But how do you make it humbuck Dan? Because you surely will have to!

And I'm no radio buff but wouldn't the whole thing be a 1/4wave folded dipole at about 75megs?

Dave.

Insulate the bridge and connect pairs of strings in series at one end, humbucker!

Given the now very low source Z, the dipole effect should be trivial to filter out (L/C filter at a few tens of Khz should get it done).

Hey just a stupid idea.

Regards, Dan.

--------------------
Audiophiles use phono leads because they are unbalanced people!

Quote dmills:

---

Insulate the bridge and connect pairs of strings in series at one end, humbucker!

Given the now very low source Z, the dipole effect should be trivial to filter out (L/C filter at a few tens of Khz should get it done).

Hey just a stupid idea.

Regards, Dan.

---

Ah! But you would have to have alternate opposite magnetic poles so you could the series strings oophase electrically but the field would put it "right"!

And hey! Don't knock "stupid" ideas! I understand one hotshot Japanese exec' said of the Walkman "Who's going to buy a cassette that does not record?" !!!

Dave.

Quote:

---

It sure would. A tin containing a TL072 and a PP3 (better 2) clipped to the strap and connected by less than a mtr of low cap' cable would make ALL the cable arguments redundant.

---

Dave, get that circuit sketched out! I'm firing up the soldering iron as we speak!
Simon

--------------------
"Ignorance more frequently begets confidence than does knowledge" Charles Darwin.

Quote Huge Longjohns:

---

Quote:

---

It sure would. A tin containing a TL072 and a PP3 (better 2) clipped to the strap and connected by less than a mtr of low cap' cable would make ALL the cable arguments redundant.

---

Dave, get that circuit sketched out! I'm firing up the soldering iron as we speak!
Simon

---

Wilco but there are options to discuss. Do you have my email addy?

Dave.

I think you'll find that damping of strings is directly proportional to the strength of the magnets, as it is the strings themselves moving through the field that create eddy currents trying to oppose the movement. The electro-mechanical effect of the coils would be pretty minimal compared to this.

With my FM idea, there would be no magnets at all, and likely no cores even. The strength of field from the carrier frequency reaching the strings would be negligible if you run at (say) 500kHz. Also being FM it would be immune to 50Hz hum pickup (AM), which has to be a bonus!

It occurs to me that this might not be such an impractical idea these days. On-chip FM decoders must be getting really tiny by now. Also, it might be possible to up-convert the signal to radio mic frequencies - now wouldn't that be fun

I've heard of the idea of using the strings directly before. No worries about electrostatic pickup, but as Dave said, some serious grief with electromagnetic. Running them in pairs with opposed magnets sounds interesting. However my feeling is that the HF response would be very poor. Can't really say why I think that, just intuition.

Another idea I've heard bandied about by electronic engineering chums is photo-electric. The idea is that you shine modulated IR light on the underside of the strings then have high speed photodiodes picking up the reflected signal. Background light is ignored, only signals exactly matching the modulation are used.

This technique is used in modern position detecting photocell sensors. They used to have a response time of about 2mS - which is useless for audio - but I was surprised recently to find ones advertising 70uS response. Still not good enough, but certainly getting close!

Oh dear. So much fun, so little money!

--------------------
It wasn't me!
(Well, actually, it probably was)

Quote:

---

Do you have my email addy?

---

Of course! I'm thinking of something that could go in the guitar or attached to the strap with a v short jack lead into the guitar? I've heard of people actually building them into leads, too, with the preamp circuit inside the jackplug at the guitar end, and the battery in a box on the other (amp) end!

--------------------
"Ignorance more frequently begets confidence than does knowledge" Charles Darwin.

Quote:

---

I think you'll find that damping of strings is directly proportional to the strength of the magnets, as it is the strings themselves moving through the field that create eddy currents trying to oppose the movement. The electro-mechanical effect of the coils would be pretty minimal compared to this.

---

But this is still insignificant compared to the pure mechanical damping of the string and guitar body.

It's easy to prove this. If the guitar is unplugged then by definition there is no damping from the magnets, because there's nowhere for the current to go. So play your guitar unplugged, then plug the guitar into an amp with the volume turned right off and play your guitar again. Any difference in string damping? I've never noticed it myself.

Not quite Grab..

You would need to put a shorting jack in the guitar and turn pots to max to get maximum current and hence damping but I am still of the opinion that give the intrinsic resistance of pickups, rarely less than 2k, the damping will be as close to FA as makes no nevermind.

I am of the shool that says IF an effect is audible and reproducably so it can be measured. After all Hugh daily measures artifacts that in all but the most stringent of circumstances would go unnoticed.

Dave.

Sure, max current (and hence max damping) would be with the jack completely shorted.

Like you say though, I don't think even that would have much effect. And with the input impedance of an amp/DI, the current (and hence damping) is going to be within a gnat's fart of sod all.

Quote grab:

---

Sure, max current (and hence max damping) would be with the jack completely shorted.

Like you say though, I don't think even that would have much effect. And with the input impedance of an amp/DI, the current (and hence damping) is going to be within a gnat's fart of sod all.

---

I'm afraid you're missing the point. It is not the windings that significantly damp the strings but the magnets themselves. To do a comparison you would have to completely remove the pickups.

While I'm prepared to accept that the bridge pup probably doesn't do a lot of damping, the one(s) nearest the fretboard are where there is the maximum string movement, with the least amount of mechanical advantage. The greater the string velocity the greater the eddy currents in the string itself, and it is this that does the damping.

I'm sure someone at sometime must have studied this, but I've not seen any results.

The only practical way I can think of to test this would be to make up a rig with a guitar fitted with powerful electromagnets of the exact same dimensions as the pups would be. Then vary the current - hence field strength and measure the decay time of the string when plucked a known amount. To avoid any possible 'contamination' I would suggest the string decay is monitored with an acoustic pickup.

--------------------
It wasn't me!
(Well, actually, it probably was)

Eddy currents?
In a string where typically only one end is grounded and the other is floating? Where is the loop?

I could see some voltage produced between the ends, but unless there is a closed loop for the current to flow in I am having a hard time seeing eddy currents induced in the strings being a major energy sink. I would expect that mechanical damping exceeds electromagnetic by many orders of magnitude.

I suppose you might get some in the magnetic structure of the pup but there are well known ways to deal with that.

Regards, Dan.

--------------------
Audiophiles use phono leads because they are unbalanced people!

Sorry Will but I am going with the buggerall current buggerall damping camp here.

Easy way to "switch off" the magnets, slab of soft iron, mumetal would be favourite!

Dave.

Quote ef37a:

---

Sorry Will but I am going with the buggerall current buggerall damping camp here.

Easy way to "switch off" the magnets, slab of soft iron, mumetal would be favourite!

Dave.

---

Mumetal? What, like Limp Bizkit?

Quote:

---

I'm afraid you're missing the point. It is not the windings that significantly damp the strings but the magnets themselves. To do a comparison you would have to completely remove the pickups.

---

Try a Variax. No mag pickups at all, only piezo bridge pickups. And it doesn't sustain any different from any other solid-body electric guitar.

Dave, would installing one of these onboard preamp/effects jobbies do the buffer job too?:

Onboard effects

--------------------
"Ignorance more frequently begets confidence than does knowledge" Charles Darwin.

Quote Huge Longjohns:

---

Dave, would installing one of these onboard preamp/effects jobbies do the buffer job too?:

Onboard effects

---

Artec Sounds EX3 Warm Tone Boost - Flick Switch
That ^ seems to be the only one that does not have a passive bypass but I can't quite make out if the "active bypass" mode is "dry" of effect?
If they would come up with a schematic (hah!) I could tell you.

Dave.

Thinking about this a bit more I do not think that there can be any significant damping due to EM effects.
After all in the very intense, tiny gap of a dynamic mic and the very close coupling. the effect of various load impedances is said to be subtle. The amount of damping in a string I would aver is at least 100times less.
Then, a microphone is a "pure alternator" wires cutting lines of force. A guitar pup is more "variable reluctance" I would say?

And as I understand it, very strong (Neo) magnets are shunned because the strong pull on the steel string give rise to intonation problems?

Dave.

Quote grab:

---

Quote:

---

I'm afraid you're missing the point. It is not the windings that significantly damp the strings but the magnets themselves. To do a comparison you would have to completely remove the pickups.

---

Try a Variax. No mag pickups at all, only piezo bridge pickups. And it doesn't sustain any different from any other solid-body electric guitar.

---

Interesting. Well that sort of settles it dunnit.

I shall just have to stand in the corner muttering imprecations (provided I can find one).

--------------------
It wasn't me!
(Well, actually, it probably was)

Quote:

---

Interesting. Well that sort of settles it dunnit.

---

Maybe. Or it could just be a worse-made guitar with less sustain to start with.