Hi Bear,
looks interesting....
http://www.bearlabs.com/NEXT/SYMPHONY.html
Perhaps you might enlighten us further in respect of your design philosophy...shematics...etc....?
looks interesting....
http://www.bearlabs.com/NEXT/SYMPHONY.html
Perhaps you might enlighten us further in respect of your design philosophy...shematics...etc....?
After '2,5K VA' and 'half farad' I decided not to spend my time reading further... My mains line peak voltage drops by nearly 25% when loaded with 2,5KW of rectified DC load [about 15KW peak power consumption!!]
People should stop wasting their money in 2K VA toroidal transfoemers and huge capacitors and build regulated SMPS [or linear regulators]. There is no other way to get good regulation since mains line itself is pretty unregulated
Active PFC is also a very interesting option since it reduces peak mains current consumption by up to 70%. It appears as a pure resistive load to mains, produces almost pure 100Hz ripple on its output [much less harmonics than standard rectification] and provides less than half the peak to peak ripple voltage with the same filter capacitance. And it offers average output regulation against mains fluctuations too
People should stop wasting their money in 2K VA toroidal transfoemers and huge capacitors and build regulated SMPS [or linear regulators]. There is no other way to get good regulation since mains line itself is pretty unregulated
Active PFC is also a very interesting option since it reduces peak mains current consumption by up to 70%. It appears as a pure resistive load to mains, produces almost pure 100Hz ripple on its output [much less harmonics than standard rectification] and provides less than half the peak to peak ripple voltage with the same filter capacitance. And it offers average output regulation against mains fluctuations too
In order for a pi filter to not resonate at audio frequencies, capacitor ESR / inductor DCR / capacitance values should be big
Further increasing inductor value in order to get a low enough cutoff causes the DCR/ESR/capacitance values required to tame the resulting third order resonant system to be huge
So pi filters damp ripple and reduce peak mains current value but allways at the expense of additional voltage drop on its output [ie: worse regulation] or resonance at audio frequencies
Pi filters were very useful for tube PSUs since inductor DCR in the range of 100 ohms was practical at values like 500V and 200mA [resulting in no filter resonance], but this is no longer true for solid state values like 50V and 5A
Further increasing inductor value in order to get a low enough cutoff causes the DCR/ESR/capacitance values required to tame the resulting third order resonant system to be huge
So pi filters damp ripple and reduce peak mains current value but allways at the expense of additional voltage drop on its output [ie: worse regulation] or resonance at audio frequencies
Pi filters were very useful for tube PSUs since inductor DCR in the range of 100 ohms was practical at values like 500V and 200mA [resulting in no filter resonance], but this is no longer true for solid state values like 50V and 5A
Working PI-filter
This is totally wrong.
Some Pass model has indeed a working PI-filter. Maybe Nelson Pass himself can persuade you....
I am sorry I don't remember which Pass model.
For your information I have 2 x15mH and 4x 12000µF in my Ampzilla and it is a working circuit even at full power into a 4 ohm load. The DC resistance of the coil is 0.57 Ohm
I still remember Nelson's post: Pi-filter multo bene.
Eva,Eva said:
This is totally wrong.
Some Pass model has indeed a working PI-filter. Maybe Nelson Pass himself can persuade you....
I am sorry I don't remember which Pass model.
For your information I have 2 x15mH and 4x 12000µF in my Ampzilla and it is a working circuit even at full power into a 4 ohm load. The DC resistance of the coil is 0.57 Ohm
I still remember Nelson's post: Pi-filter multo bene.
Assuming 0.05ohm capacitor ESR, your nice pi filter provides 36dB attenuation at 100Hz but at the expense of a peak of nearly 6dB at 11Hz, so it will resonate like hell with any music program containing 'beats' at 11Hz or at any subharmonic of 11Hz or also with mains line fluctuations at any of these frequencies
Options to get a damped system :
- Reduce L to about 2mH
- Increase L RDC up to about 1.5 ohms
- Increase output capacitor up to about 70mF
Loading the filter with a class-A circuit with constant bias would get rid of the ringing problem due to music program content, but ringing due to mains fluctuations will be still here
Loading the filter with a class AB circuit or a class A circuit with adaptive bias [fast enough to excite 11Hz ringing] would be funny at least
Did you ever heard about resonant switching power supplies or class E amplifiers?
Also I wonder how practical is a 15mH inductor with something like 10A saturation current, capable of storing 0.75 Joules
In comparison, the biggest SMPS inductors I've built are rated at 0.65mH 20A [0.13 Joules] and use a pair of E65 ferrite cores with 2.7mm air gap and 48 turns. They measure almost 7cm W, 7cm D, 7cm T, weight about 0.75 kg and each one is part of a 2KW converter
Options to get a damped system :
- Reduce L to about 2mH
- Increase L RDC up to about 1.5 ohms
- Increase output capacitor up to about 70mF
Loading the filter with a class-A circuit with constant bias would get rid of the ringing problem due to music program content, but ringing due to mains fluctuations will be still here
Loading the filter with a class AB circuit or a class A circuit with adaptive bias [fast enough to excite 11Hz ringing] would be funny at least
Did you ever heard about resonant switching power supplies or class E amplifiers?
Also I wonder how practical is a 15mH inductor with something like 10A saturation current, capable of storing 0.75 Joules
In comparison, the biggest SMPS inductors I've built are rated at 0.65mH 20A [0.13 Joules] and use a pair of E65 ferrite cores with 2.7mm air gap and 48 turns. They measure almost 7cm W, 7cm D, 7cm T, weight about 0.75 kg and each one is part of a 2KW converter
Bear's Philosophy, from http://www.bearlabs.com/NEXT/Design.html
Design Philosophy
BEAR Labs designs and builds equipment that is technically superior and unique. If I couldn't offer superior and higher performance
gear, then I wouldn't spend the time and effort to duplicate the work of others.
In most audio gear, especially speakers, there are no definitive and unequivocally “perfect” designs. So there are always sets of choices and compromises that engineers and designers must make. The ones that I choose offer unique combinations of advantages and benefits that are not found elsewhere.
Usually I decide upon a new product because I need it myself, or one of my friends or clients asks me to find a way to solve a problem - and this results in a new product.
I always rely upon solid engineering and design. Then I choose parts and materials based upon both quality and performance. Of course aesthetics and "look" play a role in the process of selecting materials, finishes and making design decisions. This is where "Art Meets Technology." tm
Engineering and Science?
Those who rely solely upon “engineering and science” often make a simple mistake of believing that measurements and/or equations can truly account for all factors in design. Do all amplifiers that are below some distortion level really sound identical?
Which brings up questions that are often debated in the audiophile magazines and on internet forums and newsgroups. What is audible? What makes a piece of equipment good? How good does a given piece of equipment have to be? Can things like parts and wires actually make an audible difference?
Despite the debates, and those who have published ABX and DBT results, there is little doubt that materials properties play some role in the ultimate “sonic character” or “sonic signature.” Materials properties are hardly the primary factors in the design of something like an amplifier. Even so, they should not be disregarded in the design of an amplifier, especially one that is expected to approach the performance limits of today's technology.
In the case of something like interconnect cables or speaker cables attention to materials is extremely important. I've done tests to compare two cables that were identical in every way except for one single factor - the wire in the cables were made of different metals. Two things need to be said. First, it would have been to my liking if there was no difference found between the two, since one of the two types of wire was considerably less expensive to manufacture. Second, I had no engineering basis to expect a difference, nor did I have an expectation that anyone would hear any differences!
Needless to say the tests I conducted did indicate that there was a notable difference in the perceived sonic character.
The tests I made were not scientifically incontrovertible. Indeed, there are real questions as to the scientific methodology that would be suitable for such incontrovertable tests. But that is a topic big enough for its own web site.
The Key Issue - Clarity
The difference between good, very good, and nearly perfect gear is the central issue! After all, if this audible difference did not exist and diminish listening pleasure then there would be no incentive to apply the technology, materials and expense involved in building high quality equipment!
Describing these crucial differences is difficult and almost impossible to achieve in words, but easy to identify once you compare BEAR Labs and competing equipment - by simply listening!
But, let's not avoid the question. Simply stated, the difference is clarity. Clarity in its simplest terms means that the superior equipment reproduces all of the harmonics (the subtle differences in timbre) so correctly and precisely that your brain recognizes exactly what it is hearing more quickly and accurately. In simple terms that is the difference.
What are examples of clarity?
When listening to a large choral piece, during a crescendo do the individual voices remain clearly defined - indeed, were they even truly defined at lower levels?? Or is the sound blurry, a large amorphous and undifferentiated mass?
Here's another example: listening to a solo voice - is it completely natural in both tone, position in space, and relationship to other voices or instruments? In many recordings, especially “pop” recordings vocals are “doubled” (the same part is sung twice and mixed together to add “body” to the vocal track). Can you tell instantly when a vocal has been doubled? Can you hear the difference between digitally produced reverberation and natural reverberation?
These two examples of clarity are good indicators of a given system's ultimate quality. If the system you are listening to can in fact reveal these differences clearly, and without any particular effort on your part to find them, that's a very high quality system.
All of BEAR Labs' products and equipment meets these criteria and others equally as rigorous. Does what you are listening to now do as well? If this level of performance and quality is what you want, then please look into my product line in detail, and by all means contact me personally for more information.
Design & Engineer For Tomorrow?
The reality is that few of us truly have a system that will reveal these differences without some uncertainty, and without some things sounding better than others. You may ask why this is true.
The answer is not all that simple. First the source material and its technology is only just now becoming good enough to equal the best playback, and to truly challenge our ears! Secondly, because the source material is so variable in quality, at times it actually has been the case that one can not hear differences between components because of deficits in the recordings themselves.
In essence, there is no "standard" by which one can assemble a system and know, a priori, how it will perform and how it will sound. Given a dozen recordings which were all of "mediocre" technical quality, you would hear little difference if they were played back on a superlative system, and if they were played back on a very average system. Indeed, if one then used the "average" system to judge the quality of recordings, the results obviously would be limited by the inherent quality of the playback system. So, a very high quality recording would be limited and only as good as the quality of the playback system itself. Thus making it impossible to know "good" from "bad." This sort of paradox and conundrum, a type of "chicken and egg" problem, has been a long standing hurdle in audio.
Keep in mind when we are thinking about audiophile systems that the ultimate comparison has to made to real live sound. Audiophile systems today can at best recreate a crude approximation of live sound. Even so, the less “electronic” or “mechanical” the sound of said system, the better.
Just in case you doubt this appraisal here's a simple test to consider. Take one or more coins and toss them into the air, let them fall to a hard floor at some distance from you. Do this with your eyes closed. Note how you can point to where the coins landed! Note how you know how many coins bounced and where they went. I challenge anyone to make an audio recording that can do this. It is impossible at this time. So, from this it is clear that a stereo system is incapable of reproducing even this simple event - and that there is a big difference between recorded and live sound.
Until the recent advent of good quality CD (A/D & D/A) few have had access to source material as good as an analog studio master - which technically speaking may not be all that good. Most studio multi-track recorders have a S/N on the order of 60-80dB, not as good as the CD itself. On the other hand the studio recorder may have better HF frequency response than the CD.
As this is being written new digital storage formats are entering the market (SACD & 24/96) that have the potential to exceed previous methods and perhaps go beyond the equipment used in today's studio and home recording and playback chains. I believe that when the time arrives that these new formats are in common use , the differences being hotly debated today will be found to not only exist, but will be taken for granted!
I design and engineer everything with this idea in mind - tomorrow's source material and technology will reveal differences and subtleties that are almost invisible today. So, when you acquire BEAR Labs equipment you will have purchased equipment that will not only last almost forever, but is designed to perform so well as to meet your needs for years and years to come.
'Nuff said
Design Philosophy
BEAR Labs designs and builds equipment that is technically superior and unique. If I couldn't offer superior and higher performance
gear, then I wouldn't spend the time and effort to duplicate the work of others.
In most audio gear, especially speakers, there are no definitive and unequivocally “perfect” designs. So there are always sets of choices and compromises that engineers and designers must make. The ones that I choose offer unique combinations of advantages and benefits that are not found elsewhere.
Usually I decide upon a new product because I need it myself, or one of my friends or clients asks me to find a way to solve a problem - and this results in a new product.
I always rely upon solid engineering and design. Then I choose parts and materials based upon both quality and performance. Of course aesthetics and "look" play a role in the process of selecting materials, finishes and making design decisions. This is where "Art Meets Technology." tm
Engineering and Science?
Those who rely solely upon “engineering and science” often make a simple mistake of believing that measurements and/or equations can truly account for all factors in design. Do all amplifiers that are below some distortion level really sound identical?
Which brings up questions that are often debated in the audiophile magazines and on internet forums and newsgroups. What is audible? What makes a piece of equipment good? How good does a given piece of equipment have to be? Can things like parts and wires actually make an audible difference?
Despite the debates, and those who have published ABX and DBT results, there is little doubt that materials properties play some role in the ultimate “sonic character” or “sonic signature.” Materials properties are hardly the primary factors in the design of something like an amplifier. Even so, they should not be disregarded in the design of an amplifier, especially one that is expected to approach the performance limits of today's technology.
In the case of something like interconnect cables or speaker cables attention to materials is extremely important. I've done tests to compare two cables that were identical in every way except for one single factor - the wire in the cables were made of different metals. Two things need to be said. First, it would have been to my liking if there was no difference found between the two, since one of the two types of wire was considerably less expensive to manufacture. Second, I had no engineering basis to expect a difference, nor did I have an expectation that anyone would hear any differences!
Needless to say the tests I conducted did indicate that there was a notable difference in the perceived sonic character.
The tests I made were not scientifically incontrovertible. Indeed, there are real questions as to the scientific methodology that would be suitable for such incontrovertable tests. But that is a topic big enough for its own web site.
The Key Issue - Clarity
The difference between good, very good, and nearly perfect gear is the central issue! After all, if this audible difference did not exist and diminish listening pleasure then there would be no incentive to apply the technology, materials and expense involved in building high quality equipment!
Describing these crucial differences is difficult and almost impossible to achieve in words, but easy to identify once you compare BEAR Labs and competing equipment - by simply listening!
But, let's not avoid the question. Simply stated, the difference is clarity. Clarity in its simplest terms means that the superior equipment reproduces all of the harmonics (the subtle differences in timbre) so correctly and precisely that your brain recognizes exactly what it is hearing more quickly and accurately. In simple terms that is the difference.
What are examples of clarity?
When listening to a large choral piece, during a crescendo do the individual voices remain clearly defined - indeed, were they even truly defined at lower levels?? Or is the sound blurry, a large amorphous and undifferentiated mass?
Here's another example: listening to a solo voice - is it completely natural in both tone, position in space, and relationship to other voices or instruments? In many recordings, especially “pop” recordings vocals are “doubled” (the same part is sung twice and mixed together to add “body” to the vocal track). Can you tell instantly when a vocal has been doubled? Can you hear the difference between digitally produced reverberation and natural reverberation?
These two examples of clarity are good indicators of a given system's ultimate quality. If the system you are listening to can in fact reveal these differences clearly, and without any particular effort on your part to find them, that's a very high quality system.
All of BEAR Labs' products and equipment meets these criteria and others equally as rigorous. Does what you are listening to now do as well? If this level of performance and quality is what you want, then please look into my product line in detail, and by all means contact me personally for more information.
Design & Engineer For Tomorrow?
The reality is that few of us truly have a system that will reveal these differences without some uncertainty, and without some things sounding better than others. You may ask why this is true.
The answer is not all that simple. First the source material and its technology is only just now becoming good enough to equal the best playback, and to truly challenge our ears! Secondly, because the source material is so variable in quality, at times it actually has been the case that one can not hear differences between components because of deficits in the recordings themselves.
In essence, there is no "standard" by which one can assemble a system and know, a priori, how it will perform and how it will sound. Given a dozen recordings which were all of "mediocre" technical quality, you would hear little difference if they were played back on a superlative system, and if they were played back on a very average system. Indeed, if one then used the "average" system to judge the quality of recordings, the results obviously would be limited by the inherent quality of the playback system. So, a very high quality recording would be limited and only as good as the quality of the playback system itself. Thus making it impossible to know "good" from "bad." This sort of paradox and conundrum, a type of "chicken and egg" problem, has been a long standing hurdle in audio.
Keep in mind when we are thinking about audiophile systems that the ultimate comparison has to made to real live sound. Audiophile systems today can at best recreate a crude approximation of live sound. Even so, the less “electronic” or “mechanical” the sound of said system, the better.
Just in case you doubt this appraisal here's a simple test to consider. Take one or more coins and toss them into the air, let them fall to a hard floor at some distance from you. Do this with your eyes closed. Note how you can point to where the coins landed! Note how you know how many coins bounced and where they went. I challenge anyone to make an audio recording that can do this. It is impossible at this time. So, from this it is clear that a stereo system is incapable of reproducing even this simple event - and that there is a big difference between recorded and live sound.
Until the recent advent of good quality CD (A/D & D/A) few have had access to source material as good as an analog studio master - which technically speaking may not be all that good. Most studio multi-track recorders have a S/N on the order of 60-80dB, not as good as the CD itself. On the other hand the studio recorder may have better HF frequency response than the CD.
As this is being written new digital storage formats are entering the market (SACD & 24/96) that have the potential to exceed previous methods and perhaps go beyond the equipment used in today's studio and home recording and playback chains. I believe that when the time arrives that these new formats are in common use , the differences being hotly debated today will be found to not only exist, but will be taken for granted!
I design and engineer everything with this idea in mind - tomorrow's source material and technology will reveal differences and subtleties that are almost invisible today. So, when you acquire BEAR Labs equipment you will have purchased equipment that will not only last almost forever, but is designed to perform so well as to meet your needs for years and years to come.
'Nuff said
I'm not sure how much 'clever' has to do with it. All it takes is a bridged amp, such as the Aleph-X. Or something like the Zen, driven by a fixed current source.
Over-reliance on numbers and theory tends to blind people to practical solutions.
Or I guess you could just listen.
Nah, that's too much to ask...you've already made up your mind.
Grey
Over-reliance on numbers and theory tends to blind people to practical solutions.
Or I guess you could just listen.
Nah, that's too much to ask...you've already made up your mind.
Grey
I like this quote a lot:
I also like the nose on that bear. But this beats the bear's nose hands down. http://www.whosgottabignose.com/
I also like the nose on that bear. But this beats the bear's nose hands down. http://www.whosgottabignose.com/
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.