Over last couple of years I went through many stages of involvement in
audiophilia. It included reading Stereophile back to back 10 times per
issue, followed by neglecting Stereophile and instead travelling to
High
End shows (mainly Frankfurt Kempinski and Warsaw High End Sobieski),
followed by maniacal DIY
activity, followed by reading Audio Express/SpeakerBuilder / Glass
Audio, followed by going crazy in DIY forums on the internet like
Madisound, Audioasylum, etc. (with nick LukaszF.)
There was one thing it all had in common - I was never satisfied with
the sound. That lead me to question the status quo and search for
truth. Studying MBA helped me a lot to understand the economy of
Hi Fi and why we get the product we get, why those products don't play
as well as we expect them to play, and things like that. In general
there is much
more economy in hi-fi business than we want to believe. Even in niche
industry,
even in DIY, even in forums.
Before I write how to get to audio nirvana and have eargasms every day
and night, just in order to clear the field, in this chapter
first I want to deal with some strange opinions which I
heard and read SO MANY TIMES in the recent past that I can't take it
anymore. Jesus, who creates all these idiotic heresy? Take it
from an electrical engineer, please.
HERESY No 1. SIGNAL PATH
I read about signal path so many times I am almost ready to believe it.
Short signal paths, pure s.p., elegant s.p. silver wire in s.p. you
name it. I am sure everybody knows what I am talking about.
The bitter truth is IT IS NOTHING LIKE what people think it is. The so
called "signal" does not flow along some PATH. Lets take a pre amp for
an example. The signal (current) enters via RCA jack, and the
first thing it sees
is usually a parallel resistor or some kind of parallel pot. The signal
sinks to the ground through this resistor and that's all. Yes. The
journey is over. It is like the movie hero who dies in the first scene.
Hard to believe?
Having said that - lets agree once and for all - the CURRENT flows, and
the VOLTAGE IS. The voltage does not flow.
The Waves PROPAGATE in circuits but they happen everywhere at the same
time and involve all circuits.
The minuscule current flowing from your CD source to the ground via
this parallel impedance of a mentioned pot produces small voltage
resulting from the
impedance of the pot (Ohm's law) This voltage is then being "read" by
the grid electrode of the tube, or in non-hifi units - the base of
transistor, and this signal in turn regulates the series impedance of
the active element. The electricity from power supply then copies the
original signal in what we call "amplification stage". So this is a
copy, not the original. Signal path is a myth. The VOLTAGE - does not
flow by definition. The voltage IS. The current flows. But it does not
flow from source to the load (receiver). The current flows from power
supply to the ground via active elements. In every STAGE of
amplification the current flows in VERTICAL manner, not "horizontal".
If an amp has 3 stages, there will be 3 cases of current flowing from
PSU to ground by the active part. So path is from PS to ground, not
from CD to speakers. Once we understand it - it is easier to talk
further.
Another thing is timing of signal - it does not go from one place to
another. The WHOLE CIRCUIT responds to signals instantly, the whole
event HAPPENS. It does not flow. The circuit response is everywhere at
the same time, all elements at the same time. No flow. Input receives -
output responds. At the same moment.
HERESY NO 2. AMPLIFICATION
Many people believe, that amplifiers amplify the signal, so do
preamplifiers. In their popular belief huge amplifier like KRELL
amplifies the signal to monstrous levels.
Well, not quite. Amplifiers, what they effectively do, is REDUCE the
output impedance of the output device. So they increase the current
available
at small impedance loads. But in most cases of sane listeners,
amplifiers REDUCE signals. By signal I mean what is coming out of a
source - like CD - which is VOLTAGE wave form.
My CD for example is a balanced unit. Standard CD has 2 V at the output
when the CD plays all 16 bits as ones that is at full signal 0dB. So
balanced unit has then 4 V at the output. Most amplifiers quote a
parameter like sensitivity, which is a signal level that drives them to
max power. That level in my mono amps is 0,7 V. So If my CD produces 4
V, it would cause 4/0,7 = 6 times overload. I measured the nice musical
signal in my room to be around 1 watt of power, so I need only 1/30th
of full signal at the input. (my amps are 30 W PC) I need 0,7 V / 30 to
be satisfied. So I will use 6*30 times LESS signal than comes out of my
CD. Funny? My preamp reduces signal by 180 times!!!
Speaking of amplifiers, my speakers are 99 dB sensitive so I need just
2,8 V to play one watt, which is very very loud. In fact my amp
(because there is a preamp already reducing the signal) increases the
signal from 0,0 something Volt to 2,8 V, not by much.
It is easy to measure - just use AC voltmeter at the output terminals
to speakers. Rarely exceeds 1 V really. Having said that, because the
load impedance presented by speakers (say 5 ohm) is infinitely lower
than that of
an amp presented to preamp (say 50 K - 10000 times higher) the
ability of an amp to
respond to that load according to ohm's law with 10000 times higher
current must be admired. That is a result of REDUCTION OF OUTPUT
IMPEDANCE in comparison with the source. Just what I said in the
beginning.
If we don't use a preamp, and most of us don't, the same story is just
combined - 4 V coming out of CD to become 2,8 V at amps terminals.
Almost halved.
HERESY No. 3.
Bass drivers are a big load and need huge power.,
tweeters need small power. Much less current than bass.
Well, think again.
This is particularly stupid heresy, endorser by 99% people whom I heard
or read.
First the load. Most tweeters are 6 Ohm in all their usable frequency
range. So they present a load of 6 Ohm to the amp. Bass drivers usually
due to mechanical resonance are anything between 16 to 50 Ohm from say
30 Hz to 100 Hz. In most usable range. Therefore are MUCH EASIER load
to the amp. They suck hardly any current at resonance and some octaves
below and above.
Some filter topologies are so ugly that the filters to the bass
(lo-pass) sucks 10 times the current available to drivers. Call that
engineering.
Now about tweeters power versus bass power. People think of bass as
BIG, using BIG power, using THICK cables, oh everything is so big.
Wrong.
At best, all drivers use SAME power. Because the frequency response is
near flat, that means that at equal level of musical material voltage,
and at near equal impedance say 8 Ohm, all drivers by Ohm's law draw
SAME current. Not AMPERES in the bass and milli-amps in the tweeter.
Simple
Ohms law. Kinder garden physics. So why should the wire to bass driver
be THICK and to tweeter thin???
Having said all that, some MUSIC contains a lot of drumming and less
cymbals, so energy content in the respective frequency range is bigger
in the bass section.
HERESY No. 4
"Critical components" - series components versus parallel.
Oh I heard it so many times. "In this crossover network use premium
caps in series with the driver, but the coil is ONLY (!) parallel so it
is unimportant. And this parallel cap can be WIMA el cheapo because it
is not in the path." PUHLEEZE! People think of the electricity as
a row of ants marching through a path. The series component must be
good because they walk on it like over a bridge. Parallel components
are
like road signs on the side of the path, They are there, but don't
affect the "marching process". NOT TRUE.
Electricity is an electromagnetic energy propagating through the
network, NOT marching ants. The parallel components distort the signal
THE SAME WAY AND THE SAME AMOUNT as parallel.
Imagine a sheet of paper. A4 on this side of Atlantic. Now tear it in
half. Which torn part has more distorted edge??? See? Both equally.
Because what is removed takes away from the whole some amount of
distortion, or what stays- leaves some distortion. No difference.
Mathematically speaking there is no difference between the effect that
on the mathematical equation has the application of say z=jwc or
z=1/jwL. For example, if you open a series cap and if you short
the parallel coil in second order filter the result is THE SAME. No
signal. 100% distortion ! ;-)
Still don't believe me?
OK. The coil in parallel application of second order network is not
really parallel to the signal. It is in series! Yes. The current from
amp flows through the speaker wire, through the series cap, and through
the parallel coil to earth. This current produces over the coil's
impedance some voltage proportional to the impedance (reactance) of
coil with ALL ITS DISTORTION COMPONENTS and this voltage is fed to the
driver.
Does it still look unimportant?
HERESY No. 5
(Beethoven's ;-)
Digital cables conduct digital signal.
Not quite true. There is no digital signal in electricity. It is as
analogue as it gets. zeros and ones come out of CD disk but after
becoming electricity it is no longer a row of zeros and ones but a
square wave , and not 44 kHz but high
frequency over 2 megahertz square wave going out of transport to dac.
It carries musical
information mathematically embedded in this sine, but the cable
conducts analog electrical wave form just like any other. So by digital
cable we can mean a cable that is good for tens of megahertz. By the
Fouriers theorem the square wave is an infinite sum (sigma) of the sine
waves with one fundamental frequency and its infinite even harmonics,
at least over 10*Fs.
Knowing the physics of high frequency electricity, more like radio-wave
propagation, we can have a good cable with matching electromagnetic
impedance, low losses, low reflections,
good screening, and minimal signal distortion. That makes this cable
"good".
But it is not "only digital" signal, and it is not that zeros and ones
are zeros and ones, no matter what cable.
READ MORE HERE
HERESY No. 6
STIFF speaker cabinets are better than less stiff.
We could argue about the end result but in fact making a cabinet stiff,
heavy and strong does not improve the cabinet a bit. Seriously.
The driver produces energy X. It is propagated to the surrounding
universe by piston movements of the cone (or dome). By definition
EQUAL portion, that is 50 % goes directly to the room and 50 %
goes in the box. This energy in the box has NOWHERE TO GO. If the box
was made of 10 cm walls of diamond, or granite, or beryllium or you
name it, the sound inside would keep bouncing inside infinitely, less
the portion which escapes through almost totally transparent cone (1/10
th. mm of paper or 1/100 mm of silk) back to the room, causing echo or
other form of distortion. We can not "sink" the back wave into black
hole by strengthening of the cabinet.
The only form of sinking is by converting the back wave to heat before
it jumps back out to the room. It is doable by using sophisticated wool
mixtures but it is frequency dependent, selective, messy etc. It also
somehow kills the musicality. It rarely works well.
In my experience the only way to have musical speaker is to use both
waves - back and front - productively , that is by playing them
on open baffle.
That is especially true with tweeters. Just imagine - 1/3 rd of total
musical energy of a given speaker (for a three way that is) being
squeezed behind the dome, where is 1 cubic cm of space and sometimes -
one gram of wool. It CAN'T BE SUNK. It comes back immediately via the
dome. (except maybe Nautilus tweeter).
HERESY No. 7
There is positive phase and negative phase in music.
This is really stupid heresy. I cant understand why 99 % of people
believe it.
The usual test is like this: take a 1.5 V aa cell, apply it to speaker
terminals - if the cone moves outward - your speaker produces
true positive impulse. Otherwise it is phase reversed and signal is not
true because if a drum beats - the speaker cone "sucks in".
WELL, NOT TRUE.
First, lets deal with the driver movement vs. absolute phase of signal.
Why moving from idle position towards listener should be "positive" ???
The musical signal is a mix of sine waves. Sine has no beginning and no
end. It is infinite and continuous. Low pressure and high pressure of
air happen in cycles, no cycle is preferred versus the "negative one".
A 1 kHz sound is a low followed by high air pressure followed by low
etc. 1 000 times per second. Does not matter which was "first" because
we can't discern between the two. Our ear drum being pushed inside our
head is no more real sound than our ear drum being sucked outside.
Now lets think of musical instruments. The DRUM (easy to imagine). If
the drum kit has the main foot-drum on the floor, is the HIT on it
producing positive wave??? How? The hammer (sorry I don't know the
vocabulary) hits the drum on the drummer side, hence producing INWARD
flexing of the drum skin. This is heard outside in the room as
BOOM. Positive or negative? See? And this usually feeds the pressure
inside the drum. There is a mike inside this drum. It reads the high
pressure by flexing the mike membrane to the left. Or Right. Or In. Or
.. Or ... ??? And the electrical signal goes to preamp, console, A/D
converter. Is it still positive or negative?
And what if the drumskin is parallel to the floor, like in congas? Is
downward hit positive, or upward?
And what if this is a cymbal? Is a flat cymbal hit by the drumstick
producing positive or negative impulse??? Anybody answer?
And how about the bass string being plucked? Is positive from left to
right or the opposite?
This is truly a stupid divagation. Positive and negative speaker wiring
are equal and it is a waste of time using your remote on that Wadia of
yours to switch the absolute phase and argue which is more true.
And what if a Jazz ensemble has 5 musicians, all miked in a different
way? And what if music is SAMPLED from 10 records by a deejay? Which
part of the signal is positive and which negative?
HERESY No. 8
Thick AC cables are better. Big capacitance in power supply is better.
It is funny, but few people understand how the diode bridge works in
combination with capacitor bank in power supplies. The time constant RC
of cap bank and load impedance seen by power supply determines time it
takes to discharge the caps by "some degree". During the period when
AC, after the transformer, has higher value than DC on the caps,
the caps are re-charged to the full. If the cap bank is HUGE (very
macho indeed) then R*C time constant is so large that the AC sine wave
is only exceeding the DC level during milliseconds of the peak, every
time the AC cycle hits its maximum. So the given energy X needed by the
amp must be sucked not during say half of the AC cycle, but say
1/100th. And because a sine peak happens 100 times per second, that
means that we feed the amp from the wall only during a sharp peak
1/10000 of a second and 100 times per second. This peak must therefore
be 100 times bigger than average power consumption during whole cycle.
So it creates huge demand on power supply from the wall. And one meter
of COBRA like power cord does not help. The limiting factor is TRAFO,
and in-wall wiring. Trafo starts distorting, buzzing, also distorting
it's other, smaller secondaries etc.
The caps should be just big enough that the charging time
(current, timing) is equal to discharging demand. So the power supply
wave is a nice triangle shaped signal not a row of sharp peaks followed
by 90 % of silence.
I experimented with series resistors with power cords. Guess what. I
could not hear any difference in sound, including bass, impulse,
perceived power - going up to 50 Ohms. Yes - 50 Ohms. Compare it to the
stupid debate if a standard PC cable of 0,5 Ohm is inferior to python
of 0,01 Ohm. (followed by 150 m of standard home wire to the street
trafo, hahaha).
Of course the AC cables alter the sound but not by resistance. Maybe by
filtering capabilities of screening, capacitance, and wire geometry.
And with usual aid of 10 cent's worth of ferrite rings and 100 nF caps
hidden inside
the "pythons belly".
HERESY No. 9.
"I changed the circuit breakers in my home from 6 A to 20 Amp so I have
JUICE now !!! WOW !!!"
Hey Mr. Heretic, before you burn the house or get electrocuted, note
that the amount of electrical power coming to the stereo DOES NOT
depend on the breaker. Of course if your Krell triggers the breaker
sometimes, there is no music. But if it works, the breaker rating only
tells you WHEN it will trip if current is exceeded. Does not give you
more juice, even the slightest bit.
And because all in-house breakers by code must have 1,6 times bigger
ones outside of the home, if we change a 10 A breaker to a 20 A
type, that means that it is followed by the outside one with 16 A. So
in case of equipment failure, the outside breaker will trip before the
in-house one. This will require a walk with a candle to the cellar or
staircase in the middle of the listening session or finding the
goddamned key to the street electrical box.
Heresy No. 10
"The tubes color the sound by adding pleasant harmonic distortions, the
only real sound is from transistor, but many people voluntarily like to
feed themselves with rosy tubey sound". This is the transistor salesmen
mission and vision. But nothing could be more false. Transistors and
opamps are semi conductors. SEMI. The tubed circuits do have a natural
tendency of sounding better because they are MORE SIMPLE and more
elegant. It is VERY expensive in engineering terms to employ a tube -
we need some 10 W of heater power to just lit a tube, and a whole
dedicated circuit to power it up. Transistors come cheap and stone cold
so engineers use them by bulk, and hence OVERENGINEER products. A
circuit with 2 transistors will sound as good as a circuit with 2 tubes.
Today's engineers don't know how to design with transistors, so they
build the easy circuits with minimal risk with the LEGO like building
blocks - op-amps. I bet that most products are produced without
listening. Just autocad in the office. It MUST work.
Transistor design is a bigger voodoo today than even tubes !!! Only
Marantz uses transistors for CD output and calls it
HDAM. High
Definition Amplification. They consider it a BIG DEAL. If I
want
to hear an absolute and total truth about a signal, I will use a tube
10 times out of 10 . But your mileage may vary.
Heresy No. 11
Last one... Spikes eliminate vibrations.
Oh yes, once I get started on that one I can't stop.
Yeah - spikes under CD players behave like a mechanical diode. The
vibration of the table disappears and the music is PURE AND SWEET.
Holy shit who invents all that crap ? What do they smoke that I can't
buy ??!
Once and forever: the spikes were invented by British audiophiles, who
faced the problem of firm and straight placement of floorstanding
speakers (and even more - standmounted monitors). The British homes are
wall to wall carpeted and under the carpet they put extra foam liner so
a speaker will lean forward, wobble, rock, and play muddy sound.
Spikes address that by piercing through the carpet, through the foam
and through the mites and it stands firmly on the hard floor. THAT IS
VERY COOL SCENARIO. We applaud it.
But whoever sells the golden spikes for CD players and amplifiers or
floorstanding speakers for wood floors like parquet - he is so smart
and the customers are so dumb, he must be laughing all the way to the
bank. I am jealous how smartly these sellers fool naive people.
In my opinion, the products may stand well on any shape of solid feet -
the conical spike shape is totally irrelevant. The brass feet can
have a shape of crocodile legs or chicken eggs. The board of the table
sees a point, but has no idea what the rest of the "spike" looks like.
The board could not care less about the other 5 cm of conical; shape,
couldn't care less.
So standing firm is a nice thing, its okay, but it does not eliminate
vibrations. On contrary, the CD is so well coupled to the goddamned
shelve, that the whole CD will perfectly resonate in tune with the
music. Air moved by speakers will move the shelve and in turn - the
spiked CD. Some people will find it amusing that there will be an echo
of resonance correlated with the music sound. This definitely adds
pleasant dither to the music but this is NOT THE STORY that the spike
salesman sold you, is it ? It would be cheaper to put the CD player
directly on the speaker. That would play in perfect harmony,
unisono so to
speak.
To deal with vibrations dear folks we must use different technique -
vibration transmission media density change (hard - soft - hard again
soft again) and the soft one must be not springy but lossy and
damp the vibrations. Lossy structures are sand, potting soil, cat
litter gravel, heavy rubber, foam toys, sleeping matts, bubble wrap,
leather, cork, wool felt, soft polymers, plumbing silicone, oil,
etc.
To improve damping factor it is advisable to add mass to the vibrating
thing. We push the natural mechanical resonance below audible range so
no musical contant has a chance to excite it. A 9 Hz resonant platform
would be nice. Most effective lossy media is a big bag of slightly
moist potting soil but some folks ant their wives may find it over the
board.
Realistically, something like a sandwich - heavy table, soft layer of
neoprene or squash balls and heavy plinth again and CD on the plinth
with felt liners on the feet. Add a phone book on top, or a marble slab
lined with wool felt again.
If you really want to full monty - open the cd and put a half pound of
sand in a cotton bag on the main PCB. Don't use the plastic bags
because hot parts may pierce it. First - dry and sanitize the sand in
the oven - 200 degrees for one hour. Let it cool down of course.
Wood blocks are HORRIBLE vibration killers - wood only selectively
resonates which may or may not hit a pleasant note. The wood block
sellers must not only laugh on the way to the bank, they ROTFL(T)AO.
