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post #1 of 17 (permalink) Old 08-07-2012, 11:57 AM Thread Starter
 
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Instrument/speaker frequencies

Hey all! Just got my new studio monitors which i am very pleased with. But being the inquisitive nerd i am i wanted to understand sound better.

My speaker range is 60hz-20khz.

From reading online, i have found that the low E string played open on a BASS guitar is around 40hz. So if this is the case how comes i can hear the bass guitar in songs through my speakers?

Really want to get to the bottom of this so any help would be great thanks again.
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post #2 of 17 (permalink) Old 08-07-2012, 12:48 PM
 
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Re: Instrument/speaker frequencies

You're hearing the overtones, the harmonics that make the signal sound different to just a pure sine wave.

The human brain is very good at filling in the missing information based on that. You'd still notice a massive difference if your speakers could do 40Hz though.
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post #3 of 17 (permalink) Old 08-07-2012, 12:49 PM Thread Starter
 
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Re: Instrument/speaker frequencies

So through my speakers am i hearing a higher pitch of whats actually being played?
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post #4 of 17 (permalink) Old 08-07-2012, 12:57 PM
 
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Re: Instrument/speaker frequencies

Quote:
Originally Posted by GuitarBizarre View Post
You're hearing the overtones, the harmonics that make the signal sound different to just a pure sine wave.

The human brain is very good at filling in the missing information based on that. You'd still notice a massive difference if your speakers could do 40Hz though.
To add to this, it's part of what makes a bass guitar sound different from a clarinet, flute, saxophone, distorted guitar, etc...
The fundamental pitch is the lowest frequency in this collection of harmonics/overtones.
A really neat (or kind of neat) demonstration is to sit at a pipe organ (you know we all have one of those in the attic someplace :P ) and you can start with a pure-ish tone, and add sounds to it. Some of them you actually end up adding different notes (like a 3rd and a 5th) to the original note. So you play a single key and you kind of end up with a major chord, but after you start playing a melody or chords with it (multiple keys pressed), the brain kind of recognizes it as a single note, and not a collection of notes.
They mess around with this when comparing digital to tube distortion also I think. I read an article a long time ago comparing how certain harmonics are weaker or stronger (unless you go out of your way to tweak them) with you use digital or solid state distortion as opposed to tube distortion, and this is part of the difference in sound.
There are something like 11 or 12 harmonics that we are capable of hearing that can be added or subtracted from any fundamental pitch to make an instrument sound like a clarinet, or a buzzy distorted guitar (or saw wavey like a saxophone).
Interesting stuff actually.
We did the pipe organ thing in one my music classes in college.

And to bring it back to the point I quoted above, I think that is correct, that you can have all of the harmonics (because they follow the Harmonic Series, a good thing to look up, same thing as if you play harmonics up any particular string heading toward the nut), and if you play the correct harmonics for a particular fundamental tone, you can actually remove the fundamental pitch and your brain will still know what note it's supposed to be. Hence playing open E on a bass guitar through 60Hz minimum speakers, and still knowing it's a low E, even though the speakers probably can't produce that note, or not very strongly.

http://en.wikipedia.org/wiki/Harmoni...es_%28music%29

These would be the actual sounding harmonics for the lowest C that is notated:



It's a little tough to explain (for me at least), but easier to demonstrate.
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post #5 of 17 (permalink) Old 08-07-2012, 01:01 PM
 
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Re: Instrument/speaker frequencies

Also of note: The brain sets up "ghost" frequencies.

If you're played 2 tones together, you'll ALSO percieve a third frequency, at the tone that would be the difference between the two extant tones.

so for example, hearing 400 Hz and 600Hz, your brain would also percieve 200Hz under it, even though its not there.
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post #6 of 17 (permalink) Old 08-07-2012, 01:03 PM Thread Starter
 
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Re: Instrument/speaker frequencies

Wow what an explanation. Thats amazing though i had very little knowledge of this area of music. Looks like i have opened yet another can of worms for myself! So when i heard a bass guitar playing a Low E in real life, as opposed to on my speakers, i hear the fundamental as WELL as the harmonics? Then on my speakers im only hearing harmonics?
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post #7 of 17 (permalink) Old 08-07-2012, 01:04 PM
 
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Re: Instrument/speaker frequencies

There are probably some good YouTube videos demonstrating how it works, I found this one, not sure if it's the best, but it's something:

http://youtu.be/YsZKvLnf7wU?t=5m45s

If your speakers from your amp are able to produce the fundamental frequency, then yes you should be hearing the fundamental note. Likewise, since no speaker is "ideal" from a physics standpoint, they will all emphasize and de-emphasize different harmonics of a given note (depending how flat or uneven their response curve is). You can still usually tell what they are supposed to sound like, but they will all sound a little different.
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post #8 of 17 (permalink) Old 08-07-2012, 01:08 PM
 
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Re: Instrument/speaker frequencies

Sorry to keep babbling here, hopefully this isn't confusing.
In the video near the starting point that I have the link, he mentions how a square wave has no even harmonics. So if you start out and work up the harmonic overtone series, skipping all of the even numbered harmonics (2, 4, 6, etc...), you will more or less be constructing a square wave. He shows how to build them for the saw wave too.
A bass guitar isn't exactly any of these, but it serves to illustrate some of the ideas here.

You can also create the harmonic series if you play a trumpet or saxophone (a more experienced player). By playing any open note, tightening the lips will produce the next harmonic, tightening more makes the next harmonic, and you can keep going up as long you can push fast enough air and maintain control of the lips. With saxophone it involves air speed affected by tongue position inside the mouth and some adjustment of lips on the reed.
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post #9 of 17 (permalink) Old 08-07-2012, 01:39 PM Thread Starter
 
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Re: Instrument/speaker frequencies

This is actually making sense! Thankyou for your input lastsnare.

Just did a sound test through youtube. Frequency plays that sweeps from veryyyyy high to veryyyy low indeed. I found i could still hear at as low as 5hz but obviously quite muffly and crappy sounding. So i guess to some extent the frequency range of my speakers is higher than i thought? Or are my speakers themselves producing some kind of higher harmonic again??? SO confused again!
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post #10 of 17 (permalink) Old 08-07-2012, 01:43 PM
 
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Re: Instrument/speaker frequencies

Quote:
Originally Posted by Curtis08ltd View Post
This is actually making sense! Thankyou for your input lastsnare.

Just did a sound test through youtube. Frequency plays that sweeps from veryyyyy high to veryyyy low indeed. I found i could still hear at as low as 5hz but obviously quite muffly and crappy sounding. So i guess to some extent the frequency range of my speakers is higher than i thought? Or are my speakers themselves producing some kind of higher harmonic again??? SO confused again!
No problem at all !

It could be that either:
1. The type of wave that they used isn't completely stripped of overtones, so you are still hearing some higher overtones when it sweeps very low, but not actually hearing the fundamental
2. Your speakers roll off below 60Hz but don't completely cut out right away, so that perhaps you are hearing something at 40Hz or 20Hz, but it's just not as loud as all the other frequencies in it's advertised frequency response range. Like, most speakers don't completely cut out below their advertised range, but the volume drops off below that point (or around that point). I think it would be quite a stretch for a 60Hz speaker to produce anything as low as 5Hz (I think 20Hz is a stretch for a lot of speakers), but it's possible I guess. At that frequency though, you can usually count the pulses and feel the air. 5Hz is 5 pulses per second if I recall correctly. When it comes out of one of the few pipe organs in the world that can do it (with their 60 foot long pipes or whatever), it kind of makes you feel a little sick and might mess with people who have inner ear vertigo issues. On a smaller speaker I guess you could probably watch it move in and out 5 times per second (or whatever the Hz frequency was that you were playing).
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post #11 of 17 (permalink) Old 08-07-2012, 01:45 PM Thread Starter
 
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Re: Instrument/speaker frequencies

Yeah at 5hz it kind of sounded like it was stuttering?
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post #12 of 17 (permalink) Old 08-07-2012, 01:50 PM
 
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Re: Instrument/speaker frequencies

Quote:
Originally Posted by Curtis08ltd View Post
Yeah at 5hz it kind of sounded like it was stuttering?
that is probably about right, 5Hz is pretty much too low for us to hear as an actual pitch like we hear other notes of higher frequency, so we just feel it like a fluttering pulse of air (which is all that sound really is, but we're just use to much faster pulses that we perceive as notes). A really large, long-excursion speaker will really blow your hair back though if it's loud enough, kind of like a fan, haha.
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post #13 of 17 (permalink) Old 08-07-2012, 01:51 PM Thread Starter
 
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Re: Instrument/speaker frequencies

I see how this works then!! So might it be worth getting a subwoofer to add to these speakers i have for a truly accurate representation of the music im listening to?
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post #14 of 17 (permalink) Old 08-07-2012, 01:53 PM Thread Starter
 
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Re: Instrument/speaker frequencies

Also i just tried doing the bast test again but with my hands over the speakers to feel. I found at about 40hz followed by 30 then 20 and 5 etc, i could hear the flapping but i couldnt feel any air being displaced!
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post #15 of 17 (permalink) Old 08-07-2012, 02:07 PM
 
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Re: Instrument/speaker frequencies

You will probably get more of the lower sounds with a subwoofer. I don't do any serious recording, so I just have computer speakers hooked up to my computer, and that subwoofer makes some frequencies very loud and others very quiet (probably optimized for computer game explosions). So if it's a decent one (or decently better than my computer speakers), you will probably get better sound. If it's a sub that's designed to work with your existing speakers, even better. By that I mean, it's made to pick up where your monitor speakers leave off in terms of low frequencies. If there is overlap you will end up with too much sound in one range. I guess you could just EQ it out, but it's probably almost always better when a system is designed together from the start...less fiddling later to get it sounding perfect, if perfect is what you are after.

For the air displacement, if the speaker is small enough or if the cone and voice coil don't move far enough, you won't actually feel any air. But with some long-throw subwoofer type speakers (that you will occasionally find on a boom-box or something, like a small, low powered 4 or 6 inch subwoofer with a soft cone material, you can see and feel the air moving.

Last edited by lastsnare; 08-07-2012 at 02:09 PM. Reason: I edit my posts a lot
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