Field Coils for Audio Systems

morricab

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Lagonda

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Nice OTL kit you got there!
Carlos has nice gear laying around everywhere, Cello, Nakamichi rare tube gear. Love the collection ! :)
 

TooCool4

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Yes, it is the three piece Nakamichi 1000 system, which is comprised of a DAT transport, CD transport and a DAC chassis. It is part of my Accuphase, Micro-Seiki, Klyne, eXD DSD DAC and Tannoy mastering DMT mk-II monitors system.
Very nice. :cool:
 

AMR / iFi audio

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After a few setbacks, including a bad Harrison DC power supply, my Supravox 215 2000-EXC field-coil based system is finally up and playing music:

View attachment 81725

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I will be posting the details of the new system, listening impressions and comparisons videos on my Friday night listening thread.
The collection looks really impressive. It seems that you could easily build a few listening rooms with your gear. How long did it take you to collect all of them?
 

Carlos269

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Mar 21, 2012
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Must have been interesting 35 years. Throughout your entire audio career which set-up are you the most sentimental about?

Not ignoring your question, just very difficult to answer with so many great systems over the years and so many very special pieces of equipment. I am tremendously enjoying each and every one of my systems. In the early days, when I was in pursuit of the mythical “Absolute Sound”, there was less enjoyment as every listening session was a critical one, listening for audiophile attributes (soundstage width/depth, image delineation, details resolution, black backgrounds, bass depth, micro dynamics and so on) but once I saw the light, it has become all about enjoying the music and the different flavors in presentation and tone that each system delivers.

To try to answer your question more directly, the one significant system that altered my outlook is my big mastering system, as it allowed me to explore and gave me first hand experience in that all audiophile attributes can simply be dialed in with the right equipment and insight into just how powerful the mastering tools are. At the end of the day it is all just about frequency, amplitude, phase, and surprisingly distortion.

Many unique and one of a kind pieces of equipment have come into my listening room, and most have never left, too many to name and they all come to mind all at once so it is hard and very difficult for me to order them in any type of hierarchy or emotional priority list. Some of the most notable components in my collection are well documented in my Friday night listening thread, while others such as the one-of-a-kind Krell KRS-400 monoblocks amplifiers can be seen in the pictures but have not yet been discussed. I like equipment that is unique and that no one else has, and that keeps me away from the “me too“ and “flavor of the months” brands and components that come AND go on this and other forums. Never been a bandwagon type person in my choice of music, stereo equipment, cars or personality.
 

AMR / iFi audio

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Thanks for sharing your thoughts. You have touched upon a important, and yet underdiscussed topic. I have observed (also on myself) that the pursuit of the mythical “Absolute Sound” can be very frustrating and may take the joy away.

I think the unique-one-of-a-kind equipment is the most inspiring sort of audio gear, because you can tailor all the factors to your needs, and secondly, there will always be only one type of your setup.
 

cal3713

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Not ignoring your question, just very difficult to answer with so many great systems over the years and so many very special pieces of equipment. I am tremendously enjoying each and every one of my systems. In the early days, when I was in pursuit of the mythical “Absolute Sound”, there was less enjoyment as every listening session was a critical one, listening for audiophile attributes (soundstage width/depth, image delineation, details resolution, black backgrounds, bass depth, micro dynamics and so on) but once I saw the light, it has become all about enjoying the music and the different flavors in presentation and tone that each system delivers.

To try to answer your question more directly, the one significant system that altered my outlook is my big mastering system, as it allowed me to explore and gave me first hand experience in that all audiophile attributes can simply be dialed in with the right equipment and insight into just how powerful the mastering tools are. At the end of the day it is all just about frequency, amplitude, phase, and surprisingly distortion.

Many unique and one of a kind pieces of equipment have come into my listening room, and most have never left, too many to name and they all come to mind all at once so it is hard and very difficult for me to order them in any type of hierarchy or emotional priority list. Some of the most notable components in my collection are well documented in my Friday night listening thread, while others such as the one-of-a-kind Krell KRS-400 monoblocks amplifiers can be seen in the pictures but have not yet been discussed. I like equipment that is unique and that no one else has, and that keeps me away from the “me too“ and “flavor of the months” brands and components that come AND go on this and other forums. Never been a bandwagon type person in my choice of music, stereo equipment, cars or personality.
If you had to sell it all but could keep a source, pre, amp, & speaker, what would they be?

Would you be willing to play that game?
 
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DetroitVinylRob

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A little side bar please, as this subject is a somewhat rare niche within a very small community.

This is such a great conversation and with some who have far more DIY experience than I do, and with field coil implementation specifically.

My consideration is whether we need to be concerned with utilizing shielded cables between our power supplies and the field coils? Like a good AC power cord can offer a surprising improvement. I’m curious if any of you has experience with noise entering the chain through these connections? Noise being such a precarious thing, we often don’t even realize our kits are being infiltrated until we actually try a technique or technology that reduces the unwanted guests presence and then we instantly HEAR the result of it’s absence.

Any thoughts?
 
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Atmasphere

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My consideration is whether we need to be concerned with utilizing shielded cables between our power supplies and the field coils? Like a good AC power cord can offer a surprising improvement. I’m curious if any of you has experience with noise entering the chain through these connections? Noise being such a precarious thing, we often don’t even realize our kits are being infiltrated until we actually try a technique or technology that reduces the unwanted guests presence and then we instantly HEAR the result of it’s absence.
Its hard to imagine how that would make a difference, since there is low noise DC on the cable for the field coil, while a power cord has AC on it. But to be fair I've not tried it- never even thought about it.
 

DetroitVinylRob

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Thank you Ralph for commenting. A pair of modest Venom V12 NR power cords from the mains to the DC power supplies did yielded a nice improvement from the AC side, so I was just curious if the DC end would also benefit from some particular wire solution.
 

MarcelNL

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I'd suggest to try twisting and shielding the wire, it's long enough to pick up crud..
 

dcathro

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I always find unshielded cables to sound more dynamic, less constrained.
 

MarcelNL

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I always find unshielded cables to sound more dynamic, less constrained.
It depends on what shielding IME, the usual shielding as typically found IN the cable affects the sound IMO.
 
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Zeotrope

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Most power supplies sag less than permanent magnets IME, but if you want to really hear what field coils do a regulated supply is the way to do it. There's a sizable contingent that like the old Tungar bulbs for rectifiers, but if you are regulating then the kind of rectifier used isn't going to make any difference except that you will need more overhead in your design if Tungars are used.

I like the extra speed that field coil speakers are able to exhibit. You really don't want to go back after that. I regard them as similar to ESLs in that regard, but of course they are lot easier to drive. My amps at home only make 50 watts and I can't overload them in my space.
Actually, an Un-regulated supply is the best way to power field coils. There’s some content online about this, but the gist is that current is what energizes the magnet and therefore current is what you need to keep constant. You do not want voltage regulation at all.
I powered my two field coil drivers with constant voltage lab supplies for years, before I upgraded to a proper constant current supply. The difference was HUGE - could not believe it!
Keep in mind there is interaction between the “amp” powering the field coils and the audio amp. With a constant voltage field coil supply, it‘s “fighting” with the audio amp…
 

adrianywu

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Actually, an Un-regulated supply is the best way to power field coils. There’s some content online about this, but the gist is that current is what energizes the magnet and therefore current is what you need to keep constant. You do not want voltage regulation at all.
I powered my two field coil drivers with constant voltage lab supplies for years, before I upgraded to a proper constant current supply. The difference was HUGE - could not believe it!
Keep in mind there is interaction between the “amp” powering the field coils and the audio amp. With a constant voltage field coil supply, it‘s “fighting” with the audio amp…
Voltage is what is usually quoted for the field coil drivers. For my drivers, each draws a different current with the same voltage. Should we then be supplying each driver with the same current instead ?
 
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Zeotrope

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Voltage is what is usually quoted for the field coil drivers. For my drivers, each draws a different current with the same voltage. Should we then be supplying each driver with the same current instead ?
Yes, you want to match the current to each driver (L and R channels). The current is what creates the magnetic field. If the current is different, it means the resistance of the coils is not the same; but it’s not a big deal. Just connect an ammeter in series and adjust the voltage so that the current matches each driver, once the coils are hot (a few hours).
 

tima

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Actually, an Un-regulated supply is the best way to power field coils. There’s some content online about this, but the gist is that current is what energizes the magnet and therefore current is what you need to keep constant.

Do you happen to have an online reference for this? Thx
 
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