Topic: What happened? (Busman > PS2 > CA ST9100 = weird L channel)

[travelinbeat]

So I was running Busman BSC1's with hyper caps and big-ass shure windscreens, at 10" with cables running into a Denecke PS-2.  The PS2 spits out XLR, so I use a HOSA adapter (I know...) to make those dual XLR males into one stereo 3.5 for the 9100.  The 9100 pre then drops the signal into my R-09HR.  I've done this setup a million times with no problems, but this time, my 9100's clipping light stayed bright red, even though I couldn't hear anything wrong when I tried to monitor it.  I'm guessing that this problem will be the 9100, because during an intermission, I swapped out all batteries with new ones (the originals were new, but who knows), checked all connections, switched my link from the 9100 to the R09HR, and double checked that the caps were screwed down securely on the mics.  Another short test involved unplugging everything from the 9100 and just turning it on... any cable activity was met with about 30-60 seconds of no activity from the clipping light, then it came on weakly, then stronger, then all the way; even with no cables plugged in.  Unplug either the input or output, the light goes off for a while, plug in either in or out, and the light goes out for a comparable amount of time (30 seconds or so).  Just when I thought I had the whole thing solved, and that I had diagnosed a problem with the 9100, it operated fine throughout the second set (90min or so).  I have no idea what's going on, so here's a screenshot, I can get audio samples if that'll help.

BTW: The show was Counting Crows at Pier 6 Pavilion in Baltimore MD

[kirk97132]

WARNING: I have absolutely no Electrical Engineering knowledge.  But that being said.  I had a similar looking wave coming from a modded UA-5.  I talked to Chris Busman and he said it was most likely an Op amp acting up.  I did not have quite the same problem but based on the looks of the waveform it sure looked a lot like that.  I also have no idea if a mic has anything like an op amp in it or if it is the 9100 pre.  If I were you I'd try to get a way to run the mics on a different pre and different mics on the 9100 pre so you see which one is causing you grief

[Brian Skalinder]

I had a similarly odd waveform when I had an op amp in my old modSBM-1 go bad years ago.

Are you able to swap out components to try to isolate the device causing the issue?

[travelinbeat]

Well one of the strange parts about the issue is that it did not manifest itself at all in the second set, so I don't think that a swapping gear test would be accurate, as there is no conclusive way to determine whether a good result is the result of good gear or just that the bad gear isn't acting up.

[rastasean]

Well one of the strange parts about the issue is that it did not manifest itself at all in the second set, so I don't think that a swapping gear test would be accurate, as there is no conclusive way to determine whether a good result is the result of good gear or just that the bad gear isn't acting up.

But a controlled recreation/test is ideal to eliminate particular pieces of equipment and cables.

You didn't make mention of the high pass filter or windcut, were they both in matching positions?

[SmokinJoe]

I'm behind a firewall and can't see your waveform at the moment, so I'm commenting without seeing the whole picture.

If you use Hosa impedance transformers (or any other brand), one side of a transformer is just a coil, so plugging that into the ST9100 acts like a dead short across the DC "plug in power" circuit on the ST9100.  I've seen Chris Church advise against doing that with Nak CM300's, and I think this is similar.  I think he said something to the effect of "It's hard on the ST9100.  You might get away with it for a while, but eventually it will probably burn up".  I hate to say it, but if your 9100 is acting funky, I suspect that is your problem.   I think you can run PS2 > 9100 without the Hosa transformers, and the blocking caps on the PS2 will stop the plug in power like an open circuit as opposed to a short circuit.  At least I think that is the case.  Better ask Chris to be sure.

[Church-Audio]

Well one of the strange parts about the issue is that it did not manifest itself at all in the second set, so I don't think that a swapping gear test would be accurate, as there is no conclusive way to determine whether a good result is the result of good gear or just that the bad gear isn't acting up.

The only thing you can do is connect one thing at a time until you find out what in the chain is causing the problem.

[travelinbeat]

Well one of the strange parts about the issue is that it did not manifest itself at all in the second set, so I don't think that a swapping gear test would be accurate, as there is no conclusive way to determine whether a good result is the result of good gear or just that the bad gear isn't acting up.

The only thing you can do is connect one thing at a time until you find out what in the chain is causing the problem.

Well, at one point in the field, the 9100 was completely unplugged from everything (save the 9V), and it was still lighting up as though it was clipping.  I'd think for sure that this would indicate that there's something screwy going on with the 9100, but I don't know anything about how the device works.  Is there something in there that would cause a waveform like this for one recording then 20 minutes later produce a normal waveform?  Also, I tried turning the completely unplugged 9100 all the way down to just above where it clicks off, and its red clip indicator was unaffected.  Guesses?

[OOK]

Its funny, come to think of it had this same affect with a set of hypers as well.  If I remember correctly I chalked it up to wall reflection.  The Pa was far left, but i had the mics set up with a spread and I then balanced out the sound via the gain controls.....

I have a question....was there anything impeading the sound on that channel?  a wall, another mic, an object of some kind....or were you set up in a less thab ideal spot...

OOK

[travelinbeat]

I have a question....was there anything impeading the sound on that channel?  a wall, another mic, an object of some kind....or were you set up in a less thab ideal spot...

Nothing at all close by:



(of course this is while the venue was still pretty much empty, but even with people standing in front of the mics, there were several feet between the tops of their heads and the bottom of the mics)

[tbrown4]

I used to have a very similar problem when using the PS2.....and I figured out that it happened when the battery was getting close to drained.

[OOK]

I have a question....was there anything impeading the sound on that channel?  a wall, another mic, an object of some kind....or were you set up in a less thab ideal spot...

Nothing at all close by:



(of course this is while the venue was still pretty much empty, but even with people standing in front of the mics, there were several feet between the tops of their heads and the bottom of the mics)

And the plot thickens.... well I am at a loss.....  wondering why it happened to me....I was going mic > 702..... everything was charged full...

OOK

[travelinbeat]

any more thoughts?