Bipolar Caps

[Guest]

Archived from groups: rec.audio.pro (More info?)

Pooh Bear <rabbitsfriendsandrelations@hotmail.com> wrote:
>Scott Dorsey wrote:
>
>My understanding is that any rectification effects take place when an electrolytic has > 0.5 reverse V
>approx applied. It's easy to ensure this never happens in a coupling cap application - not least by
>the use of large values since the component of the signal appearing across the cap will be in the
>millivolt area.

I will buy that.

>Seems to work for the likes of Neve and SSL to mention a couple of high end names using electros with
>zero bias. Not to mention almost all pro-audio gear made.

Yes, agreed. But, I once changed the tantalums in a Neve channel strip out
for film caps, with large enough values to get good low end. Sounded very
clean and very nice to me. Everybody else in the studio also heard a change
in sound, and they all hated it and I was almost fired.

Clearly there was _something_ changing the sound about the tantalums, even
though they were all carefully biased.

>> >I'd like to see a rational reason posted for bypassing electros with film caps in coupling
>> >applications though.
>>
>> If the issue is high order harmonics being generated by small rectification
>> effects, a bypass capacitor will clean that up.
>
>Suggested value to bypass 100uF ?

I think the tradition is to use a bypass cap that is about 1/100th the value
of the electrolytic as a rule of thumb. I am not sure where that came from
or how it was derived.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

 

[Guest]

Archived from groups: rec.audio.pro (More info?)

Pooh Bear <rabbitsfriendsandrelations@hotmail.com> wrote:
>Paul Stamler wrote:
>
>> "Pooh Bear" <rabbitsfriendsandrelations@hotmail.com> wrote in message
>> news:41B0046E.450F6265@hotmail.com...
>> > DeserTBoB wrote:
>> >
>> > > On Thu, 02 Dec 2004 04:53:12 +0000, Pooh Bear
>> > > <rabbitsfriendsandrelations@hotmail.com> wrote:
>> > >
>> > > >I sometimes wonder about the condition of those NOS electros being sold
>> on ebay to gullible fools
>> > > >who think old parts are better than new. <snip>
>> > >
>> > > No need to wonder...they're "unformed" and instantly turn into a bomb
>> > > when B+ is applied.
>> >
>> > What has that to do with *coupling* caps ?
>>
>> Plenty, if the coupling caps are used on a single-supply circuit.
>
>I think the reference was to using them as supply 'bypass caps'.

As Paul points out, a supply bypass cap is directly in the audio path in
a single-ended circuit, and could arguably be considered a an audio coupling
cap if you wanted to get pedantic about it.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

 

[Guest]

Archived from groups: rec.audio.pro (More info?)

"Pooh Bear" <rabbitsfriendsandrelations@hotmail.com> wrote in message
news:41B0046E.450F6265@hotmail.com

> DeserTBoB wrote:

>> I was intrigued enough by this article to start doing some studies
>> with what bench gear I had at the time, and sure enough...my results
>> turned out identical to those in the article, with polyprops
>> distorting less than any other dielectric type tested.
>
> How were you measuring distortion ?

> How can you explain ployester/mylar 'distorting' ? I find this
> puzzling for any plastic film. I never saw a polyester cap distort
> when measured by an AP test set.

Agreed, based on measurements by other means, but with similar residuals.

 

[Guest]

Archived from groups: rec.audio.pro (More info?)

"Paul Stamler" <pstamlerhell@pobox.com> wrote in message
news:BoUrd.1021143$Gx4.993371@bgtnsc04-news.ops.worldnet.att.net
> "Pooh Bear" <rabbitsfriendsandrelations@hotmail.com> wrote in message
> news:41B0046E.450F6265@hotmail.com...
>> DeserTBoB wrote:
>>
>>> On Thu, 02 Dec 2004 04:53:12 +0000, Pooh Bear
>>> <rabbitsfriendsandrelations@hotmail.com> wrote:
>>>
>>>> I sometimes wonder about the condition of those NOS electros being
>>>> sold on ebay to gullible fools who think old parts are better than
>>>> new. <snip>
>>>
>>> No need to wonder...they're "unformed" and instantly turn into a
>>> bomb when B+ is applied.
>>
>> What has that to do with *coupling* caps ?
>
> Plenty, if the coupling caps are used on a single-supply circuit.

Except that in that case the coupling caps are loaded with high enough
impedances that explosions are pretty rare.

 

[Guest]

Archived from groups: rec.audio.pro (More info?)

Arny Krueger <arnyk@hotpop.com> wrote:
>"Pooh Bear" <rabbitsfriendsandrelations@hotmail.com> wrote in message
>> DeserTBoB wrote:
>
>>> I was intrigued enough by this article to start doing some studies
>>> with what bench gear I had at the time, and sure enough...my results
>>> turned out identical to those in the article, with polyprops
>>> distorting less than any other dielectric type tested.
>>
>> How were you measuring distortion ?
>
>> How can you explain ployester/mylar 'distorting' ? I find this
>> puzzling for any plastic film. I never saw a polyester cap distort
>> when measured by an AP test set.
>
>Agreed, based on measurements by other means, but with similar residuals.

The main distortion mode for film caps is caused by electrostatic attraction
slightly changing the value of the cap based on the charge across it. This
ought to be minimal in most audio applications (and pretty much nonexistent
in low voltage solid state applications), and not really very important in
coupling applications anyway.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

 

[Guest]

Archived from groups: rec.audio.pro (More info?)

On Fri, 3 Dec 2004 11:43:22 +1100, "Phil Allison"
<philallison@tpg.com.au> wrote:


> Your tests were obviously stupid and false - as is proved by your NOT
>detailing them. <snip>

....and you're a moron.

dB

 

[Guest]

Archived from groups: rec.audio.pro (More info?)

"Scott Dorsey"
>
>>Seems to work for the likes of Neve and SSL to mention a couple of high
>>end names using electros with
>>zero bias. Not to mention almost all pro-audio gear made.
>
> Yes, agreed. But, I once changed the tantalums in a Neve channel strip
> out
> for film caps, with large enough values to get good low end. Sounded very
> clean and very nice to me. Everybody else in the studio also heard a
> change
> in sound, and they all hated it and I was almost fired.


** Really ?? And this is your idea of proof ?????


>
>>> >I'd like to see a rational reason posted for bypassing electros with
>>> >film caps in coupling
>>> >applications though.
>>>
>>> If the issue is high order harmonics being generated by small
>>> rectification
>>> effects, a bypass capacitor will clean that up.
>>
>>Suggested value to bypass 100uF ?
>
> I think the tradition is to use a bypass cap that is about 1/100th the
> value
> of the electrolytic as a rule of thumb. I am not sure where that came
> from
> or how it was derived.


** Dorsey is not sure about any damn thing.

But just loves to spread ridiculous misinformation and waste other folk's
time and money.





.............. Phil

 

[Guest]

Archived from groups: rec.audio.pro (More info?)

"DeserTBoB" = Bob the Tosser

>
>> Your tests were obviously stupid and false - as is proved by your NOT
>>detailing them. <snip>
>
> ...and you're a moron.
>


** More proof by wild assertion - same as all the rest of your posts.




.............. Phil

 

[Guest]

Archived from groups: rec.audio.pro (More info?)

"Scott Dorsey"...

>
> As Paul points out, a supply bypass cap is directly in the audio path in
> a single-ended circuit,


** Errrr - what is "single ended" here ??

A class A tube stage with no NFB ??






................ Phil

 

[Guest]

Archived from groups: rec.audio.pro (More info?)

"Scott Dorsey"
> Pooh Bear
>>
>>Strange that almost every single high end recording console uses
>>electrolytics for coupling then ?
>
> Because in the solid-state world there isn't much choice.


** The fact is that they work in that situation with no distortion
issues - despite having no DC bias.

Blows your idiotic capacitor paranoia out the window.

Just like your even more idiotic LM301 paranoia.



>>>The 'rectification effect' in electrolytics only appears AFAIK when a
>>>reverse voltage of around 0.5 V
>>is applied. Keep the reverse volts due to an a.c. signal below that and
>>it doesn't happen. That
>>*doesn't* mean restricting the a.c. signal value to below 0.5 V though.
>>Think 'potential divider' and
>>use large value caps. I commonly use 100uF for outputs and 10uF for inputs
>>where Zin is > = 10k ohm.
>
> Right. Our question is whether there might be some other nonlinear
> effects
> in addition to this one.
>


** Been studied for years and nothing has turned up yet.

Waste of time telling a rabid capacitor paranoid like Dorsey that
though.





................. Phil

 

[Guest]

Archived from groups: rec.audio.pro (More info?)

On Sat, 4 Dec 2004 11:11:18 +1100, "Phil Allison"
<philallison@tpg.com.au> wrote:

> Blows your idiotic capacitor paranoia out the window.
>
> Just like your even more idiotic LM301 paranoia. <snip>

I think I just found the "group troll!"

> ** Been studied for years and nothing has turned up yet.
>
> Waste of time telling a rabid capacitor paranoid like Dorsey that
>though. <snip>

Someone's off their meds....

dB

 

[Guest]

Archived from groups: rec.audio.pro (More info?)

> "DeserTBoB"

>>I think I just found the "group troll!"


Yup.

 

[Guest]

Archived from groups: rec.audio.pro (More info?)

On Sat, 4 Dec 2004 16:06:15 +1100, "Phil Allison"
<philallison@tpg.com.au> wrote:

> ** "S O'Neill" = an anencephalic pig with hick ups. <snip>

HICCUPS...the word is HICCUPS. Illiterate as well, I see! And yes,
the Jung/Marsh article was what I was referring to in the outset. If
I was able to repeat their results using simple bench gear, how is it
somehow "discredited?" Never mind, I really don't think your
"opinion" matters a wit.

Next stop for Phil: Kill File City

dB

 

[Guest]

Archived from groups: rec.audio.pro (More info?)

"DeserTBoB" = Bob the Tosser
Phil Allison

>
>> ** "S O'Neill" = an anencephalic pig with hick ups. <snip>
>
> HICCUPS...the word is HICCUPS.


** Poetic license.

> the Jung/Marsh article was what I was referring to in the outset.


** But kept that fact hidden to make your posturing even more pathetic.


> If I was able to repeat their results using simple bench gear, how is it
> somehow "discredited?"


** O' Neill is not he only anencephalic round here.

Go look up the critiques dickhead - the tests were utterly irrelevant
to caps as commonly used in audio.


> Never mind, I really don't think your
> "opinion" matters a wit.


** The dribbling of a demented, witless fool like Bob the Tosser serve only
as a danger to the public.


> Next stop for Phil: Kill File City


** Shoving your fat ugly head down a dunny would be better.




............... Phil

 

[Guest]

Archived from groups: rec.audio.pro (More info?)

DeserTBoB wrote:
>
> Hobbyist-grade mag "Audio" did a fairly good article on this many
> moons ago, but concentrated more on the TYPE of dielectric, rather
> than descend into grading various brands.

It's from 1980, co-authored by Walt Jung, and it's online:

http/www.capacitors.com/portals/Information.html

Also, IIRC, Cyril Bateman (a capacitor designer) did a long series
in Electronics World a couple years ago with similar measurements
(I think the series started with details of construction of the
equipment he used to measure low level distortion for the tests).
This might provide more recent data, important if dielectric properties
have changed significantly.

It seems to me both studies demonstrate without much room for doubt
that different dielectrics give rise to measurably different levels of
distortion in coupling applications. Whether the differences are
audible is another issue....

Peace,
Tom

--

To respond by email, replace "somewhere" with "astro" in the
return address.

 

[Guest]

Archived from groups: rec.audio.pro (More info?)

On Mon, 06 Dec 2004 15:34:45 -0500, Tom Loredo
<loredo@somewhere.cornell.edu> wrote:

>It seems to me both studies demonstrate without much room for doubt
>that different dielectrics give rise to measurably different levels of
>distortion in coupling applications. Whether the differences are
>audible is another issue....


Further to this, and at the risk of drawing the ire of those who have
contrary experience, I have found not-so-subtle sonic differences
between a number of "high grade" electrolytics in certain audio path
applications. Can I measure the perceived differences with common
tools (THD, IMD, FFT, etc.)? Sorry, no. Does this invalidate
subjective results? For some it may. For me, subjective results often
take precedent over numbers.

JL

 

[mark]

Archived from groups: rec.audio.pro (More info?)

John La Grou wrote:
> On Mon, 06 Dec 2004 15:34:45 -0500, Tom Loredo
> <loredo@somewhere.cornell.edu> wrote:
>
> >It seems to me both studies demonstrate without much room for doubt
> >that different dielectrics give rise to measurably different levels
of
> >distortion in coupling applications. Whether the differences are
> >audible is another issue....
>
>
> Further to this, and at the risk of drawing the ire of those who have
> contrary experience, I have found not-so-subtle sonic differences
> between a number of "high grade" electrolytics in certain audio path
> applications. Can I measure the perceived differences with common
> tools (THD, IMD, FFT, etc.)? Sorry, no. Does this invalidate
> subjective results? For some it may. For me, subjective results often
> take precedent over numbers.
>
> JL

You're saying you could not measure "NOT SO SUBTLE SONIC DIFFERENCES".

If they were not subtle, you should be able to easily measure them.

Didn't this make you question the validity of your listening tests?

Were the listening tests A/B or did you listen one day, change the
caps, then listen the next day?

Why don't you describe the sonic differences you heard and propopse a
theory as to why they could not be measured.
Then we will have progress.


Mark

 

[mark]

Archived from groups: rec.audio.pro (More info?)

John La Grou wrote:
> On Mon, 06 Dec 2004 15:34:45 -0500, Tom Loredo
> <loredo@somewhere.cornell.edu> wrote:
>
> >It seems to me both studies demonstrate without much room for doubt
> >that different dielectrics give rise to measurably different levels
of
> >distortion in coupling applications. Whether the differences are
> >audible is another issue....
>
>
> Further to this, and at the risk of drawing the ire of those who have
> contrary experience, I have found not-so-subtle sonic differences
> between a number of "high grade" electrolytics in certain audio path
> applications. Can I measure the perceived differences with common
> tools (THD, IMD, FFT, etc.)? Sorry, no. Does this invalidate
> subjective results? For some it may. For me, subjective results often
> take precedent over numbers.
>
> JL

You're saying you could not measure "NOT SO SUBTLE SONIC DIFFERENCES".

If they were not subtle, you should be able to easily measure them.

Didn't this make you question the validity of your listening tests?

Were the listening tests A/B or did you listen one day, change the
caps, then listen the next day?

Why don't you describe the sonic differences you heard and propopse a
theory as to why they could not be measured.
Then we will have progress.


Mark

 

[mark]

Archived from groups: rec.audio.pro (More info?)

John La Grou wrote:
> On Mon, 06 Dec 2004 15:34:45 -0500, Tom Loredo
> <loredo@somewhere.cornell.edu> wrote:
>
> >It seems to me both studies demonstrate without much room for doubt
> >that different dielectrics give rise to measurably different levels
of
> >distortion in coupling applications. Whether the differences are
> >audible is another issue....
>
>
> Further to this, and at the risk of drawing the ire of those who have
> contrary experience, I have found not-so-subtle sonic differences
> between a number of "high grade" electrolytics in certain audio path
> applications. Can I measure the perceived differences with common
> tools (THD, IMD, FFT, etc.)? Sorry, no. Does this invalidate
> subjective results? For some it may. For me, subjective results often
> take precedent over numbers.
>
> JL

You're saying you could not measure "NOT SO SUBTLE SONIC DIFFERENCES".

If they were not subtle, you should be able to easily measure them.

Didn't this make you question the validity of your listening tests?

Were the listening tests A/B or did you listen one day, change the
caps, then listen the next day?

Why don't you describe the sonic differences you heard and propopse a
theory as to why they could not be measured.
Then we will have progress.


Mark

 

[Guest]

Archived from groups: rec.audio.pro (More info?)

On Mon, 06 Dec 2004 22:15:32 GMT, John La Grou <jl@jps.net> wrote:
> On Mon, 06 Dec 2004 15:34:45 -0500, Tom Loredo
><loredo@somewhere.cornell.edu> wrote:
>
>>It seems to me both studies demonstrate without much room for doubt
>>that different dielectrics give rise to measurably different levels of
>>distortion in coupling applications. Whether the differences are
>>audible is another issue....
>
>
> Further to this, and at the risk of drawing the ire of those who have
> contrary experience, I have found not-so-subtle sonic differences
> between a number of "high grade" electrolytics in certain audio path
> applications. Can I measure the perceived differences with common
> tools (THD, IMD, FFT, etc.)? Sorry, no. Does this invalidate
> subjective results? For some it may. For me, subjective results often
> take precedent over numbers.
>

Might be a case when you're not measuring the right things. Did you try
measuring the response to a step function? That often reveals things
that a steady-state measurement doesn't.

Remember how long it took EEs to acknoledge that tubes really DID sound
different from transistors?