Octave fuzz pedals at the 12th fret

[rousejeremy]

Why is the octave more pronounced while playing around the 12th fret with the neck pickup? If I'm on the D and G strings at the twelfth fret playing the notes D,E,G and A there's a great octave effect, but if I move down to the G and B strings playing the same notes at the same pitch it's weaker and on the B and E strings it's not even there. Sounds more like a ring modulator.

[mistahead]

Its about the harmonics, not about the root note...

I'm sure someone can go into depth on this one with graphs and or maths, but think about when playing harmonics via "lightly fretting" rather than pinch type, moving the "fretting" hand up and down shifts the rings but so does where you are picking, its why you need to pick and fret the same locations to match the ring and moving it over to the same note on a different string entirely changes the "background" character of the "notes".

Most octave effects use those harmonics, so getting that technique understood will assist predict the outcomes.

[Mark Hammer]

Shorter strings are stiffer.  Stiffer strings have less harmonic content.  Synthetic octaves are more audible when not buried under lots of harmonics and sideband products.  Of course, when they get too short and stiff, the strig dies out quickly.  So you get best octaving within a few frets of the 12th.

[mistahead]

Thanks Mark - I knew it was about the various harmonics polluting the desirable harmonics for the octave'er to emphasise but you've actually just explained the bit I was not making a simple logical connection on, now I can visualise it correctly and I love you man. 

Incidentally I spent a LOT of last night playing with the Pitch and octave functions (digital pitch, possibly anologue octave and fuzz... should tear it open again) from my Vox Tonelab ST. The tracking of its Pitch is better 12-top of the fretboard however I've been able to get some very synthesque (think Queen's Best Friend for the "subtle" version of what I'm talking about) from using open-7 frets and letting the Pitch latch onto the normally polluting harmonics (polyphonic  ), the result is the sustained root note gets pushed out and as the natural attack/fade of the pluck/strum ascends through the harmonics as it dies, the Vox latches on and creates pitched copies at around volume unity of those more complex harmonics that are more predominant after the string-strike has subsided.

From tracking "issue" comes thoery about ways to use analogue harmonics that are normally troublesome to the tracking, to instead create the depth and polyphonic quality of a pseudo synth...

Probably making no sense, sleep deprived and at work, just a bloody writeoff today TBH lol.

[earthtonesaudio]

Also when you fret up high the middle of the (fretted portion of) the string is swinging past your pickup.  When you fret down low it's more like 1/4 way up the string that is swinging past the pickup.  The middle is where the fundamental is.

That's also why neck pickups tend to get more "action" out of octave pedals.  They are "listening" nearer to the part of the string where the fundamental occurs.

[ashcat_lt]

Also when you fret up high the middle of the (fretted portion of) the string is swinging past your pickup.  When you fret down low it's more like 1/4 way up the string that is swinging past the pickup.  The middle is where the fundamental is.

That's also why neck pickups tend to get more "action" out of octave pedals.  They are "listening" nearer to the part of the string where the fundamental occurs.

I think I know what you're trying to say here, and I'm pretty sure that you have a pretty good idea, but I think we need to be careful on this.

The fundamental occurs all along the vibrating length of the string.  Different harmonics actually have nulls along the string where they really have no energy at certain points, but the fundamental is there anywhere the thing is actually swinging.  The proportion of fundamental to higher harmonics is greater (leans toward the fundamental) closer to the center of the vibrating length.  Neck pickups are usually placed right around where the 24th fret would be, which is halfway between the bridge and the 12th fret, and when fretting at the 12th this will be where the fundamental is "loudest" in relation to the other harmonics.

Which is what you meant, I'm sure.  

[earthtonesaudio]

I think I know what you're trying to say here, and I'm pretty sure that you have a pretty good idea, but I think we need to be careful on this.

The fundamental occurs all along the vibrating length of the string.  Different harmonics actually have nulls along the string where they really have no energy at certain points, but the fundamental is there anywhere the thing is actually swinging.  The proportion of fundamental to higher harmonics is greater (leans toward the fundamental) closer to the center of the vibrating length.  Neck pickups are usually placed right around where the 24th fret would be, which is halfway between the bridge and the 12th fret, and when fretting at the 12th this will be where the fundamental is "loudest" in relation to the other harmonics.

Which is what you meant, I'm sure.  

Whether my explanation was over-simplified or not depends on how much you already understand the problem at hand.

[Mark Hammer]

The fundamental wiggles along the whole vibrating portion of the string, but the string always has its greatest compliance in the middle of the vibrating part.  So, while imprecise, I think earthtones is well in the balllpark.

Note that the neck pickup is near that midpoint when picking in the "hot zone" for octaving.

[earthtonesaudio]

Also (another gross oversimplification coming up) ...
Given two strings tuned to the same pitch and having the same mass per unit length, the shorter one will be darker/warmer sounding.  Fretting shortens strings.  Ergo fretting reduces harmonics.

You can do this experiment with a capo.  Record a chord such as Gmaj on your standard-tuned guitar.  Then tune down one half-step, put a capo on the first fret, and record Gmaj (which will now be located +1 fret from before) again.  Compare treble content between the standard and "virtual short scale" versions.

[artifus]

also, just to throw in another curve ball... doesn't all this math assume perfectly robotic midi like playing on perfectly set up and constructed instruments? i often play more than one note at once, sometimes on purpose, sometimes not so much. the not so much can take time to mute yet contributes to initial signal and circuit response... taxi for art!

[Keppy]

also, just to throw in another curve ball... doesn't all this math assume perfectly robotic midi like playing on perfectly set up and constructed instruments? i often play more than one note at once, sometimes on purpose, sometimes not so much. the not so much can take time to mute yet contributes to initial signal and circuit response... taxi for art!

Yeah, it only works as an octave on single notes with little harmonic content. Multiple frequencies create all sorts of weird broken sounds, which is really much more than half the fun.

[gritz]

also, just to throw in another curve ball... doesn't all this math assume perfectly robotic midi like playing on perfectly set up and constructed instruments? i often play more than one note at once, sometimes on purpose, sometimes not so much. the not so much can take time to mute yet contributes to initial signal and circuit response... taxi for art!

Hold the taxi - it's a very fair point. We can all get worked up over computer simulations involving sine waves and forget that real guitar spits out very complex waveforms. The fundamental frequency can be lost amongst the harmonics, depending on the relative positions of the picking action and the pickup along the string. The trick is how to make that neck pickup / 12th fret and just above sweet spot a bit bigger without having to pick every note exactly half way along the string's length whilst concentrating so hard that you forget what you're trying to play...

Maybe judicious eq before the effect (as with all distortions) and maybe even "multiband", where you split the guitar's output into frequency bands (in a similar way to splitting a hifi amplifier's output into multiway speakers using a crossover) and applying the octaver to each band. Note separation. Lot of work though.

[zombiwoof]

Are you talking about an Octavia-type octave effect (added upper octave, not added lower octave)?.
If you don't already know, this type of effect works better on the neck pickup, with the tone rolled all the way off.
Also, I don't use the built-in fuzz, I turn the fuzz knob all the way down and run the pedal in conjuction with a fuzz or OD (either before or after, whichever works better for you).  This is what Hendrix did with his Octavias (with a Fuzz Face, of course).  I think you get the best octave effect in more positions doing it this way, although it still is not as pronounced an effect on lower frets.

If you're talking about a pedal that adds a lower octave, that's a different beast.

Al

[Keppy]

^ Some good points here. I just made an octave fuzz, and I found the octave was more prominent at lower gain settings. Of course, the traditional designs used diode rectification, so with those you needed at lease enough gain to turn the diodes on with the signal. I guess you could say there's a "sweet spot" for gain with these.

[mistahead]

There isn't that much fundamentally different between the input requirements to push an Octavia-type fuzz-octave to get nice clean octave up and most of the digital based octave/pitching effects out there - the same problems plague both effect types from different angles but ultimately they want a clean, single strike on a note and an emphasis or the complementary harmonics while minimising the "noisy" harmonics... how/why is the interesting bit.

EQ/Compression/Limiting, lofi conversion (take all the character out and leave a "radio buzz" on the root note), whatever - they are methods we are using to try to get our notes and the suitable complementary harmonics filtered out of the beatiful chaos of a real guitar...

My point of view comes from being more a solo-player than working in a band with full bass/drums/guitars/etc, trying to create a whole and full sound rather than that niche for trebbly guitars in the mix, so take it with as much salt as required for your tools and roles.

[Keppy]

There isn't that much fundamentally different between the input requirements to push an Octavia-type fuzz-octave to get nice clean octave up and most of the digital based octave/pitching effects out there - the same problems plague both effect types from different angles but ultimately they want a clean, single strike on a note and an emphasis or the complementary harmonics while minimising the "noisy" harmonics... how/why is the interesting bit.

I was under the impression that most of the digital stuff (POG, Whammy, etc.) used sample rates to pitch shift. For example, to get an octave up, a short section (a few msecs tops) of audio would be recorded, then played back twice at double speed to produce an equal length section one octave higher in pitch. This method works with any input within the dynamic range of the ADC. These pedals work just fine with complex inputs.

[mistahead]

My experience with digital on this is the Vox I use now, Zoom stuff I used to have and some short exposure to random effects that do octave and pitching digitally.

Not my experience, there is usually quite a lot more going on - even if they are just using a sample/repeat with a speed variable as you suggest it will introduce artifacts you don't want/won't like, so again you are back at square one of trying pre-groom into the pitch/octave again - although with slightly different reasons for the same BS.