Topic: SBD recording w/ bizarre issue

[junkyardt]

Alright, I pulled SBDs the other night for a couple bands that turned out pretty messed up. I ran it by a fellow taper on here and he didn't know what to make of it either, so I thought some others (FOH's maybe?) might have some insight as to what went wrong. I've pulled SBDs in that same room in the past (actually, once, in this room for the same exact band in the sample below) that turned out fine, so I'm pretty confused as to what happened.

I knew something was up with the SBD source when I first started recording, and I was getting a type of level reading I hadn't seen before, basically a combination of low levels punctuated by repeated huge spikes. I had to set the levels nearly at the minimum just so the spikes wouldn't put me in the red. Then after the show, something else weird happened that baffled both me and the FOH. He wasn't at the booth, and my cable was plugged in right in front of my face, so, not wanting to wait for him to come back, I just unplugged it myself. Instantly, the house music got way louder. I thought it was just some sort of coincidence, because I've unplugged myself many times before and it seemed that my plugging in to 1/4" outs shouldn't have affected the house music. But he came over, puzzled, and asked for my cable back for a second. He plugged it back in, and the house music got lower again. So basically my cable acted as some sort of attenuator. Really odd. Not sure if that was connected to the problem of the SBD recording having the huge spikes or not, but anyway, after both of those things, I was pretty sure that when I got home I would find there was some major problem with my SBD recordings.

Sure enough, I check them out and they are just bizarre. I've pulled dozens of SBD recordings of all different types of music and never gotten anything like this before. It's like the bulk of the music is there, sounding fine and buried way in the background due to the low levels, but something with the drumkit is causing the spikes and dominating the mix in some fucked-up way. I attached a CEP screenshot of the file and made an mp3 sample below, any thoughts would be appreciated as to what happened and/or if there's any way to fix it (I'm doubtful there is). I already tried gathering a noise profile for running noise reduction in CEP, as that's worked for me in the past for removing SBD hiss, but it didn't make a dent in this.

http://www.megaupload.com/?d=44R63YHL

[danlynch]

I had this exact problem a few months ago.  I can't be of much assistance, except to say that the FOH changed something in the middle of the set because the first half of my board recording is fine, while the second half is all spikes whenever the snare drum was hit, which was kind of like on every beat   

I tried all sorts of things to fix it but just ended up making it worse.  I ended up using only the first half of the board feed for the matrix (at only about 25%) and made level adjustments on the second half.   It didn't come out half bad, either. 

[setboy]

that's pretty messed up. Parts of it look over loaded/brick walled and other parts just look strange. Could there been any kind of limited/compression going through the SBD? 

[JonG]

Definitely an electrical problem with the board that's affecting the output of the 1/4" outs.  Nothing you could've done short of knowing that the board has problems that screw with those jacks and either using different outputs or not recording.

edit
It could be your cables or recorder, but if you rule those out then def. the board.  How long has it been since you last pulled from it?

edit2
Sounds somewhat like something isn't getting enough power.

[mattmiller]

How long has it been since you last pulled from it?

We were both there about one week before and I pulled the SBD for us.  I used the same 1/4" outputs and had no problems.  The only other output option was a mono XLR.

[Teen Age Riot]

It sounds like a bad cable or connection problem to me.

However, the fact that the output of the console increased when you pulled the cable is really odd. (How could the FOH not notice this while he was mixing?) Were you plugged into the master inserts by any chance?

[runonce]

Knowing the equipment used and signal chain might help...

Is it possible you were using one of the boards inserts for an output...?

[mattmiller]

When we were there on March 1, I was ready to hand the guy my RCA cable for the patch, to which he replied that they had a different board there now.  He had to look to see what the outputs were and gave me the option of stereo 1/4" or mono XLR.  I chose the 1/4" and got a fine patch.  Perhaps his unfamiliarity with the board resulted in him patching Andy into the wrong 1/4" "outputs"?

[yousef]

I'm a little confused - the opening post refers to a 1/4" stereo patch and to a cable (rather than cables, plural). So would I be right in thining that the lead you used had a TRS 1/4" jack at the SBD end?

That definitely sounds like someone trying to use an insert point - but I've only ever seen that technique used when wanting to get separate feeds from each channel: either to make a multitrack recording or to feed another mixer to mix to stereo on the fly.

And what would the mono XLR output offer? I know I only have limited experience of mixing desks but it all sounds very odd to me.

[rokpunk]

did he have you plugged into the main inserts possibly? that could do weird things to both your tape and the house music.

[raymonda]

Sounds like you were pluged into the inserts.

[runonce]

Sounds like you were pluged into the inserts.

Which can be ok - but you have to do it right.

Inserts are 1/4 inch and use a TRS plug...one send, one receive, one ground.

Insert signals are UNBALANCED.

If you want to use them for recording, you almost  have to have an AUX or EFFECTS send dedicated to your recording signal.

The trick is to plug the 1/4 plug into the send jack halfway...you'll feel the first contact.
That gives you the "Send" - without connecting the receive to your other input.

The second trick is to get the soundman to make you a listenable mix using whatever aux or effects send that you are getting signal from.

I guess the downside is - (unless they have effects post fader) - you wont get effects in your mix.

I remember using this approach here...

http://www.archive.org/details/aru1993-11-10.flac21

[SmokinJoe]

Here is another possibility... a floating ground.   The "signal" on a cable is across the +/- voltage across the +/- connections, and who knows what that is respect to chassis ground.  Hence the whole issue with buzzes and ground loops.

Suppose there are a set of TRS output jacks on the board... signal(+) on tip, signal(-) on ring, chassis ground on sleeve.  Someone inserts a TS connector... the signal(+) goes to tip and now signal(-) and chassis ground are tied together, not just for the outgoing signal, but for the whole chassis, which potentially effects the signal for the whole board.  If this were the case, plugging your cable into the board would do it, even if your recorder wasn't plugged in to the other end of the cables.

In a "kind of related example", I went to my brother-in-law's garage once and turned on the lights.  They were really dim.  He said "turn on the grinder and the lights will get brighter."  WTF??!!  The reason is because there was 220 coming into the garage, split into different 110V circuits, but the whole place had a floating ground.  The lights were only getting 70V instead of 110, but once we turn on the grinder, it balances out the 110 to each side.  I went into the house and tied the ground properly.

[junkyardt]

thanks for all the replies guys. I'll keep the point about the main inserts in mind for next time and mention it to him to see if he thinks that's what happened. next time I'll probably bring headphones and record the opener to make sure I'm getting a usable feed as well. it sounds like from danlynch's post that there's probably nothing I can do to salvage the recordings (which is what I was thinking anyway). the AUDs came out fine on their own, so I'll just use those.

as for this:

I'm a little confused - the opening post refers to a 1/4" stereo patch and to a cable (rather than cables, plural). So would I be right in thining that the lead you used had a TRS 1/4" jack at the SBD end?

I used a dual male RCA > single male 1/8" cable, with 1/4" adapters on the RCA ends.

[raymonda]

Sounds like you were pluged into the inserts.

Which can be ok - but you have to do it right.

Inserts are 1/4 inch and use a TRS plug...one send, one receive, one ground.

Insert signals are UNBALANCED.

Sometimes that works but often it doesn't and rather opens up ground issues and buzzes.

If you want to use them for recording, you almost  have to have an AUX or EFFECTS send dedicated to your recording signal.

The trick is to plug the 1/4 plug into the send jack halfway...you'll feel the first contact.
That gives you the "Send" - without connecting the receive to your other input.

The second trick is to get the soundman to make you a listenable mix using whatever aux or effects send that you are getting signal from.

I guess the downside is - (unless they have effects post fader) - you wont get effects in your mix.

I remember using this approach here...

http://www.archive.org/details/aru1993-11-10.flac21