Measuring line levels using a multimeter

[hyperknot]

Hi, I have a very super basic question. Is it possible to measure line level using a multimeter in AC Voltage settings?

I have a cheap but recommended "Excel DT9205A" multimeter, like this: https://www.petervis.com/meters/Excel_DT9205A/Excel_DT9205A.html

I've set it to AC Voltage mode and tested a few input sources I have.

I generated sine waves using max volume in everything and REW with the following screen:

Here are some results:
Macbook Pro built-in line out 1.32 V
Audinst HUD MX1 line out max volume: 2.25 V
Audinst HUD MX1 headphone out max volume: 3.52 V
Vocopro FA-500 banana plugs: 33 V

So what did I measure with my multimeter actually? Peak to Peak or RMS or Zero to Peak?

Does measurements like this make any sense? I heard I cannot use a multimeter, I'd need to buy a VU meter or an SPL meter or something similar.

I was quite surprised at the speaker out, it's enough for an electric shock, doesn't it? On the other hand Nelson Pass always shows that a speaker never needs more than 1 Watt, so I'm surprised. Would it be 0.03 Amps only at 33 Volts so that it's 1 Watt?

Also, about line levels, if needed, could I use the headphone out of my DAC in professional level equipment? Or practically speaking, should I use my MX1's headphone or line out out for an ICEpower 125ASX2 module without input buffer / preamp?

What happens if a poweramp / Class D module is designed for say 2 V line level in but I send 2.25 V or 3.5 V signal into it?

BTW, I found this in the ICEpower datasheet:

 

[amirm]

You have to lower the frequency to have any chance of the meter showing correct levels. Most won't do well at 1 kHz.

 

[hyperknot]

You have to lower the frequency to have any chance of the meter showing correct levels. Most won't do well at 1 kHz.

I was surprised as well, but it was showing exactly the same voltage (to 2 digits) at 50 hz, 100 hz, 400 hz and 1 khz.

At 5 khz and 10 khz its displayed value starts going up.

 

[amirm]

That's good then. As to your question, if it has RMS capability on AC Volts, than that is what it is showing, not peak.

 

[RayDunzl]

So what did I measure with my multimeter actually? Peak to Peak or RMS or Zero to Peak?

Most probably RMS.

Assuming you're in the US:

Measure your AC outlet voltage. It should read around 120V RMS, or 170V Peak, or 340V Peak to Peak.


Safety Method for that:

1. Select an appropriate AC range on the meter.

2. Plug the meter leads into the female end of an unplugged extension cord.

2. Plug in the extension cord, and read the meter.

 

[restorer-john]

At 5 khz and 10 khz its displayed value starts going up.

The flash A/D is aliasing- usually the measured value drops as the frequency goes up. I have found cheap multimeters do much better than they used to, with some remaining reasonably accurate to around 3Khz. Unless you spring for a Fluke, forget anything above 1-2KHz.

Most probably RMS.

The non True RMS meters measure average.

 

[watchnerd]

You have to lower the frequency to have any chance of the meter showing correct levels. Most won't do well at 1 kHz.

How low Hz should I go?

I was just trying to measure the output of my tube RIAA today using a Fluke 107 and a 1kHz test tone from a test LP.

It's super low gain and was measuring in the 250-400 mV (AC), which seems about right given how much I have to dial up the volume.

 

[restorer-john]

How low Hz should I go?

I was just trying to measure the output of my tube RIAA today using a Fluke 107 and a 1kHz test tone from a test LP.

Your 107 is rated to 500Hz.

How accurate or innaccurate the 107 becomes after that, is unknown. Many more expensive Flukes rate out to 20KHz. It comes down to the speed (and type) of A/D in the meter. Some are dual slope, some flash, some use two.

Fluke 87III AC specs:

 

[hyperknot]

Thanks for the replies, I just did the AC test and it shows 230 Volts. I'm in Europe.

 

[RayDunzl]

The non True RMS meters measure average.

I need education.

If I average a sine I get zero.

https://www.electronics-tutorials.ws/accircuits/average-voltage.html

 

[restorer-john]

I need education.

If I average a sine I get zero.

https://www.keysight.com/main/editorial.jspx?cc=AU&lc=eng&ckey=458364&nid=-11143.0.00&id=458364

 

[HammerSandwich]

If I average a sine I get zero.

Average the signal's absolute value.

 

[hyperknot]

So which one is 230V mains voltage in Europe? RMS or Peak to Zero?

 

[amirm]

So which one is 230V mains voltage in Europe? RMS or Peak to Zero?

RMS.

 

[DonH56]

From the Excel DT9205A manual:

3.2 ACV Range Accuracy 200mV 1.2% ±3 2V 20V 0.8% ± 2 200V 750V 1.2% ±3 Input impedance: 10MΩ Frequency range: 40 ~ 400Hz

 

[watchnerd]

Total dumbass question:

To get the total output, does one measure the left and right channels separately and then add them together?

Or is the standard rating (e.g. 2V for line level) on a per channel basis?

 

[restorer-john]

Buy yourself one of these- cheaper than a millivoltmeter and a whole lot more fun for a few dollars:

https://www.ebay.com.au/itm/DSO138-...283432?hash=item3d3db51828:g:2JcAAOSwIK9dVNFZ

https://www.ebay.com.au/itm/Assembl...hash=item3d3e1c6723:m:mrafc5vOmlx1p8KUd8RRFAw

 

[AnalogDE]

Most probably RMS.

Assuming you're in the US:

Measure your AC outlet voltage. It should read around 120V RMS, or 170V Peak, or 340V Peak to Peak.


Safety Method for that:

1. Select an appropriate AC range on the meter.

2. Plug the meter leads into the female end of an unplugged extension cord.

2. Plug in the extension cord, and read the meter.


View attachment 34059

For additional safety keep one hand in pocket

 

[restorer-john]

For additional safety keep one hand in pocket

And hold the other probe with his teeth?

 

[hyperknot]

OK, from the mains voltage I know that my multimeter shows RMS in AC mode.

I believe this means that I have the following Peak-to-Zero values:
Macbook Pro line out: 1.86 V
Audinst HUD MX1 line out: 3.17 V
Audinst HUD MX1 headphone max volume: 4.96 V
Featheramp amp ICEpower: 46 V

I've checked the manuals and I found the following values:
Audinst line out: "Level : ±3Vpp max"
Audinst headphone out: "Max Out Level : ±10Vpp ( 600Ω, when inserts the jumper )" - which is a high gain mode I'm not using
ICEpower SE mode: "Vo-max, Max output voltage, RL = 4Ω: 32 Vp"

So comparing to the specs:
1. Line out 3.17 Vp is quite different from 3Vpp max = 1.5 Vp.
2. Headphone out max volume 4.96 Vp is almost perfect with 10 Vpp, the only different from the high-low gain switch which I do not have set.
3. ICEpower SE mode: I have 46 Vp without load and the specs say 32 Vp max, with 4Ω speakers.


So if I understand it correctly
1. The measured line out on my Audinst is almost 2.11x times higher than in the specs. Is this normal?
2. The headphone out is exactly the same as in the specs, however that one is specified for the high gain settings, whereas this was with the low gain + no load.
3. The ICEpower is outputting 1.4x as much voltage as is in the specs sheet for "Max output voltage". Is this because there was no load on it?