Topic: in-line passive XLR adjustable delay ?

[Javier Cinakowski]

Anything like this on the market?  Or a small battery powered delay module?

I would like something small that I can delay a board feed when I am matrixing with an aud source from a distance.  It would be sweet if it was an xlr barrel i could plug onto the end of the xlr cable and had a knob so I could adj the time based on my distance....   

 

[DSatz]

Some day I hope there will be such a thing. For now, though there isn't--so you'd need to record on separate tracks, and delay the track(s) from the closer microphone(s) when you mix down.

You've definitely picked up on a major issue, though. When I first discovered what people here mean by "matrixing" (not to mention that I wish they'd chosen another word for it, since that word already has an important meaning in audio) I was a more than a little taken aback.

Sound travels at only about 1100 feet per second, so midrange audio frequencies have wavelengths in air of only a few feet, down to a foot or so. When you mix together two different versions of the same signal (or sound source) picked up from positions that are many wavelengths apart, you get a bizarre conglomeration of reinforcements and cancellations in the signals at various frequencies, depending on the position of the performers and the microphones. Your idea would go a long way toward solving that problem.

--best regards

[Javier Cinakowski]

thanks!

[ArchivalAudio]

when running  what I call an "ambient" recording, most call a "matrix"
if you run your stereo pair of mics onstage
and mix that signal with the house PA Soundboard source
then "in theory" there is no need for delay as the sound is traveling at the same rate through  the mic and or snake cables...
though if you are a long distance from the stage, there could still possibly be a delay
I used to always lay down 4 tracks to - 2 track DAT on the fly , with mics onstage with excellent results...
however even in a small club if you are running you mics at the SBD you will get some delay...
which may add a bit of natural reverb, and may actually add to the sound... or not it could sound hideous


run four track and mix it down after the fact - or aka a "Post" Matrix

peace
-- Ian

[Patrick]

I don't think a passive delay is possible.  Well, there is an all-pass filter, but the delay is very short.  So you'd need lots and lots and lots of them.

There are three ways to do a delay with a power source that I know of:  an analog delay, aka "Bucket Brigade Device", or BBD.  These were popular as guitar pedals until digital delays became available.  The sound quality was nothing you'd want to let near hi-fi audio though; the devices worked by passing the signal through hundreds of transistors, and it has to be frequency-limited as well.

The next of course is a digital delay, which you could do, but would only make sense if you did not have the ability to adjust in post (such as if you were recording a stereo mix of multiple sources).  You could get a digital delay guitar pedal; it should work although again quality would be an issue--much better than a BBD, but how good is the A/D/A conversion in the pedal?

The oldest delay is a tape delay, but those are larger and heavier than what you probably want . . .

I think we're talking about two different things here.  A digital delay guitar pedal is not used for delaying of audio sources, unless you want an echo-y, space effect on your recordings.  Even with the feedback controls all the way down, the delay is designed for guitar string transients, not hi-fi audio sources.  Especially considering how easy it is to apply a set amount of delay in most DAW's, bringing a guitar pedal into your signal chain is just downright silly.

[Patrick]

A live sound install will commonly have rack delays when there are banks of speakers installed at various distances from the stage.  This is to delay the speakers further away from the stage such that the ambient sound doesn't arrive long after the direct sound from the speakers.  What you would need would be pretty much the same thing, but a rack delay unit isn't quite as portable, nor as battery-powered as a guitar pedal.

You're correct when you claim that delay is delay, no matter if it's used in time-aligning speakers or using it in a guitar rig.  However, the difference between a rackmounted speaker processor and a portable battery powered guitar pedal is pretty obvious.  I could not imagine setting very precise delay times using a pot on a DD-5 or even a nicer unit like a DL-4.  If I am going to be "matrixing" I would opt to use a unit that is specifically meant for what I need.  Joel Hudson on this board uses these units for almost all of his 4 channel recordings...

http://www.jakeludington.com/gadget_envy/20051024_behringer_shark_dsp110.html

Again, it's stupid easy to apply delay in post production.  And most likely more accurate than dialing it in with headphones in the field.   

[illconditioned]

Again, it's stupid easy to apply delay in post production.  And most likely more accurate than dialing it in with headphones in the field.  

*If* you have a four track recorder.  And don't discount accuracy of headphone measurement of delays.  In this environment, getting more precise than 1ms isn't important or probably even possible.  Sample-level accuracy certainly isn't required.  It's pretty easy to monitor within a few ms.

I'm getting tempted to build a high-grade battery-powered inline digital delay device . . .    But I'm not much into programming microprocessors.  And the good converter chips use high current, so . . .

I was tempted to use something like that Behringer device for this exact reason... to keep a nice simple two track signal chain.

One other thing: we (humans) are not that sensitive to delay, as long as it is within +/- 10ms or so.  So, if you can get the mics 10' or less from the stage, adding should work.  However, another interesting point is that it is sometimes useful to put the mics a bit *before* the soundboard in the mix.  So, say the mics are 10' from the stage, then you may want to delay the soundboard by 20ms.  The reason is that humans perceive the first sound reaching them as "direct" and any other sounds as "reverberation".  So, to make the sound most natural, ie., most like the mics that are really in the room, the mics should arrive at the ears first.  This has been my experience anyway.  If I add too much soundboard, the recording tends to sound very artificial.  Not like it is coming from speakers.  In my ad-hoc experience, you can get away with a bit more soundboard if it is delayed a bit after the mics.

  Richard

[Roving Sign]

Is there a "crosspoint" where amplitude and delay "make sense" or correspond correctly - without any delay/syncing? (within reason obviously)

I've done a few where i've had time to play with the blend - and it seemed like i could make it sound decent on the fly just by keeping the ambient part at the proper amplitude. maybe not as loud as I might like/expect...but the louder the ambient part became...the less "right" it sounded...

(sorry to lapse OT there - but this has been on my mind...)

[illconditioned]

Is there a "crosspoint" where amplitude and delay "make sense" or correspond correctly - without any delay/syncing? (within reason obviously)

I've done a few where i've had time to play with the blend - and it seemed like i could make it sound decent on the fly just by keeping the ambient part at the proper amplitude. maybe not as loud as I might like/expect...but the louder the ambient part became...the less "right" it sounded...

(sorry to lapse OT there - but this has been on my mind...)

I don't know the theory behind it, but it seems like there are two different approaches to mixing.  One is mostly SBD, and a little ambient.  The second is mostly ambient and a little SBD.  I much prefer the latter, though many people (including some musicians I've recorded!) prefer the former.

It seems that if you just at 50/50 or something you might end up with a muddled recording that pleases noone.

This may have to do with our perception of sound.  Or at least how we have been *trained* to perceive live recordings, listening to too many board feeds and not enough really great ambient recordings.

I experimented a lot in the past, then finally just decided to record all ambient and forget about adding soundboard.  Then taking it a step further, I've been using mostly omnis now, since I don't think cardioids sound as natural as omnis.  Of course, I have to go to extreme measures to get my mics up close, especially in non taping venues  .

  Richard