Measurement beginner - measuring a single speaker on a stereo amplifier

[fotoalan]

I'm thinking of getting a UMIK-1 to start playing around with some measurements. I'm assuming for room measurements & corrections I want the mike at my normal listening position, with both speakers & sub running. But what if I want to try to measure my speakers? Single speaker measurements seem to be the way to go, but how?

1. Test tones with only one channel. Can/does REW do this?
2. Only plug in one RCA input
3. Use the amp's balance control to mute one channel
4. Unplug one speaker

Which is the correct way to go about this? Is there any risk of damaging the amplifier with (2) or (4)?

 

[KMO]

Absolutely REW can do single-channel test tones, and normally does, so (1) usually.

Sometimes you'll have to resort to other methods like (2)-(4), and there's no real problem with them, except mainly for the possibility of shorting the amp output while messing with speaker wires. So don't mess with connections while turned on.

Messing with subwoofers often means disconnection - when going to attempt time alignment you need to isolate just the sub's half or the speaker's half of the crossover, which are both coming from the same source signal, so (1) doesn't work. You can get a speaker's half alone by simply turning the subwoofer off, but to get the subwoofer alone means disconnecting a speaker.

Combined (multispeaker or speaker+sub) measurements are less useful than isolated measurements, because you can always combine isolated measurements in REW by trace arithmetic, and this predicts the real world combined response very well.

 

[fotoalan]

Messing with subwoofers often means disconnection - when going to attempt time alignment you need to isolate just the sub's half or the speaker's half of the crossover, which are both coming from the same source signal, so (1) doesn't work. You can get a speaker's half alone by simply turning the subwoofer off, but to get the subwoofer alone means disconnecting a speaker.

Very informative, thank you. I was assuming switching the sub off and setting the lowest possible crossover frequency on the amp would suffice for measuring a speaker, but if it's necessary to unplug the sub then I will do so.