Well, I think this subject it may be fortunate to discuss it further, but not so as before, to conflict with the forums rules.
I think too, that Joe Rasmussen have a merit in this area, as the one who pointed out for all of us, the effect of this capacitor placed over a DAC chip differential outputs. As I have learned already, calling this effect as "Rasmussen effect" it seen as enough provocative for someone, and it can easily leads to off topic discussions. So I will suggest to call it "Joe`s capacitor/cap".
What it do this capacitor as effect? Well, to use only few words for description, it improve the soundscene. To observe these improvements is only enough simple listening tests (available to everybody who may want to experiment). The differences before/after are obvious. How to quantify/measure such? Well, here is a big challenge. What to measure, and how, is up to you to comment, but I`m personally quite sceptic that what is to hear is always measurable...
What is the role of this capacitor, or what actually is this capacitor placed so in the circuits?
Here is a controversy, which in my opinion it may be beneficial to discuss about it further.
In the former (closed) thread dedicated to this subject (DAC Filtering - the "Rasmussen Effect") it was a quite hot and long enough discussion, trying to be found the right explanation for what actually is going on about this cap.
It is a filter, or what it may be?
It looks enough obvious that is a filter, or it have a filtering function. But what is more than obvious, this cap it have an effect or a big impact on the soundscene, improving it a lot. Why is like this, I will suggest to discuss it further here. But let`s discuss about the cap and not about the persons who participate to discussion..
I think too, that Joe Rasmussen have a merit in this area, as the one who pointed out for all of us, the effect of this capacitor placed over a DAC chip differential outputs. As I have learned already, calling this effect as "Rasmussen effect" it seen as enough provocative for someone, and it can easily leads to off topic discussions. So I will suggest to call it "Joe`s capacitor/cap".
What it do this capacitor as effect? Well, to use only few words for description, it improve the soundscene. To observe these improvements is only enough simple listening tests (available to everybody who may want to experiment). The differences before/after are obvious. How to quantify/measure such? Well, here is a big challenge. What to measure, and how, is up to you to comment, but I`m personally quite sceptic that what is to hear is always measurable...
What is the role of this capacitor, or what actually is this capacitor placed so in the circuits?
Here is a controversy, which in my opinion it may be beneficial to discuss about it further.
In the former (closed) thread dedicated to this subject (DAC Filtering - the "Rasmussen Effect") it was a quite hot and long enough discussion, trying to be found the right explanation for what actually is going on about this cap.
It is a filter, or what it may be?
It looks enough obvious that is a filter, or it have a filtering function. But what is more than obvious, this cap it have an effect or a big impact on the soundscene, improving it a lot. Why is like this, I will suggest to discuss it further here. But let`s discuss about the cap and not about the persons who participate to discussion..
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So, my first "contribution" to this thread...
Joe Rasmussen made it us known about, and he used this cap over the DAC outputs differential lines, or at the input of the I/V stage (as we know so far...).
I have followed this idea and I used it too so, and I could confirm at that time the Joe`s statements. Then for some particular reasons, I got bad results when using this cap, and I abandoned the idea. I found out later on about the causes of my negative results. So, I came back to this idea, and use it the cap on my new designed post DAC processing stage. The result was immediate and more than positive. So, my definitely conclusion is: this works! The effect of this cap is very real, even though is enough unclear the explanation of this effect.
They who only deny the existence of this effect, sorry, but they do not know (yet) what is actually about, or never try it.
Recently I was thinking and asking myself what it may be the effect of a such capacitor, or how it may works if is placed somewhere else than just on the DAC chip outputs.
Let`s say placed over the differential lines at the inputs of an pre-amplifier circuit. Well, the answer is: IT WORKS!
But what it may happen if heaving a such cap already placed on the DAC outputs (and working well as effect), if another one it will be placed in the same processing chain, at the input of the pre-amplifier device?
Well, this was actually the reason I decided to start again the discussion about this effect, in this new thread.
When using the samme approach with this cap over diferential lines, both on DAC outputs or I/V inputs, and at an pre-amplifier inputs, then it is possible to control the "shape" of the soundscene, or how it may "looks like" the soundscene.
I used for first experiment the same value of the cap on both DAC outputs, and at the preamp inputs. I got a distorted soundscene. Please do not misunderstand. The audio signal was not distorted at all, but always just exceptional fidelity. The soundscene itself was unreal wide, so that some instruments was positioned in unreal positions, while the another ones was in right places. Just unbelievable effect!
It was very obvious that was far from natural. I have appreciated to lower the cap value, quite by chance. Another big surprise: the soundscene became very real, with everything in its right place, and the position of the instruments became just amazing precise. The volume/space of the soundscene it were very large both left/right, and far/near, so to permit an extreme well definition in space of the sound elements. Instruments placed very near each other could be very well and easy located. I never heard a such realism in a audio playback.
This effect and the improvement is not to be obtained only by using the cap at the DAC outputs, but using it in two places in the chain. The effect obtained by placing the cap on the DAC outputs it define somehow a soundstage. The another one cap placed at the preamp stage inputs it multiply the precision and the volume of that "predefined" soundstage, and it can modified (by the used cap`s value), to obtain an optimum of an even more increased/improved sound quality, than only using this cap on DAC outputs.
What happen is just and only amazing!
I have tested playing back some old Tangerine dream albums (standard CDs). After so many years I was used with this band works. it was for the first time I have experienced the real way Tangerine dream was created and recorded. The sounds was flowing in the room, moving it far and near, from the left to right in a very large like area, with an extreme precision in space. The speakers became completely transparent or non existent in the room, but only the sounds coming right from their precise places. Very easy to locate multiple sounds in the same time in very different or very near positions. Undeliverable is a quite poor word to express such experience.
Well, as a conclusion so far, here we have an very real effect of improved soundscene in different levels as using this cap in different places into the processing audio chain.
It looks like a such cap it have filtering function here, but the effect is quite far from only a filtering result. There is something more than only filtering, which happen when this simple cap is placed over differential lines. I do not know so far, what it may be, but is very right in my opinion, to call it this as an effect. I can also hardly define this effect too...
Sorry for not coming with precise values of the caps, or the precise location of it. The values it vary quite much function of the used device, configuration, etc. The approach it have however to be customized. I only intended to share/confirm once more about the existence of this effect, adding that using this cap in two places it improve even more the final result. As I will use this approach in my further mods/improvements, I may not disclose some details.
Joe Rasmussen made it us known about, and he used this cap over the DAC outputs differential lines, or at the input of the I/V stage (as we know so far...).
I have followed this idea and I used it too so, and I could confirm at that time the Joe`s statements. Then for some particular reasons, I got bad results when using this cap, and I abandoned the idea. I found out later on about the causes of my negative results. So, I came back to this idea, and use it the cap on my new designed post DAC processing stage. The result was immediate and more than positive. So, my definitely conclusion is: this works! The effect of this cap is very real, even though is enough unclear the explanation of this effect.
They who only deny the existence of this effect, sorry, but they do not know (yet) what is actually about, or never try it.
Recently I was thinking and asking myself what it may be the effect of a such capacitor, or how it may works if is placed somewhere else than just on the DAC chip outputs.
Let`s say placed over the differential lines at the inputs of an pre-amplifier circuit. Well, the answer is: IT WORKS!
But what it may happen if heaving a such cap already placed on the DAC outputs (and working well as effect), if another one it will be placed in the same processing chain, at the input of the pre-amplifier device?
Well, this was actually the reason I decided to start again the discussion about this effect, in this new thread.
When using the samme approach with this cap over diferential lines, both on DAC outputs or I/V inputs, and at an pre-amplifier inputs, then it is possible to control the "shape" of the soundscene, or how it may "looks like" the soundscene.
I used for first experiment the same value of the cap on both DAC outputs, and at the preamp inputs. I got a distorted soundscene. Please do not misunderstand. The audio signal was not distorted at all, but always just exceptional fidelity. The soundscene itself was unreal wide, so that some instruments was positioned in unreal positions, while the another ones was in right places. Just unbelievable effect!
It was very obvious that was far from natural. I have appreciated to lower the cap value, quite by chance. Another big surprise: the soundscene became very real, with everything in its right place, and the position of the instruments became just amazing precise. The volume/space of the soundscene it were very large both left/right, and far/near, so to permit an extreme well definition in space of the sound elements. Instruments placed very near each other could be very well and easy located. I never heard a such realism in a audio playback.
This effect and the improvement is not to be obtained only by using the cap at the DAC outputs, but using it in two places in the chain. The effect obtained by placing the cap on the DAC outputs it define somehow a soundstage. The another one cap placed at the preamp stage inputs it multiply the precision and the volume of that "predefined" soundstage, and it can modified (by the used cap`s value), to obtain an optimum of an even more increased/improved sound quality, than only using this cap on DAC outputs.
What happen is just and only amazing!
I have tested playing back some old Tangerine dream albums (standard CDs). After so many years I was used with this band works. it was for the first time I have experienced the real way Tangerine dream was created and recorded. The sounds was flowing in the room, moving it far and near, from the left to right in a very large like area, with an extreme precision in space. The speakers became completely transparent or non existent in the room, but only the sounds coming right from their precise places. Very easy to locate multiple sounds in the same time in very different or very near positions. Undeliverable is a quite poor word to express such experience.
Well, as a conclusion so far, here we have an very real effect of improved soundscene in different levels as using this cap in different places into the processing audio chain.
It looks like a such cap it have filtering function here, but the effect is quite far from only a filtering result. There is something more than only filtering, which happen when this simple cap is placed over differential lines. I do not know so far, what it may be, but is very right in my opinion, to call it this as an effect. I can also hardly define this effect too...
Sorry for not coming with precise values of the caps, or the precise location of it. The values it vary quite much function of the used device, configuration, etc. The approach it have however to be customized. I only intended to share/confirm once more about the existence of this effect, adding that using this cap in two places it improve even more the final result. As I will use this approach in my further mods/improvements, I may not disclose some details.
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Before getting into a theory of operation, perhaps you could start by explaining how you determined this to be the case. Thanks!
I think the only controversy is Joe claiming it's HIS effect. This technique pre filtering the digital to analog interface is very well known years before 'joe blow' decides to plant his flag on it. We used to do this with RC filters on charge pumps for PLLs decades ago, but then we could calculate the values used and also measure the results. Did you have a question that hasn't been discussed in the closed thread?
The measuring of such a type of effect IS difficult, because the characteristic is that the information at a much lower level than the nominal signal is "clearer", less distorted. It is not the distortion of the high level envelope of the signal, it's what's happening to the low level signals riding on top of the main, obvious time domain behaviour. And the measuring of such requires evolving measurement techniques, which people are obviously very reluctant to do ...
I think you right... But I may suggest we forget for instant what it was that "controversy", and the "flag"...
But how may you think to define a such improvement effect, from the perspective of filters and so?
My appreciation is that a such cap in that place it may improve the signal`s phases or the overall quality in this area. There is known that the human perception of the sound location is based on measuring the phase differences of the sounds which hit the ears. An improvement in reproduction of the audio signals (sound) phases, with this cap in place, it may explain the improvement of the soundscene in this case... Well a supposition, quite empiric expressed...
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That was actually my point too, that is very difficult to measure/quantify such effect...
I feel the need to come back to your post, with this observation:
When about to apply such cap or filtering technique to the digital to analogue interface in a DAC system, I may agree that this cap it have a full filtering function.
But the main point of my above post and motivation for opening this new thread, is that so called filtering effect or function of this cap, it is applicable (it actually works) when using it in a full analogue domain (as at an preamp stage input, or in between two analogue processing stages).
What it may be to filter here, so to be perceptible at the chain outputs a much more improved soundscene, than when not using such cap?
So not ears-only? You might consider trying to determine if what you perceived was real before delving into theoretical explanations.
OK, I get your idea and doubts about my capabilities to discern between fantasy and real life. I take it so far, as a normal sceptical reaction...
The problem is that I`m not alone in this "perception". Some peoples who have proceed it to experiments in this area, confirmed too about such effect. At least you can quite easy try it yourself, and we may continue the discussion after such event.
It looks like this subject is similar to the UFO`s one. Some state to have seen it such, experienced it somehow, some do not believe it at all. The only difference here is that to try this effect is quite easy... Then you can conclude yourself if it is real or imagination.
At least I did not read yet about somebody who chosen to solder two caps in right places, and then making known that could not perceive any changes, any improvement, or so.
The problem is that I`m not alone in this "perception". Some peoples who have proceed it to experiments in this area, confirmed too about such effect. At least you can quite easy try it yourself, and we may continue the discussion after such event.
It looks like this subject is similar to the UFO`s one. Some state to have seen it such, experienced it somehow, some do not believe it at all. The only difference here is that to try this effect is quite easy... Then you can conclude yourself if it is real or imagination.
At least I did not read yet about somebody who chosen to solder two caps in right places, and then making known that could not perceive any changes, any improvement, or so.
That's very perceptive. However, you're also right that you could more easily get evidence of the actual existence of the audibility. Once you do, the subject is worth discussing. Lacking that, it's like discussing how the UFO anal probes operate before determining that there are such things.
The audibility is not a problem - one can have a standard amplifying circuit, and hook it up to a somewhat mediocre power supply, or alternately use a brilliantly engineered one. Then someone will say, well, it sounds "better" with the better PS, and hopefully very few will say "Prove it!!" Of course, if one has to prove it then one can set exactly the right sort of test material to evoke bad behaviour, knowing how the poor supply will behave in those circumstances, and the measuring becomes trivial.
But if the audible behaviour doesn't seem logical, using conventional thinking, then everything gets worse: those who disbelieve are more aggressive in demanding it to be verified; selecting the right source signal to trigger the variation in behaviour is not obvious, because the underlying mechanism causing the issues is not understood; and the measuring is more difficult ... it's a bumpy road, unfortunately ...
But if the audible behaviour doesn't seem logical, using conventional thinking, then everything gets worse: those who disbelieve are more aggressive in demanding it to be verified; selecting the right source signal to trigger the variation in behaviour is not obvious, because the underlying mechanism causing the issues is not understood; and the measuring is more difficult ... it's a bumpy road, unfortunately ...
For the record, once again, Joe has never to my knowledge claimed the effect as his, nor did he name it after himself. I have clearly stated before that naming the effect after after Joe was MY idea. This was suggested by me to facilitate discussing it, rather than ambiguously referring to what we were hearing simply as, the effect. To my knowledge, Joe has never claimed to be the first to observe the effect. He was the first, however, to bring it to the attention of this forum.
The effect very much does not seem to be due to simple band pre-filtering, as the filter is only first order and that seemingly trivial changes in the turnover point seem to produce a non-linear change to the percieved sound quality.
In order to have a constructive discussion around possible cause, past discussions strongly suggest to me that it is essential that one first determine for themself whether or not they even perceive the effect.
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It has always been called a pre-filter in the EE comms community.
Yes simple circuit changes sometimes have big implications ( specially true at digital to analog interfaces in my experience ), so not sure why this rules out being a called pre-filter by you? I know the mechanisms it prevents, but don't bother waxing about the sound perceptions, I'll leave that to the 'Poets of Audio' designers community.
BTW it really doesn't make sense to talk of such things without a schematic in hand, I reckon it's a mistake in earlier DAC I/V converters.
There is for sure not about filtering here, even though there is quite trivial that a cap placed into a circuit or a signal path, it does a filtering of some sort.
It was supposed that this cap placed over the differential lines at the DAC outputs it may filter somehow the HF noises, and therefore it may reveal a such effect.
Well, I have placed this cap quite far from the DAC chip, at the input of an preamp device. I got the same effect. No matter what device I connect the preamp to, the effect is present, because is generated into the preamp device. What kind of filtering of an analogue signal it may happen here to get a extremely precise placement of the sound elements into the soundscene?
I think it is happen something else here, than only filtering function over a signal.
My speculation is that a such cap placed over the differential lines, it align or improve something into the sound elements phases domain. This improvement is perceived by the human hearing or brain as a more precise sound location in the sonic environment generated by the stereo reproduction/playback (the soundscene).
Without this cap in place, the soundscene is more or less diffuse.
BTW, to perceive this effect, one should find two caps (experimental chosen values), and these caps should be solder it in the right places (mainly in the signal path, over the differential lines of an enough high level quality audio device). There is quite simple, and it does not necessary need a schematic. Lot of schematics are already published into the closed thread, which treated the same subject.
It was supposed that this cap placed over the differential lines at the DAC outputs it may filter somehow the HF noises, and therefore it may reveal a such effect.
Well, I have placed this cap quite far from the DAC chip, at the input of an preamp device. I got the same effect. No matter what device I connect the preamp to, the effect is present, because is generated into the preamp device. What kind of filtering of an analogue signal it may happen here to get a extremely precise placement of the sound elements into the soundscene?
I think it is happen something else here, than only filtering function over a signal.
My speculation is that a such cap placed over the differential lines, it align or improve something into the sound elements phases domain. This improvement is perceived by the human hearing or brain as a more precise sound location in the sonic environment generated by the stereo reproduction/playback (the soundscene).
Without this cap in place, the soundscene is more or less diffuse.
BTW, to perceive this effect, one should find two caps (experimental chosen values), and these caps should be solder it in the right places (mainly in the signal path, over the differential lines of an enough high level quality audio device). There is quite simple, and it does not necessary need a schematic. Lot of schematics are already published into the closed thread, which treated the same subject.
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The demonstration of this effect it have been done so far individual. One have read about this (and Joe was the first who brought this information in a thread), and then took one a soldering iron and the components, soldered it in place and tested it. Then experienced one that the effect it was demonstrated to him.
Some of the peoples who have experienced such individual demonstration, came here in a trial to find out more about how this is possible, how it may works, what is, and so on. Then some others repeated the experience and confirmed that the effect is real, even though an reasonable explanation is not yet found.
Some theorists, who are not so used with the soldering iron, expressed their doubts, and scepticism, so that the discussions became "high temperature", with some personal connotations... And the someone trials to find out more about what it is going on here, it was transformed into a "real/unreal" discussion, controversy. Which it seems (unfortunately) to continue further...
There is also true that an extended demonstration, involving many people, blind or A/B tests, etc. was not organized yet, no any book about this was yet written, as no any scientific demonstration it exist on something which was not even measured yet...
Some of the peoples who have experienced such individual demonstration, came here in a trial to find out more about how this is possible, how it may works, what is, and so on. Then some others repeated the experience and confirmed that the effect is real, even though an reasonable explanation is not yet found.
Some theorists, who are not so used with the soldering iron, expressed their doubts, and scepticism, so that the discussions became "high temperature", with some personal connotations... And the someone trials to find out more about what it is going on here, it was transformed into a "real/unreal" discussion, controversy. Which it seems (unfortunately) to continue further...
There is also true that an extended demonstration, involving many people, blind or A/B tests, etc. was not organized yet, no any book about this was yet written, as no any scientific demonstration it exist on something which was not even measured yet...
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So in order for me to take part in a discussion about whether there are fairies at the bottom of gardens it is necessary for me personally to experience a fairy? I can't use classical mechanics to calculate the flight of a thrown ball under gravity (and inertia) unless I have thrown a ball?Ken Newton said:
The previous thread on this subject ran into the sand because attempts to be awkward and apply circuit theory (albeit perhaps somewhat lesser known circuit theory, such as the impedance of a virtual ground) were brushed aside as irrelevant. When circuit theory is regarded as irrelevant to a discussion about circuits then little progress can be made.
When someone reports an unexpected phenomenon one of the plausibility tests which should be used is "does existing theory, carefully applied, explain the claimed phenomenon or rule it out or leave it as an open question?" This may not satisfy those who want to establish not just a new phenomenon but also a new theory to explain it. Unfortunately, in electronics there can be no new theories - we are stuck with the low frequency approximation of electromagnetism (otherwise known as circuit theory).
Wasn't that your intended result. I didn't doubt anything, but on the other hand you have NOT described any specific example either. your soldering iron experiments seem a random pattern of a 'part swapper'.
could you put forth any coherent experiment?
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