Of course. We were talking "at the same measured flux". That's the point.
A friend of mine leaving in Japan always does this. And I agree with you that the variable flux is a great advantage... But it's not the reason why...
Listening evaluation? Taste? No matter for you?
Just to understand your position.
I thought that the purpose of all this effort is to listen to Music.
Am I wrong?
Gosh then how about helping the rest of the people on here at least? I asked nicely......oh well.
I always find when training engineers it's better they work out the answers. The support burden is unmanageable otherwise, or they're downsized. Enjoy the journey.
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I have an AP too. What have you in your lab? Which "secrets" did you discover about WHYs? Do you want to share with us?
Not that easy, otherwise we had ONE amplifier, ONE loudspeaker, ONE...
True Scientific method seems to be hostile to you. It seems that for you it's easier to comment other's results-opinions. I see no positive attitude here.
But it is so easy... No mumbo jumbo. You have a theory, I suppose. I do.
So the next step is to try. From the results we must check the difference between what's expected and the results. We change the theory if needed and we try again. Everything must be done in a repeatable way.
Ops, the result is subjective... It's a matter of taste...
Maybe this is the reason you don't need to try...
So enjoy your favourite Music first. Be relaxed.
I do it right now... A great SACD from Divox (Vivaldi).
*sigh* I see your broken record is still stuck on "try"
I'm NOT the one making subjective claims with no data to back it up so how about YOU do the trying for once and supply some? You have a warped image of what the "scientific method" is
I didn't realize a "positive image" was necessary for true scientific debate and results. Maybe I should get out some magic crystals too and do some chanting......honestly I do TRY to see your points bur frankly it's mostly avoiding any real data.
Listening evaluation? Taste? No matter for you?
Just to understand your position.
I thought that the purpose of all this effort is to listen to Music.
Am I wrong?
I have no problem with listening evaluations if they are fairly done. What were yours? How closely matched where your field coil and PM comparisons? Even a dB difference would slant the comparison in the favor of the louder units. Were the test done in a blind manner? Lots of expectation bias in this subject, so knowing which unit was field coil would color the results.
Who else here has carried out a fair comparison? Who else has heard the field coil units at all? My impression was that an early poster said: "Yeah, field coils sound great" and everybody else jumped on board.
My preference is for measurements because my instruments have no bias. Show me some definitive distortion curves and I will believe the differences.
Without definitive measurable differences, what magic would you expect to be the cause of field coil superiority??
David S.
In two circumstances in which their sound impressed me, I didn't know the speakers were field coils. In one of those I didn't even know what field coils were, only learning about them later by digging through the manufacturer's manual for clues to what caught my ear about an old, broken, paint chipped cabinet at a transmitter site. It was also my introduction to RCA speakers long before either had 'cred'. Since in my regular work day I was, and still am, daily exposed to all manner of studio monitoring it was an unexpected reaction, though someone will probably try to make a case of precognitive expectation bias 30 years back loaded.
I never heard FC but I assume there's no fear in accepting what ever technical measurements may arise afterwards, in relation to quality of their output. It's only a matter of finding or reporting the differences, this is assuming they are different. Doesn't mean they are better or worse. Let's assume they are better for some,listeners very well represented in this thread. Two things can happen.I was just going to suggest that but...
I have no problem with people claiming that they heard a field coil system and loved it, as you are saying. I just don't believe the leap to "therefore field coils are superior" (as others are saying) is justifiable.
David
1. Field Coils have more distortion/harmonics > They are more musical
2. Field Coils have less distortion/harmonics > They are more musical
No the #3 is not "If they are more musical they are better" but could be. It's a variety of details that can influence (you have in mind that the distortion in tubes is more musical because they are of the type of even harmonics) the final result.
The Well-Tempered Computer
Podcast 98: Sean Olive | Home Theater
The differences must be in the gap flux, and how it changes when the voice coils are driven. The VC AC field must affect the magnet field, and differently for the two types of field magnets. If one is more constant then the other it might be audible.
Right, the current needs to stay constant for a constant field. But how much effect does the voice coil AC field have on the field coil? It must have some (the 2 coils form a transformer sorta). Then the FC current supply has to adjust for this back EMF right up to 20khz.It would be nice to know how hard the FC supply has to work. For those doing the measurements, can you scope the AC voltage on the FC supply while driving the voice coil (and the current, should show how constant the field is)? Is it negligible?
Right, the current needs to stay constant for a constant field. But how much effect does the voice coil AC field have on the field coil? It must have some (the 2 coils form a transformer sorta). Then the FC current supply has to adjust for this back EMF right up to 20khz.It would be nice to know how hard the FC supply has to work. For those doing the measurements, can you scope the AC voltage on the FC supply while driving the voice coil (and the current, should show how constant the field is)? Is it negligible?
I have no problem with people speaking of thing they never tried, on the contrary...
If you compare "the same" loudspeaker before and after the conversion, you can judge yourself. The rest is just tedious controversy.
I wait for news from Joe. I'll be back after the conversion of my personal pair of 515B.
It sounds very good. That's my point of view. And it is what Japanese friends told me after many years of testing and listening. Such a PSU sounds much better. I never measured them because I never had the chance in my lab.
I'll have in 2012 yet...
I think you are assuming that a stiff power supply can make up, with current, the variation in operating point that an applied AC signal may cause. This won't be the case. Even though a low impedance supply might be used any current variation has to go through the impedance of the field coil. Its inherent high inductance and DCR will be a high impedance to change.
Its a bit like a low impedance amplifier feeding a woofer (voice coil). Even if the amplifier source impedance is zero, the DCR limits how high the amplifier damping can be.
In addition, just having a somewhat soft magnetic set point is not an issue unless nonlinearity is involved. Without it, the variation from the AC just slightly diminishes sensitivity.
David S.
I think the notion of resisting the AC change to the DC (operating point) flux conditions is correct, but I don't think you can achieve it. Constant current helps with slow variation, such as FC DCR changing as it warms up, I don't think it combats the AC variation.
The way I would look at it is that your AC signal is added on top of the fixed flux (which is proportional to ampere turns). I think you want a low impedance to resist the externaly applied (through the voice coil, not through the field coil supply) flux variation. Unfortunatly, the high impedance of the field coil means you can't short out that applied AC, even with a stiff external supply.
What is desired is much like the flux stabilising shorted aluminum rings in the better ferrite structure. Because they are a short to magnetic variation they prevent it from happening at audio frequencies.
Thats my understanding, at least.
Of course it is only conjecture that field coils are any better in terms of operating point stability, and as I have mentioned, a soft operating point is not a problem unless significant hysteresis is associated with it.
David S.
Exactly what I've been complaining about. No need to "crow" about it.
Tests are great, listening or measurement. I don't understand the objections to A/B testing an FC and PM driver. If you like the FC better, wouldn't it be nice to know how much better you like it, and why? A simple A/B listening test could do that. If it's a level controlled, blind test, then you'll have a nice data point to brag about.
I agree with almost all of that. A constant current source will work at audio freq (they do in amplifiers). The question would be: what kind of band width and how much voltage do they need to source to keep the current constant in a big inductor for large voice coil currents? Thats why I was asking for someone with a FC driver to measure the AC voltage, and current.
I'll get around to it when I convert this pair of Altec 2 inch CDs I have laying in my storage unit. Can't remember the number off them… 292-A? They have the phenolic diaphragms, I was looking for replacements for them, though the originals seem to work, it would be nice to start with fresh domes… As I recall, one of them has a weak magnet, so it is a natural candidate for conversion. I just have no idea where to begin. Do I just make a sleeve bobbin to fit and start winding an arbitrary gauge wire until its full, or does someone know what weight conductor will give the optimal result?
This was this member last post (#25) after a problem in this forum with a member/moderator that was not politically correct. Ask him.
That was a confusing response… I assume you are referring to Audiofilonline, from the above post he sounds a bit closed minded- not exactly something conducive to open experimentation and knowledge building.
The way you assembled your last post almost makes it look as if you are suggesting that I am an alias of audiophilonline. You really don't need to quote in your post if there are none following…
The way you assembled your last post almost makes it look as if you are suggesting that I am an alias of audiophilonline. You really don't need to quote in your post if there are none following…
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