i've just realised i don't know how a bass guitar works!?!

[Bloodaxe]

[quote name='iconic' timestamp='1392566166' post='2370071']
I could of worded my question better....my question is how the different sound frequencies are related to the electricity derived by the pick-up...I've re-read that it is still clear as mud! [/quote]

The vibrating string disrupts the magnetic field of the pickup, & this disruption induces a current into the coil of the pickup that is of the same frequency (or frequencies) as that produced by the string. The amplitude (height/volume) is determined by how strongly the string is vibrating. This induced signal is sent to the amp which makes it all biggerer. The amount of bigness is normally limited by the guitarist complaining that he can hear the bass.

Different pickups have different tonalities. Put very simply, this is because of Physics.

Put slightly less simply, it's down to differences in design/manufacture (magnet strength, number of turns, wire thickness) which affect how much of the string's frequencies get sent down the line - sort of like a preset EQ.

Put more complicatedly... A straight bit of wire has a fixed resistance over its length no matter what signal you put through it - DC, AC, doesn't matter. However a [i]coil[/i] of wire has a resistance that varies according to what frequency is passing through it. Add in the capacitance caused by the insulation on the wire, and the fact that some pickups are wound in a rather random pattern & you end up with a quite complex frequency-dependant resistor. As a result none of them will truly reproduce all the frequencies that the string is generating. That's why some pickups have a mid-hump, some sound like a bucket of mud & some are fairly well balanced.

P.

[iconic]

[quote name='Bloodaxe' timestamp='1392625425' post='2370640']
The vibrating string disrupts the magnetic field of the pickup, & this disruption induces a current into the coil of the pickup that is of the same frequency (or frequencies) as that produced by the string. The amplitude (height/volume) is determined by how strongly the string is vibrating. This induced signal is sent to the amp which makes it all biggerer. The amount of bigness is normally limited by the guitarist complaining that he can hear the bass.

Different pickups have different tonalities. Put very simply, this is because of Physics.

Put slightly less simply, it's down to differences in design/manufacture (magnet strength, number of turns, wire thickness) which affect how much of the string's frequencies get sent down the line - sort of like a preset EQ.

Put more complicatedly... A straight bit of wire has a fixed resistance over its length no matter what signal you put through it - DC, AC, doesn't matter. However a [i]coil[/i] of wire has a resistance that varies according to what frequency is passing through it. Add in the capacitance caused by the insulation on the wire, and the fact that some pickups are wound in a rather random pattern & you end up with a quite complex frequency-dependant resistor. As a result none of them will truly reproduce all the frequencies that the string is generating. That's why some pickups have a mid-hump, some sound like a bucket of mud & some are fairly well balanced.

P.
[/quote]

brilliant, excellent explanation, cheers

erm, err, so this body wood influence on the tone thing that many feel they can hear, I can't understand how it can influence the frequency of the AC current derived by a magnetic field, but want to understand.

...could it simply be because given two pieces of different woods, the string is oscillating differently due to how solidly the bridge and neck is nailed on to the body wood...stiffer or slacker? I mean there are no moving parts in the pup per se, the only part that can shift about is the string and its only tethered at two ends, the neck being the weakest part, its easy to bend the neck...maybe the security of the neck is more important to the tone?

it all hurts too much now... I'm off for a MOT, thanks for the above though

.....I can feel breathing down my neck, a can of worms picture & popcorn smiley coming along soon

[muttley]

[quote name='Bloodaxe' timestamp='1392625425' post='2370640']
a [i]coil[/i] of wire has a resistance that varies according to what frequency is passing through it.
[/quote]

Sorry to be a pedant, but it's [i]impedance[/i] that rises with frequency in an inductor. Electrical resistance is only defined for direct current (ie zero Hz). Therefore the total (modulus of) impedance of a coil will be sqrt(R[sup]2[/sup]+[2(pi)f][sup]2[/sup]) where R is the [i]resistive[/i] component and 2(pi)f the [i]reactive[/i] component at frequency f Hz. It's these reactive elements (of inductors and capacitors) that give circuits their frequency-dependent characteristics, most notably electrical resonance. If everything was purely resistive, the frequency response would be flat from DC to light.

[Bloodaxe]

[quote name='muttley' timestamp='1392632750' post='2370749']
Sorry to be a pedant, but it's [i]impedance[/i] that rises with frequency in an inductor. Electrical resistance is only defined for direct current (ie zero Hz). Therefore the total (modulus of) impedance of a coil will be sqrt(R[sup]2[/sup]+[2(pi)f][sup]2[/sup]) where R is the [i]resistive[/i] component and 2(pi)f the [i]reactive[/i] component at frequency f Hz. It's these reactive elements (of inductors and capacitors) that give circuits their frequency-dependent characteristics, most notably electrical resonance. If everything was purely resistive, the frequency response would be flat from DC to light.
[/quote]

True... but, in my defence m'lud the [url=http://www.oxforddictionaries.com/definition/english/impedance]OED definition[/url] seems to hinge on the 'r' word... If I'd put your strict definition in, I fear the nice Mr Iconic's head would have done this:—

http://www.youtube.com/watch?v=pjnZO5ZgWE8

& I didn't want any more needless deaths on my conscience.

[muttley]

[quote name='Bloodaxe' timestamp='1392638692' post='2370850']
True... but, in my defence m'lud the [url="http://www.oxforddictionaries.com/definition/english/impedance"]OED definition[/url] seems to hinge on the 'r' word... If I'd put your strict definition in, I fear the nice Mr Iconic's head would have done this:—

[media]http://www.youtube.com/watch?v=pjnZO5ZgWE8[/media]

& I didn't want any more needless deaths on my conscience.
[/quote]

Furry nuff.

I think the OED definition of electrical impedance explains it quite well*

[size=1]*apart from the use of [i]j[/i] as the imaginary operator when any fule no it's [i]i.[/i][/size]

[razze06]

[quote name='iconic' timestamp='1392627636' post='2370657']
brilliant, excellent explanation, cheers

erm, err, so this body wood influence on the tone thing that many feel they can hear, I can't understand how it can influence the frequency of the AC current derived by a magnetic field, but want to understand.

...could it simply be because given two pieces of different woods, the string is oscillating differently due to how solidly the bridge and neck is nailed on to the body wood...stiffer or slacker? I mean there are no moving parts in the pup per se, the only part that can shift about is the string and its only tethered at two ends, the neck being the weakest part, its easy to bend the neck...maybe the security of the neck is more important to the tone?

it all hurts too much now... I'm off for a MOT, thanks for the above though

.....I can feel breathing down my neck, a can of worms picture & popcorn smiley coming along soon
[/quote]

As someone said earlier, the effect of stuff like material of the guitar body, bridge design/material/connection to the body is quite small overall. As the string is plucked, the whole guitar vibrates slightly, in a manner depending on the sonic characteristics of the body and the transmission of vibration by the bridge, neck, etc. In essence, certain woods/bridges can dampen certain frequencies already present in the vibration of the string, thus altering the signal produced by the pickup. Quite modestly

[Bloodaxe]

[quote name='iconic' timestamp='1392627636' post='2370657']
erm, err, so this body wood influence on the tone thing that many feel they can hear, I can't understand how it can influence the frequency of the AC current derived by a magnetic field, but want to understand.

...could it simply be because given two pieces of different woods, the string is oscillating differently due to how solidly the bridge and neck is nailed on to the body wood...stiffer or slacker? I mean there are no moving parts in the pup per se, the only part that can shift about is the string and its only tethered at two ends, the neck being the weakest part, its easy to bend the neck...maybe the security of the neck is more important to the tone?
[/quote]

I reckon you're nearly there...

To paraphrase Woodinblack's & Razze06's posts:

An open string vibrates between the nut & the bridge (there may be a tiny amount of vibration betwixt nut & tuners and bridge & tailpiece, but it's pretty safe to ignore that).
[i]Some[/i] of that vibration is also transmitted to the body & neck, which resonate in sympathy. This sympathetic resonance feeds back into the string and affects its harmonic content. How much it affects it is a combination of species, density, construction (through, set, or bolt), and how much contact the nut & bridge have with the woodwork. As a result, different woods could/can subtly affect the way a note sounds.

The issue I have with the whole 'tonewood' schtick is that I have trouble believing that it's really perceptible in a real world situation. If you're a soloist playing lots of whole notes to a quiet & appreciative gathering, then maybe it's possible to detect a difference. Be honest though, how often do you play a breve, let alone a semibreve? We're more likely to be playing quarters and eighths by braille in the back bar of the Dog & Duck.

At a tempo of 120bpm an eighth note lasts 1/4 of a second — is that long enough for the Tonewood Feedback Loop to have a tangible effect? I'd argue that it isn't, and that it's the pickups & strings that primarily define tone. Thus Tonewood = Toshwood (IMO).

P.