Double tracking guitar / comb filtering

No matter how long I've been doing it, I'm constantly learning new things. I know that double or quad tracking guitars for a bigger sound is common in metal. So, I've been fooling around with it a bit this past year for my own stuff and haven't been terribly happy with the results. Now that I have the Kemper, the primary reason for my dissatisfaction is actually even more prominent - the chorusing / comb filtering and other phase artifacts you get.

It's worth noting that I don't write or play metal, but rather gravitate towards more classic rock type stuff. Think full or 4 note chords versus the common stylistic approach of single or dual note riffs or grooves in metal. What might sound fuller on a two note riff of moving fifths can quickly sound like a Boss Chorus has been added when playing chord based material.

Prior to the Kemper my miking would vary. Sometimes a 57, sometimes 57/421, occasionally an additional room mic at either a foot or at distance, etc. I usually tried to work with two tracks on the rhythm part, so a 57/421 (with phase alignment checked) would count for one track. The comb filtering is most noticeable when both parts are at the same pan position, and you can get away with it the most if you pan them hard L/R. Which is great until you push the Mono button to check the mix.

I've also tried playing the part twice (which I can keep fairly tight) as well as tracking DI and then reamping into two different amps or settings. I've done this on the Kemper as well, reamping into two different profiles with a similar vibe. Typically we're talking high gain stuff here, albeit the classic rock variety. Think Eddie's brown sound versus the incredible saturated tones of modern metal. Perhaps it's because my miked amps were typically mono tracks and my Kemper tracks are stereo, but this comb filtering effect is even more noticeable with the Kemper. And it wasn't subtle in miked amps to begin with.

There was a great thread from back in July that talked a lot about multi tracking in general. Fun stuff, but surprisingly there was very little mention of the problem I'm talking about here.

Double tracking vs quad vs more? Is it only for sloppy players?

Thus far, my conclusion is that while this technique can give you fuller tracks for the single / dual note riffs of metal, it may not be suited for more Van Halen / Bon Jovi - ish styles that have full or mostly full chords featured prominently. @Cederick's original examples are the single / dual note style (and the guy's a freakin' precision machine on guitar), so there doesn't seem to be the opportunity for the chorus pedal effect.

I would be interested in whether or not this technique has worked well for those of you who play more chord based rock. It could be that I'm missing something fundamental in how I apply this technique, and it's equally possible that square pegs are simply not meant for round holes.

Quote from Per

I use it all the time for chordal work, I'm no pro but after lots of experimenting then my advice is pretty obvious and standard stuff :

1) Always play the part twice, if you can't play it tight enough then practice till you can. Re-amping a single part never sounds as good, if you really must reuse the same part then don't forget to offset it more than one waveform cycle, otherwise if it's ever heard in mono it'll end up either doubling volume or muting itself and ruining your carefully crafted mix!

2) Try different amps and gain levels to each part. Especially with rhythm guitar using a much cleaner sound on the second track will really help with clarity while leaving the sound heavy.

3) Experiment with panning. Traditionally double tracked guitars are hard panned left and right, this makes things sound huge. But at the right moments doubling dead center overlapping can bring a whole different and cool sound to the mix.

4) The sound is typical of 1980's and onwards guitar more than 70's and earlier when people were only just getting used to having more than 8 tracks to play with and were used to a different less studio oriented approach to making music. If you are going for classic rock sounds then double tracking and hard panning may give it the wrong sound and you'll never be able to escape that.

Good luck!

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Hey, Per.

Thanks for the ideas.

My preference is, as you suggest, to play the same part twice to get that "human" feel and introduce the minor inconsistencies that fatten the sound. Playing a part twice, it'll never be 100% the same. A DI will, so I experimented with using two renders from the same DI to exercise a principle.

If I use two different amps on the DI, there's zero discrepancy on the playing side, which eliminates one cause. There will, however, be variations from the amps. Using two moderate high gain sounds, it does widen (panned hard L/R), but there are distinctly noticeable phase issues which manifest as anywhere from a subtle chorus to a tight delay / reverb effect. This is with two perfectly matching parts. Two human parts, if I play them tight enough, will come close to that but be more inconsistent by nature, and thus replicate or even increase the effect.

I actually first started playing with this early in the year after reading from either the tracking or mix engineer on Green Day's breakthrough Dookie album that they double tracked the guitars to get a more massive sound. They also mentioned that they had a lot of trouble with it. Given that Green Day was a very seasoned band by then, I doubt that the issue was Armstrong's ability to play consistently, so I would imagine they were talking about this same sort of thing.

So far I've been mixing similar high gain sounds. While I can certainly try the cleaner / hotter sound you mentioned (I was running a bi-amp setup in the 70s using that philosophy), the result I was shooting for was the kind of homogeneous, fat, virtual-single-guitar sound, e.g. When I Come Around.

I don't doubt that it can be done, but if it takes lots of hair pulling by either the tracking or mix engineer (both me in this case) to bring it all together without artifacts, that would be problematic as I've had a shaved head for decades.

Quote from nightlight

If you are using spdif, I would suggest turning on constant latency. This can help with the chorusing and phasing.

Thanks, man. I run all analogue as my mixer / interface doesn't speak spdif. Overall sound quality with the KPA is superb, the comb filtering between tracks can be an issue no matter what gear you use.

Quote from Monkey_Man

IMHO the issue is not about trying to play tighter 'cause the the closer-together the tracks are timing-wise, the more the comb filtering will come into play.

I really appreciate everyone's thoughts and perspective, very cool stuff.

In this case, Nicky speaks to my particular issue most directly. The closer your tracks are, the more comb filtering you get, which only stops when they completely align and become, literally, identical, as in reamping two DIs. Even then the contributions of different amps will generate more of the same.

AJ, I can certainly dig the hassles of latency (which would drive me insane!), but that's not been a factor in my environment. The reason I tested with DIs is that it's essentially a "perfect" situation in that regard as the tracks will always be identical. Kinda like hiring a robot to double track your parts, which eliminates the playing part of the equation at least in my scenarios and isolates what I'm experiencing to the nature of the beast itself. Fortunately, I'm not a metal guy trying t double track those insanely impressive speed lines, since most metal six year olds can play circles around me.

Quote from waraba

Classic rock , blues and jazz stuff is much better with single tracks , but instead of double tracking it's better to harmonize, embellish and fill the background with other parts, for me.

I think Renaud also makes a very relevant point, which others have also observed, about stylistic appropriateness and arrangement.

This all started early in the year as a, "hey, while I'm in the studio, let's play around with this concept," inspired by the Green Day interview. Most of what I learn as a player and engineer comes from screwing around with stuff I know absolutely nothing about and repeatedly making a fool of myself until I accidentally stumble on a useful technique (since I've written air traffic control software among other things, you probably don't want to know how much this also applies to my professional life). So, my experimentation hasn't been so much about "needing" to accomplish a particular thing or sound but rather exploring to see where the boundaries are and maybe adding a couple of things to my rather unwieldy bag of tricks.

What I've learned thus far, which seems to be reflected in everyone's contributions, is that my satisfaction with the results will depend a lot on the style of music I'm working on. Modern rock, including but not limited to metal, is heavily influenced by the Pro Tools effect. Tracks are cheap, so songs routinely have massive amounts of duplicated instruments and layers of other parts, which generally result in a Wall of Sound that would have made Phil Spector proud.

If that's the vibe you're going for, the kinds of artifacts I mention can go completely unnoticed as there's so much happening in the overall sonic landscape that it gives you thickening without detracting from the sound. However, strip that down to a simple and sparse Green Day / Van Halen - ish guitar, bass and drums arrangement and it's immediately noticeable because there's so much empty space, by design.

While I'll probably fool around with it a bit more (e.g. Nicky's thoughts on carving up EQ, etc.), I think ultimately what I'm learning from this is closer to Renaud's perspective that for my style of music, embellishing the arrangement will benefit me more than duplicating individual parts.

And I just have to add, really enjoying the people here. It's rare for me to find a forum on the web with this much of a positive vibe. Everyone seems to understand that there's no "right" or "wrong" in art, and then offers a wealth of different perspectives to play with. It feels more like hanging out with musician friends at the local pub.

Today I've been playing with the same song from the opposite angle. Rather than trying to double track, I'm taking a profile I like for the song and just bringing a single track straight up the middle, which of course is panning the stereo hard L/R. For this particular style of thing the profile feels nice and fat, so there's really no lack of fullness.

Of course, as I'm sketching this song out I'm using EZ Drummer, a rendered KPA bass profile and the guitar, all of which are stereo, and all straight up the middle. And yet, it works just fine. Since I'm not doing a 60s Hendrix album where playing around with the stereo field for effect is part of the, er, experience, a full and balanced sound is really all that matters.

While I've read lots about the LCR approach to mixing I've never really given it a go. However, in reading the multitracking thread yesterday and @wwittman's comments that he mixed the first Cyndi Lauper record that way (which frankly I never would have guessed), I may just stop worrying so much about pan position and spend the time I save carving out the appropriate EQ territory instead. With so many people listening to music on mobile devices these days, often straight out of their tiny little speakers, I'm much more concerned with what happens as the image nears mono.

Quote from GRStudios

I have never had any problems with this. I record/produce rock, blues, country, metal and stoner rock.

When I record guitars I do it the same way almost every time. Double tracking for the majority of the song (two separate takes) and quad tracking (four separate takes. Two with the main sound and two with a different/lower gain sound) for the parts that need it, like chorus and bridge etc.

All tracks panned 100% left and right.

That's interesting to hear. While modern country (at least here in the US) is basically just pop sung with a southern twang and thus the wall of sound thing, blues is something I would have expected to be more of a sparse arrangement. As I think more about this, it seems that the benefits of single versus multiple tracked guitars has less to do with genre and more with the sparseness or fullness of the overall arrangement. Especially since, to paraphrase Yoda, "Always in motion is the music."

Of course, I have no exposure to the music scene in Norway so I don't know what the vibe is like there for things like country and blues.

Thanks, @GRStudios! Always cool to hear music from around the world.

Like @Ingolf said, Shelby Street has a very rock feel to it. All the instruments weave together to make a kind of homogeneous background, very fat. In Nashville, the steel guitar would be brighter and more prominent but that's part of their signature sound. The singer is very Johnny Cash (hope that's a compliment).

Yearning has the kind of vibe that I'm used to hearing from North men playing metal. Sounds modern and yet Viking at the same time.

In contrast, one of the things I was working on last night is a clean, bluesy, neck pickup Tele thing. Guitar, bass and drums with just a single guitar. That gets honest in a hurry since you can hear even the slightest nuance, so I'm not happy with the playing on it yet. However, when I finally have the performance I want, it'll be right up front (for better or worse).

Another one is a rock thing (Strat / Friedman) with a three or four note voiced moving rhythm part. For the verse it's one guitar to maintain the bite I grabbed the Strat for in the first place. The chorus opens up a bit with full chords, at which point I shift to double tracked Strats on similar amps (3rd Power on extra Strat) panned hard L/R. That takes the feel from a prominent guitar up front to a more wall of sound background.

I think the multi tracked guitar thing is like most everything else, a particular color that you can paint with when that's the look you want. A nice thing to have in the bag of tricks.

Reactivating this thread because in discussing a similar topic, I just realized that all of my tracks thus far have been stereo out of the main L/R, including all of the double tracking.

It occurs to me (I'm not always the brightest bulb in the box) that perhaps those of you doing a lot of double or quad tracking are doing it mono, and hence not encountering the phase related stuff that I started this thread to discuss.

With that in mind, I'd be interested in hearing whether you're doing your double / qaud / gazillion tracking in stereo or mono. If you're mono and not getting phase issues that makes perfect sense to me. If you're doing it in stereo, however, and not getting any audible phase artifacts, that's a horse of another color.