Sub Bass FX

[jucas]

At least, that's how I think it works its magic. Anyone else care to weigh in?

Thanks. I doubt my little amp'll be able to do much with that, but for 25 bucks it sounds like its worth a shot.

 

[The BurgerMeister]

There's a few different ways to look at a single note. A single plucked bass note (or piano, gtr, etc.) may contain the octave above and below the fundamental, as well as many other frequencies. So some people/fx get their "subharmonic" tones by emphasizing the octave-below harmonic that is already there. Some get it by "reading" the incoming fundamental frequency and mathematically dividing it in half in order to put out a new fundamental tone an octave below. Some get it by using a self-resonant lowpass filter which, when resonating, puts out its own tones- the pitch of those tones is controlled by the "cutoff" of the filter.

The FX25 uses a bit of the first and third methods "by accident". It is a lowpass filter. It does resonate some, but not to the point where it is a pure oscillator. At the point where the Sensitivity control is off, the frequencies emphasized by the filter happen to be the subharmonics of the incoming note. And the filter is also resonant at those frequencies, so you get a combination of the original subharmonics and the "synthesized" frequencies of the resonant filter.

At least, that's how I think it works its magic. Anyone else care to weigh in?

That method does completely avoid tracking issues, because tracking is exclusively a process of digital processing and digital note generation. Typically, a digital unit will "read" every incoming frequency, try to identify it, and then create a new output signal, and that's where the tracking problems occur.

all sounds about right to me. bongomania = smart!

i've found that dub tones are best achieved with envelope filter effects. they seem to favor a bunch of very low frequencies rather than an octaver which creates only one. (see bongo's explanation above for more details.) with a filter effect, you tend to get a rounder, fuller tone for your subsonic assaults. with an octaver, it seems to be a little lighter. i'm not entirely sure that makes any sense. but i tried.

 

[michele]

There's a few different ways to look at a single note. A single plucked bass note (or piano, gtr, etc.) may contain the octave above and below the fundamental, as well as many other frequencies. So some people/fx get their "subharmonic" tones by emphasizing the octave-below harmonic that is already there. Some get it by "reading" the incoming fundamental frequency and mathematically dividing it in half in order to put out a new fundamental tone an octave below. Some get it by using a self-resonant lowpass filter which, when resonating, puts out its own tones- the pitch of those tones is controlled by the "cutoff" of the filter.

The FX25 uses a bit of the first and third methods "by accident". It is a lowpass filter. It does resonate some, but not to the point where it is a pure oscillator. At the point where the Sensitivity control is off, the frequencies emphasized by the filter happen to be the subharmonics of the incoming note. And the filter is also resonant at those frequencies, so you get a combination of the original subharmonics and the "synthesized" frequencies of the resonant filter.

At least, that's how I think it works its magic. Anyone else care to weigh in?

That method does completely avoid tracking issues, because tracking is exclusively a process of digital processing and digital note generation. Typically, a digital unit will "read" every incoming frequency, try to identify it, and then create a new output signal, and that's where the tracking problems occur.

That's a nice informative post, Bongo!
I'm very interested in the subharmonic thing: I know that Bill Laswell uses an FX25 and his dub tone is just amazing. I'm wondering if such results could be achieved with every low pass filter because I'm actually pondering the purchase of a Moog MF-101.

 

[bongomania]

Yeah, somebody posted some clips of the Moog recently which DID have that awesome dub sound. I wouldn't say "every" low pass filter can do it, but one that is on the brink of self-resonance at those frequencies will.

As a side note, the ultra-low bass of techno music came originally from a monophonic analog synth with a resonant filter pushed fully into self-oscillation, where the pitch was controlled by the cutoff frequency of the filter, and that cutoff was set to "track" to a keyboard or MIDI note information. Of course nowadays you just select the "techno bass" preset sample. In MY day, we had to walk ten miles uphill, in the SNOW, to get that sound!

 

[SFjonstarr]

I couldn't get much of a Laswell style dub tone from the Moog when I had it. I felt like I needed to manipulate the cutoff in order to keep it tracking as you play different notes. When I would plug in an expression pedal to try to do so I only needed to move the cutoff along a small portion of it's range. This made a full range foot controller ineffective and unwieldy. I'm sure someone who knows what they're doing could wire up a control voltage pedal that you could adjust to taylor the range to different situations. The Moog can generate some mean humming sine waves though when you push it into self-oscillation by juicing the resonance control. You can even cop some cool synth drum tones by playing into the filter with the envelope tracker on and the resonance above the theshhold.

 

[michele]

Thanks Bongo & SFjon.
Of course I'm not interested into the moog only to get the Laswell's sound. From what I've read here it's capable to put out some serious subharmonics as well as a lot of other interesting things ...
Aside from Laswell's work, everytime someone mention the word DEEP I immediately think about this:

http://www.mmw.net/av.jsp

Watch the first video, Uninvisible
This really opened a new door to me ...
I know Chris used a Bass Microsynth on this track.

 

[Nyarlathotep]

My "take" on dub useing my Bass PODxt:

 

[greenboy]

A single plucked bass note (or piano, gtr, etc.) may contain the octave above and below the fundamental, as well as many other frequencies. So some people/fx get their "subharmonic" tones by emphasizing the octave-below harmonic that is already there.

Mon par-don,

But I don't think that's correct. I sure haven't seen any evidence of 1/2 fundamental in any fft frequency analysis plots of plucked string instruments. If there is any significant content below the fundamental it's been incidental non-harmonic-series noise from thumping of pickup or other spurious stuff.

 

[bongomania]

OK, I sure haven't looked at any fft frequency analysis plots, I was just going by what my ears tell me. So, in your opinion, what frequencies are being emphasized by the LPF in this case? Is it just that the fundamental "sounds" lower psychoacoustically with much of the upper harmonics filtered out? Is the presence of new harmonic content from the resonating filter 100% of the effect in this case? (I'm not challenging you, I'm genuinely curious.)

 

[greenboy]

Hoi bongomania,

Got to be honest; I just skimmed the thread lightly and what I quoted was what caught my eye. I've used various methods including subharmonic generators, octave "dividers", sampling circuits which includes pitch shifters ... as well as faking it with bass "synths" that supply an oscillator (and if lucky a suboscillator), and autowah filters with the sensitivity set minimum with sometimes the resonance set high, etc.

But to the best of my knowledge there is no significant harmonically related "undertone" on plucked strings. If there was I suspect it would be called a fundamental and the old fundamental would become an overtone ; }

My current and longstanding low bass solution (other than playing the octave-lower 39.5"-scale Knuckle Quake bass or other ERB solution) has been the Roland V-Bass using several of the above methods. It may not be the best at some of them, but it's definitely an incredible all-around-package. I'd probably go for the latest and greatest Eventide otherwise...

 

[Nyarlathotep]

I read a review on the Quake bass, which quite interests me...

I personally aggree with bongo's thoughts on the fundamental sounding lower with all the OTs filtered out. From personal experience I've found that even my P pup has a lot more low mids than actual fundamental, so when I boost that fundamental over that of the low mid OTs, and kill off all the other OTs, my bass sounds like it's lower simply because I'd never really heard the fundamental out front.

The other way around is also true. I found that playing such a dub tone all the time tuned my ears into thinking that a "normal" bass tone was "weak", if for the simple fact that there were more OTs present over/out front of the fundamental.

Just a little personal experience speaking. YMMV and such...

 

[SFjonstarr]

For copping a good deep dub tone there are some simple things you can do that don't require electronics. I like to mute the strings with the edge of my right hand palm right by where the strings meet the bridge and pluck down with my right hand thumb. Once you get used to it you can gain a good deal of control over how much treble and overtone information you muffle away. You also have a deal of control over how long your notes ring out when you get comfortable enough to roll more of your palm down on the string to end notes. Also if I was doing a dub gig or recording that style of bass I would be playing with flatwound strings. Flatwound strings take a lot of the overtone emphasis away and leave you with a stronger sounding fundamental and a definate increase in percieved bass. Doing the palm muting thing on the B string of a flatwound strung fiver through a good system with powerful subs has got to be one of the most satisfying feelings there is.

 

[michele]

For copping a good deep dub tone there are some simple things you can do that don't require electronics. I like to mute the strings with the edge of my right hand palm right by where the strings meet the bridge and pluck down with my right hand thumb. Once you get used to it you can gain a good deal of control over how much treble and overtone information you muffle away. You also have a deal of control over how long your notes ring out when you get comfortable enough to roll more of your palm down on the string to end notes. Also if I was doing a dub gig or recording that style of bass I would be playing with flatwound strings. Flatwound strings take a lot of the overtone emphasis away and leave you with a stronger sounding fundamental and a definate increase in percieved bass. Doing the palm muting thing on the B string of a flatwound strung fiver through a good system with powerful subs has got to be one of the most satisfying feelings there is.

+10.00000000....
Just yesterday at home I was toying with my Sadowsky (strung with TI Jazz Flats) doing some palm muting/thumb pluckin deep dub lines. I played with a drop of drive in my Prunes & Custard and through my Thunderfunk/Accugroove rig ... windows seemed on the point of flyin' away!

 

[SFjonstarr]

The Prunes & Custard is awesome with palm muting. When you push down with your palm to muffle a note away it does a little downward filter sweep. You can do some really cool articulations.