Recording is Changing
Marketing Director Stefan Fischer interviews
Product Manager RŁdiger Forse about the MindPrint DTC
digital age, achieving a new level of quality is something
that is nearly impossible to do with just higher sampling
rates or bit depths. Digital processing quality is better than
ever, and has reached a level that
meets even the highest sonic and dynamic requirements. With a
sampling rate of 96 kHz we can reproduce frequencies that are
more than double the highest frequencies manís hearing
mechanism is capable of perceiving. A resolution of 24 bits
offers us a dynamic range that can capture sound at pressure
levels that go far beyond the threshold of pain of human
hearing. In the past, our attempt to reproduce all the
perceptible nuances of a sound was severely limited by the
available technology; today we are much closer to capturing
all the details of a sound in its full glory.
The mission of the DTC
digital technology today is capable of such high resolution,
one would think that the best and shortest connection would be
a pure analog-to-digital converter. So why is MindPrint
developing high-end analog technology?
even more important than the recording quality and
reproduction quality of the digital converter itself is the
quality of the analog circuitry preceding the converter. Today
the only part of the signal chain that is subject to loss is
the analog section that prepares the signal right before it
hits the digital realm. The task of the DTC is to make this
part of the path as good and as short as possible.
can in fact be done, canít it, without additional components
in the signal chain?
this is easy to imagine. We already have digital microphones,
and guitars with digital pickups wonít be far behind. Thank
God, it would be the end of analog cabling.
the beginning of synchronization chaos.
Besides, there are different instruments, microphones, and
other things that people will continue to want to use. A
Neumann U47 tube mic, for example, doesnít have a digital
output. Youíve got to keep in mind: the sound of instruments
and microphones occur in the analog realm, as waves and
current, and not as bits and samples. And waves and current
are very sensitive as to how they react to physical quantities
such as impedance, capacitance, and induction. And only when
we pay proper attention to these quantities, and waves and
current are turned into the "right form," do we stand a good
chance of performing a proper conversion to digital.
"right form" do you mean the processing of the frequencies and
that too. Good sound starts well before the processing, in the
input stage itself. Technically speaking, the job of the DTC
is to take a very weak modulating electrical signal with a
very broad frequency range and amplify it and "shape" it. But
this electrical signal has its own peculiarities: depending on
whether the induction and the capacitance is set up in the
circuit to run in parallel or in series, these can have a
dampening effect on the bass and treble. With all analog sound
sources, whether pickup or microphone, or even a normal cable,
the capacitance and inductance play a role and influence the
sound. The special input circuitry of the DTC respects them in
a very special way, so that they do have the necessary "raw
form" required for the subsequent frequency and dynamics
microphone input of the DTC includes a transformer.
Technically, transformers alter the sound. As the noise
quotient of analog signal sources has constantly improved, we
were happy that we no longer needed to use a transformer. Why
the step backwards now?
not a step backwards, on the contrary. The complex interplay
of impedance, capacitance and induction in the input
transformer is responsible for the optimal matching of the
microphoneís diaphragm to its electronics, and aids
considerably in enabling the microphone to reproduce sound in
a natural manner. MindPrint has researched these phenomena and
collaborated with the company Hauffe to develop a new
transformer. This sophisticated transformer possesses the
advantageous sound characteristics known from older models,
but avoids their common side effects, such as phase distortion
in the treble region, because it has such an extremely broad
frequency range (up to 100 kHz) that the phase distortion
occurs out of the range of human hearing. Furthermore, because
it has a turns ratio of 1:5 the transformer makes life easier
for the subsequent amplifier stage, thereby reduces distortion
and makes it possible to achieve an extremely good
thing that struck me about the DTC is the impedance of the
microphone input. At 5 kOhms it is considerably higher than
usual with microphone preamps. Why does MindPrint deviate so
greatly from the 600-Ohm standard?
simply, it sounds better!
course. Can you go into greater detail?
Certainly, but weíll have to get fairly theoretical: as we
already discussed, the impedance of microphones is not a
constant but is frequency dependent. Within the frequency
range of microphones certain there exist certain impedance
peaks which can far exceed 1000 Ohms. If the input impedance
of a microphone preamp is less, these peaks are damped, which
in effect automatically changes the frequency response. Since
these peaks occur especially in the treble region, the
automatic damping of low-impedance preamps leads to a loss of
brilliance. The DTC, due to its high-impedance design, can
handle even extreme peaks and thereby avoids losses in the
highs. This especially makes dynamic microphones sound more
transparent and natural. Condenser microphones also sound
better, since their amplifiers, which are not loaded down as
much, can operate with less distortion. Finally, since the
highs are reproduced better, less equalization is
talk about equalization here for a moment. What makes the EQ
of the DTC special is the parallel arrangement of the filters.
Not everyone is familiar with the technical difference. Can
you give a brief explanation here?
Normally, filters are placed in the circuit one after another.
In doing so, the complete frequency spectrum of the signals
goes through all the filter stages, which can lead to a
considerable degradation of the signal quality. You can think
of this like a winding, one-lane road that slows down the
signal. In contrast, the equalizer of the DTC uses parallel
filters, so that the signal is divided into all four bands at
the same time. Like a straight four-lane Autobahn, on which
the signal moves ahead without any obstructions.
logical. But thereís still the issue of the passive nature of
how the original signal is handled. Whatís that all
original signal goes through the EQ practically like through a
thick cable, without interruption. The bands of EQ, which are
laid out parallel to the original signal, only operate on
those frequencies that are to be processed. If a frequency
range is to get a boost, it will be mixed into the original
signal in phase, and if cut, with phase reversed. But the
original signal remains. This way, you maintain optimum
fidelity to the original signal.
treble band and the bass band are set up as shelving filters,
whereas both mid bands are laid out as bell filters. An
adjustable Q control, common with bell-shaped filters, is
uncommon with shelving filters. How are we to understand a
"bandwidth" with shelving filters?
right, a Q-factor control is quite uncommon with shelving
filters, although it adds considerably to the sonic
flexibility. High Q-factor settings in the case of boosting
will at first produce a slight dip in the middle frequency
range before the curve rises to the edges.
before the bell there is first a dip?
A: You can
think of it like this: if you want to boost the highs above 10
kHz, for example when mastering, you can shape the curve in
such a way that the frequency range before it, from 8 to 10
kHz, is cut. This will result in a supremely soft sound. Or
you can boost the low bass without having to worry about
ending up with mud between 150 ad 300 Hertz. When cutting
instead of boosting, the effect is just the opposite: at first
there is a boost, and only then a cut. The good thing about it
is that this can be adjusted with infinite variation. This
gives you a lot of control, so much so that you often donít
even need to use the mid controls. The applications are really
very flexible and lead to astonishing sonic results.
The dynamic section
compressor/limiter is also supposed to be capable of
astonishing results, I understand. But it has only two
right, all the filters together have a total of 14 controls
per channel. The compressor has only two, plus one switch. The
first control very effectively combines threshold and ratio,
while the second adjusts the times, and the filter switch
replaces a side-chain EQ. In other words, all parameters are
Q: And how
does this work in practice?
compressor/limiter control functions in a way that is quite
effective: When turned completely counterclockwise all that
happens is that there is a mild compression of the loudest
signal peaks. The more you turn the control clockwise, the
lower you set the threshold. In the controlís middle position,
"Limit @ 0dBfs," the channel will be dependably kept from
being overdriven. All signals are brick-wall limited at 0 dB.
Thatís something that you absolutely want with digital
recording. At the same time with this setting, soft signals
are amplified considerably. The more you turn the control
clockwise, this amplification becomes greater, while the
limiting function stays the same.
Q: So, the
more I turn this setting up, the fatter the sound I
and at the same time it gets brick-wall limiting. Ordinarily
you would need to make further adjustments to Threshold, Ratio
and Make-Up Gain, and still send this signal through a
limiter. The DTC takes care of this by itself.
Q: And the
Release control determines when the compressor will again
raise a soft signal after having reduced a loud signal. If you
design it so that it responds too quickly, you might
overemphasize reverb trails, for example, which would overly
thicken the sound. With longer release times, more of the
character of the original signal is preserved. The attack is
not changed, thatís something which is handled by the Adaptive
exactly is Adaptive Response?
A: Our big
secret! But the basic principle is easy to imagine: Adaptive
Response operates with several control times which are
mutually interdependent. A standard compressor will kick in,
for example, when signal peaks appear in material that is
already fairly dense, and you will hear pumping. Here thereís
an addition controlling function kicks in which handles fast
transients, independently of the basic setting.
Q: But I
thought the filter was supposed to prevent pumping.
Exactly. But pumping can occur when bass-heavy signals affect
the sensors too strongly. Typical scenario: the bass drum
causes the highs to be reduced. For this reason the filter was
set up in such a way as to make the compressor less sensitive
to low frequencies, resulting in a type of compression that
corresponds much more closely to the way the human ear
actually works. Since we are modeling a natural function of
human hearing, this filter circuitry improves practically
every signal thrown at it.
what role do the opto-couplers and the tubes perform
A: Both of
them do what they do best: the opto-coupler compresses in a
very unobtrusive and pleasing way. Since an opto-coupler is a
passive component, it sounds substantially cleaner than an
active semi-conductor circuit. The tube with its natural form
of saturation reliably handles the limiter function, and is
naturally responsible for the harmonic overtones.
hard limiting at 0 dB, is the sound similar to that of a
A: No, not
at all. The limiter in the DTC doesnít slam the signal against
the wall, on the contrary. The compressor function turns into
a limiting function very gradually, i.e. soft-knee. The sound
that results is comparable to that of large-head analog tape
machines. Thanks to the added overtones, compressed signals
are more perceptible to the human ear, so they are experienced
as if they were louder than they actually are.
does the DTC do this?
the DTC, the tube circuitry is tweaked in such a way as to
emphasize the uneven overtones and minimize the even
other words, the octaves are not emphasized, while the fifths
and the thirds are?
Exactly, and that results in a very pleasing, unobtrusive
sound. The human ear simply likes it more when signal peaks
make themselves heard in the form of added presence rather
than increased volume.
Analog and digital outputs
Output control is at the end of the signal chain. What can you
tell me about this?
A: At a
position of 0 the optional digital converter is driven to its
optimal level. If you limit to 0 dB full-scale, the dynamics
of the converter is used to optimum advantage.
Q: So, you
mean maximum level together with prevention of
however to play it safe, you still shouldnít run critical
material as hot as 0 dB, even with full-scale limiting. The
best way to monitor it is to keep an eye on the input meter in
the recording software you are using. But you can also see it
in the display of the DTC.
The digital option DI-MOD 24/96
digital converter operates with 24 bits and at 96 kHz. The
spec sheets says that weíre dealing with a dynamic range of
113 dB (A). But there are other converters that go higher,
converter chip itself will do more. In any case today
practically all the manufacturers of converters - is the
manufacturers of hardware built around the converter chip -
tend to use the same model of chip. All the same, the finished
products both sound different and have a different dynamic
range, because itís not just the chip that determines the
quality, itís the entire analog circuitry built around it, the
filters, the signal paths, and other factors. You can, of
course, design the circuitry around the chip in such a way as
to absolutely optimize the dynamic range, but those measures
will take a toll on the sound. Maybe not measurably, but
very good specs donít automatically guarantee that the
conversion will also be very good.
would be great, wouldnít it! Think about the good old CD
standard. Thereís a world of difference in sound between cheap
CD players and expensive high-end units. The same thing goes
for AD converters. Even when they have similar technical
specifications and test results.
kind of digital interface does the digital module
S/P-DIF it uses an optical interface in TOSlink format, and an
electronic one on coaxial RCA connectors, with AES/EBU
available as an option. A great feature of this module is the
Auto/Master switch, which forces the DI-Mod into Master mode
at the selected sampling rate, regardless of the sampling rate
of the incoming signal.
Q: So the
AD converter operates completely independently of the DA
right. For example, you can process 44.1 kHz recordings with
the DTC and convert them to 96 kHz. Or you can do it the other
way around, for example starting with 96 kHz material from a
project you might be mastering with the help of the DTC, and
convert it to the right sampling rate to press the CD.
Originally this feature was conceived just as a way to avoid
the stress of synchronization problems, but in practice it has
turned out to be quite handy. Another very useful feature is
the stereo DA output of the DI-Mod. In other words, with the
DTC and the installed digital option you can operate
that mean that the DI-Mod can be used to monitor the digital
output signal of a computer-based digital audio
example, yes. Just think about the direct connection to any Apple computers as they also feature optical digital in/out.
The DTC concept
That brings us to the end of the signal chain. To sum up,
then, what is the DTC?
A: The DTC
is a front end with a unique combination of tried-and-true
analog components together with the sonic authenticity of
todayís most advanced circuit designs. The best of both analog
and digital worlds in a single unit, yet with the same type of
extraordinary value that MindPrint is known for.
what other units could it be compared?
original idea behind the design of the DTC was the all-in-one
channel strip. The DTC is different from other existing
designs in that it is affordable and will make the expensive
sound of esoteric outboard units available to every project
studio owner who wants extraordinary sound. Since it is the
only unit with this sound quality and combination of features
in its price class, itís hard to make comparisons.
Furthermore, it is a two-channel device, whereas most channel
strips are only single-channel.
channel is often enough, so why two?
A: Man has
two ears. (smiles) No, the whole point of the DTC is simply to
offer a comprehensive solution. A single channel only goes
half-way. After all, when you record, you not only want to
record solo guitar or voice; you might want to record a choir
in stereo, or take a stereo feed from a keyboard and submix.
Furthermore, the DTC is a superb mastering tool and can also be seen in live racks.
Q: At a
price of about 2000 Euros, the DTC is not exactly something
youíd decide to buy while youíre waiting in the checkout line
at the store. For whom exactly did you design the
every project studio. Recording is constantly expanding and
changing for the better. But most musicians still use cheap
preamps, mediocre equalizers and ineffective compressors that
definitely degrade the signal. It is important to realize that
a high-quality microphone needs an input channel of similarly
high quality, or its value is lost and its quality degraded.
If the preamp stage and the analog signal processing are
crappy, then no software in the world, no matter how good, are
going to be able to restore the tone and expressiveness of a
particular voice. The DTC meets the needs of high-end studios
and fulfills the dream of every project studio
Alesis did when it came out with the ADAT and made
high-quality 8-track recording affordableÖ.
Exactly! Suddenly, professional multi-track recording quality
was no longer reserved exclusively for the well-to-do. The
ADAT started a revolution; you might even call the ADAT the
"mother of all project studios."
Q: It was
the solution for thousands of musicians. The unit itself
actually cost quite a bit, but what you got for your money was
extraordinary for the time.
A: The DTC
is quite a similar story. It is the equivalent of a classic
high-end outboard rack, but with such features and at such a
price that itís a perfect fit for the project
would you say that the DTC is intended for everyone who is
looking to upgrade his digital equipment?
a good way of putting it. And it would be an upgrade that
would last a lifetime, because unlike digital, the analog
technology in the DTC will never be outdated. Plenty of
musicians are excited about existing high-end analog units,
but their price scares them away; or in the case of vintage
units, they may not even be available any more. The DTC will
make high-end recording accessible and affordable, plus its
quality will appeal to anyone seeking a dedicated preamp, EQ,
or compressor. Because it is such an outstanding value, it is
a real alternative to many of the expensive analog outboard
units. For those looking for exceptional - yet affordable -
recording quality, the DTC is the logical answer. The ultimate
instrument for every ambitious musician who takes recording