Topic: Help me identify this BUZZ problem

[justdmbobbo]

Ok, so as I mentioned before, DMB Starlake night 2 I had a very low freq. buzz that developed in the right channel during the encore break and the encore.

Source Info - AKG 460 JW Mods ck61 caps > Ice homemade cables > SD 722 @24/96   
Also note, I only got a partial charge on the 722 the night before, so the battery was just about drained completely out during the encore break and encore..though it did last the whole show, yet the batt light was blinking when I shut it down.

History - I recall MAYBE a couple years ago that I had a DMB Alpine tape that had this noise in it, but it was only for like 30 seconds and then went away.  I never knew what it was and I don't think I ever converted the tape.
(it wasn't that good of a tape anyway)  Between then and now I got the AKG 460's modded and have used them without a problem both before and after without problems, Prime example, DMB Starlake 1 came out gorgeous.

Possible causes -
Cell Phone interference?
Bad Cable?
Bad CK61 Cap?
Low Batt on the 722 causing the mic to try and pull too much power?

Thanks,
(See Attached File)

[BCostigan]

Judging by the noises fast rise and fall in the middle of the clip I'd say it was either the battery issue or *maybe* a cell phone.

Cell phones can cause some major noise in electronics.....my PC monitor clicks and pops just before my cell phone rings.      Ahh the wonders of EMF.


Maybe try draining the 722 again and see if the problem happens again....if so done deal.  If not....I doubt you figure it out as it doesn't sound like cable/connection noise to me.

[grider]

I had this problem the first night of a three night taping run back in October, and curiously did not have it the following two nights; my guess is it was just a loose cap, or loose connection, or something about the way I set up the first night but did not repeat the following nights, but I never pinpointed the problem; one of taping's mysteries

[justdmbobbo]

Judging by the noises fast rise and fall in the middle of the clip I'd say it was either the battery issue or *maybe* a cell phone.

Cell phones can cause some major noise in electronics.....my PC monitor clicks and pops just before my cell phone rings.      Ahh the wonders of EMF.


Maybe try draining the 722 again and see if the problem happens again....if so done deal.  If not....I doubt you figure it out as it doesn't sound like cable/connection noise to me.

From a few others that have given me feedback, the inital reaction might be the fact that the battery was so low on the unit it was struggling to power the right channel.  I'm attempting now to do a test by recording till the thing dies, then try and listen back to the last 5 mintues or so to see if the problem repeats.
I'll report back.

[BobW]

My guess......"Motorboating" self-oscillation, usually at a low frequency.
Maybe the low power from the dying batts reduced feadback to an amp to the point that it "took-off" (began oscillating)

As always, moisture, grounds, phantom PS noise, etc. are suspect.  Cellphones, wireless anything can all do wierd stuff like this too.

Let us know if you pin it down.

Good luck !