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Gear / Technical Help => Ask The Tapers => Topic started by: dmaster on August 23, 2004, 05:30:37 PM

Title: odd looking waveform, any clues?
Post by: dmaster on August 23, 2004, 05:30:37 PM
I've got a weird problem that I'm wondering if anyone's seen before.

(http://toritraders.com/pics/weirdwaveform.png)

That just ain't right.  It's the second time I've seen my waveforms look like that,  and both times I was taping with a mic stand and putting the mics rather close to the stack while taping. 

So, is this a characteristic of taping really close to a stack with small microphones (AT853/cardioid), the way I had my mics pointed, distance from the speakers, or just something wrong with my mics/battery box/deck?   I may have an incomplete understanding of how to situate mics when in a non-stealth sort of situation, but I had them in an ORTF configuration since that's produced the best results while stealthing it.   I've only done two shows with the stand and up on the stacks, and both of them have looked like that, so is ORTF not a sane thing to do when you're 2 feet away from the stack and 10 feet in the air in a small club?

It doesn't -sound- odd, but my ears may not be picking up whatever weirdness may be there or my speakers may not be good enough to relay the weirdness, so I'm not terribly concerned about it, but it does look like something's not being recorded as accurately as possible and I think I'd like to adjust what I do before the next show I go to if possible. 
Title: Re: odd looking waveform, any clues?
Post by: Craig T on August 23, 2004, 05:39:19 PM
My guess - either brickwalled from overloading the preamp, or you're seeing the result of the limiter/compressor of the PA system.  If it sounds ok, its probably the PA.
Title: Re: odd looking waveform, any clues?
Post by: dnsacks on August 23, 2004, 05:45:25 PM
what's the rest of your recording setup?  If analog into a dat dec, are you running mic or line in?
Title: Re: odd looking waveform, any clues?
Post by: dmaster on August 23, 2004, 11:47:07 PM
what's the rest of your recording setup?  If analog into a dat dec, are you running mic or line in?

line-in on a D8.   Nothing in between except for the battery box and bass roll-off at 85hz. 
Title: Re: odd looking waveform, any clues?
Post by: phanophish on August 24, 2004, 12:47:34 AM
I'll bet you are overloading the analog input on the D-8.  That is a fairly common problem as I remember.....
Title: Re: odd looking waveform, any clues?
Post by: pfife on August 24, 2004, 09:12:30 AM
Are you talking about the waveform being off-center?   I used to get that in my waveforms in Sound Forge, but it would happen when I would use the analog line-in on my computer soundcard to do the transfer (yeah, it sucked...)   The way I would fix it, in the past, was to run a DC Offset on it.   

Initially, if this is the problem, you won't hear it.  But, it will lead to nastiness when you start to build on it (like normalizing, eq'ing...) - Its like building your house on a bad foundation.

Hope this helps, but I am not sure if it will.

Title: Re: odd looking waveform, any clues?
Post by: dmaster on August 24, 2004, 03:59:13 PM
Are you talking about the waveform being off-center?   I used to get that in my waveforms in Sound Forge, but it would happen when I would use the analog line-in on my computer soundcard to do the transfer (yeah, it sucked...)   The way I would fix it, in the past, was to run a DC Offset on it.   

Hmm, I've been transferring things with a UA-1D using the 7-pin cable on my deck and I THOUGHT it was digital.   Would this sort of thing still show up in a digital transfer, or do I inadvertently have the thing set to do it analog?  (I know the cable has a switch, but I thought the UA-1D only did digital transfers, but I could be wrong..)

If it's not, is it the UA-1D that's screwing me?
Title: Re: odd looking waveform, any clues?
Post by: pfife on August 24, 2004, 04:11:46 PM
I am really outta my league in answering this, because I have never used/owned a DAT, but I am pretty sure the 7-Pin is a digital connection.  The cord is 7 pin on one end, and what on the other end?  What do you have it plugged into on the computer?  Do you have digital inputs on the computer?

I only got DC offset using analog input on my computer.   But, I have never done a digital transfer like you are talking about... the two methods I have used to transfer digitally were ripping from a CD, and transfering over firewire using a NJB3.  My assumption would be that either you are unwittingly using an analog signal, or this is not a DC Offset issue... but it looks like DC offset.

Title: Re: odd looking waveform, any clues?
Post by: F.O.Bean on August 25, 2004, 03:07:35 PM
the UA-1D is NOT bit perfect either, FWIW :)
Title: Re: odd looking waveform, any clues?
Post by: dnsacks on August 25, 2004, 03:11:47 PM
analog clipping on d8 issue, if your volume knob needed to be set at 4 or lower in order to keep the levels from going too high, the d8 will analog clip/brickwall.  if this was the case (input level below 4 on d8), this could be the source of your problem. Also, are you sure the batteries in your battery box were fresh/full?
Title: Re: odd looking waveform, any clues?
Post by: dmaster on August 25, 2004, 03:50:37 PM
I didn't know the UA-1D wasn't bit perfect, that's a shame.  :(   is there another affordable portable digital input I can use with my laptop?

and my knob was set somewhere halfway between 3 and 4, so maybe it's that.   Does this mean that I should get farther away from any volume sources and make sure I have to set my volume at least beyond 4 to avoid any problems?   If so, that's a very good thing to know, thanks a lot for the info.  I'll be sure to watch out from now on, cause that seems like the most likely cause since the last time I had the same issue, I was taping close to a stack and had to keep the level low also, and I did notice some very very slight distortion, but I didn't think it was brickwalling.  Guess I was wrong!   Thanks a lot, you guys are really helpful!   ;D
Title: Re: odd looking waveform, any clues?
Post by: F.O.Bean on August 25, 2004, 04:38:06 PM
+T and welcome :)