Someone Please Explain Modulation & Compression Effects To Me???

Discussion in 'The Stomp Box' started by tonytrout, Mar 14, 2019.

  1. tonytrout

    tonytrout Friend of Leo's

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    Hey, fellas & ladies!!!!

    I should know this but.....can someone be so kind as to explain (in language I can understand) what "modulation" & "compression" effects do??

    Thanks!

    I should know all of this stuff since I've played guitar for over thirty years but....I don't know half the stuff I should know...LOL!!!
     
  2. mexicanyella

    mexicanyella Tele-Holic

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    I'll take a stab at it:

    Modulation effects (delay, chorus, flanging, phase shifting) incorporate some form of delaying the guitar signal (in other words, "storing" it momentarily and playing it back either as echo-sounding delay repeats, or along with the undelayed signal in varying time intervals and amounts to cause chorusy shimmer (numerous Police songs, Crowded House's "Don't Dream it's Over") or jet-engine swooshy flange effects (Van Halen's "And the Cradle Will Rock") or chewy-sounding phase shifting (Bowie, "Golden Years"). By combining a slightly delayed signal with an undelayed one, you get phase cancellation of various frequencies in the signal. Shifting the delay interval around causes shifting phase cancellation.

    Compression effects basically reduce the initial spike of volume when a note sounds, then "turn it up" as the note decays, making it feel fatter and sustainier. There's usually some sort of adjustable makeup gain control which allows you to boost the output signal to compensate for the amount you reduce that initial volume spike, or even to give an overall boost over and above whatever the initial signal was. Some of the appeal of cranking a tube amp comes from the natural compression process that occurs when you ask a tube amp to deliver at levels near its operating limits. You can also get some compression effects when you push speakers past a certain point, as you start to lose some of the efficiency of converting the signal into sound through running into the speaker's mechanical limitations, or you start to lose some of the signal to heat in the voice coil and magnet assembly. Using a compressor with guitar or bass can give you some of that cranked-amp feel at lower volumes when set conservatively. Set to extremes, it can give a really sustainy, squishy-feeling response, which can be cool or weird depending on the context.

    Related to compression is limiting, which just limits incoming volume spikes from passing a certain amplitude, or loudness, threshhold. That's found more often with bass amps, or PA equipment, where you are trying NOT to overdrive the power amp or speakers because you want higher fidelity than you usually do with guitar.
     
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  3. Lawdawg

    Lawdawg Tele-Holic

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    I'll do my best!

    "Modulation" effects typically refer to effects that "modulate" or alter the guitar tone at a set rate/tempo. The most common examples are tremolo, flanger, chorus, phaser, and vibrato.

    Tremolo is easiest to explain and start with -- the effect "modulates" the tone by increasing and decreasing the guitar volume at a set rate of speed.

    Vibrato does the same thing except it modulates the pitch of the guitar tone instead of the volume.

    Flange/Chorus are a little more complicated. Both of these effects use a short delay time to create a filtering effect. What is technically being modulated is the delay time which creates the classic whooshing sound of the flange or chorus effect.

    Phaser is a little more complicated still. In this case, the whooshing effect (think EVH's tone in "Eruption") is created by combining the original guitar signal with the same signal that's been put through an all pass filter which then has its phase modulated. When you combine two identical signals with an altered phase like this it creates a filtering type of effect.

    All of these are easier to demonstrate than explain but that's a basic explanation. There are other more esoteric modulation effects, like ring modulation for example, but these are the most common ones.

    Compression is an effect that reduces the increase in volume of a guitar signal after a certain threshold is crossed. The practical effect is to even out the guitar volume which can be good or bad depending on what you're trying to do. Think of it this way, you play a guitar softly the volume is low, you play medium the volume is medium, you play it super hard and the volume is as loud as the guitar can go. Now you insert a compressor with a medium threshold. Now when you play softly the volume is low, when you play medium the volume is medium, but now when you play loud the volume is just a little bit more than medium. There's a bit more to it than that, but that's the very basic concept.

    Not sure if any of this helped, effects are usually easier to demonstrate than describe. Hopefully there are other folks here who can do a better job!
     
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  4. logans_tele

    logans_tele Tele-Meister

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    Modulation effects are wooshes, swooshes, wah-wah-wah, swirly sounds. Compression is making your softest picking and loudest picking closer to the same volume. Either one can be very subtle and almost not noticeable, but they can also be very dramatic depending on exact settings.

    Gross oversimplification, I know. But really, your ears are the best teachers here. Go watch a youtube demo of a Strymon Mobius pedal and you will then understand what modulation effects are.

    Watch youtube demos of a few compression pedals and you'll get the idea there too.
     
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  5. Art VanDelay

    Art VanDelay Tele-Afflicted

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    Modulation is always time-based and repeating. Tremolo is the simplest because you speed it up or down (frequency of repeats), and then determine the depth (high & low of signal wave).

    Compression reduces volume spikes and amplifies lower powered dynamics. It's the second part that stumps people because any microphonics you might have will be brutally amplified. I think of compression as taking a mathematical average of your signal's highs and lows in volume.
     
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  6. Guitarteach

    Guitarteach Poster Extraordinaire

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    Modulation... swirly, throbbing, whooshing stuff

    CoMPReSsION >>> compression.... squashes/flattens the loud bits so they don’t jump out and everything is more even
     
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  7. E5RSY

    E5RSY Poster Extraordinaire

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  8. telepraise

    telepraise Tele-Holic

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    Mexicanyella covered them about as succinctly as anyone could. I think genre plays a big part of what's useful and what isn't. Compression is used pretty heavily in hot country hybrid picking and chicken picking, really helps you just hammer through the runs with less pick action. Listen closely to what Brad Paisley does and you can hear it at work. Dang, Wampler has even made some pedals that he had a hand in designing.

    Modulation can flesh out your tone on slower numbers (I prefer chorus modestly applied) and add some shimmer to your sound when carefully applied. When overdone, it can start to sound like the 80s all over again.
     
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  9. Art VanDelay

    Art VanDelay Tele-Afflicted

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    Did someone say 80's?????

     
  10. mexicanyella

    mexicanyella Tele-Holic

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    Oh, I've got some 80s chorusy modulation meltdown for you:

    pretty much all the guitar in this, but especially the outro figure, beginning at 4:08

     
  11. codamedia

    codamedia Friend of Leo's

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    Modulation is not (in itself) an effect. It is just a blanket term that encompasses Phase, Flange, Chorus, Vibrato and all of it's variants.
     
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  12. 65 Champ Amp

    65 Champ Amp Tele-Afflicted

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    Modulation, is relatively easy to grasp. Modulation is what happens when two or more vocalists try to sing in unison. The slight variations between voices can create depth, fullness, atmosphere, dimensionality, etc. Most modulation effects are achieved by ... modulating one of those voices in some way and mixing it back in with an unmodulated voice.


    Compression, on the other hand, is complex and mysterious. And anyone who actually does understand it had to sign a binding document in bodily fluids not to share the secret.

    There are two kinds of guitarists ~ those who do not have a single clue what compression is, how it works, or how to set the parameters, but pop into every compression thread to say that compression ruins their dynamics.

    The other kind of guitarists are those who do not have a single clue what compression is, how it works, and how to set the parameters and pop into every compression thread to say it does “something” for their sound, and they miss it when it’s off. (I am more in this camp)

    The single most important thing to know about comp is that compression is how the television stations are able to make commercials seem incredibly loud and in your face without actually turning up the volume.
     
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  13. tonytrout

    tonytrout Friend of Leo's

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    Thanks, guys! Those explanations helped a bunch!!! I appreciate you teaching me these things. :)
     
  14. mexicanyella

    mexicanyella Tele-Holic

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    I belong to the third camp: guitarists who can visualize clearly what is going on as they pump signal into a compressing signal path. Seems intuitive to me, and maybe that's more from dinking around with recording and mixing and playing bass. But I think it's from playing into loud tube amps as much as anything.
     
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  15. 65 Champ Amp

    65 Champ Amp Tele-Afflicted

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    Hey! You’re a big help.
    Which bodily fluid did you use when you signed the contract not to divulge the secrets of comp?
    I’m only being blunt because you seem to gloss over truth based humor in your rush to toot your own horn.


    Sorry, OP-
    Check out this guy’s website~
    Ovnilab.com
    He’s a bass player who has accumulated a huge data base of comp pedal reviews as well as sharing knowledge about how they work. Guitar comp pedals are often simplified, with some parameters like threshold and knee being preset, while more elaborate or studio comps have controls for everything.
    Put simply, think of a big hand across the top of your sound waves which presses down and keeps everything below a certain level. As you visualize that, think of how your sound waves are more densely packed into that space under the hand~THAT is how tv stations get away with saying they don’t turn up the volume for commercials while it sounds much louder in your living room.
    All of those other parameters control how quickly that giant hand clamps down, does it let some initial attack slip by first?, how long it clamps down, what levels it clamps down on, etc...
    As a guitar player, you don’t “need” to know all that, but it helps.
    Also be aware that tube amps also create compression when pushed, and a lot of dirt pedals do, too. A lot of us use comp pedals more when playing clean.
     
  16. mexicanyella

    mexicanyella Tele-Holic

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    Wow! Didn't see that coming; I did register the humor and did not mean to come off as a twerp.

    But I do stand by what I said, and I think whatever help I can provide in understanding how compression works was included in my post #2 near the top of the thread.

    I didn't mean to brag about it. My last post was admittedly a tossed-off affair, written in a hurry--but to me, compression doesn't seem hard to grasp if you take a basic explanation and start compressing some things and listening as you do it. And maybe observing the way it changes the waveform displays on a digital recorder.

    With all the interest in tube amps, both classic and modern, that gets so much "air time" with guitarists, it surprises me that compression would be seen as mysterious. This is not a rip on the OP or any kind of intended pretentious, exclusive attempt to come off as an expert at something. Maybe a lot of the people talking enthusiastically about tube amps are playing them at low enough volumes to not experience much of the increasingly compressed feel that comes with higher volume levels, or they haven't yet dinked around with adding compression to a snare track or whatever and listening to it or looking at the waveform. No shame in that. But I have...which is why I felt I could take a shot at explaining it in the first place.

    EDIT: 65 Champ Amp's recommendation of checking out the info and compressor reviews on the Ovnilab site is a good one. Just reading the pedal reviews will give a person some idea of what to listen for and what benefits a compressor can offer. Mostly geared toward bass guitar, but it's still interesting and instructive even if you aren't into bass.

    Also, I thought of another non-guitar example of compression at work that's pretty easy to hear. Listen to a snare drum being hit, live, in a room. You hear a hard, fast initial "spike" of sound, followed by a quick decay, which is pretty much the drum head reacting to the stick hit, and you also hear a lower-level, longer-sustaining sound which is partly the snare wires continuing to vibrate on the bottom head and the room reverberation being excited and dying off...which lasts longer than the slam of the stick hit.

    Now listen to the Wallflowers' song "One Headlight," and pay attention to the snare track.



    The level of the stick hit is somewhat subdued, and the ring of the drum shell and buzz of the snare wires is proportionally greater in relation to the stick hit than you would hear "llive in the room." A lot of that is compression at work. There are other factors...that snare is probably being picked up by close and distant mics and some of them have noise gates on them that are triggered to pick up the hit from a more distant position--so emphasizing the room reverb--by the initial drum hit, and which "close" or cut off the distant pickup once the sound level drops below a certain threshold to keep the overall kit from being a reverby mess. But you can hear the smoothing and "re-proportioning" of the snare's sound that comes from the compression even if you ignore the fact that the other stuff is going on.

    Cutting down the level of that initial volume spike, from the stick hit, and having the ring and snare wire sound more "up" in relation to it, kind of boosts that snare's character, and it allows the engineer to run that snare track louder in the mix without the spike obliterating the other drum sounds. Or the other instrument sounds, or the vocals. So you get an arguably unnatural-sounding snare, but one that can really be a propulsive force in the mix without stepping all over the other mix elements.

    It's useful to apply this same thinking to a guitar part. Say you want to play a blazing-fast flurry of notes and you want it to punch through a mix without having to use a bunch of distortion to do it...compress it and turn it up. Your pick attack won't step all over the other bandmembers with harsh transients, but you'll get a boost in apparent sustain and actual note sounds. Or you want to play a really driving chord rhythm part, which requires whacking the strings pretty hard, and again don't want to obliterate the mix with pick attack harshness. Here's and example of that at work:



    Hard-strummed uncompressed guitars don't sound like that, and some people are put off by the unnatural aspect of that. But dependent on context, it can be a useful tool.

    I used to play a guitar that responded to compression in an interesting way: the boingy ring of the trem springs was accentuated and gave the effect of a crude spring reverb even when I played into a dry amp. I used to get a kick out of that. I play a hardtail strat copy now and it's pretty much devoid of weird noises like that, but I still like the effect of "mellowing" the pick attack in exchange for "enhancing" the sound of the ringing, decaying strings. Aside from that, I get some of the same "yee-haw!" feeling of maximum guitar liveliness from minimum input that I'd get with a cranked-up, distorting amp...but at lower levels, with a cleaner tone.
     
    Last edited: Mar 21, 2019
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  17. 65 Champ Amp

    65 Champ Amp Tele-Afflicted

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    @mexicanyella ~
    Hey I'm sorry for being kind of a jerk. I was fasting, INCLUDING COFFEE:eek: for a ct scan, and was a little twitchy. You're correct. Post #2 was good stuff. As well as this last post!
     
  18. mexicanyella

    mexicanyella Tele-Holic

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    @ 65 Champ Amp...Hey, man, thanks for that but no apology needed. After re-reading my post #14, and especially if one didn't connect it to post # 2, I can see where you were coming from. A good reminder for me to edit carefully for tone and attitude before hitting "post reply."

    Good luck on the procedure and wishing you a happy return to not fasting.
     
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