Post recording processing
 

For what's it worth an outline of what I do for solo guitar recordings:

Once I have a raw stereo recording I like and can work with the usual post recording sequence I use is:

1. Balance volumes R and L and bring up to average listening level (around mid eighties decibels).
2. Check R and L phase correlation and if helpful delay one or the other channel (usually a fraction of a millisecond) for best sound. BTW doing this I need not bother placing the two mikes that I record with equidistant to the inch(es) from the guitar – that is too limiting in set up choices.
3. Equalize: I usually use just a high pass filter. Spot frequency band adjustment used on occasion for something harsh. Also BTW I have almost always been equalizing on a stereo track. However equalizing tweaks on R and L track separately (e.g. say just the right track is the culprit for a particular frequency) is an interesting thought and I may explore more of it in the future.
4. Recheck listening volume levels. May diminish or increase volume on a particular note or passage.
5. Add some sort of reverb.
6. Adjust volume level again to to a few decibels shy of clipping of the loudest note.

I don't use compression or a limiter, or dither (it's never that quiet).

Thanks for that, Rick in San Louis Obispo.

How do you delay a fraction of a millisecond?

Jim

I use:
https://www.voxengo.com/product/sounddelay/

Another useful tool for adjusting for mic delays is Sound Radix's Auto-Align:

https://www.soundradix.com/products/auto-align/

I'm not sure I'd use it for what Rick's doing, since time/phase differences are part of what makes spaced pairs sound the way they do, but it's very useful when using multiple pairs of mics, or using individual mics on different sources. It seems to have been designed to align drums on mics. It ends up just doing what Rick's doing manually - delaying one track by some small amount, but it computes the exact difference and then applies the delay.

The plus or minus of a certain amount of delay of one side of a stereo track is determined by ear. You can play with it to a degree
just for tonal effect but the range of delay is limited by the onset of the Haas Effect where perceived localization of the sound starts
to move to the left or right.

Naturally these small adjustments are more audible and consistent listening with headphones versus with speakers where you
yourself may be moving around and where there are more audible room acoustic reflections while you are listening to adjustments.

I like to select or not select a track delay prior to adding reverb as I feel it has a noticeable effect on reverb (especially mono reverb).

You often hear or read about the importance in stereo recording of having the microphones equidistant to virtually the inch from the
sound source to prevent or lessen phase issues. I can't say I agree with this in the case of recording an acoustic guitar, however even
if I did the effect of small differences in distances can be easily compensated with post recording micro delays.

Thanks for this, Rick. The phasing fix is something I've never tried.

Your welcome. The effect is usually somewhat subtle unless the initial phase is way off, and it may be difficult to judge if using speakers instead of headphones.

Keep in mind that phase differences are a feature of spaced pairs - there's not really anything to "fix" as far as phase. You can get different sounds by manipulating the timing on a track, or by moving the mics. I use several meters while positioning mics, as well as listening by ear, so that I'm happy with the sound going in. Whatever works is fair game, but I'd generally try to get the mic setup right to start with rather than trying to alter it later, if possible. Even with the adjustment plugin I posted, I started out using it to make sure multiple pairs of mics were better in phase, but based on what it showed me, I've tended to place the mics to minimize the differences, to the point that I don't actually use the tool much anymore.

But there's always lots of approaches that can work, all that matters is that it sounds good in the end.

It's usually not a matter of "fixing" the phase in the sense of being more in phase, (100% phase alignment is mono) but of adjusting the tone to taste.

Also needing to set up the mikes "right" in the first place is a big part of the advantage of time delay tweaks. It gives you more mike positioning flexibility.
For example say you set up a pair of spaced mikes and start playing listening back live through headphones and you find that a little bit of a body turn or
move to the right or left rather than straight on or in the middle improves the sound, or that you want one mike in a little closer for a particular sound and
the other mike further out for another sound, or some other thing like over the shoulder mic'ing of one of the mikes.

Sure, it's always nice to be able to adjust things will listening instead of while playing. I personally just wouldn't rely on it - mic placement is 99% of the game with solo guitar, and there's more to it than timing/phase between mics, as you know. So I try to get it right going in. If a tweak is necessary to save a good performance, that's cool, but I'd try to fix it with the mic placement for next time. Just my approach, tho. You know there are also these plugins that let you change the mic placement (somewhat) virtually during the mix. I've played with them, but never heard anything I'd use.

Always try to set up the recording with the best sound you can get. Of course as the guitar player you will be hearing
a combination of the guitar itself and the sound coming out of the headphones. Listening back later the recording will
sound different than the sound you heard when playing the guitar at recording time.

Basically be open to experiments. Phase adjustment is one in a list of many things to experiment with, and one that
does not cost money and one that is very easily changed around, or not used at all, as your ear dictates.


An acoustic guitar is an interesting instrument to record compared to something like a small wind instrument due to its
size and various timbers coming from different parts of the instrument. Very good sounding recordings can have a wide
range of phase alignments. For example Pete Huttlinger's recordings are pretty tight phase wise, whereas Howard
Emerson's are very loose and random. Recordings by both sound great.

Agreed, I never do that. I can't tell anything in headphones, and never use them unless I need to play to a click or overdub. I rely on repeated trials - record, listen over monitors, repeat... I also use lots of meters that I can monitor during setup, so once I know what I like, I can visually repeat it.

A before/after example of your phase adjustment would be interesting to hear.

That's also a good example of tweaking in the mix vs non-tweaking. Pete used an XY setup (vertical), so a pretty traditional sound. Pretty much a bit of reverb on an XY mic setup. Howard has reported here on his pitch adjustment technique, where he (or his engineer) raise the pitch of one side and lower it on the other - pretty drastic! I haven't been able to make that work without hearing artifacts, but it certainly produces an interesting sound.

Pete used some other mike setups according to email conversations with him a few years back. Howard did the pitch altering thing on his latest CD.
The CD sound of his I like the best was his 2004 "Crossing Crystal Lake". I did a small (like 2 cents worth) pitch alteration on only one recording that
I liked the results of.

Good thread. I bumped this for more review tomorrow.