Topic: Microphone Testing/Level testing to prove problem

[gmm6797]

OK... running Schoeps MK4 caps, matched pair, serial number sequential.

Had a heavily used active cable, and thought that was the problem, just bought a new (used) active cable (KCY 250/5 I), stealthed a show last night and the left channel is still a few DB less than the right channel (the the softer channel was closer to the stack ironically, as I was not 100% centered.... unless I swapped the R/L cables when I wired up in the 95 degree heat)

I have had this issue with different decks (D100, M1, R1, DAP1), different pre-amps (2 different VMS02s and 1 VMS)

I did not watch the caps to see if the right went to the right on the new cable, so that is a tough one, and I have already taken the caps off the active cable, so I cant be for sure which one was where.

I sent the whole rig (all Schoeps parts) to Redding Audio and it got a clean bill of health back in January

So... any proven ways to record some sort of a test @ home to see if I can narrow down the issue?

Thanks

[Chuck]

Unfortunately many manufacturers use a 1 kHz tone. I prefer to use white noise which covers the whole spectrum. It's not too good for your speakers though. The goal is to play the sound at a high enough level that the ambient noise in the test room doesn't influence the results.

I wait for my wife to go shopping before I test equipment. 

[gmm6797]

Thanks for the suggestion... how can one make a "white noise" track to crank out of the stereo?

Any suggestions on mic placement with regards to the stereo (which should probably be upgaded before this test)?

[anodyne33]

My thought is that if it's only "a few db" why worry about it. If you're running Schoeps you can most likely afford the software to fix it in post.

[gmm6797]

Dont you think it would be nice to just put a show on CD after and not have to mess with every single one?

Any why does the cost of the mics assume I have other money to burn?

[anodyne33]

Okay, maybe that sounded wrong. I agree that I'd want it to be spot on right out of the box, but there a many places where this can go wrong. My point is that rather go crazy trying to figure out if the problem is in the caps, cables, pre, interconnects.... and then trying to fix it or getting it professionally repaired I'd be more inclined to basically create a template in my favorite editing software that I can apply every time if the problem is indeed consistent.

[willndmb]

Thanks for the suggestion... how can one make a "white noise" track to crank out of the stereo?

Any suggestions on mic placement with regards to the stereo (which should probably be upgaded before this test)?

you can make whitenoise in a few programs such as cool edit
for a test i think you can just use your comp speakers if you like
as long as they are the same distance away you will be able to swap out the cables, pre and whatnot to see if the caps are actually the prob or not

at least thats what i did to set my svu and see exactly how much difference my caps had

[guysonic]

Quick way to check balance is to tune portable or home stereo in-between FM stations (muting off) for 'pink noise'.  Place mics close together and up-close centered of one of the speakers.  Look at VU meters or better to make a recording to view on an editor for bandwidth and specific (usually 1000 cycle) balance.   Just 1 dB of inbalance makes an audible difference for stereo imaging, but most do not have accurate stereo imaging mic arrays, so channel balance less audible but still important.

Note 1000 cycle balance mis-match of the mics, label each mic with 1000 cycle measurement like MIC 1 = 0.0 dB; MIC 2 = -2.4 dB.  In this way, you can use the editor to always adjust for exact channel re-balance that is very difficult to do just listening to or looking at live recording levels afterwards.   

Of course, if your preamplifier/deck has non-ganged REC level adjustments, inbalance of channels may also be from not having these EXACTLY adjusted equally for each channel and this is another common source of channels being off even with matched microphones.

[gmm6797]

Thanks for the ideas everyone, I am going to try these suggestions here and see what my results are.

The easy part of my gear, is only the R1 has levels to adjust, and just one knob so very little room for "user error".

I was thinking I would also try some different cables out of my VMS (no levels and just BNC out) to my R300 just to make sure it is not the R1 (which i assume not since my M1 has the same results).

Thanks again, I will post results when I am done testing.