That’s the summary for you
speed-readers. Now join
us as we explain it all.
The Old Way
First, let’s look at how we have
traditionally have worked with our vinyl recordings.
Since the late 1800s, music has
been distributed to the masses thru the medium of records.
If there was a song or artist whose performance you liked, you
could buy that performance cheaply and enjoy it at home. In
other words, records were meant for playing.
Many of us have fond memories of carefully choosing stereo
components and setting up our home audio systems in order to get the
most enjoyment from these records.
Things changed radically in the
1980s as records were supplanted by CDs.
Even though there are still modern recordings being issued on
new vinyl, the era of vinyl recordings was over.
But a funny thing happened.
People didn’t rush out to dump their old vinyl records.
In fact, there are many people out there today who still prefer
the analog sound of vinyl to the sound of CDs.
Even if you like CDs generally, many vinyl recordings never
made it to CD or, if they did, suffered from inferior restoration.
Let’s also not forget that since we already owned the record,
we’d actually have to pay twice to buy the CD – an important point
for the more thrifty among us!
So vinyl remains a very popular
medium 25 years after it “died” and appears to actually be
increasing in popularity as many audiophiles continue to search for
the best combination of cartridge, stylus, turntable, preamp, etc.
Many of us, however, had a
somewhat simpler idea.
Why not just play our records into our computer, remove the
clicks, pops, surface noise and rumble and make a CD from them?
For years, we have thought about this subject just like you did
and have offered the best noise reduction and audio enhancement tools
on the market – recently culminating in the very successful release
of DC Six. In effect, the
idea has all along been that we would play our records just like it
was 1975, record them into the computer and clean them up.
This is a good approach and will yield some good sounding CDs.
But today, we think we can do
better because times have changed.
Indeed, we are suggesting that we no longer think of our vinyl
records the way we did in 1975. We
are suggesting that we not simply play them into the computer in
exactly the same way we played a popular album such as “Dark Side of
the Moon” on our stereos in 1985.
Our present method of restoring
our vinyl and ending up with a CD is, in our opinion, more akin to
copying a computer disk than it is to lovingly restoring a vintage
vinyl recording. Imagine
for a second that your vinyl record is really just music data like any
other computer data. To
transfer to CD, we start with music data on a vinyl disk.
We copy it to our hard drive.
Then we remove extraneous stuff from the recording and write
this data to a CD. Doesn’t
this sound as much like editing a spreadsheet as it does bringing
analog music to life? Certainly,
a recording engineer pays MUCH more attention to the overall sound of
the music than to the tools he uses.
His digital recording tools and effects units are there simply
to allow him to achieve his artistic vision – not to do rote
transfer of one medium to another.
We can hear you saying, “Now
wait a minute. My record
contains the music in exactly the form that the original artist and
recording engineer wanted. The
best I can ever do is faithfully record this into my computer and
remove the noise. If I do
this, I’ll end up with something that is true to the artistic vision
of the people who made the record.”
Sorry.
Not true. For the
reasons why, let’s look at the world of audiophiles.
We have recently been studying
audiophile catalogs and web sites.
These outlets offer literally hundreds of preamps, cartridges,
amplifiers, speakers, and other devices to make your audio sound
better. On audiophiles
newsgroups, you’ll find them discussing why a $1500 preamp actually
sounds better than a $2000 preamp.
There will be arguments as to which cartridge sounds the best
– and the same for all the major stereo components.
You’ll hear discussion that preamp A provides “upper
frequencies that are sweet and delicate”, “great mid-range
punch” and “warmth and liquidity”.
This may sound a bit strange, but
consider how difficult it is to describe small differences in sound
using English words. We
can certainly understand the problems our audiophile friends have in
describing their audio especially when wine tasters have to resort to
something like, “smooth with just a touch of impertinence”.
But here’s the bottom line –
there is no reference standard for what you hear when you simply play
a record (or a CD for that matter).
Even in the multi-thousand dollar audiophile world, every piece
of equipment is different and will produce a different result.
This is why audiophiles go to great lengths – and expense –
to get a sound that is pleasing to them.
For them, the answer is to accumulate a series of components
that produces this sound. Here’s
a look at the traditional way of PLAYING audio.
http://www.tracertek.com/newway/olway.pdf
. Later we’ll show you
The New Way.
However, even in the audiophile
world, there is no gold standard for what recordings should sound
like. Play the same record on 10 different $30,000 stereo systems,
and you’ll get 10 different sounds.
That’s just a fact.
So where do these differences come
from and why do they exist? There
are 4 major answers:
Finally to the point
Ok, we’ve finally come to the
point. It’s not 1975
anymore and, for many of us, records are not meant to be played as
they used to be. Instead,
times have changed and now records are meant to be transferred.
And, this process of transferring the music on records to
another medium needs to be based on our individual preferences. In effect, we are going to suggest that we start thinking
like audiophiles and change our method of restoring our vinyl from one
that is akin to copying a computer disk to one that gives us a much
better opportunity to create a final result that is just perfect to
our ears. After all, this
is what audiophiles have been doing for years.
It’s 2004, and with a new approach, you can now create
recordings that are dramatically better.
This is The New Way.
Tada! Here’s
The New Way
So, what does this mean
specifically as regards transferring vinyl to CD or DVD?
Here’s the overview.
First, we are going to provide a
fully flat recording from the record to the computer.
We’re going to do this with a phono
preamp that has no built in RIAA equalization.
Next, we are going to use a test
record and DC Six to fully “dial
in” your system to remove non-linearities in all the components from
the cartridge to the sound card.
You’ll only do this once and we’ll then know we are getting
the best (and flattest) audio from the record into the computer.
We’ll also now suggest we record
at high bit widths and sample rates – all the way up to 24 bit
192khz. Today we have the ability to make audio DVDs at these quality
levels, but even standard CDs will greatly benefit from this new
approach.
Now we’ll provide an almost
perfect RIAA EQ to this recorded audio.
We’ll not use the much more error prone RIAA EQ that is in
normal phono preamps, but rather the almost perfect one in DC Six.
Then, in another break with the past, we’ll use audio
enhancement tools in DC Six to adjust the audio so it sounds best on
our equipment and to our ears.
Lastly, we’ll write this
high-resolution audio to CD or DVD-A.
We’ll end up with something that is much better than we have
in the past.
Why
a Flat Preamp?
First a question - Do you want to
hear the audio EXACTLY as it appears on the record or do you want to
hear EXACTLY the audio the original mastering engineer created?
As many of you may know, what is
on the record is way yonder different from what the original mastering
engineer heard when he mixed the master two track audio tape.
In fact, if you were to hear the audio exactly as it is
recorded on the record, you may even be shocked.
We suspect that most of you have never ever heard the audio
exactly as it is on an LP (or 45rpm or 78 record for that matter).
Let’s take an example.
Suppose you are the head engineer on Pink Floyd’s Dark Side
of the Moon, Alan Parsons . You
are given a tape with multiple audio tracks that contain all the
musicians’ performances.
You ever so carefully mix the 16 individual tracks of audio
together. You make sure
the volume of each musician is perfect.
You use your years of experience and a wondrous array of
technical tools to create just the perfect sound.
After hundreds of hours of painstaking work, the band signs off
on the master tape and you listen one more time to the final result. “Perfect”, you think.
You audience thinks so too.
Your album remains in the top 200 selling albums in America for
724 weeks.
It’s a classic album that has
just an amazing sound.
But that sound is not on your LP. It’s nothing like what the original mixdown master tape
sounded like. Instead,
what is on the record has almost no bass.
It’s has very shrill high frequencies.
It sounds like a poor AM radio on steroids.
And we don’t have to pick on Pink Floyd, every album in your
collection sounds this way.
“Now wait just a doggone
minute”, I can hear you say. “My
albums don’t sound like that at all.
With my Mitsuwama vintage tube preamp, and my Hectordyne 9000
gravitationally coupled amplifier, I get great sound.
These are the finest stereo components ever made.
They were hand made by Elves in a clean room without any air in
it. They are absolutely transparent and are almost perfect in
reproducing the sound on the album”.
If you screamed this at your
computer screen, please take a break now to get your blood pressure
back to safe levels.
Feeling better?
Actually you are half right. You probably do have good stereo equipment, but the sound on
your LP has almost no bass and is very shrill and bright in its high
frequencies. Bank on it.
This is simply the way records are
made. They are made this
way on purpose. The bass
frequencies are reduced by a whopping 20db and the high frequencies
are increased dramatically BEFORE the master tape is written to a
record. The result is
just what we have been saying - very little bass and shrill high
frequencies. That’s
what is actually on your records.
Ok, you are starting to believe
us. But why in the world
would the record companies not record the exact audio from the master
tapes right on the records? There
are two reasons - one has to do with recording physics and the other
has to do with our old friend, noise.
First, let’s start with the
physics. The amount of
bass on a record is a function of the width of the groove. The more low frequencies and the louder the bass, the wider
will be the groove. This
is the way records work. So,
if we have a recording with lots of loud bass, we’ll make very wide
grooves. The wider the grooves, the more space that is required
between them and therefore the fewer that we can put on a record - and
the less time we can record on an album side.
Heck, a rap record might only last for a minute or two on a
record because the grooves would be so wide.
This may be a good thing, but it’s beside the point.
So the record companies reduce the bass simply so that the
record grooves are not unnaturally wide.
The frequency below which this occurs is referred to the
turnover frequency. This
is the frequency at which the cutting head reverts from a constant
velocity mode of operation to a constant amplitude mode.
For RIAA, this value is 500hz.
That covers the low amount of bass
on records, how about the excess of high frequencies?
To understand this, let’s cover how a master record is
actually made.
Basically, a record mastering
machine consists of a cutting head which is similar to your stereo
cartridge. The stylus in this cutting head actually has a heat element
in it to help make the grooves on the record.
This cutting element is connected to an amplifier which drives
the cutting head in time with the music.
Thus, your music is translated into a series of spiral grooves
on the disk.
Since we have an electronic
amplifier as an integral part of the record mastering machine, we have
broad spectrum noise from the amp which sounds like hiss.
This is due to the nature of electronics and can be reduced but
not eliminated in the design of the equipment.
The record itself has noise as a normal part of the medium due
to tiny imperfections in the master record and in the vinyl that you
end up owning. There’s no way not to have this noise. It’ll be there and it’ll be hearable. What to do?
We can use the fact that the
amount of noise generated by the amp and by the record itself is
relatively fixed in volume. You’ll
get some noise but it’ll not vary a lot.
What if we then simply made the high frequencies in the good
audio much louder? This will cause the good audio to be much louder in the high
frequencies while the noise added by the mastering equipment and
record would be fixed. The
result will be a good Signal to Noise Ratio - that is the difference
in volume between our good audio and the volume of the noise will be a
large number. This process is called Pre-emphasis and is applied
during the creation of the lacquer master.
The frequency above which this is applied is called the
Roll-off frequency. For
RIAA this occurs at 2120hz.
This is why the high frequencies
on records are pumped up a lot. It’s
simply so our good audio high frequencies are much louder than our
noise floor. We’ll see how this helps us later.
So now you know why the audio on
our records is recorded with very little bass and with lots of high
frequencies. The next
question has to be, “why do my records sound good when I play
them”.
The answer is a nice little thing
called a Compensation Curve.
You see, the problem with wide
grooves at low frequencies and with noise in the high frequencies has
been known since the beginning of records.
And even starting with the electrical recording era, which
began in the mid to late 1920s, record companies fixed the problem by
reducing the bass. As you might guess, here’s the secret - your stereo
equipment does exactly the opposite thing when you play a record.
It increases the bass and it decreases the highs.
Basically, your stereo equipment has a pretty complex tone
control inside it to do this job.
The theory is this - if we drop
the bass by exactly 20db when we record, but increase the bass exactly
20db on playback, we’ll get the original sound.
The same idea works in the high frequencies; we pump them up
when we record and we drop them back to normal when we play back
We are sure you can see that this
makes perfect sense. But
there is a complication, and it‘s a big one.
To see the problem, let’s travel
back to the early days of LPs. Don’t
worry, we won’t be there for long.
Now let’s assume you are going to make a record and you are
familiar with the “wide groove” problem at low frequencies.
After some experimentation, you decide that dropping the volume
of a 30hz signal by 20db will result in just the right width of the
record groove.
That’s all well and good, but
what about 300hz audio? 300hz
is a higher frequency than 30hz, so it won’t make as wide a groove
on the record to begin with. If
we drop it by a whopping 20db, we’ll end up with relatively narrow
grooves. Not a good idea,
you think. Again you
experiment and find that at 300hz you should really only decrease the
signal volume by about 2db in order to get reasonable groove widths.
Next you turn your attention to
the high frequencies. You
know that you are going to have noise in your recordings in this
frequency range, so you find that at 10,000hz you need to increase
this frequency by a gigantic 16db.
This makes the good audio at 10khz so much louder while, of
course, the noise inherent in the recording process is mostly fixed.
You realize that on playback, the equipment must now reduce the
volume at 10khz by 16db, thus making our good audio sound right while
reducing the noise by 16db. But,
like in the low frequencies, you discover that at 2000hz the amount of
boost while recording, and cut while playing, needs to be only 2db.
In fact, it’s even messier than
this. As you continue to
experiment, you find that each frequency in the audio spectrum needs
to be adjusted individually either up or down in volume in order to
achieve reasonably sized groove widths along with low noise.
How in the name of Alexander Graham Bell can we do this?
The solution is a compensation
curve. Here’s a picture
of the RIAA curve right out of DC Six.

Here’s a screen shot from DC
Six. Notice how the
equalization is represented by a curved line.
This is a playback curve, so the low frequencies are boosted
while the highs are attenuated. This
curve is exactly the opposite of the one used to make an LP.
Notice how the amount of boost or cut changes with frequency in
a non-linear manner.
This curve works to create good
sounding records, but it’s not the only possible one that could be
used. In the early days,
there were many different curves which meant that records from one
company didn’t sound exactly as intended when played on another
company’s equipment. This
was especially true with 78 rpm records (and early mono vinyl from the
1950s), which used a variety of compensation curves.
This is also why some vintage stereo equipment had switches to
choose which curve to use on playback.
There’s even some very high dollar equipment made today which
has this feature. Audiophiles
pay this price since they want the best possible reproduction.
When the LP became popular, a
standard EQ curve was proposed by the RIAA and was adopted by all
manufacturers. This is now known as the RIAA compensation curve and it is
implemented in just about every piece of audio equipment which as a
jack labeled “phono”. If
you plug your turntable into a jack labeled “phono”, you can be
just about 100% certain that there is a circuit inside which attempts
to apply an RIAA compensation curve to the audio that comes off your
records.
So, that’s the history.
Time to return to the 21st century. We hope you enjoyed your trip.
What the??
“OK, what’s the point?”
“I already have a RIAA preamp built into my stereo.
I’ve got a decent turntable and decent stereo system.
Seems like I must be hearing what the original recording
engineer intended.”
If Alan Parson dropped by this afternoon, he could listen to
your copy of Dark Side of the Moon and he’d hear just what he heard
when he made the master tape. Right?
Wrong.
You see, what you actually hear
when you play a record depends on a LOT of things.
In order to hear EXACTLY what Alan heard on that day he made
the mixdown master, you’d have to have the exact same equipment that
he did and you’d really have to listen to it at the same spot he
did. You see, no piece of
equipment is perfect – they all fail at least in some small way to
do their job without flaw. This
shouldn’t be surprising. Your
turntable, amp and speakers play a part in presenting the music and
these are not perfect devices either. But let’s focus on the preamp
for a minute.
Yes, you have a preamp even if you
don’t have a separate box labeled Preamp.
If you have an input labeled “phono”, there’s a preamp
right behind it. If you are playing records, you have one.
Inside your preamp is an
electronic circuit that provides the RIAA EQ curve we have been
discussing. Ideally, it
should provide exactly the curve we see in the illustration above.
However, it doesn’t. Like
all man-made audio equipment, it falls short here or there.
If you could plot the actual curve from your own preamp,
you’ll likely find that in some places yours is above our perfect
curve, and in others, it’s below it.
Ok, that doesn’t sound too bad until you realize that even a
3db error above the curve will cause the audio to sound louder at
these frequencies than it should.
The preamp you use will make a lot
of difference in the sound of the resulting audio.
Why is this? While
there are a lot of things that can make one piece of equipment sound
different from another, one of the areas of greatest importance is the
RIAA EQ circuit. You see, these circuits are made up of electronic components
– typically resistors, capacitors, and op amps, tubes or
transistors. These
components themselves are less than perfect and each one adds its own
imperfections to the resulting audio.
Here is a list of the types of
problems that will occur to some greater or lesser degree with any
RIAA analog preamp: (note: this
list is a bit technical. If
it’s Greek to you, just skim over it.
The point is that analog RIAA circuits do fail to accurately
reproduce the original audio by some amount.)
These
reviewers are right. Preamps
do sound different from each other and that difference is, at least in
part, caused by various approaches to try and implement an RIAA EQ
curve along with the problems we talked about above.
Remember, these are comparisons of high end, expensive preamps.
Even here, it’s obvious that they sound different from each
other. And if we assume we want to get the audio the way it was
meant to be, they can’t all be right.
So
what to do? One approach
would be run out and buy a bunch of expensive preamps.
You can then whittle away some happy hours as you swap them in
and out to see which one sounds best.
We’re not likely to suggest that many folks follow this path.
Another
approach is a bit more radical. What
if we built a preamp without any RIAA compensation in it at all?
We’d not then have any problems with the EQ circuit since it
simply wouldn’t be there. How’s
that for a solution?
Well
that might work, but wouldn’t we end up hearing what is REALLY on
the record? Wouldn’t we
hear the audio with almost no bass and highs that are way too loud?
Wouldn’t we have to apply an RIAA EQ somewhere along the
line?
The
answer is yes, we would, but wouldn’t it be great to apply an RIAA
EQ curve that was just ever so slightly shy of perfect?
You either already have one or can get one for much less than a
high end preamp. It’s
the RIAA preset in the Paragraphic EQ in DC Six.
This RIAA EQ curve is amazingly accurate to the limits of the
math we perform. Even the
best hardware based RIAA EQ will miss the perfect curve here and
there. A great one would
be off by perhaps as little as a few dB while most will be off by as
much as 9db at places along the curve.
There is simply nothing out there that is more accurate.
One More Thing
So, if
we apply a great RIAA eq curve, we are getting better audio.
But that’s not all. Your
phono cartridge also has it’s own curve which is, you guessed it,
not perfect either. A
perfect cartridge would output a fully flat frequency response across
all the audio frequencies. You
don’t have a perfect cartridge, so we’re going to suggest you also
fix it.
The
way we are going to do that is by using our test
record. We are
going to play a pink noise signal into our flat preamp and we are
going to record it into the computer.
Next, we look at the signal with our spectrum analyzer in DC
Six and adjust the signal until it is what it should be.
Since we have a known and accurate signal on the record, we can
use this to fully flatten out our cartridge, preamp and even sound
card input.
When
you play the pink noise track you have recorded, you need to create a
Multifilter that includes TWO Eqs – one for RIAA and another to
compensate for the problems in your system.
Your Multifilter will look something like this:
Now,
you just leave the RIAA one alone and adjust the other one for full
system flatness. You’ll
only have to do this once as it won’t change unless you change some
piece of hardware. Notice we used the 20 band EQ to flatten out our system, but
you could use a second Paragraphic if you want.
Basically,
you just adjust the 2nd EQ until it looks close to this:

So why
is the line sloping to down and to the right?
This is because pink noise should drop by 3db per octave.
Trust us, this is the way it is.
To
adjust your own system, use the Spectrum Analyzer set just the way we
have it here and duplicate this exact line as closely as possible with
the 2nd EQ you have in your Multifilter.
Note that the Spectrum Analyzer is set to Averaging mode –
this means you’ll have to be patient after you make an adjustment to
let the instrument average to it’s real readings.
In practice, you make a small adjustment, click on clear in the
spectrum analyzer to make it reset and then wait for a minute or so as
the line settles.
That’s
all there is to it.
Until now, it was not easy to find
a phono preamp without an RIAA curve built in.
So we thought we’d fix this problem and announce not just
one, but two new very high quality and RIAA-less flat preamps.
We call them the Computer Transfer Preamps or CPT series.