Isnt any more complex, really. Windings are maybe cheaper than magnets and machined metal parts and dont loose magnetism with heat etc.
The advantage being that the coil can be 'shaped' in winding density (physically or electronically) and form factor etc. to cause more linear operation of VC over distance travelled.
Maybe some one else will want to think about it more.
THx-RNMarsh
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Hi Richard,
-Chris
Edit: Come to think about it, I have one in my bedroom right now.
I still repair those for myself as a hobby.
-Chris
Edit: Come to think about it, I have one in my bedroom right now.
You haven't priced copper lately, no??😉 switchmode supplies are pretty cheap, but I'm not sure how OEM SMPS pricing stacks up to OEM magnet pricing..
Problem is to get the correct field orientation within the gap itself with additional coils. The iron focusses the flux lines, extra coils would have to intercept part of the iron loop to get into the gap.
If there was a second front plate with associated iron circuit....but again, getting quite complex.
jn
How is the magnet coil and Vc positioned to each other. can you make a sketch or link to drawing?
THx-Richard
Hi Richard,
They seem to be on axis with each other with the coil covering most of the voice coil gap. The hum bucking winding seems to be in the rear. I've only seen one or two amplifiers where the electromagnet isn't part of the power supply, and those went from high B+ to common ground as a load. My guess is that they used the load to keep the minimum current up for the supply chokes. Otherwise it seems to be a waste of power, and knowing how engineers back then thought, there must be a good reason for them to do that.
-Chris
They seem to be on axis with each other with the coil covering most of the voice coil gap. The hum bucking winding seems to be in the rear. I've only seen one or two amplifiers where the electromagnet isn't part of the power supply, and those went from high B+ to common ground as a load. My guess is that they used the load to keep the minimum current up for the supply chokes. Otherwise it seems to be a waste of power, and knowing how engineers back then thought, there must be a good reason for them to do that.
-Chris
I'm not sure what you are asking. Field coils are not rocket science, there's not much that can be done. The coil is just there to provide a magnetic field. Using a ferrite is just a simple physical substitution.
The reluctance is gap dominated, neo magnets with free air permeability hadn't been used yet, so the mag circuit was iron dominated and low reluctance.
Jn
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can field coils be modulated to compensate or correct error from VC/cone?
Or act like sense coil at same time...
-RNM
Or act like sense coil at same time...
-RNM
That field coil is around a lot of steel. Don't expect it to change its field easily.
Hmmmm. I'm trying to get you guys to think outside the box and I keep getting The Box.
What can you do with a magnet coil that you cannot do with a PM?
-RM
What can you do with a magnet coil that you cannot do with a PM?
-RM
Field Coil is overkill, it's enough to be able to change the field a few percent.
Like what the 18sound AIC static coil in the gap does (at least partly). When it's driven with a scaled copy of the actual VC current it should work even better than with the standard voltage drive, parallel to the VC.
As for the optimum magnet, I think Neodymium is just fine. The only problem is that it is conductive (as is its standard nickel coating) so slicing it up into like 8 segments should help for low eddy current. Looks like almost any shape can be had (provided you can still magnetize it), this would easily allow for a motor without any steel in the magnetic circuit. Especially with a circuit like 18sounds TetraCoil this looks feasible to me. Only two relatively simple shaped parts would be needed, a inner segment and an outer segment.
Like what the 18sound AIC static coil in the gap does (at least partly). When it's driven with a scaled copy of the actual VC current it should work even better than with the standard voltage drive, parallel to the VC.
As for the optimum magnet, I think Neodymium is just fine. The only problem is that it is conductive (as is its standard nickel coating) so slicing it up into like 8 segments should help for low eddy current. Looks like almost any shape can be had (provided you can still magnetize it), this would easily allow for a motor without any steel in the magnetic circuit. Especially with a circuit like 18sounds TetraCoil this looks feasible to me. Only two relatively simple shaped parts would be needed, a inner segment and an outer segment.
I don’t think you’ve looked into it.
A few steps further down the road (from the same Inventor).
US1758797A
US1723864A
US2190318A
George
Aww heck, that's an easy question.
Turn it off.😀
Not inconsequential if you have a pacemaker that has a 5 gauss reset function switch. (old guy!!) 😉 we have 5 gauss safety thresholds, and measure stray fields to determine keep out distances for tours.
Jn
😀. Best reply of the week.
On another topic, this interview concerns me MQA: Aliasing, B-Splines, Centers of Gravity | Stereophile.com mainly because certain flat earthers will pick on on 'post-Shannon sampling theory' to claim digital bad!
On another topic, this interview concerns me MQA: Aliasing, B-Splines, Centers of Gravity | Stereophile.com mainly because certain flat earthers will pick on on 'post-Shannon sampling theory' to claim digital bad!
Applying "theory" to this stuff is insulting to the scientific community. What they describe seems little different than the development of MP3. Lets see what what x% of the population can really hear.
That's it...I'm Out | InnerFidelity
I will miss Tyll as he was a good writer with minimal veils and inky blackness. But admire his honesty for accepting that his ears weren't up to the job any more.
I will miss Tyll as he was a good writer with minimal veils and inky blackness. But admire his honesty for accepting that his ears weren't up to the job any more.
Retiring a myth
That's a great story Bill my daughter wants to build a tiny house.
I finally took a phono cart and put a pulsed on and off 200mV rms @1kHz on one channel and watched under a microscope. Nada, naught, nothing, not even a few microns of motion, cartridge motors have virtually zero reciprocity and mechanically "damping" them electronically is not possible.
That's a great story Bill my daughter wants to build a tiny house.
I finally took a phono cart and put a pulsed on and off 200mV rms @1kHz on one channel and watched under a microscope. Nada, naught, nothing, not even a few microns of motion, cartridge motors have virtually zero reciprocity and mechanically "damping" them electronically is not possible.
I was already thinking about putting another voicecoil in the gap and modulating it to either make it a more effective shorting ring or make it do the opposite. Sort of like adding another coil to a CMC and driving it with an opamp to increase the CMC's apparent inductance.
Perhaps the thinner wire in a coil vs a shorting ring would mean less eddy current effects. With a single turn it's near impossible to cancel out a significant portion of the resistance but with a larger coil resistance you can cancel out more and get a higher turns^2/resistance ratio.
Do you think it would be better to drive the coil as a shorting ring or make it do the opposite? I suspect the latter will only worsen eddy currents and increase the effective permeability of the motor assembly, although perhaps you could modulate it in such a way it increases the effective permeability and linearizes the motor at the same time?
Perhaps the thinner wire in a coil vs a shorting ring would mean less eddy current effects. With a single turn it's near impossible to cancel out a significant portion of the resistance but with a larger coil resistance you can cancel out more and get a higher turns^2/resistance ratio.
Do you think it would be better to drive the coil as a shorting ring or make it do the opposite? I suspect the latter will only worsen eddy currents and increase the effective permeability of the motor assembly, although perhaps you could modulate it in such a way it increases the effective permeability and linearizes the motor at the same time?
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