Insert the ZROCK2 anywhere
in the signal path.
There are three things you can adjust:
1) EQ Level - fully variable from flat
to boosted.
2) EQ Curve - two available
equalization curves.
3) Bypass - a true bypass switch
to disable the ZROCK2.
Below is a graph of the less-aggressive
of the two available EQ curves.
The graph above shows the ZROCK2
EQ turned all the way up. The lower
dotted line is what you get when the ZROCK2
is bypassed.
This means the knob on the front of the
unit can adjust your music from
flat all the way to the bass heavy,
treble rolled curve shown above or
anywhere in between.
As you can see, the blue line creates a
linear shelf of bass between 20 ~ 60 Hz
followed by a gradual slope out to 260
Hz where it flattens out through the
midrange and then gently rolls the
treble.
Remember this EQ is infinitely
adjustable so if you want less bass and
more highs simply adjust the EQ knob a
bit.
More info with graphs can be
found in our support forum at the following
post.
WHY WE CREATED THE
ZROCK2
This long overdue
product was originally designed
to make listening to classic rock on
streaming internet-radio a less hateful
experience on high-end systems that have
no means to adjust frequency balance.
Happily it is also usable in high
fidelity settings and with any type of
music.
It can be used to fix bass shy
recordings, fix bass shy
speakers or fix overly bright
listening rooms or any combination
of the three.
Remember when classic rock was
recorded... speakers were generally
large and had no shortage of bass.
Receivers had a loudness button that in
concert with the bass and treble
controls made the frequency balanced of
these recordings more enjoyable. Also,
music was analog which in general
contains more density. Fast forward to
today where audiophiles are trying to
listen to classic rock mp3's streamed
over the net on systems that have no
tone controls or loudness contour and
you can see the problem.
The most commonly seen fix for this has
been to add a sub-woofer and turn it up
a bit. Sadly the sub-woofer often does
as much damage as it does good,
resulting in a sound that is
smeared.
Even a perfectly executed sub-woofer
will do nothing for enriching the tone
of the midrange which is also essential
to balancing an increase in bass. The
truth is, you need help all the way out
to around 1 kHz. A sub-woofer
usually stops at 100 Hz.
ZROCK2 shown with its
12AU7 tube removed
Unlike a
loudness button which peaks the response
at around 100 Hz, the ZROCK2 creates a
low-frequency shelf which has flat
response from 20 Hz ~ 60 Hz followed by
a controlled roll-off where things
flatten out in the midrange. In addition
there is a subtle roll-off above 10 kHz
to remove edginess. The result of this
is an incredibly rich, full sound with
big increases in midrange tone. It
animates the music rather well.
REASONS TO USE A ZROCK2
The reality is that many speaker/room
combinations will roll off the lower
bass leaving you with a leaner, drier,
less rich sound. Below is the typical
low-bass performance found in many
listening rooms:
When you
combine typical low-bass performance
like that shown in the room above with a
ZROCK2 you end up with a much flatter
bass response in the bottom octave where
many systems lack.
A ZROCK2 restores this missing
information and makes your music sound
full and rich at lower volumes. Using a
ZROCK2 gives music gains a nice "hit"
that you normally don't get unless
you're at a concert or club, and does so
without having to be turned up loud.
DUAL EQ SETTINGS
The ZROCK2 has two
built in EQ curves that have been
crafted to accomplish the goal on two
basic types of systems. Both are fully
adjustable letting you "dial-in" just
how much EQ you want.
The EQ switch is located on the
rear. When the switch is UP it is
using EQ-A and when the switch is DOWN
it is using EQ-B.
EQ-A is designed for systems that
characteristically sound lean.
That is to say the speaker/room
combination yields results similar to
the graph above where bass is
diminished.
EQ-B is designed for systems that have
perfectly good bass when it's in the
recording, but you want to listen to
classic rock where many of the
recordings lack bass at low
volumes. EQ-B makes it possible to
dial in a nice dry perfectly articulate
hit without becoming too heavy.
Both of these equalization curves have
been designed so that the "perfect
sound" is obtained at about the 3/4
position on the dial. This way
EQ-A can still be used to not only fix
your room speaker issue, but still add
bass when needed to lean
recordings. EQ-B, while
characteristically drier is also a
steeper EQ slope capable of more bass
boost, and more high frequency cut when
turned up all the way.
BYPASS SWITCH makes setting the EQ
completely painless. This is
because it lets you hear exactly what
effect the EQ is having as you adjust
it. It does this by letting you
compare your equalized setting to the
non-equalized (flat) setting as many
times as you want while you're adjusting
the knob. You hear exactly what effect
it your adjustments are having.
TRANSPARENCY
One of the reasons bass and treble
controls and graphic equalizers died off
with the rise of hi-end audio is because
they were often done in such a way that
they created changes in the phase angle
resulting in a subtle but noticeable
smearing of the sound. To ensure these
side effects don't find their way into
the ZROCK2, we use
a simple passive filter and a
single-ended triode to restore the gain
lost from the filter.
ZROCK2
shown with bottom cover removed
There is no
negative-feedback in this design and
only a single tube with no circuit
boards keeping the transparency
extremely high.
Most users who showed concern about a ZROCK2
having negative effects on imaging and
sound stage size reported that instead
of getting worse those things actually
got better.
APPLICATIONS
A ZROCK2 is
appropriate virtually any time you wish
there was more bass and more hit and
better tone with less glare. This makes
it possible to listen at lower volumes
since the bass is not lost when the
volume is turned down. It is also
possible to listen louder in untreated
rooms that are bright to begin with.
A SIMPLE PREAMP?
The ZROCK2 is not
designed as a preamplifier, it is
assumed that you will have either a
preamp or amplifier with a volume
control to actually adjust the volume in
your system.
The way the ZROCK2s
variable EQ knob was deigned is this:
From 0 to 1/2 way, the control acts as a
regular volume control with no EQ.
At the 1/2 way point, the output level
and the sound exactly match the way the
ZROCK2 sounds
when it is bypassed.
From this 1/2 way point to 3/4, the
sound will get louder and the EQ slope
grows proportionately.
From 3/4 to full the EQ slope continues
to grow and high frequency attenuation
starts to becomes apparent.
OPTIONS / Available in the
shopping cart.
Rear
view
Voltage - Select the proper
voltage for your country
Signal Capacitors - Select
from standard film caps to hi-end copper
foil Miflex caps.
Knobs
- You may choose from the following
knobs.
Left to right is
Ebony, Gold, Black Chicken
Head, Cream Chicken Head,
Rosewood.
RCA Jacks - Choose between Gold
or Silver RCA jacks, both are precision
made in the USA.
Note:choose the metal that matches your
cables.
Left to Right are
Silver and Gold RCA jacks.
SUPPORT
If you purchase one
second hand and ever have questions or
technical problems we WILL be happy to
check it out for you and service it if
needed for a very reasonable rate.
We also have a support
forum with many people who's
experiences you may benefit from.
REVIEWS
You may
read reviews on our
products here.
SPECIFICATIONS
| Weight |
|
7 lbs. ea.
|
| Dimensions
|
|
2.5" H x 6" W x
11.0" D |
| Circuit type
|
|
Single ended
Class A Triode |
| Input voltage
|
|
0 ~ 15 volts max
|
| Input
Impedance |
|
47 K Ohms |
Will
Drive
|
|
Preamps
or amps with 10Kohms to 500Kohms
inputs.
|
| Noise / Hum
|
|
-80dB / -62dB
|
| Response
|
|
5 Hz ~ 90 kHz
|
| Feedback
|
|
ZERO negative
feedback used |
| Rectification
|
|
UN4007 |
| Signal tube
|
|
12AU7 / 5963
|
| Biasing
|
|
Self-Biasing
|
| Resistors
|
|
precision WW/MF
by DALE, VISHAY |
| Signal Cap
|
|
Film or Copper
Foil |
| AC cord |
|
Removable power
cord |
| Consumption
|
|
13.5 watts at
the outlet |
| Warranty
|
|
Lifetime
to original owner |
REVISION HISTORY
Dec 2016 ~ July 2017 original model
ZROCK
July 2017 ~ ZROCK2 with the fully
adjustable EQ.
Aug 2019 - Anniversary Mods were made
available in the shopping cart.
RELATED
ITEMS
ZBOX
- Flat response tube buffer stage that
has no gain.
ZSTAGE
- Flat response tube gain stage that has
gain.
ZROCK front view
showing level control, bypass switch,
12AU7 tube
30 DAY IN HOME TRIAL - 10% RESTOCK
FEE
|
