Hi,



I have a question about the audiophile capacitor replacement. In normal
production boards, signal coupling capacitor normally using polar
electrolytic capacitors. In some higher grade models, bi-polar electrolytic
capacitors will be introduced. Some people will upgrade it will audio grade
capacitors such as oil caps, polypropylene caps. In my audio device, the
coupling caps are 100uF polar electrolytic caps. I am looking for Jensen
oil caps and it will be very expensive and the size is very big. Someone
suggests me I can replace with 20uF oil caps instead of huge big one. If it
is right, is there any rule of thumb to do the exchange calculation or any
theory behind the idea. It seems the capacitor values will be 5 times lower
than the original value and I am worry about the filter DC function. Thanks
a lot for any input for the information.

Eric ha escrito:

Hi,



I have a question about the audiophile capacitor replacement. In normal
production boards, signal coupling capacitor normally using polar
electrolytic capacitors. In some higher grade models, bi-polar electrolytic
capacitors will be introduced. Some people will upgrade it will audio grade
capacitors such as oil caps, polypropylene caps. In my audio device, the
coupling caps are 100uF polar electrolytic caps. I am looking for Jensen
oil caps and it will be very expensive and the size is very big. Someone
suggests me I can replace with 20uF oil caps instead of huge big one.

This all seems rather unscientific to me, with more than a whiff of
snake oil (dunno about capacitor oil!)
- since when can you reduce the capacitance to a fifth of the value of
the original and expect good perfomance?
What utter crap. You'd end up with a result as if the amp had aged 20
years and the caps had lost their capacitance. Use always the same
value as the original: 100uF, with same or slightly greater voltage
rating.

Unless there is a fault with the appliance, (often evidenced by hum,
motor boating or excessive hiss on the output) I'd say don't mess about
changing caps for the sake of it. You won't hear any perceptible
difference. There are people out there making a living by spreading
this nonsense about to the non-technical.

-B.

"b" wrote in message
ups.com...

Eric ha escrito:

Hi,



I have a question about the audiophile capacitor replacement. In normal
production boards, signal coupling capacitor normally using polar
electrolytic capacitors. In some higher grade models, bi-polar
electrolytic
capacitors will be introduced. Some people will upgrade it will audio
grade
capacitors such as oil caps, polypropylene caps. In my audio device, the
coupling caps are 100uF polar electrolytic caps. I am looking for Jensen
oil caps and it will be very expensive and the size is very big. Someone
suggests me I can replace with 20uF oil caps instead of huge big one.

This all seems rather unscientific to me, with more than a whiff of
snake oil (dunno about capacitor oil!)
- since when can you reduce the capacitance to a fifth of the value of
the original and expect good perfomance?
What utter crap. You'd end up with a result as if the amp had aged 20
years and the caps had lost their capacitance. Use always the same
value as the original: 100uF, with same or slightly greater voltage
rating.

Unless there is a fault with the appliance, (often evidenced by hum,
motor boating or excessive hiss on the output) I'd say don't mess about
changing caps for the sake of it. You won't hear any perceptible
difference. There are people out there making a living by spreading
this nonsense about to the non-technical.

-B.

Jensen copper foil / oiled paper caps as upgrade replacements, are usually
more associated with the lower values that you tend to find as coupling caps
in valve amplifiers. They are physically bigger than the bog standard
polyesters that you would normally find fitted, and are very expensive.
There is, however, a measurable improvement to be had by fitting them, but I
would have to question if the cost was warranted.

Their electrolytic caps are, IIRC, all high voltage types for valve amp
power supplies, so not appropriate for interstage coupling on semiconductor
amps. As they are high voltage caps, their physical size will be
correspondingly larger, so the only way to get the size back down, would be
to reduce the value. I agree with the other poster, that this would be a bad
move for the performance of the amp, and far from giving a performance
improvement, would likely result in a detrimental effect.

There may be a measurable difference to be had, by replacing conventional
interstage coupling electros with bipolar types, which are readily
available, and no bigger than conventional types, but I doubt that you would
be able to notice the difference in a real-world music playing situation.
Again, I would agree with the other poster that if it ain't broke, don't try
to fix it.If you want to know more about the subject, you could try the
people over on uk.rec.audio. I know for sure that there are a couple of
people there who have fitted Jensen caps to amps, and may be better able to
advise you.

Arfa

In article . com, "b" wrote:

Eric ha escrito:

Hi,



I have a question about the audiophile capacitor replacement. In normal
production boards, signal coupling capacitor normally using polar
electrolytic capacitors. In some higher grade models, bi-polar electrolytic
capacitors will be introduced. Some people will upgrade it will audio grade
capacitors such as oil caps, polypropylene caps. In my audio device, the
coupling caps are 100uF polar electrolytic caps. I am looking for Jensen
oil caps and it will be very expensive and the size is very big. Someone
suggests me I can replace with 20uF oil caps instead of huge big one.

This all seems rather unscientific to me, with more than a whiff of
snake oil (dunno about capacitor oil!)
- since when can you reduce the capacitance to a fifth of the value of
the original and expect good perfomance?
What utter crap. You'd end up with a result as if the amp had aged 20
years and the caps had lost their capacitance. Use always the same
value as the original: 100uF, with same or slightly greater voltage
rating.

Well 5 of them will work. Some people replace passive speaker
crossover components, but you have to watch ESR which can change requirments.
I have seen certain types of electrolytics dry up and cause severe frequency
response errors in coupling caps.

greg

Unless there is a fault with the appliance, (often evidenced by hum,
motor boating or excessive hiss on the output) I'd say don't mess about
changing caps for the sake of it. You won't hear any perceptible
difference. There are people out there making a living by spreading
this nonsense about to the non-technical.

-B.

GregS wrote:

I have seen certain types of electrolytics dry up

That'll be because they were poorly specified originally.

Graham

Eric wrote:
I have a question about the audiophile capacitor replacement. In normal
production boards, signal coupling capacitor normally using polar
electrolytic capacitors. In some higher grade models, bi-polar electrolytic
capacitors will be introduced. Some people will upgrade it will audio grade
capacitors such as oil caps, polypropylene caps. In my audio device, the
coupling caps are 100uF polar electrolytic caps. I am looking for Jensen
oil caps and it will be very expensive and the size is very big. Someone
suggests me I can replace with 20uF oil caps instead of huge big one. If it
is right, is there any rule of thumb to do the exchange calculation or any
theory behind the idea. It seems the capacitor values will be 5 times lower
than the original value and I am worry about the filter DC function. Thanks
a lot for any input for the information.

In general, replacing coupling caps with smaller values would create
high-pass filters, so you will have less bass. Are you sure they really
are 100u?

--
Met vriendelijke groet,

Maarten Bakker.

I find some of this hard to believe. I guess a little bit of knowledge
really is dangerous.

If anyone around here other than me knows how to design a transistor
amplifier stage, they know the cap is critical to some extent. You
cannot make the input impedance really high, like you can with a tube
(valve) amp.When dealing with bipolars, almost any stage needs an
emitter resistor and maybe even some bootstrap. Based on the gain of
the transistor you can raise the input impedance, perhaps even use a
common collector stage in front.

The problem is for a low distortion audio stage you need to drive the
base with a smoothly changing current, not a solid voltage.

I have experimented too, I have made amps distort in a certain way, so
I could see it on a scope as well as hear it, so I am not a babe in the
woods here.

Now I say this, you make the input impedance and gain of the stage what
you want, then select a coupling capacitor that will pass effectively
down to like 10Hz. But when driving a tube (valve) or FET it doesn't
matter as much. On high input impedance devices of course you need a
resistor, in the case of a tube, from grid to ground as well as a
cathode resistor to provide negative bias. In the case of FETs, well
some of them are enhancement mode and don't need a source (cathode)
resistor. Still if you intend to couple capacitively, there must be a
resistor across it.

When the input impedance is really high, it makes sense not to shunt it
out with a low value resistor. All you need is enough mhos to keep the
leakage and a few other things out of the picture. The higher the value
resistor, the lower value capacitance needed. Reactance + Ohm's law,
simple.

On that note I will add, keeping the input impedance high is good for
good sound. No capacitor is perfect. The thing is, what is imperfect
about capacitors ? ESR and ESL. For the uninformed these are effective
series resistance and inductance. (or just not up on all the three
letter acronyms)

The impedance of a capacitor is the vector sum of it's actual reactance
(admittance) and ESR and for higher frequencies the ESL must be brought
into the equation. ESL can usually be ignored for audio frequencies,
except maybe in high power crossover capacitors (in speakers, I mean
passive crossovers)

No matter what the quality of the coupling cap, the higher the input
impedance that it is couplinjg to, the better the quality. This is
because the ESR and ESL become very minimal when a capacitor is feeding
a high impedance.

Also, I totally disagree with switching to bipolar caps in any
equipment, unless you have speakers so cheap that....nevermind that. To
explain:

Capacitors have several variables. Size, capacity, voltage rating,
ESR/ESL, longevity and cost. You shouldn't go lower in capacity and you
can't go lower in voltage. If you get smaller caps they are likely to
not have as low ESR and ESL ratings as the originals. If you get
bipolars they will be bigger or have higher ESR and ESL at any given
rating. That is unless they are made for current and if that is so they
will either be bigger physically, or very expensive.

If the OP can supply me with a schematic of the unit, I might be able
to come up with some good modifications. Wouldn't be the first time.
Pioneer and Realistic both made mistakes in the FM stereo decoder, that
was one I couldn't handle. The problem was inside the chip. All I could
do is throw in a couple resistors to reduce the distortion but that
resulted in a subdued high frequency response. See that's the other
thing, in transistors, you never put a capacitor across an analog
output unless it is ballasted, that is has a resistor in series with
it.

Really the problem with these recievers was partly over modulation by
the FM stations, but this IM and THC was coming from the earlier
generations of PLL stereo demod chips. Although the signal wasn't
really over modulated, it was more than the engineers expected. The
result was that it sounded great on classical and some other types of
music, but on hard rock it was almost intolerable. Especially on
material that was REALLY in stereo, I mean had alot of seperation.

If anyone really wants to improve sound quality, let's face it, as long
as the amp has less than 1% THD and IM, get away from it. No speaker is
that good. Wonder why there is no THD or IM ratings on speakers ? You
would shreik.

My speakers are actually among the very very few rated for THD. The
rating is 0.7% at 1 watt 1Khz sine wave. And that is a fantastic rating
for a speaker. At 10 watts it is probably up there close to double
digit, but that is ALL speakers. They used to say that what comes out
of a speaker is only as good as what goes into it, and that is
absolutely true. But setting sights on the real problems is better than
wasting a ****load of money on things that will not solve the problem.

I paid $400 for these BAs, they were ten years old and I paid MSRP for
them, why ? Because I heard them. They rival Dahlquists and Cantons,
other really good speakers of the days of yore. Big names do not even
approach the sound quality of certain speakers. Pioneer, Bose, even
Technics alothough their electronics used to be pretty good. Macintosh.
Macintosh for _____ sakes !, not even close. Macintosh may have made
some of the finest electronics in the world for audio, but they did not
really excel in speakers IMO.

The only Mac I ever had was a Stereotech 1200, their first reciever.
Little known, but I have it still even though it fried out. I had some
Mac copies of their monoblock tube amps, but that is not the same.
Later they came out with the Mac 4100, their first "official" reciever.
Was nice too, cost alot too. But the brochure had the lid off, and you
could see ALOT of similarity to the Stereotech 1200. ALOT. I mean it
used the very same power amps, with darlington outputs in the SJ series
from Motorola. Nice smooth gain curve on those SJ series outputs, very
smooth for a darlington.

Anyway, I say this to all, if you want better sound, 90% of the time
you need to look at speakers and speaker placement. Amps are pretty
much how they are if designed properly. If they're any good at all you
won't hear a difference. Of course they can put better tone controls on
one and make it sound better in a certain environment. But the speaker
makes the most difference.

JURB

wrote:

I find some of this hard to believe. I guess a little bit of knowledge
really is dangerous.

If anyone around here other than me knows how to design a transistor
amplifier stage, they know the cap is critical to some extent.

Ignorant, arrogant self-obsessed fool.

Graham

wrote:

Eric wrote:
I have a question about the audiophile capacitor replacement. In normal
production boards, signal coupling capacitor normally using polar
electrolytic capacitors. In some higher grade models, bi-polar electrolytic
capacitors will be introduced. Some people will upgrade it will audio grade
capacitors such as oil caps, polypropylene caps. In my audio device, the
coupling caps are 100uF polar electrolytic caps. I am looking for Jensen
oil caps and it will be very expensive and the size is very big. Someone
suggests me I can replace with 20uF oil caps instead of huge big one. If it
is right, is there any rule of thumb to do the exchange calculation or any
theory behind the idea. It seems the capacitor values will be 5 times lower
than the original value and I am worry about the filter DC function. Thanks
a lot for any input for the information.

In general, replacing coupling caps with smaller values would create
high-pass filters, so you will have less bass. Are you sure they really
are 100u?

For an output coupling cap it's very likely.

That's what I use myself for output coupling and it's pretty much standard in
pro-audio.

There's a reason for it that's nothing to do with -3dB points btw.

Graham

"Eric" wrote in message
...

I have a question about the audiophile capacitor replacement.

The term, "audiophile capacitor" is a red flag.






--

Eric:
When you get done with this expensive waste of money.... please contact me
so I can sell you very expensive oxygen free, biradially wound copper
speaker wires and interconnect cables with gold connectors...about $10 per
foot...... and while you are at it you should consider a $1500 or more,
power line conditioner so that your equipment gets cleaned up power so it
can produce much "improved" sound.
Daniel Sofie
Electronics Supply & Repair
- - - - - - - - -



"Eric" wrote in message
...
Hi,



I have a question about the audiophile capacitor replacement. In normal
production boards, signal coupling capacitor normally using polar
electrolytic capacitors. In some higher grade models, bi-polar
electrolytic
capacitors will be introduced. Some people will upgrade it will audio
grade
capacitors such as oil caps, polypropylene caps. In my audio device, the
coupling caps are 100uF polar electrolytic caps. I am looking for Jensen
oil caps and it will be very expensive and the size is very big. Someone
suggests me I can replace with 20uF oil caps instead of huge big one. If
it
is right, is there any rule of thumb to do the exchange calculation or any
theory behind the idea. It seems the capacitor values will be 5 times
lower
than the original value and I am worry about the filter DC function.
Thanks
a lot for any input for the information.

Sophie, haven't you been paying attention? Oxygen free wire is passe. All
good audiophiles know that it makes no difference whether you use OF copper
or not, since the best sound comes from bare copper oxidized on the surface
by the urine of virgin ferrets that have been raised listening to Bach's
Tocata and Fuge in D minor. Of course, some say that Dr. Pepper works as
well. The oxide slows the conduction to allow the slower electrons to
arrive in phase with the ones that would otherwise travel faster.

Leonard

"Sofie" wrote in message
...
Eric:
When you get done with this expensive waste of money.... please contact me
so I can sell you very expensive oxygen free, biradially wound copper
speaker wires and interconnect cables with gold connectors...about $10 per
foot...... and while you are at it you should consider a $1500 or more,
power line conditioner so that your equipment gets cleaned up power so it
can produce much "improved" sound.
Daniel Sofie
Electronics Supply & Repair


--------------------------------------------------------------------------------
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"Leonard Caillouet" wrote in message
...

Sophie, haven't you been paying attention? Oxygen free wire is passe.
All good audiophiles know that it makes no difference whether you use OF
copper or not, since the best sound comes from bare copper oxidized on the
surface by the urine of virgin ferrets that have been raised listening to
Bach's Tocata and Fuge in D minor. Of course, some say that Dr. Pepper
works as well. The oxide slows the conduction to allow the slower
electrons to arrive in phase with the ones that would otherwise travel
faster.

Actually all you need to do is store it under a titanium pyramid between one
full moon and the next.








--