Survey fun!

Just a guess :D

.01uf in parallel may act as a low pass for speaker, all high frequencies above some point will pass through capacitor.

i have done that in past but with 2200uf and the result was, capacitor absorbs high frequencies and bass was clear.

It may be a little dangerous because high frequencies are getting short for amplifier.

but i think frequency corresponding to .01uf will be very high and it should not damage a 10-25 watt amplifier.

Note : Just a Guess :D
 

BWRX

Ex-Moderator
2005-01-17 5:29 am
Pennsylvania
danielwritesbac said:
If the answer is application specific, I'd like to see specifics about real amplifiers that are currently in service.

Generally speaking, linear amplifiers do not like having capacitance directly at their output. I believe you are asking this question because you saw or read that the T-amp (class d) has small value capacitors directly across the outputs. This is OK for most class d amps because they have a LC lowpass filter between the switching output stage and the speaker in order to recover the audio signal. That cap across the output is effectively in parallel with the C of the LC filter, and its only purpose is to provide some more RF filtering at the point where the speaker wires exit the chassis.
 
That was interesting!
Howabout this?
 

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A quote from Texas Instruments Filter Pro

The TI Filter Pro design software has this to say about capacitors.
Keep in mind that capacitors generally have a wider tolerance. For this reason, when precision is desired, buy precision capacitors, or enter measured values

Texas Instruments doesn't mean a capacitance-only measure if they direct you towards "precision capacitors."

Measures for capacitors:
Capacitance
ESR
Speed/Signal/Ripple

It takes those three measures (at least) to employ a capacitor reliably.
For example, if an audiophile marketed capacitor and an economy capacitor match on all three measurements, then they will sound the same (not including bypass divisionals, component interreactions, and operating temperature).

ESR, and capacitor types, from lowest to highest:
(per same voltage rating)

Ceramic (lowest ESR)
Polypropylene
Electrolytic
P.E.T
(blend)
Mylar
(blend)
Polyester (highest ESR)

Lowest ESR types will almost-exactly match design software, however they are costly. Manufacturing specs, unless otherwise mentioned, are calibrated to least-cost components. See the conflict?

The T-amp cap appears to have a P.E.T-Mylar blend, scoring 3.5. That looks like a weird choice.

On the post above that is a polyester 50v cap, scoring 22; however, if that were a 100v version, you may expect from ESR 10 to 15.

For a polypropylene cap, you should expect ESR1 or less (best quality goes less ESR--much less).
If it is a greater figure than 1, then its either defective or an economy version; however, smaller physical sizes have higher ESR as a consequence of their size (usually indicates a lower voltage rating than advertised).

ESR is resistance during an AC signal, such as audio.
 
Piezo Tweeter

If this were ceramic, it would be known by a different name. . . Piezo Tweeter. Ceramic is very low ESR (very high efficiency), the safe operation of a Piezo Tweeter is to add at least 4 ohms in-series resistance to it, and so. . .

What type of capacitor from the chart above, does not require an additional in-series resistor, corresponds to one of the possible answers of the survey, and thus answers the survey?

This will also answer it: Which R is the largest value of RCR as illustrated by the E.S.R (note the R) meter?
 
One out of over 200

YES!!! Here we give a gold star for the highest grade in the class. ;)

Polyester 0.1uf 100v (and less) won't harm the amp.
It represents a 16 ohm tweeter with a 1st order crossover of 0.1uf and zero efficiency (no sound output of its own).
Specifically, its polyester's much wider than expected (sloppy) bandwith that's able to follow digital hetrodynes (any digital source adds that noise), and shunt them. . . at somewhat greater proportion than clean audio.

It also helps compensate for long speaker cables, and it can be used with additional in-series resistance (at a cost of being less effective), although none is required for polyester.

Of course I'd like to remove noise before it gets amplified. Vacuum tubes are more elegant for the job. But, polyester does several jobs at once for about 25 cents.

Anyway, thanks for the answer!
 

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Re: A quote from Texas Instruments Filter Pro

danielwritesbac said:

Measures for capacitors:
Capacitance
ESR
Speed/Signal/Ripple

It takes those three measures (at least) to employ a capacitor reliably.
For example, if an audiophile marketed capacitor and an economy capacitor match on all three measurements, then they will sound the same (not including bypass divisionals, component interreactions, and operating temperature).

ESR, and capacitor types, from lowest to highest:
(per same voltage rating)

Ceramic (lowest ESR)
Polypropylene
Electrolytic
P.E.T
(blend)
Mylar
(blend)
Polyester (highest ESR)

I am doing some testing of coupling capacitors for Tripath amps on another thread and I was referred to this thread. Your ranking based on ESR reflects quite accurately what I have been hearing in my test.

However, one poster has commented on the benefits of silver mica. Where would silver mica and polystyrene fit into the ESR rankings?

TIA
 

BWRX

Ex-Moderator
2005-01-17 5:29 am
Pennsylvania
Re: A quote from Texas Instruments Filter Pro

danielwritesbac said:
The TI Filter Pro design software has this to say about capacitors.

"Keep in mind that capacitors generally have a wider tolerance. For this reason, when precision is desired, buy precision capacitors, or enter measured values"

Texas Instruments doesn't mean a capacitance-only measure if they direct you towards "precision capacitors."

Actually they do... They leave it up to you to decide what kind of capacitor you want to use in your circuit. Obviously some types are better than other for certain applications.


danielwritesbac said:
Measures for capacitors:
Capacitance
ESR
Speed/Signal/Ripple

Speed = dV/dt Rating = largest change in voltage per unit of time the capacitor can reliably handle.

Signal = not sure what this is supposed to mean.

Ripple = Ripple Current Rating = how much ripple current the capacitor can reliably handle.


danielwritesbac said:
It takes those three measures (at least) to employ a capacitor reliably.

It really depends on the application and the design criteria.


danielwritesbac said:
For example, if an audiophile marketed capacitor and an economy capacitor match on all three measurements, then they will sound the same (not including bypass divisionals, component interreactions, and operating temperature).

Can you please share your proof of this with us?
 
Share the proof? On how it sounds?
Wow. That's one heck of a request!
Okay. You asked for it. ;)
But, on this topic, I can't go to either empirics or scientific measures because. . . Within the context of a hi-fi audio amplifier as a device to please ears, then, empirics are a complete measure with no baseline, in stark contrast to incomplete scientific measures with no use. It is only when the two are in harmony that the amplifier is optimal.

So, for more-complete measuring. . .

Certainly this:
http://www.flippers.com/esrktord-form.html
*see especially, the many documents in the links

Probably this:
http://clientes.netvisao.pt/greenpal/evb1.htm
*because its available

See also Panasonic capacitors with model code beginning in ECW and ending in JB. Those are known to conform to both empiric and scientific use. . . simultaneously. In my opinion, I offer it for consideration because of this stunning correlation at such a low price.
http://www.diyaudio.com/forums/showthread.php?postid=1201802#post1201802
Wise indeed! ;)

While the price is low and performance high, its possible (likely) that the manufacturer of a chip may have specificed a "lower" cost component (capacitor) for the design specifications.
So, if expected results don't happen, one would believe that the cure is to add additional in-series resistance in order to partially duplicate the expected performance of the capacitor in the chip manufacturer's documentation.
That's the simplest way to compensate so that the capacitors effects occur on the intended frequency--although there's probably much more elegant ways to do that. I have no idea.
 
Capacitor Sound Studies

Davet said:


I am doing some testing of coupling capacitors for Tripath amps on another thread and I was referred to this thread. Your ranking based on ESR reflects quite accurately what I have been hearing in my test.

However, one poster has commented on the benefits of silver mica. Where would silver mica and polystyrene fit into the ESR rankings?

TIA

So let's help the Tripath guys with the one idea I do have.
I'm not an expert, but I am doing my very best to produce solid proof and stay firmly within the boundries of where science and empirics are in harmony.
I would sincerely appreciate it if folks wiser than myself review the work to resolve any errors and to expand further with specific examples of how science and empirics can be brought together (the highest achievement for applicable results) within the context of a high-fidelity audio amplifier.

Thanks guys!
Shortly, I'll be over my head so that I should not continue the topic; however, I think I've spotted the problem with the empiric capacitor test, and I'll do my best to illustrate it within the context of ESR and capacitive divisionals (where one capacitor may directly or near-directly send a signal to another to cause the effects of more or less capacitors than are present).

I believe he's comparing a large collection of capacitors on an amplifier with an incomplete input circuit. That isn't hardened against interreaction with the source.

The various ESR of the different capacitors is also changing resistor Rb (in series resistance of the input circuit) every time he compares capacitors.
That change in bandwidth (rocketing up and down all over the scale) will foil empiric studies or at least make it very confusing.

If an ESR meter is available, add resistors to make all of the capacitors compared in the empiric study. . . read out all exactly the same ESR. Use only capacitors that have been exposed to voltage for some time (I don't know how long).

If an ESR meter isn't available, add a resistor of at least 2.2k in-between C and Rin (between the cap and the potentiometer).
That will make the varying ESR less significant.
The figure of 2.2k is a guess. Could someone please provide a more exact figure for when source materials are assumed worst-case scenerio?

------------

If a potentiometer is in use, it must be set at exactly the same position during the comparisons. Otherwise its materials *may* act as a variable filter that may or may not conduct capacitive divisionals from the source, which is a possible effect that, if present, is certain to invalidate the empiric study of capacitors.
"Don't touch that dial!" ;)

What we need is a study of a single effect, 1 at a time, be it empiric or scientific, involving ears, or not--just one effect at a time. Then, we need to measure the effects to find out why--just one at a time. Otherwise its pretty far over my head.
The study, as illustrated to me, has 3 effects at once, if not more.

So, I have proposed to add a significant, fixed, in-series resistance so that there is less audiable effect from ESR and also less effect from variance of sources--a "hardening" of the input circuit. This has reduced the number of different effects, but we need to get them all.

Let's make absolutely sure of it.
To do this, we further isolate the amplifier from interreactance with the source (both contain capacitors or at least capacitive elements).

I sincerely hope that those wiser than myself can come up with a more elegant solution than this, but here is what I have as an available solution.

We put a lousy conductor or an inductor in-between the amplifier and the source to stop/reduce capacitive divisionals that could invalidate the empiric studies of capacitors.

When one leg of a capacitor touches another, there is one obvious possible source of trouble. But, this effect also happens when a capacitor has inbuilt divisionals (all do to *some* extent) that create a signal in addition to the audio. This is passed into another capacitor whereby all sorts of summing and cancellations occur.
A poor conductor or an inductor is marginally helpful at hardening the input circuit to prevent this problem--just because it makes a poor connection. I'm sorry that its the best idea I have to offer at this time.

Some people have used cat5 pairs to resolve the problem, despite the reduction of detail, it also wiped out unwanted harmonic effects. Personally, I dislike this option.

Some have gone through a large collection of potentiometers to find the one that filters nicely and/or is better at conducting unwanted signals to ground rather than passing them.

In contrast, some go for the best conductors possible and believe that any divisionals are extra detail because they have either added chords or amplified them out of proportion. OR, with luck and money, they have selected a perfectly matched source for their amplifiers. As you can see, that "extra detail" approach is the opposite needed for the empiric studies of the sounds of capacitors, and an amplifier built this way will not respond to traditional attempts at regulating its tonality.

I sincerely hope the owners of such amplifiers aren't Egyptian. In the case of a nearby black-n-white Bast cat exposed to any form of pain, including ultrasonics, the lawful penality for the human criminal, should provide interesting reading, if one likes horror genre.

Just because the average adult male cannot hear ultrasonics and just because the wavelength may be too tight for the measuring equipment to resolve, still doesn't mean its okay for audiophile equipment to cause pain to women, children, and pets.

I hope that someone wiser than myself can resolve the following:
It seems that we're boxed in between the choice of masking detail, or providing extra detail with output that's not proportional to the source with additional risk of corrupting hearing.


You knew it was coming. . . that 2.2k resistor? Well, to make the studies of capacitor sounds valid, it needs to be a poorer conductor than metal. What material is that? Its carbon. Metal, a better conductor, would invaidate the study by allowing possible interreactance from the source to pass into the amplifier to a greater extent.

Finally, results of capacitor studies have not yet been measured. I wish that someone would fully measure each percieved capacitor effect, as seen within a professional "hardened" input circuit, and also list each capacitor's perceived effects together with its full measurements.
If both sets of data can be fully measured and synchronized, then we have empirics and science in harmony--the ability to predict sound by measure.

I don't own the remaining meters necessary, can't quite afford the collection of capacitors necessary, and don't have matching empiric data for the capacitors to use for associating the scientific measurements to a meaningful use.
SO, my ability to continue the topic is at an end.
I've done the best I could.
Can someone please contribute the remaining information?


Thank you so much for the input and examples. I have tripped upon much of the topics by error--as in searching for a solution to a problem that I had caused. Lately, it (my error in need of a solution) was combining a chipamp.com amplifier directly to a Soundblaster X-fi source and achiving a car-horn coloration. Much research later, I learn to either buy a preamp or simply isolate the amplifier from interreactance with the source.

It would be much nicer to do the research when not faced by an immediate need. Oh well.

Thanks again!!
 

Bobken

Member
2002-12-23 11:22 pm
UK
Re: Re: A quote from Texas Instruments Filter Pro

Davet said:


I am doing some testing of coupling capacitors for Tripath amps on another thread and I was referred to this thread. Your ranking based on ESR reflects quite accurately what I have been hearing in my test.

However, one poster has commented on the benefits of silver mica. Where would silver mica and polystyrene fit into the ESR rankings?

TIA

Hi,

There are a couple of points to bear in mind here which might add to this picture.

The ESR of caps is not usually linear as it varies with frequency, and if you look at graphs of impedance-v-frequency, mostly they will show a strong curve. These curves will also vary in shape and severity, usually commencing with a higher figure at LF and with a 'dip' being seen at a higher mid-frequency, but after the dip the curve rises steeply again at VHF.
So comparing alternative caps based merely on data-sheet specs can be misleading if accurate comparisons of ESR are involved. It will all depend upon the frequency of interest and with audio this is quite a large spread, so what might seem better at LF might be worse at HF, or vice versa.

Also, as resistors are generally not considered to be frequency-dependent in operation (when used normally) I don't believe that it is possible to replicate the ESR effects from one cap to another by adding resistors in series to caps, if this is what is being discussed here.

Having seen some measurements taken with very sensitive equipment, the measured distortion (which is more significant than, but almost certainly related to DA and probably ESR) in 'average' silver micas is similar to that of 'average' polystyrenes, but silver micas do show a little more THD. This can vary from make-to-make, though, so it is quite possible that some better sil micas might measure lower in distortion than some polystyrenes.

Regards,