Hey Dweekie,
The two things that might be affecting this could be:
First, I read the bypass cap is supposed to have a higher voltage rating than the coupling cap! The MKP 1837s are either 160 volts or maybe 250 volts. The Obbligatos are 630 volts.
Second, maybe these Obbligatos might need the 10% AND the 1% double bypass or just 10% only or .5% only or any combination in between. Please experiment more, I know I am involved hoping to find the Nirvana Combination too! (just like you)!
Let me know what you think!
Regards//Keith
The two things that might be affecting this could be:
First, I read the bypass cap is supposed to have a higher voltage rating than the coupling cap! The MKP 1837s are either 160 volts or maybe 250 volts. The Obbligatos are 630 volts.
Second, maybe these Obbligatos might need the 10% AND the 1% double bypass or just 10% only or .5% only or any combination in between. Please experiment more, I know I am involved hoping to find the Nirvana Combination too! (just like you)!
Let me know what you think!
Regards//Keith
Hi,
In case it helps to know, it is my belief that the voltage-rating per se is just a red-herring here, although it does need to be adequate for the purpose concerned, of course.
Having 'listened' carefully to literally thousands of caps in many parallel configurations, I am quite confident of this, but as a general rule with film caps, higher voltage-rated devices do perform rather better sonically than their similar but lower voltage-rated brethren. There are some theoretical reasons to support this related to their construction, incidentally, but I won't go into these.
The phenomenon mentioned by dweekie is not unusual in my experience and can simply result from an 'unhappy' match with two parallel caps. In all such cases there is the risk of creating tank circuits or other peculiarities giving rise to resonant behaviour, which can accentuate or possibly even curtail certain frequencies, but there are other factors involved here, too. Some film caps do perform better at HFs than others (this is well-known), and accordingly, they do not benefit sonically so much (if at all) by any HF 'enhancement' due to bypassing.
At the risk of being ridiculed, yet again, 'blending' caps like this takes a certain amount of trial and error, and slightly different overall subjective results can be heard with the same combination of caps, but in different circuit locations. It is a bit like cooking, in that maybe you wouldn't wish to add much sugar in a recipe where there is some natural sweetener in with the other ingredients, but in other instances, it can make all the difference and much improve the overall taste.
No caps (that I have come across) are perfect and absolutely benign in passing signals at all frequencies of interest for audio, when used in coupling locations like you dealing with here. The result is some kind of 'difference' added or subtracted from the input signal which is distortion, and if with 2 caps in parallel this happens to occur at a similar frequency, this will accentuate any unwanted sonic effects.
Good small-value film caps will (almost) always tend to accentuate high frequencies (i.e. make the HF seem more prominent, subjectively) in my experience when used in coupling situations, in comparison with larger value caps of a similar type. This is mainly due to their *comparatively* lesser ESR (impedance to passage of signal) at HF, and is basically the reason for bypassing in the first place, of course. If you try using say 10 x 0.1uF caps (in parallel) of identical construction and make etc., and directly compare this with a single (same make/voltage etc.) cap of 1uF, to me it will always seem as if the parallel arrangement is subjectively slightly 'brighter' sounding in overall balance, even when the overall capacitances are precisely matched to each other.
The MIT 'RTX' series of caps which many think are quite good sonically, are made with ten internal smaller caps in parallel, to exploit this effect. Most, if not all caps (I haven't tried every cap in the world) will have a tendency to slightly reduce HF responses, depending a lot on the type of cap, its value, and the local impedances in the circuit where they are used, simply as a result of their increasing impedance at HF which caps suffer from.
Doubtless someone will soon point out that this should be at stratospheric frequency levels if the caps are of a sensible value for the application, but this is not the entire story here. Some 35 yrs ago, I demonstrated to the late JLH that changing an input HF roll-off cap in one of his designs from a -3dB point of around 35k (IIRC, but anyway it was way outside of our hearing threshold for normal sounds), to a higher frequency, made a very noticeable difference which subjectively improved the HF response. In fact, changes between 100k and much higher roll-offs, also had an effect which JLH even with some age-related hearing shortcomings at HF, could still discern.
So, it is my belief (as these minor subjective differences cannot yet be measured) that for example the parallel MIT caps are actually more 'even handed' across the spectrum. In other words, there is less of a subjective loss (small though these differences are) at HF, whereas with a single larger value cap, these subjective HF losses are greater. It is hard to think why else adding a smaller cap as a bypass will have such an effect by way of 'enhancing' the HF responses, as you and so many others have found, and bear in mind that *when listening to music* fractions of a dB in amplitude at different frequencies *can be readily apparent*, even though it is often suggested in comparative listening-trials with sine-waves (or whatever) that this is not so.
Regrettably, there are some inherent problems with any bypassing, and a few of us who have been doing this for very many years, nowadays tend to avoid bypassing whenever possible, but this usually results in much higher costs for the best-sounding 'single' caps, which may be prohibitive for many DIYers.
Quite close results can be obtained with bypassing, though, to some of the finest caps I am aware of, but it takes more time and patience, although the results are frequently very rewarding.
The answer here is simply to do what you are already trying out for yourselves, but there will always be the odd combination which doesn't work well together, in my experience, even though the individual caps may be good in other locations. Indeed, using the same caps, but with slightly different values, might provide a much better result, but only a 'suck-it-and-see' trial *in that specific location*will make this clear.
This is a fascinating (and not well-understood) method of getting the best sonic results out of audio circuits, and there are substantial potential gains to be had through patient trials like these. However, there is no universal 'one size fits all' individual cap, or combination of caps which I have yet come across, unfortunately, and what might work very well in one coupling location, may not be so effective in another.
Good luck with your experiments.
Regards,
In case it helps to know, it is my belief that the voltage-rating per se is just a red-herring here, although it does need to be adequate for the purpose concerned, of course.
Having 'listened' carefully to literally thousands of caps in many parallel configurations, I am quite confident of this, but as a general rule with film caps, higher voltage-rated devices do perform rather better sonically than their similar but lower voltage-rated brethren. There are some theoretical reasons to support this related to their construction, incidentally, but I won't go into these.
The phenomenon mentioned by dweekie is not unusual in my experience and can simply result from an 'unhappy' match with two parallel caps. In all such cases there is the risk of creating tank circuits or other peculiarities giving rise to resonant behaviour, which can accentuate or possibly even curtail certain frequencies, but there are other factors involved here, too. Some film caps do perform better at HFs than others (this is well-known), and accordingly, they do not benefit sonically so much (if at all) by any HF 'enhancement' due to bypassing.
At the risk of being ridiculed, yet again, 'blending' caps like this takes a certain amount of trial and error, and slightly different overall subjective results can be heard with the same combination of caps, but in different circuit locations. It is a bit like cooking, in that maybe you wouldn't wish to add much sugar in a recipe where there is some natural sweetener in with the other ingredients, but in other instances, it can make all the difference and much improve the overall taste.
No caps (that I have come across) are perfect and absolutely benign in passing signals at all frequencies of interest for audio, when used in coupling locations like you dealing with here. The result is some kind of 'difference' added or subtracted from the input signal which is distortion, and if with 2 caps in parallel this happens to occur at a similar frequency, this will accentuate any unwanted sonic effects.
Good small-value film caps will (almost) always tend to accentuate high frequencies (i.e. make the HF seem more prominent, subjectively) in my experience when used in coupling situations, in comparison with larger value caps of a similar type. This is mainly due to their *comparatively* lesser ESR (impedance to passage of signal) at HF, and is basically the reason for bypassing in the first place, of course. If you try using say 10 x 0.1uF caps (in parallel) of identical construction and make etc., and directly compare this with a single (same make/voltage etc.) cap of 1uF, to me it will always seem as if the parallel arrangement is subjectively slightly 'brighter' sounding in overall balance, even when the overall capacitances are precisely matched to each other.
The MIT 'RTX' series of caps which many think are quite good sonically, are made with ten internal smaller caps in parallel, to exploit this effect. Most, if not all caps (I haven't tried every cap in the world) will have a tendency to slightly reduce HF responses, depending a lot on the type of cap, its value, and the local impedances in the circuit where they are used, simply as a result of their increasing impedance at HF which caps suffer from.
Doubtless someone will soon point out that this should be at stratospheric frequency levels if the caps are of a sensible value for the application, but this is not the entire story here. Some 35 yrs ago, I demonstrated to the late JLH that changing an input HF roll-off cap in one of his designs from a -3dB point of around 35k (IIRC, but anyway it was way outside of our hearing threshold for normal sounds), to a higher frequency, made a very noticeable difference which subjectively improved the HF response. In fact, changes between 100k and much higher roll-offs, also had an effect which JLH even with some age-related hearing shortcomings at HF, could still discern.
So, it is my belief (as these minor subjective differences cannot yet be measured) that for example the parallel MIT caps are actually more 'even handed' across the spectrum. In other words, there is less of a subjective loss (small though these differences are) at HF, whereas with a single larger value cap, these subjective HF losses are greater. It is hard to think why else adding a smaller cap as a bypass will have such an effect by way of 'enhancing' the HF responses, as you and so many others have found, and bear in mind that *when listening to music* fractions of a dB in amplitude at different frequencies *can be readily apparent*, even though it is often suggested in comparative listening-trials with sine-waves (or whatever) that this is not so.
Regrettably, there are some inherent problems with any bypassing, and a few of us who have been doing this for very many years, nowadays tend to avoid bypassing whenever possible, but this usually results in much higher costs for the best-sounding 'single' caps, which may be prohibitive for many DIYers.
Quite close results can be obtained with bypassing, though, to some of the finest caps I am aware of, but it takes more time and patience, although the results are frequently very rewarding.
The answer here is simply to do what you are already trying out for yourselves, but there will always be the odd combination which doesn't work well together, in my experience, even though the individual caps may be good in other locations. Indeed, using the same caps, but with slightly different values, might provide a much better result, but only a 'suck-it-and-see' trial *in that specific location*will make this clear.
This is a fascinating (and not well-understood) method of getting the best sonic results out of audio circuits, and there are substantial potential gains to be had through patient trials like these. However, there is no universal 'one size fits all' individual cap, or combination of caps which I have yet come across, unfortunately, and what might work very well in one coupling location, may not be so effective in another.
Good luck with your experiments.
Regards,
Hi Bob,
Thank you for helping us all with trying to understand this Phenomena. I really appreciate the time you spent explaining your experience and factors that do/may influence the sound. This is so much better than the average one-liner.
I know you are an advocate for testing for direction before installing. Are their any simple hand held devices capable of determining direction of a cap? I wonder if this may also influence Dweekie's results. The Obbligato is a film/oil, 630 volts and the VR MKP1837 is a polypropylene/metal film 160 volts. Do you think the direction may impact the outcome here?
As far as ridicule, In my world, how can anybody ridicule someone with 35+ years of hardcore experience, even if everything they experienced was the opposite of your findings. They can disagree based on their experience and maybe investigate as to why there are differences (possibly broadening their view of the matter), but ridicule....Nah.
Look at Stephen Hawking. He came up with a theory that explained how the universe worked. It was promising until others explored deeper into it because there were holes in the theory. Stephen was out of ideas. He sat on it for decades and a few years back a light went on again. His theory wasn't totally wrong. It needed a few adjustments but the real problem was that it was incomplete and newer technology and ideas made it possible to now go there and get closer to completion, filling the holes. So we may ridicule based on ignorance of the whole picture sometimes. I guess we are all guilty of that from time to time.
Keep up the good work and for every one that may ridicule, there are fifty quiet ones that appreciate the learning of your vast experience!
Regards//Keith
Thank you for helping us all with trying to understand this Phenomena. I really appreciate the time you spent explaining your experience and factors that do/may influence the sound. This is so much better than the average one-liner.
I know you are an advocate for testing for direction before installing. Are their any simple hand held devices capable of determining direction of a cap? I wonder if this may also influence Dweekie's results. The Obbligato is a film/oil, 630 volts and the VR MKP1837 is a polypropylene/metal film 160 volts. Do you think the direction may impact the outcome here?
As far as ridicule, In my world, how can anybody ridicule someone with 35+ years of hardcore experience, even if everything they experienced was the opposite of your findings. They can disagree based on their experience and maybe investigate as to why there are differences (possibly broadening their view of the matter), but ridicule....Nah.
Look at Stephen Hawking. He came up with a theory that explained how the universe worked. It was promising until others explored deeper into it because there were holes in the theory. Stephen was out of ideas. He sat on it for decades and a few years back a light went on again. His theory wasn't totally wrong. It needed a few adjustments but the real problem was that it was incomplete and newer technology and ideas made it possible to now go there and get closer to completion, filling the holes. So we may ridicule based on ignorance of the whole picture sometimes. I guess we are all guilty of that from time to time.
Keep up the good work and for every one that may ridicule, there are fifty quiet ones that appreciate the learning of your vast experience!
Regards//Keith
Hi Keith,
I am not aware of any very simple way of determining the caps 'direction' as such without any test gear, and maybe thinking a bit more about this, the construction of the caps hasn't been commented upon either.
What appears to be (mainly) the determining factor in these cases, is discovering which lead is attached to the 'outer foil' of the cap when it was constructed. Most such film caps are made like a swiss-roll, with the plastic film being wound up in a roll, with either a separate metal film being interposed between the plastic films, or one side of the plastic film being 'metallised'. i.e coated with a metallic substance. Sometimes they are squashed (to bind everything together and help eliminate any air-pockets) to give an oval shape, and often the physically smaller types are enclosed in another outer plastic box. These caps are usually quite directional, simply because there is more shielding from the outermost foil, and this is generally placed at the lower impedance part in any circuit, for best sonics.
In shunt cases, this shielding is more effective when connected to ground, of course.
However, there are several other methods of construction, 'stacked-foil' being the obvious main type for film caps, but these are made like a pack of cards with lots of separate pieces of foil being laid face to face. These are not generally so easy to obtain any reliable measurements of this nature on, but fortunately, they don't appear to be very 'directional' in my experience. They are better for HF response generally, too, in view of their less-inductive properties, as with the earlier-mentiond RTXs which have no more inductance (it is reduced by paralleling 10 individual sections in each cap) than a single piece of wire of the same overall length.
Ceramics, which have no place in analogue audio circuits in my view (in spite of many others using them, apparently quite happily) and silver micas, as other examples don't seem to exhibit any directionality, but if you go into how they are manufactured, this is not so surprising.
Any way in which one can determine without any doubt which is the outer foil in the rolled-up caps, is just as valid as any other, I am sure, but simply out of habit, I generally stick to my own methodology here as referred to in my earlier post.
If you have a reasonable 'scope to use, I have also merely connected caps across a 'scopes leads before now, and simply moved the cap concerned close to a mains source like a live wire, or transformer, and have seen a 'direction' as a result of the signal pickup (normally to be avoided like the plague, in circuits, of course!) from the 50Hz, or 60Hz for you, mains frequency. If the outer foil is connected to the 'hot' probe, a larger signal will be showing on the 'scope than if the outer foil is connected to the ground side, as in this latter orientation the grounded shielding of the outer foil lessens this transmitted pickup.
As I suggested before, apart from the fact that generally-speaking higher voltage caps do perform better sonically in my experience than lower voltage similar caps, the differences I have observed are small enough that you can forget about voltage ratings in these instances as being a noticeable influencing factor.
Also, my guess is that the directionality in this case is not the culprit here, but one can never say for certain until you try out the changes, and I still see some surprises in such instances. Once in a while, and for reasons I don't understand, in one odd location, better subjective results have occured with caps 'reversed', but this is very rare.
A while ago I suggested to another Member who had sibilance problems with Black Gate caps to try damping them physically, as I know of old that this will have an effect here. He, and some others apparently, were quite amazed at what they found when trying this suggestion, and IIRC they were mostly people with conventional electronic engineering backgrounds, who admitted that they were sceptical initially and didn't expect such a difference was possible. I have found exactly the same with some film caps, incidentally, and this is always worth a try, too.
40 yrs or more ago, when I believed unreservedly that these issues were impossible, and I merely measured everything in conventional ways as this was the accepted doctrine in those days, I would probably have laughed at what I have since discovered. However, and you have touched on the matter, I certainly would not have been so overbearing as to consider it my duty to continually dictate to others about these issues, and I would have been quietly sceptical but with still keeping an open mind until I had discovered the truth of this for myself.
I am quite capable of 'holding my own' in any such discourses, but I simply detest the continual ill-informed bickering which frequently follows any of my 'exposures' of this nature, and look what happened recently when a chap asked a simple question on resistor substitution, with the final result being that his entire thread was sent to Texas. I didn't even pass any opinion or give any advice myself on resistors, but I felt very sorry for the guy concerned at what I knew from many earlier experiences would be the certain outcome there. Someone who seems to watch my moves like hawk, subsequently even tried to ridicule me personally, and said " shame on me". Why, but much more importantly, what must the thread-starter think about other people and their attitudes when this happens so frequently when anything of a subjective nature is posted?
Actually, after listening to upwards of 20 different source/emitter resistors in different amps over the years (and maybe 10 in one circuit alone), I can hear (albeit tiny) variations in their sonic effects and I have a preference which I will always use nowadays. I won't say so in a thread like that for obvious reasons, but I cannot run a mile in under 4 minutes like some can, because I discovered I had no natural aptitude nor ability in athletics, and I therefore didn't spend many years developing and honing methodologies, techniques and my skills in that arena.
It is so sad, and I just hope to goodness that what I have shared here in a sincere attempt at helping others based on many years of careful listening trials (which most will never get around to doing) might be of some interest, and will not be the start of any more trouble.
Regards,
I am not aware of any very simple way of determining the caps 'direction' as such without any test gear, and maybe thinking a bit more about this, the construction of the caps hasn't been commented upon either.
What appears to be (mainly) the determining factor in these cases, is discovering which lead is attached to the 'outer foil' of the cap when it was constructed. Most such film caps are made like a swiss-roll, with the plastic film being wound up in a roll, with either a separate metal film being interposed between the plastic films, or one side of the plastic film being 'metallised'. i.e coated with a metallic substance. Sometimes they are squashed (to bind everything together and help eliminate any air-pockets) to give an oval shape, and often the physically smaller types are enclosed in another outer plastic box. These caps are usually quite directional, simply because there is more shielding from the outermost foil, and this is generally placed at the lower impedance part in any circuit, for best sonics.
In shunt cases, this shielding is more effective when connected to ground, of course.
However, there are several other methods of construction, 'stacked-foil' being the obvious main type for film caps, but these are made like a pack of cards with lots of separate pieces of foil being laid face to face. These are not generally so easy to obtain any reliable measurements of this nature on, but fortunately, they don't appear to be very 'directional' in my experience. They are better for HF response generally, too, in view of their less-inductive properties, as with the earlier-mentiond RTXs which have no more inductance (it is reduced by paralleling 10 individual sections in each cap) than a single piece of wire of the same overall length.
Ceramics, which have no place in analogue audio circuits in my view (in spite of many others using them, apparently quite happily) and silver micas, as other examples don't seem to exhibit any directionality, but if you go into how they are manufactured, this is not so surprising.
Any way in which one can determine without any doubt which is the outer foil in the rolled-up caps, is just as valid as any other, I am sure, but simply out of habit, I generally stick to my own methodology here as referred to in my earlier post.
If you have a reasonable 'scope to use, I have also merely connected caps across a 'scopes leads before now, and simply moved the cap concerned close to a mains source like a live wire, or transformer, and have seen a 'direction' as a result of the signal pickup (normally to be avoided like the plague, in circuits, of course!) from the 50Hz, or 60Hz for you, mains frequency. If the outer foil is connected to the 'hot' probe, a larger signal will be showing on the 'scope than if the outer foil is connected to the ground side, as in this latter orientation the grounded shielding of the outer foil lessens this transmitted pickup.
As I suggested before, apart from the fact that generally-speaking higher voltage caps do perform better sonically in my experience than lower voltage similar caps, the differences I have observed are small enough that you can forget about voltage ratings in these instances as being a noticeable influencing factor.
Also, my guess is that the directionality in this case is not the culprit here, but one can never say for certain until you try out the changes, and I still see some surprises in such instances. Once in a while, and for reasons I don't understand, in one odd location, better subjective results have occured with caps 'reversed', but this is very rare.
A while ago I suggested to another Member who had sibilance problems with Black Gate caps to try damping them physically, as I know of old that this will have an effect here. He, and some others apparently, were quite amazed at what they found when trying this suggestion, and IIRC they were mostly people with conventional electronic engineering backgrounds, who admitted that they were sceptical initially and didn't expect such a difference was possible. I have found exactly the same with some film caps, incidentally, and this is always worth a try, too.
40 yrs or more ago, when I believed unreservedly that these issues were impossible, and I merely measured everything in conventional ways as this was the accepted doctrine in those days, I would probably have laughed at what I have since discovered. However, and you have touched on the matter, I certainly would not have been so overbearing as to consider it my duty to continually dictate to others about these issues, and I would have been quietly sceptical but with still keeping an open mind until I had discovered the truth of this for myself.
I am quite capable of 'holding my own' in any such discourses, but I simply detest the continual ill-informed bickering which frequently follows any of my 'exposures' of this nature, and look what happened recently when a chap asked a simple question on resistor substitution, with the final result being that his entire thread was sent to Texas. I didn't even pass any opinion or give any advice myself on resistors, but I felt very sorry for the guy concerned at what I knew from many earlier experiences would be the certain outcome there. Someone who seems to watch my moves like hawk, subsequently even tried to ridicule me personally, and said " shame on me". Why, but much more importantly, what must the thread-starter think about other people and their attitudes when this happens so frequently when anything of a subjective nature is posted?
Actually, after listening to upwards of 20 different source/emitter resistors in different amps over the years (and maybe 10 in one circuit alone), I can hear (albeit tiny) variations in their sonic effects and I have a preference which I will always use nowadays. I won't say so in a thread like that for obvious reasons, but I cannot run a mile in under 4 minutes like some can, because I discovered I had no natural aptitude nor ability in athletics, and I therefore didn't spend many years developing and honing methodologies, techniques and my skills in that arena.
It is so sad, and I just hope to goodness that what I have shared here in a sincere attempt at helping others based on many years of careful listening trials (which most will never get around to doing) might be of some interest, and will not be the start of any more trouble.
Regards,
Hi Bob,
I did get a laugh at one comment on the Resistor thread but it was like a kid fight in a school yard. I couldn't get anywhere with getting them to calm down. Don't pay any attention to any attack. They usually come from an "unhealthy place" anyway like insecurity.
I don't know what being sent to "Texas" means but if it is anything like being "Sent to Detroit" from "Kentucky Fried Movie" (hysterically funny), the piece called "A Fist Full of Yen," it can't be good!
I thought about it and I don't want you to run a 4 minute mile. However, think about designing that device and get a patent and market it (I can help with the patent and marketing, hint hint) and retire!
Thanks again for your educational instruction and especially because your intention is coming from the right place!
Regards//Keith
I did get a laugh at one comment on the Resistor thread but it was like a kid fight in a school yard. I couldn't get anywhere with getting them to calm down. Don't pay any attention to any attack. They usually come from an "unhealthy place" anyway like insecurity.
I don't know what being sent to "Texas" means but if it is anything like being "Sent to Detroit" from "Kentucky Fried Movie" (hysterically funny), the piece called "A Fist Full of Yen," it can't be good!
I thought about it and I don't want you to run a 4 minute mile. However, think about designing that device and get a patent and market it (I can help with the patent and marketing, hint hint) and retire!
Thanks again for your educational instruction and especially because your intention is coming from the right place!
Regards//Keith
Hi Keith,
Apologies to the thread-starter for this slight off-topic, but you did raise the subject.
I tried to retire around 18 mths. ago, but a high-end UK speaker manufacturer heard the results of some of my work when it was demonstrated at the UK's most prestigeous Audio Show in Heathrow, London, and I have been busier than ever since that time!
I have spent around a year on developing associated bespoke electronic circuit designs for them, because they couldn't find anything good enough to adequately show off their speakers.
Regards,
Apologies to the thread-starter for this slight off-topic, but you did raise the subject.
I tried to retire around 18 mths. ago, but a high-end UK speaker manufacturer heard the results of some of my work when it was demonstrated at the UK's most prestigeous Audio Show in Heathrow, London, and I have been busier than ever since that time!
I have spent around a year on developing associated bespoke electronic circuit designs for them, because they couldn't find anything good enough to adequately show off their speakers.
Regards,
Thanks BobKen
Bob,
Thank you ever so much for sharing your experience and insights into an area (I amongst others) are only dabbling. You have given me a lot to think about regarding capacitors, bypasses, and capacitor topologies.
After reading your last two messages, they have introduced a plethora of questions and problems that I and other DIYers may wish to consider before settling on a "capacitor solution".
I have strived to avoid "the best" or "better than" comparisons in my testing; nor have I ranked or rated caps. To me there are all too many factors that can determine best or better. I prefer to leave the actual preference to the reader and DIY implementer. I have tried to be as objective as I, humanly, can be. I have noted my biases and I would like to think this lets me off the hook for preferences.
My testing has been something I have enjoyed doing. Your definitive explanation of the science that is behind the caps is a tremendous help. You have given a foundation to a lot of the beliefs I had regarding these capacitors and especially bypassing.
I was very skeptical about the effects of bypassing a signal (coupling) capacitor. Although, skeptical (really on the approach of believing it to be snake oil) I have heard a difference that I do find pleasurable. The acid test for me is to take the various bypass caps out of the circuit one at a time to try and discern what is being augmented by the cap - by removing that augmentation. This allows my mind and ears to focus on the difference if notable. Thus allowing me to try to put into words the difference.
Your outer foil test with the scope is something I want to try out. I want to as best I can compare apples to apples and this test my allow me to refine methodology.
Bob,
Thank you ever so much for sharing your experience and insights into an area (I amongst others) are only dabbling. You have given me a lot to think about regarding capacitors, bypasses, and capacitor topologies.
After reading your last two messages, they have introduced a plethora of questions and problems that I and other DIYers may wish to consider before settling on a "capacitor solution".
I have strived to avoid "the best" or "better than" comparisons in my testing; nor have I ranked or rated caps. To me there are all too many factors that can determine best or better. I prefer to leave the actual preference to the reader and DIY implementer. I have tried to be as objective as I, humanly, can be. I have noted my biases and I would like to think this lets me off the hook for preferences.
My testing has been something I have enjoyed doing. Your definitive explanation of the science that is behind the caps is a tremendous help. You have given a foundation to a lot of the beliefs I had regarding these capacitors and especially bypassing.
I was very skeptical about the effects of bypassing a signal (coupling) capacitor. Although, skeptical (really on the approach of believing it to be snake oil) I have heard a difference that I do find pleasurable. The acid test for me is to take the various bypass caps out of the circuit one at a time to try and discern what is being augmented by the cap - by removing that augmentation. This allows my mind and ears to focus on the difference if notable. Thus allowing me to try to put into words the difference.
Your outer foil test with the scope is something I want to try out. I want to as best I can compare apples to apples and this test my allow me to refine methodology.
Some very nice posts Bobken, thank you.
With less experience, and most of that concerned with crossover capacitors, I, nonetheless, will be so bold as to add that my listening comparisons are not useful without the capacitors being run in.
When newly installed, the most common symptoms are usually harshness and often a "thin" spectral balance. Forty hours seems to be a good rule of thumb, although various caps differ quite a bit in the breakin time needed.
One capacitor that we used as the mid highpass was markedly directional. A higher voltage, metallized construction, unit it was only available up to 10 uF, and 100 uF was needed. Ten parallel units, with five installed in each direction was a surprisingly neutral solution; the colorations cancelled to our gratified surprise.
With less experience, and most of that concerned with crossover capacitors, I, nonetheless, will be so bold as to add that my listening comparisons are not useful without the capacitors being run in.
When newly installed, the most common symptoms are usually harshness and often a "thin" spectral balance. Forty hours seems to be a good rule of thumb, although various caps differ quite a bit in the breakin time needed.
One capacitor that we used as the mid highpass was markedly directional. A higher voltage, metallized construction, unit it was only available up to 10 uF, and 100 uF was needed. Ten parallel units, with five installed in each direction was a surprisingly neutral solution; the colorations cancelled to our gratified surprise.
Rob M said:
Hi Rob,
You didn't miss anything here, including my obvious mistake.
Just delete the word "grounded" from that sentence so that it now reads "as in this latter orientation the shielding of the outer foil lessens this transmitted pickup."
Regrettably, I couldn't have been thinking so carefully when I wrote about that method, but this incorrectly added single word doesn't affect anything else I said there. I probably had in mind that in actual audio circuits it is better to have the outer foil grounded, or at the lower ground potential side, for the best sonic results.
A better and entirely positive method for measuring all such caps was referred to by me in an earlier post in this thread, if you are interested in this, although this method suggested here does work in some instances.
Regards,
Hi Bob,
You wouldn't be working with Stewart Tyler? It is from his company that I have a nice pair of Studio Monitors and I love them.
Obviously, being rudely interrupted in your retirement to design crossovers (because nothing was available) deserves a little respect too. What a gift to have you in this thread! Don't worry about changing the subject here, Dave is a great guy too!
Regards//Keith
You wouldn't be working with Stewart Tyler? It is from his company that I have a nice pair of Studio Monitors and I love them.
Obviously, being rudely interrupted in your retirement to design crossovers (because nothing was available) deserves a little respect too. What a gift to have you in this thread! Don't worry about changing the subject here, Dave is a great guy too!
Regards//Keith
Hi Dave,
It is often a bit dangerous to say which caps are better or always preferred, as this can vary a bit with applications, and there are different attributes to them all which may or may not suit a particular application.
However, by far the most transparent and seemingly neutral-sounding (which I find hard to identify in a direct comparison with a straight wire) are the Teflon V-Caps. Probably second in my usual choice would be the Teflon film MIT Exotica TFT, and then some other no-name Teflons I have tried.
After that, and a bit lower down the 'goodness' scale would be MIT RTXs (mentioned before) which are polystyrene and tin foil, but they have this unusual internal makeup of 10 individual caps in parallel. Mundorf Supreme Silver/oil are about in the same league as these MITS, but I have not done a true side-by-side comparison between these and RTXs in any circuit (yet!), so I cannot state any clear preference.
I used to purchase RTXs by the hundred, so I still have a lot of these to play with until they get used up!
Some non-magnetic silver-micas are good for low (pF) values, especially as they are virtually non-inductive giving a good HF performance, and they are good for RF circuits.
Then my ranking for 'non-specialist' caps is much the same as I discovered well over 30yrs ago, although I don't use these nowadays, unless for some obscure reason there is no alternative.
Polystyrene (the extended foils are usually better), Polypropylene, Polycarbonate (hardly ever seen nowadays), and lastly Polyesters.
I don't share the apparent enthusiasm that others do for Auricaps, unfortunately, and I think this is due to being made from Polypropylene. The Polypropylene caps I have tried are all generally too 'coloured' and lacking in overall transparency for my tastes, but Auricaps have a newish Teflon film cap in their range, which I guess might be quite good.
Regards,
It is often a bit dangerous to say which caps are better or always preferred, as this can vary a bit with applications, and there are different attributes to them all which may or may not suit a particular application.
However, by far the most transparent and seemingly neutral-sounding (which I find hard to identify in a direct comparison with a straight wire) are the Teflon V-Caps. Probably second in my usual choice would be the Teflon film MIT Exotica TFT, and then some other no-name Teflons I have tried.
After that, and a bit lower down the 'goodness' scale would be MIT RTXs (mentioned before) which are polystyrene and tin foil, but they have this unusual internal makeup of 10 individual caps in parallel. Mundorf Supreme Silver/oil are about in the same league as these MITS, but I have not done a true side-by-side comparison between these and RTXs in any circuit (yet!), so I cannot state any clear preference.
I used to purchase RTXs by the hundred, so I still have a lot of these to play with until they get used up!
Some non-magnetic silver-micas are good for low (pF) values, especially as they are virtually non-inductive giving a good HF performance, and they are good for RF circuits.
Then my ranking for 'non-specialist' caps is much the same as I discovered well over 30yrs ago, although I don't use these nowadays, unless for some obscure reason there is no alternative.
Polystyrene (the extended foils are usually better), Polypropylene, Polycarbonate (hardly ever seen nowadays), and lastly Polyesters.
I don't share the apparent enthusiasm that others do for Auricaps, unfortunately, and I think this is due to being made from Polypropylene. The Polypropylene caps I have tried are all generally too 'coloured' and lacking in overall transparency for my tastes, but Auricaps have a newish Teflon film cap in their range, which I guess might be quite good.
Regards,
KP11520 said:
Hi Keith,
No it isn't Stewart Tyler, although I know of his work, and it was through Stewart many years ago that I first became acquainted with the excellent ATC drivers, especially their mid-dome units, which I currently use in one set of my speakers.
To save another question (as I am under an NDA, anyway, and cannot answer you) it isn't ATC either, although I have had quite bit to do with that company from time to time, and have spent some entertaining hours at their works.
Interestingly, maybe 30 yrs ago, I spoke to their chief tech guy, from memory one Tim Isaac (?), and tried to persuade him to try polypropylene caps instead of their 'usual' electrolytics, to improve the sonic results in their passive X'overs. He didn't wish to know then, and maybe I can understand why with greater costs, and physically larger caps etc., to accomodate for, and in those days my comments would have been seen as heresy. Last time I was at ATC and went around their various departments, I noticed that they were using all polypropylene caps in the various X'overs which were laying around!
Also, I am not responsible for the speakers or even the X'overs at the company which I mentioned, as that is very capably handled by another very talented and forward-thinking designer.
My involvement has been to develop all of the electronic circuits from front-end to amps which are primarily being used in the testing and demonstrating of their speakers, and which will probably be marketed sometime later this year.
Regards,
Curmudgeon said:Some very nice posts Bobken, thank you.
With less experience, and most of that concerned with crossover capacitors, I, nonetheless, will be so bold as to add that my listening comparisons are not useful without the capacitors being run in.
When newly installed, the most common symptoms are usually harshness and often a "thin" spectral balance. Forty hours seems to be a good rule of thumb, although various caps differ quite a bit in the breakin time needed.
Hi,
I couldn't agree more with your commments here, and I'll add another one.
Some caps can take up to weeks or months before they cease these small changes, and this can be extremely aggravating on occasions as just once-in-a-while the changes are not what is needed. Where developing passive x'overs is concerned, this can require further work to get the overall 'voicing' back to what is desired.
Having unwittingly monopolised this thread with these answers in the last few posts, I will duck out of this thread for now.
Regards, and good luck with these trials.
Hi Curmudgeon,
I know there are a lot of posts here on this thread but burning in the caps has been done by Dave since the beginning. I think he burned in most for hundreds of hours each before any evaluations were made. Panomaniac suggested an easy circuit to build to accomplish this. I made one too so when I tested the caps, burn-in time, would not cloud the impressions. I could go from one to another with them already sounding like what they would normally settle to eventually.
Check it out and read this thread from the beginning, you may choose to build one too! You will also see that Dave has done a nice job explaining his impressions! Also there has been a lot of help from posters like Bob, you, etc.
Sorry Bob, good info is not a monopoly!
Regards//Keith
I know there are a lot of posts here on this thread but burning in the caps has been done by Dave since the beginning. I think he burned in most for hundreds of hours each before any evaluations were made. Panomaniac suggested an easy circuit to build to accomplish this. I made one too so when I tested the caps, burn-in time, would not cloud the impressions. I could go from one to another with them already sounding like what they would normally settle to eventually.
Check it out and read this thread from the beginning, you may choose to build one too! You will also see that Dave has done a nice job explaining his impressions! Also there has been a lot of help from posters like Bob, you, etc.
Sorry Bob, good info is not a monopoly!
Regards//Keith
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