I would like to say that while these efforts here are laudable, you are barking up the wrong tree. First, even I would not criticize 0.7uH. Maybe, it would be useful with many feedback circuits, but it is the 2uH or MORE that I am concerned about. Just TRY it in an open A-B test with good audio playback equipment, and a power amp that doesn't really need the coil to keep from oscillating. Just listen to the coil with perhaps a 10 ohm resistor in parallel. Just listen, and quit overanalyzing what something should sound like or not in a circuit. This is the difference between the instructors and the sophomores.
John,
As so many times, you don't listen to others. Your comment is OT. We were talking about ill designed Zobel networks (i.e. a wrong topology), and NOT whether you can hear a 0.7uH vs a 2uH coil.
As so many times, you don't listen to others. Your comment is OT. We were talking about ill designed Zobel networks (i.e. a wrong topology), and NOT whether you can hear a 0.7uH vs a 2uH coil.
Now that the smoke has cleared "cough! cough!", I would like to thank again all those who contributed to this highly spirited discussion. Yes, traderbam did a great job of summarising the answers to the fundemental question about the output inductor.
I did a review of several amplifier circuits and I found that the following amplifers do not have any inductor circuit: Parasound HCA-2200II, McCormack DNA-2, Nakamichi PA-7, Adcom GFA-545, and Krell KSA-100 Mk II. In contrast I found the following Japanese and British amplfiers were using inductors: Sony TA-N77ES, Onkyo P-508, Audio Lab 8000A, Denon POA-6600. All of the amplifiers BTW had the RC series network for RF filtering. This is the Zobel network I believe. I can only conclude that one group of designers must be doing something right that do not require the output inductor.
This begs another question: Do you put the RC series circuit before or after the inductor-resistor circuit? I have seen it done both ways.
I did a review of several amplifier circuits and I found that the following amplifers do not have any inductor circuit: Parasound HCA-2200II, McCormack DNA-2, Nakamichi PA-7, Adcom GFA-545, and Krell KSA-100 Mk II. In contrast I found the following Japanese and British amplfiers were using inductors: Sony TA-N77ES, Onkyo P-508, Audio Lab 8000A, Denon POA-6600. All of the amplifiers BTW had the RC series network for RF filtering. This is the Zobel network I believe. I can only conclude that one group of designers must be doing something right that do not require the output inductor.
This begs another question: Do you put the RC series circuit before or after the inductor-resistor circuit? I have seen it done both ways.
john curl said:
And while you are at it you should toss out your tweeters as well 😉 That voice coil inductance is really having a profound effect on the sound and there is not a lot you can do about it 😉
Audax HD12x9D25 Soft Dome Tweeter
Lvc = 75uH 😱
You must listen first and foremost. If you will not listen, then why bother arguing whether a coil is audible or not? I personally went through the computation and measurement of what most of you are now doing, over 30 years ago. I, too, found no measurable problem, but later, I found an audible problem. How many times do we have to go over this?
john curl said:
I guess until you or someone else demonstrates conclusively that there in fact is an actual audible difference, instead of simply asserting your subjective perceptions as objective reality.
se
How can we 'prove' that we have heard a difference? And, who cares? By the way, Steve Eddy does or has sold an expensive connecting cable that he claims sounds good to him, but offers no measurements to 'prove' anything about it. It sounds to me like the pot calling the kettle, 'black'. (an old proverb)
john curl said:
John, consider these scenarios.
You have a SS audio amplifier with a load stabilizing network consisting of a parallel combination of some L and R. Lets say 2uH in parallel with 10 ohms etc. You then decide to use that amp in an active speaker system and use it to drive a tweeter directly which has 75uH of voice coil inductance. Do you mean to tell me that you are really going to notice a lot of difference with and without the load stabilizing network installed ?? If you are please explain why ??
Alternatively consider your typically valve amplifier with large output transformer and most likely a large amount of leakage inductance and high output impedance compared to its SS counterpart !!! From what you are saying people who use these amps are doing themselves a disservice and compromising their listening experience because of this large amount of series inductance 🙁
I think they have different purpose. Before L, the RC is for loading the amp at HF, so the amp is stable without speaker load attached.
After L, the purpose is to equalize the speaker load to look as close as resistive.
snoopy said:
My dear Snoopy,
Apparently, you have missed John's explanation. It's the position of the coil that matters. Inside the speaker box, no problem at all, but inside the amplifier's cabinet, it shows its true nature. Why? Simply because inside or near the tweeters magnet, the electrons are sonically aligned and the greater the distance to that magnet the greater the disorder of the electrons in the coil. You get it? (I don't)
Cheers,
Edmond.
What I am trying to say is that coils have been shown to not be necessary with many audio power amplifiers that have been designed to not need the coil. Please remember that the loudspeaker tweeter, for example is a MOVING coil and the amplifier coil is a FIXED coil. Does this make the difference? I don't really know, but it IS a difference.
I might say that what first concerned me was the doubling of the coil inductance with bridged operation. For many years, before I worked for Parasound, all my big power amps were bridged designs. This doubled the coil inductance seen by the loudspeaker, and this worried me. Still, for many years, I used 1-2uH output coils, faithfully, but then a friend and audiophile showed me that the coils could be audible, and since then I have tried to eliminate them, if possible.
Parasound engineers in Taiwan agreed with this approach, and we just lose some maximum slew rate, reducing it down to something like 100V/us instead of 300V/us or so. Big deal.
I might say that along with Julian Vereker of Naim, Nelson Pass started removing the output coil about 30 years ago, at least I think so; and Charles Hansen would not add an output coil for any reason. Why don't you look at people who have A ratings in power amps in 'Stereophile' over the last few years, and realize that we independently came up with 'losing' the coil, if possible, to get the best sound.
I might say that what first concerned me was the doubling of the coil inductance with bridged operation. For many years, before I worked for Parasound, all my big power amps were bridged designs. This doubled the coil inductance seen by the loudspeaker, and this worried me. Still, for many years, I used 1-2uH output coils, faithfully, but then a friend and audiophile showed me that the coils could be audible, and since then I have tried to eliminate them, if possible.
Parasound engineers in Taiwan agreed with this approach, and we just lose some maximum slew rate, reducing it down to something like 100V/us instead of 300V/us or so. Big deal.
I might say that along with Julian Vereker of Naim, Nelson Pass started removing the output coil about 30 years ago, at least I think so; and Charles Hansen would not add an output coil for any reason. Why don't you look at people who have A ratings in power amps in 'Stereophile' over the last few years, and realize that we independently came up with 'losing' the coil, if possible, to get the best sound.
john curl said:
By controlling for the ambiguity of human beings being known to subjectively perceive differences even when there are no actual audible differences by means other than ego and vanity.
Anyone who makes claims of actual audibility and who expects to be taken seriously should care. If you don't care, then don't expect to be taken seriously or to have your claims accepted without question.
Not at all. The problem is your continued inability to grasp some rather simple concepts.
Yes, I sell cables which I have claimed sound good to me. But the distinction here is that is all that I claim.
Do they sound good to me because of any actual audible differences? Or do they sound better to me for purely psychological reasons?
I don't know. I've never done any listening tests which control for the ambiguity of human beings being known to subjectively perceive differences even when there are no actual audible differences.
And not knowing, I don't make any claims to the contrary. And further, I'm fully prepared to accept the possibility that what differences I perceive may well be purely psychological. That possibility simply doesn't threaten my ego the way it seems to threaten the egos of others.
se
john curl said:
Which at the end of the day proves absolutely nothing with regard to actual audibility.
se
john curl said:
And the coils of the cross-over filter? Are they MOVING too, so they can't do any harm?
john curl said:
John for a moving coil loudspeaker the inductance stays fairly constant and only deviates around a nominal value due to the voice coil moving in and out of the gap.
The point I am trying to make here is that there are other dominant sources of series inductance so removing the load stabilizing network for the sake of purity maybe a bit short sited.
Hi Snoopy,
You better give up. You will never get a straight answer when putting tough questions.
Cheers,
Edmond.
You better give up. You will never get a straight answer when putting tough questions.
Cheers,
Edmond.