|26th January 2008, 08:53 PM||#21|
So, the ESR can vary by frequency?
Does this explain the "bypass cap" practice, and, if so, why wouldn't one want the widest bandwidth cap, polyester (popular bypass-cap in loudspeakers), for that purpose?
Oh! Is that bandwidth unnecessary because a bypass cap at 10% (the usual practice?) will cascade divisionals evenly by octave until its value is equal to the main cap? That topic gets me confused, so its a lot of trouble to me. I'd rather be able to employ it than work against it. Can you clarify it?
I had avoided those topics because I don't have the measuring equipment to photograph in operation (someone would ask), and because I don't understand exactly how to select the main cap and the bypass cap.
Thank you for adding necessary parts to the discussion, and its understandable too! This is thrilling!
P.S. Perhaps we could make a start on predicting the sounds of capacitors with the popular value performers, and demonstrate through measuring, how they sound?
I'd like that because it could subtract/reduce trial&error guesswork in cap selection.
It seems that my ESR meter needs an upgrade--switch to deliver its ac pulse into bass, or midband, or treble of the audio band. Is that a step in the right direction?
|26th January 2008, 10:24 PM||#22|
Empiric data validation
It was 2.2k in-series resistor positioned in-between the potentiometer and the input filter cap for empiric comparison testing varities of capicitors for their effects on sound.
I thought that the vast differences in sources needed isolation away from the discussion topic of capacitor sound effects.
Problem: There is no isolation between the documented signals (recordings) and the usually undocumented, always dissimilar, source equipment producing it.
So, howabout 2.2k? Is that a good start?
Given the scenerio, do you think that this is helpful to reduce "external factors" that may interfere in the empiric testing of capacitor sounds?
I think that we'll need those studies to be easily duplicable in order to make up a chart or database so that a particular sound effect can be firmly associated with a particular scientific measure.
I mean, let's make it predictable.
For those comparing capacitors along with their peers who may or may not have a potentiometer, a mild load, say 100k (no idea) can be substituted instead of a potentiometer, but I do believe that you need a load at this point.
Someone please correct and/or elaborate? Thanks!!
|26th January 2008, 11:30 PM||#23|
Join Date: Dec 2002
Until around 35 yrs ago, I simply measured everything, and (wrongly it later turned out) I assumed that measurements would tell me the whole story here, and that if a component measured in the same way as another component, it should have the same effect on the sound.
Having then accidentally discovered certain sonic effects which didn't seem to be explained by measurements alone, I have spent the intervening years in carrying out careful listening trials on every imagineable electronic component. As time went by, it appeared that certain measurable capacitor parameters like DA and perhaps ESR etc., had a large bearing on the sonic differences I observed, but they didn't fully explain all that was happening to my satisfaction, unfortunately.
There probably are more parameters which may be capable of measurements and quantification involved in these phenomena, but so far I haven't discovered what these might be, and I urge others to pursue this avenue. I openly admit that even after all this time, I am still learning new things about this fascinating and not well-understood area of circuit development, and this is reward enough to encourage me to continue with my experiments while I still can.
As I have no real proof about some of these sonic effects, I am obliged to use some inspired guesswork for their reasoning, but that is all that I have to rely on in my continuing efforts to obtain the best sonic results from various circuits which I have been working on. My gut feelings are that much of the missing 'information' is related to the quality of materials used, and the care taken in manufacture of components, but there may be other issues at work here. There are definite characteristics which are shared across various materials used in the making of components, and I can usually recognise these family likenessess quite readily if a new (to me) component comes my way for some trials
It is my long-term experience that the only way to obtain the finest possible results is through practical trials and by actual listening tests, and that is what I spend a lot of my time on as I don't have much alternative, regrettably, and I am now getting beyond my 'sell-by date'.
I have now reached the stage in life where I simply accept what I hear whether it is explicable or not, and I don't agonise over these still unexplained effects like I used to, although I do still spend a lot of my time on various measurements related to components and to entire audio circuits. The fact that these sonic effects are repeatable, reversible, and consistent, and that some others reach very similar conclusions quite independently, is sufficient indication to prove to me that they are not illusiory, in spite of what the majority of audio enthusiasts would have one believe.
Regrettably, I cannot clarify matters much more than this, but seeing some of your comments concerns me a little, as I don't believe that this area is an exact science, as I think you hope it will be, and it may be impossible to quantify all that can be heard with these trials. After being around for so long, I have realised that some things in life are just not capable of being quantified and/or justified, and one has to live with this, like it or not. These effects are usually very subtle, and this is not an easy and straightforward area like say mathematics where if the equation is solved correctly, there is always only one right answer to whatever is under consideration.
Our ears (or some of our ears, anyway) are remarkably sensitive organs, and the subtleties involved for example in assessing the differences in sounds between a Strad violin, and another fine-sounding similar instrument, may not be measurable, but anyone accomplished with playing such an instrument will be able to tell them apart in just a few seconds.
Finally, in attempting to answer one of your questions, of course I will always attempt to minimise all other external influences which can affect any subjective judgements, and I often attempt to exaggerate any potential effects by adding a string of similar parts together (even if unnecessary for the circuit concerned) in the hope of making any potential sonic differences easier to observe.
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