[mfsoa]

I have some basic questions that maybe you more experienced folks can help with.

I think I am having a channel imbalance on my preamp. Images seem shifted to the right (there's no balance knob). No, I haven't done the "switch cables - does the imbalance swap channels or not" test but I was wondering, if I wanted to use a multimeter:

1) Is there a special type of meter to use? I have an older analog model, but would like to get a better digital one for this purpose, and also for general home and audio use. Any suggestions on a good all-around amateur DIY kinda multimeter?

2) To check the output of the preamp, I was thinking of using a cheap RCA interconnect, chopping it up and using the two leads inside for connection to the meter (alligators?) Any better ideas/advice?

3) What source to use? I have the Sphile test CD, but the test tones are warbles, which might not be good. There is also some pink noise which might be better? I also have the 10-300 hz tones from Realtraps - would these be good? I was going to simply switch the input cable to the preamp to avoid any channel imbalance upstream. Again,advice?

4) I guess I'd be looking at 1-2 mv signals at the high end, but would also like to go lower to see linear behavior of each preamp channel. Does an "all-around" multimeter go this low w/ good accuracy?

Thanks for any tips you can give me.

[Bob Reynolds]

Hi,

Though I'm not one "of the more experienced folks" around here, I recently posted a question regarding doing level matching with a voltmeter. So we are looking at a similar issue.

I decided on the Fluke 112 DMM, which I ordered from HMC Electronics.

I intend on checking the voltage at the speaker binding posts. But, in your case checking it at the preamp output makes sense to me. Of course, there could be a gain difference between channels in your amplifier that is causing the imbalance. There could also be an acoustic issue as well, see below.

For a test tone, I'm going to use the 1 KHz sine wave at -20dBFS that is on the M&K setup CD that came with my bass management controller. You can download the test signals from the M&K pro web site here:
http://www.mkprofessional.com/wav/index.htm

Using an SPL meter and these test tones you can verify if an imbalance actually exists or not. When doing my subwoofer setup I detected a 1.5 dB imbalance which I attribute to the furniture arrangement in our living room. The M&K LFE-4 bass management controller has level controls on each channel so it was easy to correct the imbalance.

Hope some of this helps,
Bob