Been doing a lot of A/B testing with assorted monitoring systems lately, amps, monitors, DA converters, monitor controllers, etc...
And I'm finding that in certain cases, my ears are detecting slight left / right balance issues. Not sure how to check for sure. No, it's not the room.
So, I happen to have a Coleman Audio MBP2 pair of analog VU meters handy:
http://www.colemanaudio.com/prodimages/MB2large.jpg
Figured I'd measure assorted outputs (everything but the amplifier outputs of course) using these meters. I realize that these aren't professional "testing" meters, but I'd like to think that they would still be helpful in revealing any balance issues in the outputs of typical audio gear.
I then got out my trusty dusty Alan Parsons audio check CD that has assorted test tones on it, such as a "1k sine wave at -14dBFS" etc (other test tones listed below in this post).
Ok, first, the Coleman VU meters have gain trim pots on the back and it is very possible that these need calibrating. So, step one, using my test tone CD, played through a pro-grade CD player (that happens to have consumer level -10dbu analog outputs), what is the best way to calibrate the VU meters? Like, if I play the -14dBFS test tone out of the -10dbu CD player, where should it be reading on the VU meters? I realize there are multiple "conversions" going on here (dBFS, dBu, VU).
I also have a DA converter that seems to be having obvious output balance issues and it DOES have output calibration trim pots on the rear. These analog outputs should be at pro-grade +4dBu level. So when going into the VU meters, where should the VU meter needles be pointing when I'm at +4dBu at the converter outputs?
To sum up, how does both -10dBu and +4dBu read on a standard VU meter?
And what is the best way to calibrate my VU meters? Is it reasonable / possible to at least get close using the test tone CD?
If there is a good, recommended, somewhat affordable test tool that can do all these types of tests / measurements easily, please fill me in and I'll order one tomorrow. I don't mind spending even several hundred $ if necessary... but hopefully not much more than that.
I do remember that one way to test the outputs of amplifiers is to just run a volt meter on the outputs... so that's pretty easy.
Finally, I am hoping to fully diagnose all my systems here and make sure that all my levels are correct as well as the balance. There's nothing more annoying than listening to a piece of music and detecting an ever so slight difference in left to right balance by ear and then wondering, is this just an issue / characteristic of the mix or is the system out of calibration or faulty or what? Often it's not very obvious so it can get you wondering.
I had an amp / controller a while back that had an inaccurate stereo volume pot, as you'd turn it, the left / right volume balance would shift a tad toward the right, then toward the left etc, drove me nuts until I finally put a voltmeter on the output of the amp and could actually observe that there was indeed a balance issues going on with the system. It was a faulty stereo volume pot of course which I have now learned is not such an uncommon thing.
I did see this:
http://www.gearslutz.com/board/attac...ital-scale.jpg
And also saw this:
http://www.sonelec-musique.com/image...o_echelles.gif
But yet certain things are still not making sense here, even with respect to these charts. I suspect I'm just still making some errors or simply do not understand... either that or some of the gear I'm measuring is just very far out of calibration.
I will also mention that the Alan Parsons check / test CD has the following tones on it:
Pink Noise Band
1 kHz sine wave ref. – 14 db FS
Sine & Square Waves Spot Frequencies
1 kHz ref. – 14 db FS
1 kHz square wave @-20 db
5 kHz square wave @-20 db
Max. Level Tone
1 kHz sine wave at 0 db FS.
Again, I'm playing these out of a good CD player that has "consumer level" -10dBu outputs.
Any help would be appreciated. kfhkh
And I'm finding that in certain cases, my ears are detecting slight left / right balance issues. Not sure how to check for sure. No, it's not the room.
So, I happen to have a Coleman Audio MBP2 pair of analog VU meters handy:
http://www.colemanaudio.com/prodimages/MB2large.jpg
Figured I'd measure assorted outputs (everything but the amplifier outputs of course) using these meters. I realize that these aren't professional "testing" meters, but I'd like to think that they would still be helpful in revealing any balance issues in the outputs of typical audio gear.
I then got out my trusty dusty Alan Parsons audio check CD that has assorted test tones on it, such as a "1k sine wave at -14dBFS" etc (other test tones listed below in this post).
Ok, first, the Coleman VU meters have gain trim pots on the back and it is very possible that these need calibrating. So, step one, using my test tone CD, played through a pro-grade CD player (that happens to have consumer level -10dbu analog outputs), what is the best way to calibrate the VU meters? Like, if I play the -14dBFS test tone out of the -10dbu CD player, where should it be reading on the VU meters? I realize there are multiple "conversions" going on here (dBFS, dBu, VU).
I also have a DA converter that seems to be having obvious output balance issues and it DOES have output calibration trim pots on the rear. These analog outputs should be at pro-grade +4dBu level. So when going into the VU meters, where should the VU meter needles be pointing when I'm at +4dBu at the converter outputs?
To sum up, how does both -10dBu and +4dBu read on a standard VU meter?
And what is the best way to calibrate my VU meters? Is it reasonable / possible to at least get close using the test tone CD?
If there is a good, recommended, somewhat affordable test tool that can do all these types of tests / measurements easily, please fill me in and I'll order one tomorrow. I don't mind spending even several hundred $ if necessary... but hopefully not much more than that.
I do remember that one way to test the outputs of amplifiers is to just run a volt meter on the outputs... so that's pretty easy.
Finally, I am hoping to fully diagnose all my systems here and make sure that all my levels are correct as well as the balance. There's nothing more annoying than listening to a piece of music and detecting an ever so slight difference in left to right balance by ear and then wondering, is this just an issue / characteristic of the mix or is the system out of calibration or faulty or what? Often it's not very obvious so it can get you wondering.
I had an amp / controller a while back that had an inaccurate stereo volume pot, as you'd turn it, the left / right volume balance would shift a tad toward the right, then toward the left etc, drove me nuts until I finally put a voltmeter on the output of the amp and could actually observe that there was indeed a balance issues going on with the system. It was a faulty stereo volume pot of course which I have now learned is not such an uncommon thing.
I did see this:
http://www.gearslutz.com/board/attac...ital-scale.jpg
And also saw this:
http://www.sonelec-musique.com/image...o_echelles.gif
But yet certain things are still not making sense here, even with respect to these charts. I suspect I'm just still making some errors or simply do not understand... either that or some of the gear I'm measuring is just very far out of calibration.
I will also mention that the Alan Parsons check / test CD has the following tones on it:
Pink Noise Band
1 kHz sine wave ref. – 14 db FS
Sine & Square Waves Spot Frequencies
1 kHz ref. – 14 db FS
1 kHz square wave @-20 db
5 kHz square wave @-20 db
Max. Level Tone
1 kHz sine wave at 0 db FS.
Again, I'm playing these out of a good CD player that has "consumer level" -10dBu outputs.
Any help would be appreciated. kfhkh