In article , Andy Evans
wrote:
It would be interesting to know how many on this group think/find that:
a) capacitor "upgrade" results in a clearly audible improvement. b) a
capacitor is a capacitor, and all caps of the same value and voltage
rating sound the same.

My own listening experiences in A-B substitutions - alone and with
several others over many years and about 60 capacitor types - leaves me,
personally, in no doubt that the differences are audible in a high
resolution transparent system.

[big snip]

Alas, since you seem not to:

1) Do the set of measurements/observations required to determine the actual
relevant characteristics in operation. Varying other relevant factors in a
measured, controlled manner.

or

2) Carry out the comparisions in a 'blind' manner.

The rest of us have no way to decide if your conclusions have any relevance
to anyone other than yourself.

Since you speak 'personally' I'll say that I will personally take your
comments more seriously once you use that scope - and other equipment - to
carry out the fairly obvious checks that would test some fairly simple
properties of the amp before/after a cap change.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

"Iain M Churches" wrote in message
...
Happy New Year to All:-)

It would be interesting to know how many on this
group think/find that:

a) capacitor "upgrade" results in a clearly audible
improvement.

**It may, depending on a whole bunch of factors.


b) a capacitor is a capacitor, and all caps of the same
value and voltage rating sound the same.

**Anyone who believes such a thing is a moron. Capacitors all have various
losses and characteristics which may adversely affect sound quality, in
various parts of a circuit.


--
Trevor Wilson
www.rageaudio.com.au

"Trevor Wilson" wrote in message
...

"Iain M Churches" wrote in message
...
Happy New Year to All:-)

It would be interesting to know how many on this
group think/find that:

a) capacitor "upgrade" results in a clearly audible
improvement.

**It may, depending on a whole bunch of factors.

Yes indeed. Care to elaborate?

The sales technician to whom I refer below tells me that
polytetrafluoroethylene (Teflon) capacitors are close to
perfect with sonic superiority, and have the lowest value
of "tan d" (I am sure Jim and Don will know what he is
talking about:-) This is also what Andy has discovered
in his own listening tests.


b) a capacitor is a capacitor, and all caps of the same
value and voltage rating sound the same.

**Anyone who believes such a thing is a moron. Capacitors all have various
losses and characteristics which may adversely affect sound quality, in
various parts of a circuit.

So quite a few morons on this NG then? :-))))

I posted a similar question to another (closed) group run by a broadcasting
organisation. Of the twenty two who replied, seventeen had experienced
or thought they would experience a clearly audible change/improvement,
three were undecided, and two thought that their level of auditory
perception may not yet be high enough to hear what they expected to be
extremely subtle changes.

The reason for my question is that a local valve amp builder/component
salesman who uses Jensen caps, above all others has suggested that
we should build two identical µ-follower pre amps, one with
Jensen and the other with RS or Farnell standard components.

He says that the reason that Jensen seem to sound better is due to
their "dielectric absorption" factor. Music is made up of a series of
transients of pulses. If we apply such a pulse to a capacitor this is
equivalent to charging and discharging it, and that any voltage left
on the capacitor at the end of the pulse is distortion. He refers us
to Morgan Jones for further reading.

He is confident that a competent listening panel will pick and
prefer the amp with the Jensen caps, type for type.
If not, some interesting eating of hats will follow:-))

Mike G seems to have already done a similar test, with
Jensen silver foil caps in one channel of a power amplifier.
His group picked out the Jensen channel every time.
I am not suggesting that these audible differences only apply
to Jensen. There are many other makers whose products
may well fall into the same category. Interesting.

Cordially,

Iain

On Mon, 3 Jan 2005 10:55:02 +0200, "Iain M Churches"
wrote:


Yes indeed. Care to elaborate?

The sales technician to whom I refer below tells me that
polytetrafluoroethylene (Teflon) capacitors are close to
perfect with sonic superiority, and have the lowest value
of "tan d" (I am sure Jim and Don will know what he is
talking about:-) This is also what Andy has discovered
in his own listening tests.

You can't simply talk about the sonic effects of capacitor types. Tan
d is indeed a very necessary parameter of a capacitor, but its
relevance to performance depends on the circuit topology and what the
cap is doing. In power supply decoupler, Tan d is the first thing you
look at after the actual value. It tells you about the ability of the
capacitor to deliver current, how warm it may get and a whole heap of
other stuff.

In the audio path things are different. Tan d can be seen as a
resistance which appears in series with the capacitor. In a bad one,
it would be an ohm or so. So what is that going to do in a circuit in
which it is in series with 100,000 ohms - even more in a valve amp,
possibly? This is the case for an audio coupling cap. Well, the answer
of course is that it is going to attenuate the signal by a factor of
1/100,000 - in other words it is doing nothing. An audio coupling cap
charges up when you turn on, then it effectively vanishes from the
circuit provided it is big enough for the job.

So the question of the possible audible effects of different capacitor
types is a nonsense. Unless you specify the circuit and exact
operating conditions, it doesn't admit of an answer. And in most
situations where one might be found in an audio chain, there can be no
effect.

Of course you can obviate the problem by going ss and direct coupled.

d

Pearce Consulting
http://www.pearce.uk.com

"Don Pearce" wrote in message
...
(huge snip)

So the question of the possible audible effects of different capacitor
types is a nonsense. Unless you specify the circuit and exact
operating conditions, it doesn't admit of an answer. And in most
situations where one might be found in an audio chain, there can be no
effect.

Most seem to consider the psu also as an inetgral part of the audio
chain, so changing just the interstage coupling capacitors will not
be enough. To do it properly, we should perhaps also change
the cathode bypass caps


For myself, I cannot decide in advance if there will or will not
be an improvement, and even more important will I be able
to hear it. That's why I think it will be interesting to carry out
the test. I already have a panel of ten people interested to
take part. They range from an amp technician to a
professional cellist.

Do you wear a hat Don? :-)

Of course you can obviate the problem by going ss and direct coupled.

Thanks but No thanks:-)

Cordially,
Iain

On Mon, 3 Jan 2005 11:35:31 +0200, "Iain M Churches"
wrote:


"Don Pearce" wrote in message
...
(huge snip)

So the question of the possible audible effects of different capacitor
types is a nonsense. Unless you specify the circuit and exact
operating conditions, it doesn't admit of an answer. And in most
situations where one might be found in an audio chain, there can be no
effect.

Most seem to consider the psu also as an inetgral part of the audio
chain, so changing just the interstage coupling capacitors will not
be enough. To do it properly, we should perhaps also change
the cathode bypass caps

Interstage coupling caps would be the last thing to change - ie the
least effect. Cathode resistor bypass caps would be more effective
when bypassing higher rather than lower value resistors. Power supply
caps would be most effective.

The PSU caps are of course as much in the signal path as any other
caps in an amplifier, and should be chosen with that in mind.

However, it must be said that a competently designed amp will deal
with most types of cap without any change in performance.


For myself, I cannot decide in advance if there will or will not
be an improvement, and even more important will I be able
to hear it. That's why I think it will be interesting to carry out
the test. I already have a panel of ten people interested to
take part. They range from an amp technician to a
professional cellist.

Do you wear a hat Don? :-)

Only when I'm skiing or motor cycling!!! This is a worthwhile test, I
suppose, provided it is designed and proctored effectively (I'd be
interested to see the protocol you propose). But do go for the caps
that stand at least a fighting chance of making a difference - ie
anything other than interstage couplers.

Of course you can obviate the problem by going ss and direct coupled.

Thanks but No thanks:-)

Cordially,
Iain

d


Pearce Consulting
http://www.pearce.uk.com

In article , Iain M Churches
wrote:

"Don Pearce" wrote in message
... (huge snip)

So the question of the possible audible effects of different capacitor
types is a nonsense. Unless you specify the circuit and exact
operating conditions, it doesn't admit of an answer. And in most
situations where one might be found in an audio chain, there can be no
effect.

Most seem to consider the psu also as an inetgral part of the audio
chain, so changing just the interstage coupling capacitors will not be
enough. To do it properly, we should perhaps also change the cathode
bypass caps

A problem here is that you may be introducing complications by choosing to
focus on (low feedback?) simple valve designs. For reasons like those you
indicate these may be sensitive to a number of sources of problems which
other designs may not be prone to.

If you wish to check capacitors as such, I would personally think it
necessary to consider the actual circuit design/topology again to avoid one
effect looking like something else, and risk giving mileading results, or
masking something. This would improve the chance that you can just change
*one* component and have that produce an effect (or not!) without other
effects coming into play.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

Don Pearce wrote:
have the lowest value
of "tan d"
Tan
d is indeed a very necessary parameter of a capacitor,


Is that the odds of finding one in a Radio Shack store?


--
Teal'c: "Dr Jackson's preliminary electroencephalogram proved anomalous"
O'Neill: "I dare you to say that again"

On Mon, 3 Jan 2005 09:41:27 -0000, "Tim S Kemp"
wrote:

Don Pearce wrote:
have the lowest value
of "tan d"
Tan
d is indeed a very necessary parameter of a capacitor,


Is that the odds of finding one in a Radio Shack store?

Puns like that should be against the law ;-)

d

Pearce Consulting
http://www.pearce.uk.com

In article , Iain M Churches
wrote:

"Trevor Wilson" wrote in message
...

The sales technician to whom I refer below tells me that
polytetrafluoroethylene (Teflon) capacitors are close to perfect with
sonic superiority, and have the lowest value of "tan d" (I am sure Jim
and Don will know what he is talking about:-) This is also what Andy
has discovered in his own listening tests.

FWIW from being involved in making lenses for use in the 30GHz - 1 THz
range then I'd say that the 'PTFE' and 'HDPE' families have low dielectric
loss values, and hence low tan delta values, up to frequencies like these.

However the loss does tend to scale with the frequency, so the losses of
many commonly-used dielectrics at audio frequencies should be quite low.

I am therefore somewhat doubtful that simple loss tangent values can
explain the claimed differences in audible performance. Precise models are
complicated, and we can consider the losses to have both 'shunt' and
'series' components. However a simple example can illustrate the reason for
my doubts.

I can't find any capacitor examples in the books I have at home, only
'optical' or dielectric propagation ones, so the following may be
incorrect. If so, someone let me know.

Lets assume a 1 microfarad cap with a nominal loss tangent of 1E-5 at
10kHz. IIRC This means that the in-phase (resistive) part of the impedance
is 1E-5 times less than the reactive part.

The nominal reactance of 1 microfarad cap at 10 kHz is 16 Ohms if I pressed
the right buttons on my calculator. :-)

This implies that if the loss is modelled with a shunt resistance we have a
shunt of 16 x 1E5 = 1.6 MOhms in parallel with the cap to represent the
loss tangent.

Alternatively, if we assume the loss tangent is a series resistance it will
have a value of (approx) 16 / 1E5 = less than 1 milli-Ohm.

Either way, I find it difficult to think that such small (linear) changes
in the total impedance have much effect. I suspect the resistive losses and
parasitics of the wiring would be more significant.


The reason for my question is that a local valve amp builder/component
salesman who uses Jensen caps, above all others has suggested that we
should build two identical µ-follower pre amps, one with Jensen and the
other with RS or Farnell standard components.

The interesting part here will be the 'identical' part... :-)

He says that the reason that Jensen seem to sound better is due to their
"dielectric absorption" factor. Music is made up of a series of
transients of pulses. If we apply such a pulse to a capacitor this is
equivalent to charging and discharging it, and that any voltage left on
the capacitor at the end of the pulse is distortion. He refers us to
Morgan Jones for further reading.

Afraid I don't regard a "pulses" description of musical waveforms like the
above to be very helpful. Real waveforms are rather more complicated so I'd
regard "pulses" as misleading here.

He is confident that a competent listening panel will pick and prefer
the amp with the Jensen caps, type for type. If not, some interesting
eating of hats will follow:-))

Mike G seems to have already done a similar test, with Jensen silver
foil caps in one channel of a power amplifier. His group picked out the
Jensen channel every time. I am not suggesting that these audible
differences only apply to Jensen. There are many other makers whose
products may well fall into the same category. Interesting.

The difficulty being that I haven't yet found either such reports - or the
attempts at specifying a physical mechanism - very plausible in the cases I
have seen so far.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html