How to measure output level to speakers?

run_Forrest_run

Hi All,
I have recently purchased a new pair of Mission M32i speakers. After setting them up and started to break them in I noticed when the amp is on a very low level there is a difference in volume levels in both speakers (yes, the balance is set to 50/50!).

I checked the wiring, polarity etc..and all is OK. Now I am wondering is it something with the amp (NAD amp). I only noticed this at such low volume levels because my daughter was in bed so I could not check to see if the problem persists as the volume increases.

I think it may be a problem with the amp but can anyone tell me if there is such a tool/meter to measure the power/output levels being sent to each speaker? Is there a tool I can connect to the speaker posts to measure the output??

Apart from that the speakers sound great.

Red Alert

First thing to do is swap the speakers around. That should straightaway tell you if the problem is with the amp or the speakers.

I don't know if the M32's are bi-wireable/bi-ampable, i think they might be. Make sure if you're using them normally (i.e. one amp, one wire to each speaker) that the bridging plates are installed properly and that both drivers are working in each speaker.

If the problem is with the amp:

Turn off as many features of the amp as you, put on the tone-defeat or pure direct switches if the amp has them. A dodgy tone-control could be responsible.

Check what's connected to the tape outs, if anything. Depending on if the tape loops are buffered or not, a dodgy tape or MD deck or indeed interconnect could be the cause. Best idea would be to start with just CD player, amp and speakers, everything else disconnected.

Hope you get it sorted I've a pair of the similar M33 floorstanders and they really are awesome!

run_Forrest_run

thanks for the info Red Alert...OK I will try that. I have a funny feeling it is the amp but I will swap the speakers and see. Yes the M32i are bi-wireable. OK, will check the bridging plates also...I have never removed them but will check anyway. I do have outputs for MD, tape, Video jacks connected to interconnects but they are connected to nothing on the other end. I will remove all interconnects also.

I previously had Mission 702e floorstanders...they served me well. I need to free up some floor space hence the m32i now on board.

Red Alert

I forgot to actually answer the question you asked - yes you can get power meters but any reasonably priced ones are only for measuring mains voltage power (like how much your microwave is using). The audio bandwidth is much higher and the voltages are much lower, and also because of the way audio amps work any device to measure the power can end up loading the amp and giving a bad reading unless done carefully. Audio power metering is best done with bridge circuits and oscilloscopes!

mathias

What you need is a SPL meter , thats a sound pressure level meter , this one is cheap and does the job , at low volumes it should be accurate enough within itself to tell you if both speakers are outputting at the same level in decibels ,

Its best to use the amps test tone to measure , they should be the same level from both speakers with the meter the same distance away from each speaker.

These are invaluable for setting up a surround system in an uneven room , you know the way that you can set the level for front and rears with a frequency disk ( one came with my mordaunt shorts ) , well this is the type of meter you need to use that frequency disk to full effect.

http://www.radioshack.com/sm-digital-display-sound-level-meter--pi-2103667.html

run_Forrest_run

thanks for that mathias...I will keep that in mind but for the moment the problem seems to have gone away. I think it may have had something to do with the position of both speakers. Since then I have put the speakers on dedicated brackets on the wall, equal distance apart (each side of the fire place) and the sound is nice and balanced. I followed some of the steps discussed by Red Alert above.