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Help using a multimeter to do some testing!

teapea

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I stream everything round the house with Chromecast, it's easy and works, and also means I can create "groups" for multi-room etc.
In my living room, I have a choice though. I can use a Chromecast Audio which is plugged into my amp using phono - so using the CCA DAC, or I can use the Chromecast in the TV, send that via TosLink into the amp, and hence I assume I'm using the DAC of the amp.
I have them set up both in the same Chromecast group - so can easily just change the source on my amp to switch between them.
Now, I "hear" a difference, but I know there really shouldn't be one! I mean, the DACs in the amp or CCA aren't amazing - but better than my hearing so I'm assuming it's simply down to the levels of the sources not being matched and one is simply louder than the other. (Hear, is in inverted commas as my blinding is not exactly robust so probably still have a hunch as to which source is which by the sighs given by the other half when asking her to randomly switch between the sources or not at all but record her selections haha)
I have a multimeter... but quite literally where do I put it and what do I need to measure?
 

Blumlein 88

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If using speakers check ac voltage at speaker terminals. I would suggest using a 400 hz sine wave. Match the two sources within plus or minus 1.5%. Set one source to a comfortable listening level with music then match both with the test tone. Then listen with music.

Also good idea to check both channels as you might have a channel mismatch.

Warning: use a tone at -20 db full scale. A tone at max level will be much too loud.
 

Philbo King

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A smart phone with sound level app and a ruler. Measure one at 6" away, measure the other at 6" away also. Compare. That compensates for different speaker sensitivities.

It'll sound different regardless (different rooms, different speakers) but that will at least get rid of level differences.
 

Blumlein 88

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A smart phone with sound level app and a ruler. Measure one at 6" away, measure the other at 6" away also. Compare. That compensates for different speaker sensitivities.

It'll sound different regardless (different rooms, different speakers) but that will at least get rid of level differences.
Damn it No.

To the op maybe I misunderstood. Are you comparing two different speakers? If not don't match with a mic and spl app. The voltmeter is the way to go.
 

staticV3

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I can use a Chromecast Audio which is plugged into my amp using phono
I hope your CCA isn't actually plugged into a Phono input, since that will typically apply RIAA equalization to the sound.
 
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teapea

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No - one amp, one set of speaker. Just testing between different sources of the amp from the exact same stream being sent to a group of Chromecasts.

So yes, AC Voltage was what I need to do the measurement.
Do I leave the speakers connected, or am I just testing the speaker terminals on the back of the amp? Does it even matter?

Also - where would I find a "test tone" to use?
 
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teapea

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I hope your CCA isn't actually plugged into a Phono input, since that will typically apply RIAA equalization to the sound.
3.5mm to red and white phono connectors... that's phono in my book!
 
D

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3.5mm to red and white phono connectors... that's phono in my book!
Mostly referred to as RCA connectors. Phono being a "vinyl player" "record player" which outputs a "phono signal" which needs processing and a lot of pre-amplification.

Thus the concern about whether you have connected to a phono input. Which will result in non-optimal results.. ;)

1707491880219.png
 

staticV3

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Do I leave the speakers connected, or am I just testing the speaker terminals on the back of the amp? Does it even matter?
Leave the speakers connected.

Also - where would I find a "test tone" to use?
You can use online tone generators like this: https://www.szynalski.com/tone-generator/

Or you can use programs like REW, Audacity, Audition to make your own Flac or Wav files for testing.

If you can't be bothered, I've attached a 60Hz sine wave below.
Just set your multimeter to AC and play it on repeat.

3.5mm to red and white phono connectors... that's phono in my book!
Please make sure that that input is intended for the output of a phono preamp, not for directly plugging in a turntable.

If it's for a turntable, then you really shouldn't plug your CCA into it.
The CCA's comparatively high output voltage may damage the built-in phono pre and the sound won't be correct in the first place due to RIAA EQ.
 

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  • Sine_60_0_dBFS_44k_PCM16_01.flac (1).zip
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Deleted member 48726

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Leave the speakers connected.


You can use online tone generators like this: https://www.szynalski.com/tone-generator/

Or you can use programs like REW, Audacity, Audition to make your own Flac or Wav files for testing.

If you can't be bothered, I've attached a 60Hz sine wave below.
Just set your multimeter to AC and play it on repeat.


Please make sure that that input is intended for the output of a phono preamp, not for directly plugging in a turntable.

If it's for a turntable, then you really shouldn't plug your CCA into it.
The CCA's comparatively high output voltage may damage the built-in phono pre and the sound won't be correct in the first place due to RIAA EQ.

Or find the test tones on Spotify.
 
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teapea

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Amazing - thanks all for your input.

OK it's not a true "phono" - it's a line level input so no issues there thankfully.

Thank you for posting a test tone - I would have no idea how to use any of the other tools to create one so that's great. I'll just whack it on VLC on repeat and cast that to the group - should be perfect.

Will post back with how I got on next week!
 
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