[Eeyore]

Re the performance of aluminium electrolytic caps for audio coupling in a zero
bias situation.


I've observed, indeed I first heard of it decades back, that provided the signal

*across* the capacitor doesn't exceed about 100mV ac there is no measureable
non-linearity. I've confirmed this using Audio Preciosn test gear which measures

down to 0.0008% THD (-102dB). Hence if the value of the cap is such that 100mV
is never exceeded, there will be no distortion contribution from the cap. I've
also confirmed that if the 100mV is exceeded, you do indeed get distortion.

The mechanism seems to be electrolytic rectification AIUI. I presume that the
absence of any effect below ~ 100mV is due to the 'forward' voltage of this
rectifier, and current only flows when it's exceeded.

Any more thought on this ?

I did find this page about electrolytic rectification btw.
http://home.earthlink.net/~lenyr/borax.htm

The oscillograms are rather interesting.

Graham

[GregS]

In article , Eeyore wrote:
Re the performance of aluminium electrolytic caps for audio coupling in a zero
bias situation.


I've observed, indeed I first heard of it decades back, that provided the
signal

*across* the capacitor doesn't exceed about 100mV ac there is no measureable
non-linearity. I've confirmed this using Audio Preciosn test gear which
measures

down to 0.0008% THD (-102dB). Hence if the value of the cap is such that 100mV
is never exceeded, there will be no distortion contribution from the cap. I've
also confirmed that if the 100mV is exceeded, you do indeed get distortion.

The mechanism seems to be electrolytic rectification AIUI. I presume that the
absence of any effect below ~ 100mV is due to the 'forward' voltage of this
rectifier, and current only flows when it's exceeded.

Any more thought on this ?

I did find this page about electrolytic rectification btw.
http://home.earthlink.net/~lenyr/borax.htm

The oscillograms are rather interesting.

I have always wondered how much AC across a cap will depolarize it,
and exactly how NP caps maintain integrety.

greg

[Eeyore]

GregS wrote:

In article , Eeyore wrote:
Re the performance of aluminium electrolytic caps for audio coupling in a zero
bias situation.


I've observed, indeed I first heard of it decades back, that provided the
signal

*across* the capacitor doesn't exceed about 100mV ac there is no measureable
non-linearity. I've confirmed this using Audio Preciosn test gear which
measures

down to 0.0008% THD (-102dB). Hence if the value of the cap is such that 100mV
is never exceeded, there will be no distortion contribution from the cap. I've
also confirmed that if the 100mV is exceeded, you do indeed get distortion.

The mechanism seems to be electrolytic rectification AIUI. I presume that the
absence of any effect below ~ 100mV is due to the 'forward' voltage of this
rectifier, and current only flows when it's exceeded.

Any more thought on this ?

I did find this page about electrolytic rectification btw.
http://home.earthlink.net/~lenyr/borax.htm

The oscillograms are rather interesting.

I have always wondered how much AC across a cap will depolarize it,

If it's got a DC polarising voltage applied, basically you can't.


and exactly how NP caps maintain integrety.

The NP caps work by leaking enough initially to build up a charge on both 'halves' so that they end up
'self-biasing' themselves. They are no diferent to a 'back-to-back' pair of ordinary electrolytics.

Graham

[Ian Iveson]

Eeyore wrote

Re the performance of aluminium electrolytic caps for audio coupling
in a zero
bias situation.


I've observed, indeed I first heard of it decades back, that
provided the signal

*across* the capacitor doesn't exceed about 100mV ac there is no
measureable
non-linearity. I've confirmed this using Audio Preciosn test gear
which measures

down to 0.0008% THD (-102dB). Hence if the value of the cap is such
that 100mV
is never exceeded, there will be no distortion contribution from the
cap. I've
also confirmed that if the 100mV is exceeded, you do indeed get
distortion.

The mechanism seems to be electrolytic rectification AIUI. I presume
that the
absence of any effect below ~ 100mV is due to the 'forward' voltage
of this
rectifier, and current only flows when it's exceeded.

Any more thought on this ?

I did find this page about electrolytic rectification btw.
http://home.earthlink.net/~lenyr/borax.htm

The oscillograms are rather interesting.

Graham


Most of the differences between cap types occurs outside the grasp of
your inadequate instrumentation and test methodology.

Distortion increases with bias.

Bipolar electrolytics can be as good as plastic film for audio
purposes.

Stop clutching straws and do some proper reading.

Ian

[Eeyore]

Ian Iveson wrote:

Most of the differences between cap types occurs outside the grasp of
your inadequate instrumentation

Audio Precision test equipment is inadequate ? Do tell who makes better !
www.ap.com


and test methodology.

I haven't said anything much about my 'test methodology'. Not much to say
really.


Distortion increases with bias.

Distortion increases with signal level with unbiased electrolytics. DC biased
electrolytics don't distort AFAIK ( I haven't measured to make sure becasue that
wasn't my area of interest at the time).


Bipolar electrolytics can be as good as plastic film for audio
purposes.

Absolute garbage. Film caps don't distort at all at any practical signal level.
NPs do. Considerably so.


Stop clutching straws and do some proper reading.

Damn.... you're one cluless ****wit. No one else manages to get everything wrong
quite as predictably as you do.

Graham

[Eeyore]

Soundhaspriority wrote:

Maybe both of you are wrong.

Iveson's an utter idiot. He can't even get basics right !


You both seem to lack humility. You both demand that strangers accept your
conclusions.

I'm met too many idiots to bother spending any time being humble to them any
more. They drive me nuts (almost quite literally once). Idiot is as idiot does.

Graham

[Laurence Payne]

On Tue, 1 May 2007 22:26:51 -0400, "Soundhaspriority"
wrote:

Graham, we should be humble towards everyone. Lack of intelligence is not a
reason for disrespect.

Sure it is. Disrespect for the person's opinions, at any rate.

[John Phillips]

On 2007-05-02, Ian Iveson wrote:
Most of the differences between cap types occurs outside the grasp of
your inadequate instrumentation and test methodology.

Distortion increases with bias.

Bipolar electrolytics can be as good as plastic film for audio
purposes.

Stop clutching straws and do some proper reading.

Ian - in a related thread I mentioned that I had done some searching and
had found little on nonlinear distortion in capacitors. I would be very
interested in some references.

--
John Phillips

[Arny Krueger]

"Ian Iveson" wrote in
message
news
Eeyore wrote

Re the performance of aluminium electrolytic caps for
audio coupling in a zero
bias situation.


I've observed, indeed I first heard of it decades back,
that provided the signal

*across* the capacitor doesn't exceed about 100mV ac
there is no measureable
non-linearity. I've confirmed this using Audio Preciosn
test gear which measures

down to 0.0008% THD (-102dB). Hence if the value of the
cap is such that 100mV
is never exceeded, there will be no distortion
contribution from the cap. I've
also confirmed that if the 100mV is exceeded, you do
indeed get distortion.

The mechanism seems to be electrolytic rectification
AIUI. I presume that the
absence of any effect below ~ 100mV is due to the
'forward' voltage of this
rectifier, and current only flows when it's exceeded.

Any more thought on this ?

I did find this page about electrolytic rectification
btw. http://home.earthlink.net/~lenyr/borax.htm

The oscillograms are rather interesting.

Most of the differences between cap types occurs outside
the grasp of your inadequate instrumentation and test
methodology.

And your suggested alternative is?

Distortion increases with bias.

Absolutely bass-ackwards.

Bipolar electrolytics can be as good as plastic film for
audio purposes.

This correlates with your other statements, how?

Stop clutching straws and do some proper reading.

Doctor, cure thyself.

[Arny Krueger]

"Soundhaspriority" wrote in message

"Eeyore" wrote
in message ...


Ian Iveson wrote:

Most of the differences between cap types occurs
outside the grasp of your inadequate instrumentation

Audio Precision test equipment is inadequate ? Do tell
who makes better ! www.ap.com


and test methodology.

I haven't said anything much about my 'test
methodology'. Not much to say really.


Distortion increases with bias.

Distortion increases with signal level with unbiased
electrolytics. DC biased
electrolytics don't distort AFAIK ( I haven't measured
to make sure becasue that
wasn't my area of interest at the time).


Bipolar electrolytics can be as good as plastic film
for audio purposes.

Absolute garbage. Film caps don't distort at all at any
practical signal level.
NPs do. Considerably so.


Stop clutching straws and do some proper reading.

Damn.... you're one cluless ****wit. No one else manages
to get everything wrong
quite as predictably as you do.

Graham

Maybe both of you are wrong. You both seem to lack
humility. You both demand that strangers accept your
conclusions.

If irony killed... !!!!!!!!!!!

[Ian Iveson]

Soundhaspriority wrote

Stop clutching straws and do some proper reading.

Damn.... you're one cluless ****wit. No one else manages to get
everything wrong
quite as predictably as you do.

Graham

Maybe both of you are wrong. You both seem to lack humility. You
both demand that strangers accept your conclusions.

Moi?

I suggested he does some proper reading. That's a long way from
telling anyone to accept my conclusions.

Humble apologies, of course, if it seemed otherwise.

And for the intrusion, strangers. I'll go away now.

cheers, Ian

[Ian Iveson]

John Phillips wrote

Ian - in a related thread I mentioned that I had done some searching
and
had found little on nonlinear distortion in capacitors. I would be
very
interested in some references.

This may be a useful starting point, and gives a few references:

http://sound.westhost.com/articles/capacitors.htm

But nothing on the net is error-free and unbiased.

The series of articles in Electronics World by Cyril Bateman seems to
be widely cited. I haven't found a serious critique of it,
unfortunately, because it raised a few questions in my mind. I don't
think it's available for free and I've lost mine.

I posted a very crude resume to rec.audio.tubes ages ago, only to be
savaged by a monkey with a posh machine.

I came here by accident. Oops.

cheers, Ian

[Eeyore]

John Phillips wrote:

On 2007-05-02, Ian Iveson wrote:
Most of the differences between cap types occurs outside the grasp of
your inadequate instrumentation and test methodology.

Distortion increases with bias.

Bipolar electrolytics can be as good as plastic film for audio
purposes.

Stop clutching straws and do some proper reading.

Ian - in a related thread I mentioned that I had done some searching and
had found little on nonlinear distortion in capacitors. I would be very
interested in some references.

From Ian ?

LOL !

Graham

[Eeyore]

Ian Iveson wrote:

Soundhaspriority wrote

Stop clutching straws and do some proper reading.

Damn.... you're one cluless ****wit. No one else manages to get
everything wrong quite as predictably as you do.

Maybe both of you are wrong. You both seem to lack humility. You
both demand that strangers accept your conclusions.

Moi?

I suggested he does some proper reading.

Do please tell me what you read to come up with the nonsense you posted.

Graham

[Eeyore]

Ian Iveson wrote:

John Phillips wrote

Ian - in a related thread I mentioned that I had done some searching
and had found little on nonlinear distortion in capacitors. I would be
very interested in some references.

This may be a useful starting point, and gives a few references:

http://sound.westhost.com/articles/capacitors.htm

Please inspect the test method for appropriateness. It tests the capacitors with
90V ac applied across them ! That's about a thousand times more than they will
ever receive in an audio coupling application.

I find the test method questionable too.

Graham

[Arny Krueger]

"Eeyore" wrote in
message
Ian Iveson wrote:

Soundhaspriority wrote

Stop clutching straws and do some proper reading.

Damn.... you're one cluless ****wit. No one else
manages to get everything wrong quite as predictably
as you do.

Maybe both of you are wrong. You both seem to lack
humility. You both demand that strangers accept your
conclusions.

Moi?

I suggested he does some proper reading.

Do please tell me what you read to come up with the
nonsense you posted.

Reading Marsh and Jung can have that outcome, it seems.