Ah, Mr. Pass, you start it again 😀. You likes to make short comments but meaningfull (if the one who read it understand)
I can understand this
But I don't have a clue about this
If you don't mind, could you add more clue about the later part?
Hi Lumanauw,
I understand the your comments and respect them. But probably I don't write in a comprehensible language.
In connection with the not linearity of the speakers, have not done a "philosophical" comment or of "method" of measure. I have explained my affirmation in way simplified but technical, founding me on the mathematical relationships that are to the base of the study of this models. I invite to deny me with mathematical or analytical reasonings, non philosophicals.
You have touched (in accordance with me) the key of the problem of a lot of "experts"( or seniors ).
You are in degree of shows me the effects that the electric behaviour of a amp has on the "mechanic" behaviour of a SPK without even analysing the dynamicses of a spk?
In accordance with you the studies of "acoustics" and "spsycho-acoustic" that some planners have done am to insert in the category " loudspeakers forum " and "psychology forum " ?
I have read the developments of some planners, but don't understand the connection with the discussions of this forum.
To interest me because the select one is ( or they have to ) is winning, and I perform my experiment to understand it and show it.
Besides you from the for discounted that the problem exists, that the problem is well quantified, and that the results are discounted.
If you reasons so, buy me the Sony TA-N86 and not think more!
In connection with NFB, I have the fortune of has not this type of "paranoias". I have feel optimize sounds come from systems with high NFB and from systems with low NFB ( have not had never the "fortune" to listen "without" NFB systems, but given that the electronics in audio is an opinion I am confident... ).
For me is the contrary thing. This planners are an example in person "tender" to the amp-spk problem, to the point to arrive to study the "mechanics" phenomenona and abdicate to other instrumental performances ( THD & DF ) in the name of a better amps-spks interfacing.
Ciao
Mauro
I understand the your comments and respect them. But probably I don't write in a comprehensible language.
In connection with the not linearity of the speakers, have not done a "philosophical" comment or of "method" of measure. I have explained my affirmation in way simplified but technical, founding me on the mathematical relationships that are to the base of the study of this models. I invite to deny me with mathematical or analytical reasonings, non philosophicals.
You have touched (in accordance with me) the key of the problem of a lot of "experts"( or seniors ).
You are in degree of shows me the effects that the electric behaviour of a amp has on the "mechanic" behaviour of a SPK without even analysing the dynamicses of a spk?
In accordance with you the studies of "acoustics" and "spsycho-acoustic" that some planners have done am to insert in the category " loudspeakers forum " and "psychology forum " ?
I have read the developments of some planners, but don't understand the connection with the discussions of this forum.
To interest me because the select one is ( or they have to ) is winning, and I perform my experiment to understand it and show it.
Besides you from the for discounted that the problem exists, that the problem is well quantified, and that the results are discounted.
If you reasons so, buy me the Sony TA-N86 and not think more!
In connection with NFB, I have the fortune of has not this type of "paranoias". I have feel optimize sounds come from systems with high NFB and from systems with low NFB ( have not had never the "fortune" to listen "without" NFB systems, but given that the electronics in audio is an opinion I am confident... ).
For me is the contrary thing. This planners are an example in person "tender" to the amp-spk problem, to the point to arrive to study the "mechanics" phenomenona and abdicate to other instrumental performances ( THD & DF ) in the name of a better amps-spks interfacing.
Ciao
Mauro
Hi guys
as another thread seems to pass away slowly... in case you didn't notice:
http://www.diyaudio.com/forums/showthread.php?postid=678314#post678314
as another thread seems to pass away slowly... in case you didn't notice:
http://www.diyaudio.com/forums/showthread.php?postid=678314#post678314
Hi, Mauro,
I really found your work interesting, but since English is not my daily language, I have difficulties understanding your important findings. Like post #396, I wanted to write that I think what you wrote there is important, but I have difficulties understanding them. I didn't write that, because I'm afraid I would offended you.
Sometimes you feel that nobody take attention to your findings, and you wanted to stop. When you still have the spirit to explore this, please continue, because you know what you are doing and how to do it (I don't).
I really found your work interesting, but since English is not my daily language, I have difficulties understanding your important findings. Like post #396, I wanted to write that I think what you wrote there is important, but I have difficulties understanding them. I didn't write that, because I'm afraid I would offended you.
Sometimes you feel that nobody take attention to your findings, and you wanted to stop. When you still have the spirit to explore this, please continue, because you know what you are doing and how to do it (I don't).
All the discussions on this argue, even that more "warm" as some my questions and answerses with Jan and other, never don't consider it offensives in my comparisons ( and I hope that it is the same thing for my interlocutors!).
I believe that (within certain limits) is correct to defend in way " strongly " her really convictions.
My words on the "language" are always a "self-criticism", because rarely it succeeds to write of the concepts grammatically corrected.
The rest is a matter of stimuluses; Without your Thread, you would not have made curious me on this matter. Without the seem un other members ( even the more "bad") have not " as amended " my test...
Ciao
Mauro
I believe that (within certain limits) is correct to defend in way " strongly " her really convictions.
My words on the "language" are always a "self-criticism", because rarely it succeeds to write of the concepts grammatically corrected.
The rest is a matter of stimuluses; Without your Thread, you would not have made curious me on this matter. Without the seem un other members ( even the more "bad") have not " as amended " my test...
Ciao
Mauro
Voltage vs. current mode drive.
Several posts back (or was it on the other thread?), I remarked I liked voltage mode drive better and vowed to post my view though making room for other's convictions in between.
In between came the link to Hawkford's paper about the benefits and tradeoffs with current drive, and Nelson Pass's remark about the relationship among sound pressure and cone acceleration, which he links with force and thus with current.
With respect to Mr. Hawksford paper, it was clear there was a problem at the low end because of undesirable effective Q, to be corrected with either equalization or with motional feedback.
The issue of electromechanical distortion due to variations in driver "constants" with position and how it improves with current mode drive, I at least am not fully convinced there is a solid link.
With respect to the sound pressure-acceleration relationship, as I remarked previously it happens to exist because of the on-axis far field response that results proportional to frequency times piston velocity. As said this does not imply the causative agent is cone acceleration.
Even if that were the case - which I suspect not - neither is correct to associate acceleration with force and thus with current.
Acceleration is proportional to force through mass, **only if mass is the single mechanical reaction **. Of course this is not the case, for there are the elastic restoring forces from air loading and suspension. Elastic forces are proportional to displacement, meaning that at best are proportional to double integration of acceleration.
I am not aware at this time of a realistic electromechanical coupling model. This coupling in a practical case is a very complex phenomenom and my hunch is it can eventually (probably has been) solved by numerical methods (finite element model) where not only the actual geometries but also boundary layer effects due to viscosity are included. At least in aerodynamics, this usually neglected because of analytical intractability issues have proved to be extremelly significant.
Given the above scenario, I bet for cone velocity control, which is achieved matching as closely as possible what has been baptized here as "back EMF" with the desired signal.
The implication then is to have the lowest achievable output impedance, implying among other things to avoid passive crossover networks and go bi/tri amplification (and reap additional benefits to boot, including cost).
Going for voltage (velocity) mode, the only nonlinear impedances in the speaker model are the voice coil inductance and resistance, implying in both cases best results are obtained with a working regime far below driver maximum ratings. Note that excursion dependent variations are an issue only at low frequencies where it is significant.
Rodolfo
Several posts back (or was it on the other thread?), I remarked I liked voltage mode drive better and vowed to post my view though making room for other's convictions in between.
In between came the link to Hawkford's paper about the benefits and tradeoffs with current drive, and Nelson Pass's remark about the relationship among sound pressure and cone acceleration, which he links with force and thus with current.
With respect to Mr. Hawksford paper, it was clear there was a problem at the low end because of undesirable effective Q, to be corrected with either equalization or with motional feedback.
The issue of electromechanical distortion due to variations in driver "constants" with position and how it improves with current mode drive, I at least am not fully convinced there is a solid link.
With respect to the sound pressure-acceleration relationship, as I remarked previously it happens to exist because of the on-axis far field response that results proportional to frequency times piston velocity. As said this does not imply the causative agent is cone acceleration.
Even if that were the case - which I suspect not - neither is correct to associate acceleration with force and thus with current.
Acceleration is proportional to force through mass, **only if mass is the single mechanical reaction **. Of course this is not the case, for there are the elastic restoring forces from air loading and suspension. Elastic forces are proportional to displacement, meaning that at best are proportional to double integration of acceleration.
I am not aware at this time of a realistic electromechanical coupling model. This coupling in a practical case is a very complex phenomenom and my hunch is it can eventually (probably has been) solved by numerical methods (finite element model) where not only the actual geometries but also boundary layer effects due to viscosity are included. At least in aerodynamics, this usually neglected because of analytical intractability issues have proved to be extremelly significant.
Given the above scenario, I bet for cone velocity control, which is achieved matching as closely as possible what has been baptized here as "back EMF" with the desired signal.
The implication then is to have the lowest achievable output impedance, implying among other things to avoid passive crossover networks and go bi/tri amplification (and reap additional benefits to boot, including cost).
Going for voltage (velocity) mode, the only nonlinear impedances in the speaker model are the voice coil inductance and resistance, implying in both cases best results are obtained with a working regime far below driver maximum ratings. Note that excursion dependent variations are an issue only at low frequencies where it is significant.
Rodolfo
Hi Rodolfo,
your synthesis is excellent and share it.
In this period am continually "outdated" from the post and simulations of some members, that me induce to move my attention on analysis more "practices" that theoretical. My curiosity in the ffts that ( in part ) I shown you is concentrated in this doubts:
- We know that the voltage driver inserts in the transfer function the variables that increase the THD ( and IMD ) ( O.J.Hawksford J14pdf ref.) The evidences of this theories find in the thds of the current ffts , that diminish to the increase of the Zout of the amp. If us linearized the current, us linearized even the "dynamic" behaviour of the SPK ( within certain limits ). We know that a driver of "pure" current is not practicable on systems to full band and without specific equalizations.
With my measures it shows that even exist condition it "half-way" (low DF). In this cases, is demonstrable that the thds of the current are in inverse relation to the external DF (amp). Other non very considered important point is to advantage of the Graham theories; If the damping of the amp is not linear ( not in phase with the back_EMF ), the aftermathes on the spk current it is able increase much the THDS and IMD ( in voltage drive mode ).
- Other my idea is the study of the " current modulations " that a NFB system with high Zout OL performs, in the conditions that have described. ( NFB sees the voltage back_EMF and elaborates it, modulating the output current), it linearized or worsens the thds of spk?)
ciao
Mauro
your synthesis is excellent and share it.
In this period am continually "outdated" from the post and simulations of some members, that me induce to move my attention on analysis more "practices" that theoretical. My curiosity in the ffts that ( in part ) I shown you is concentrated in this doubts:
- We know that the voltage driver inserts in the transfer function the variables that increase the THD ( and IMD ) ( O.J.Hawksford J14pdf ref.) The evidences of this theories find in the thds of the current ffts , that diminish to the increase of the Zout of the amp. If us linearized the current, us linearized even the "dynamic" behaviour of the SPK ( within certain limits ). We know that a driver of "pure" current is not practicable on systems to full band and without specific equalizations.
With my measures it shows that even exist condition it "half-way" (low DF). In this cases, is demonstrable that the thds of the current are in inverse relation to the external DF (amp). Other non very considered important point is to advantage of the Graham theories; If the damping of the amp is not linear ( not in phase with the back_EMF ), the aftermathes on the spk current it is able increase much the THDS and IMD ( in voltage drive mode ).
- Other my idea is the study of the " current modulations " that a NFB system with high Zout OL performs, in the conditions that have described. ( NFB sees the voltage back_EMF and elaborates it, modulating the output current), it linearized or worsens the thds of spk?)
ciao
Mauro
mauropenasa said:
Hello Mauro,
Maybe it is usefull to recall that the best performer in the Hiraga graphs was the 20+ year old SONY TA-N86, a plain vanilla, standard, high feedback type amplifier.
Jan Didden
lumanauw said:
Hi David,
Is ther anybody that can explain the 'interaction problem'? I read a lot about it, ideas, proposals, but what actually is the problem?
The Hiraga article, for example, that is the basis for this thread, shows that the best performer when tested with impressed output signal simulating back-EMF (I just use the term here as is done by others), is a very standard, high feedback, 20+ year old mass produced amp. I mean, WHAT IS THE PROBLEM?
Jan Didden
Re: Voltage vs. current mode drive.
That's the unavoidable result of just current driving a speaker - the Qts of the driver becomes equal to the Qms and there will be a bass bump...🙁
ingrast said:
That's the unavoidable result of just current driving a speaker - the Qts of the driver becomes equal to the Qms and there will be a bass bump...🙁
Hello,Jan
Any idea of the general topology of this amp? 3 gain stages, bootstrap, whatever?
Thanks,
janneman said:
Any idea of the general topology of this amp? 3 gain stages, bootstrap, whatever?
Thanks,
Hi, Janneman,
I don't know, there is something different when hearing a non feedback and feedback amp. I cannot explain in words or provide you the difference in technical measurement, but there is something different in the sound. What is it? What do you think the major difference between those 2?
Janneman is generous enough putting the schematic of this amp in former pages. You can search in this thread.
lumanauw said:
Of course there is! The changes in frequency response resulting from low of very low damping alone are massive. The distortion spectrum and ratio is also quite different. All differences that can be readily measured and documented. You really must be deaf if you would not hear that, even I hear it with my wooden ears!😀
Jan Didden
lumanauw said:
And here is the root for the vast majority of argments in audio!
You like A, I like B, so B must be better than A - ot the other way around!
Thanks a lot!
The SONY TA-N86
This amp fared the best in Interface distortion tests according to posts above.
But it seems it was not a very good sounding one...
From the schematic Jan posted:
Lots of NFB (4 stages of amplification!), so, this ends for true the mith that NFB is bad for interface distortion, AKA 'Back EMF'.
Low open loop output impedance (triple EF stage), what's good in accordance to theory.
And then why it was not a good sounding one?
It is from the time Japanese mfgr strived to the widest possible freq response and lowest possible distortion number, sacrifiying all else (read stability, phase margin) for it.
I've heard about berillium tweeters been destroyed due to oscilations in Japanese amps of this generation!:
This amp fared the best in Interface distortion tests according to posts above.
But it seems it was not a very good sounding one...
From the schematic Jan posted:
Lots of NFB (4 stages of amplification!), so, this ends for true the mith that NFB is bad for interface distortion, AKA 'Back EMF'.
Low open loop output impedance (triple EF stage), what's good in accordance to theory.
And then why it was not a good sounding one?
It is from the time Japanese mfgr strived to the widest possible freq response and lowest possible distortion number, sacrifiying all else (read stability, phase margin) for it.
I've heard about berillium tweeters been destroyed due to oscilations in Japanese amps of this generation!:
andy_c said:
Andy,
This is what Oliver said in his paper, "Distortion in Complementary-Pair Class-B Amplifiers", in Hewlett-Packard Journal, vol 22, no. 6, p. 11-16, Feb 1971.
He was looking for an optimum value of output emitter resistor. He stated "To find an optimum R, we need only minimize the variation in output resistance with signal current."
He calculated an optimum bias of between 13 to 26 millvolts across each resistance.
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