Earthworks 521-ZDT Data Sheet

Architectural & Engineering

Specications

521 ZDT Preamplier Module

The preamplier module has a frequency re­sponse of 1Hz - 200kHz +0.5dB and distortion
less than one part per million (0.0001%). It shall

have an input noise of 1.6nVHz½ at 20dB gain
and 0.6nV/Hz½ at 60dB gain and a slew rate
of 22V/μs. It shall have a DC oset, servo bal-

anced of +1 mV typical. Power requirements
are +16 VDC, supplied by standard 500 Series

rack. Inputs will be transformerless, dierential

balanced terminating a 500 Series EDAC Edge

connector. Input impedance shall be 10KΩ with
phantom on and 100KΩ with phantom o. The
amplier will have a balanced dierential output

which will only feed balanced signal lines, and

a front panel auxiliary 1/4 inch t-r-s (tip+ & ring

ref) output connector which will feed either bal­anced or unbalanced signal lines. It shall have
a front panel polarity reverse switch, a standby

(channel on/o) switch and a 48V phantom
power on/o switch with a phantom power LED

indicator. It shall also have a LED clip indicator

and DC power on LED indicator. The amplier

shall be available in single channel module for
a standard 500 Series rack. The single channel

preamplier will have dimensions of 1.5” x 5.25”
x 6” (38 x 133 x 152mm) and occupy one 500
Series rack space, weighing 0.8 lb. (0.36kg).
The Earthworks 521 is specied.

521 ZDT Preamplifier

Zero Distortion Technology Preamplifier for 500 Series Racks

• ZDT Preamplier Module for
Standard 500 Series Racks

• Zero Distortion, Less Than One
Part Per Million (>0.0001%)

• Lowest Noise of any Preamp

on the Market

• All Discrete Components, Class A
Amplication (no ICs in signal path)

• No Electrolytic Capacitors in
Signal Path

• Greater Transparency with Minimum
Signal Path and Minimum Features

• High Output Level +30dBu

• Full Differential (balanced) from
Input to Output (i.e. no internal

conversion to single-ended)

• 15-year Warranty

ZDT Preamp for a 500 Series Rack

Earthworks Zero Distortion Technology preampli­ers were previously only available as standard rack­mount units in single, two and four channel models.

The new 521 ZDT single channel module will t into

a standard 500 series rack. This provides the user

with ZDT pristine amplication at a lower cost per

channel, and the ability to choose as many or as
few 521 ZDT modules as they desire for their 500
series rack(s).

Zero Distortion Technology -

in ampliers was invented by David Blackmer, the

engineering genius of dbx® and founder of Earth-

works®. His goal was to create an amplier which

contributed no audible noise, distortion, or color of
any kind - absolutely pure amplication with noth­ing added, “Like Wire with Gain.” And he did it! We
proudly present the Earthworks ZDT series of pre-

ampliers for those who wish to hear no unwanted
additives in their amplication.

Many audio engineers have expressed the need for
a preamp with “pure gain” which will allow you to
hear the true characteristics of a microphone and
an artist’s performance. Then, if desired add color
(signal processing or special eects). David Black­mer’s Zero Distortion Technology preamps have in­credibly low distortion (less than 1 part per million
(<0.0001%). It’s like having “wire with gain,” mean­ing pure gain with not color, no distortion, phenom­enal headroom and extremely low noise. The 521
ZDT preamps are Class A and made with all discrete
components in the main signal path (no ICs) for un­paralleled transparency. The remarkable 521 ZDT

single channel preamps will t into a standard 500

series rack. Let “Pure Gain” start working for you,
and take greater control of your sound.

The Proof is in the Pudding

Many would tell us that our claim of “Like Wire
with Gain” was too bold, and may not stand up to
scrutiny. So, we decided to measure the distortion
of a straight piece of wire on an Audio Precision
Audio Analyzer which is the industry standard for
measuring distortion. We measured the distortion of
the wire and stored it on one trace, then we mea­sured the distortion of a ZDT preamp channel and
stored it on a separate trace. Then we overlaid the
two traces, which can be seen in the graphic above.
The results show that both the wire and the ZDT
preamp have distortion levels so low, that they were
immeasurable.

Looking Deeper into the ZDT Preamp

The primary signal path, input to output is fully dif­ferential and is balanced all the way through, from
input to output (i.e. no internal conversion to single­ended). The gain control for the main signal path is
controlled with a precision stepped gain switch from

5dB to 60dB, in 5dB steps. In addition, there is a

simultaneous front panel t-r-s output with a variable

gain control that allows 20dB of gain variation from

each stepped switch setting. When you change

gain from the main 5dB stepped gain control, 5dB

steps may be too much or too little. The t-r-s output
is controlled by a continuously variable potentiom­eter on the front panel to provide you the exact level
you desire.

There is a 48-volt phantom power switch with an
accompanying LED indicator and a standby switch
to mute the channel output when desired. A clip in-

dicator shows imminent overload conditions (ring

at 10% below clipping level). There is also a polarity
reversal switch, in addition to a “power on” LED in­dicator. Follow that up with an impressive frequency
response of 1Hz to 200KHz within + 0.5dB (almost
DC to light). The Earthworks 521 ZDT Zero Distor-

tion Technology preampliers set a new and impres­sive standard for 500 series preampliers.

More information including complete specications

are on the reverse side of this page.

Earthworks, Inc. • 37 Wilton Rd. • Milford, NH 03055

Phone: [phone], ext 114 • Fax: [phone]

[e-mail] • ea rthworksa udio.com

®

ZDT the Ultimate in 500 Series Preampliers

Many of today’s sound and recording engineers

choose microphone preampliers for their color
or unique sound. Earthworks takes a dierent ap­proach, in making microphone preampliers which

have “no color” and are “pure” with no unwanted
additives. Also, the noise is extremely low and the
distortion is immeasurable. There are some profes­sionals who want an uncolored microphone pream-

plier that will pass the amplied sound from their

521 ZDT Preamplier Front & Rear Panel Information

Phantom Power

“on” LED indicator

LED Signal Clip

Indicator

Signal Polarity

Reverse Switch

LED Indicator to indicate

channel is powered “on”

1/4 inch t-r-s output,

controlled by front panel

variable output control.

Will feed balanced or

unbalanced lines.

microphones untainted, uncolored and unaltered.

The Earthworks ZDT preampliers are the perfect
choice for these individuals. The ZDT pre ampliers

will let you hear all of the character and minute detail
of your microphone and the sound it is picking up.
Just pristine! Then you can add any additional color
you desire with signal processing or other enhance­ments. The sound of the Earthworks ZDT preampli­ers are “pure” and “transparent” with no added ar-

Phantom Power

on-off switch

Standby Switch

to mute output of

preamp channel

Stepped switch gain control

that uses precision resistors in

5dB increments. This controls

the level of the differential bal-

anced amplier output.

Continuously variable

attenuator adjusts the out-

put level from 0dB to

-20dB with respect to the

setting of the stepped

decibels gain control knob

which feeds the 1/4 inch

t-r-s front panel output

tifacts, no added noise and no added distortion. If it
is a pure signal path you desire, then look no further.

The Earthworks ZDT 521 500 Series preampliers or
our standard rack mount ZDT preampliers are the
masters choice. These preampliers are backed by

a 15-year warranty. You can’t go wrong! Just pick a
521 ZDT module or one of our rack mount models
with the number of channels you require and enter

the world of pristine preamplication.

Rear Panel
Connector
Pin-out

Pin 1
Chassis Ground

Pin 2
Output +

Pin 4
Output -

Pin 5
Signal Common

Pin 8
Input -

Pin 10

Pin 12
+16VDC

Input+

Pin 13
Power Supply
Common

Pin 14

-16VDC

Pin 15
+48V for
phantom power

Specications

Preamp Type:

Number of Channels:

Frequency Response:

Impulse Response:

Distortion:

Input Noise:

Slew Rate:

Output DC Oset:

Input/Output Connector:

Input Impedance:

Front Panel Balanced Out:

Dimensions

37 Wilton Rd. • Milford, NH 03055 • Phone: [phone], ext 114 • F ax: [phone] • [e-mail] • earthwor ksaudio.com

Solid State

One

2Hz to 100kHz ±0.1dB, 1Hz to 200kHz ±0.5dB

1.4μs

main out: less than 1ppm (0.0001%); 1/4” out: 0.001%

1.6nVHz½ at 20dB gain; 0.6nV/Hz½ at 60dB gain

EIN:

-132dBV at 20dB gain; -143dBV at 60dB gain

22V/μs

±1 mV typical, servo balanced.

500 Series EDAC Edge connector

10KΩ phantom on, 100KΩ phantom o

¼” t-r-s Fem. balanced transformerless (variable)

1-500 series rack space 1.5” x 5.25” x 6”

0.8 lb. (0.36kg)

Weight: