saw a high noise floor with the Scarlett when measuring the AVR. It wasn’t just a ground loop. Maybe it was defective. I returned it and bought a MOTU M4 which has a very low noise floor in the same configuration.

 

[SIY]

Looks like a bot to me.

Yes, it's a copy/paste that's been posted all over the web. Bot for sure.

 

[Lambda]

If you measure power amplifiers be very cautions and aware of your ground and signal paths!
You can blow up your interface and or USB/PC fast if you make a mistake.

As safety procession avoid having an low impedance path to you interface (including ground!).
You don’t need it anyways since your interface has very high input impedance.
Have some Capacitor in line to avoid DC.

Maybe get an transformer bases true isolated DI-Box

DI unit - Wikipedia

en.wikipedia.org

Only costs ~20$
It will causes some Frequency response change (you can calibrate out)
and some extra distortion, but this won’t matter for noises measurements.

 

[SIY]

It's best not to expose your interface to the raw dangers of the cruel world. That's why the Linear Audio Autoranging Attenuator is a vital accessory for soundcard/interface measurement of electronics.