ART TUBE CHANNEL User Manual

TUBE CHANNEL

USER’S MANUAL

FEATURES......................................................................................3

OVERVIEW.....................................................................................3

HY USE AN EXTERNAL PROCESSING CHANNEL

ESIGN NOTES

................................................................................4

?...............................3

SETTING UP...................................................................................5

NPACKING

AC P A

UDIO CONNECTIONS

NSTALLATION

AFETY PRECAUTIONS

OWERING UP

....................................................................................5

OWER HOOKUP

........................................................................5

......................................................................5

................................................................................6

.....................................................................6

.................................................................................6

FRONT PANEL CONTROLS & INDICATORS ...........................7

REAMP CIRCUIT

.............................................................................7

Gain Control..............................................................................7

Gain Switch................................................................................ 7

Phantom Power Switch...............................................................7

Tube Drive/Gain Reduction Display...........................................8

Preamp Output...........................................................................8

PTICAL COMPRESSOR CIRCUIT

.......................................................9

Slope Switch...............................................................................9

Speed Switch ..............................................................................9

Compressor Bypass Switch.........................................................9

Compressor Threshold and Output Controls.............................10

Compressor Threshold Control (outer control).........................10

Compressor Output Level Control (inner Control)....................10

Clip Indicator...........................................................................11

QUALIZER CIRCUIT

......................................................................11

Low Frequency Control............................................................11

Low Shift Switch.......................................................................11

Lo-Mid Frequency Control.......................................................12

Lo-Mid Shift x 10 Switch ..........................................................12

Hi-Mid Frequency Control.......................................................12

Hi-Mid Shift x 10 Switch...........................................................12

High Frequency Control...........................................................12

High Shift Switch...................................................................... 13

EQ Bypass Switch.....................................................................13

Master Output Level Control....................................................13

Phase Switch ............................................................................13

Output Level VU Meter............................................................ 14

Power....................................................................................... 14

REAR PANEL CONNECTIONS.................................................. 15

NPUT AND OUTPUT CONNECTIONS

........................................................................................... 15

NPUT

O L

........................................................................................ 15

UTPUT

OOP INSERTS

............................................................................... 15

................................................ 15

Preamp - Compressor Loop...................................................... 16

Compressor - EQ Loop............................................................. 16

Loop Connections.................................................................... 16

APPLICATIONS ........................................................................... 17

PECIAL EFFECTS

EQ T

....................................................................................... 19

IPS

.......................................................................... 18

What is the best way to use EQ?............................................... 19

TUBE REPLACEMENT...............................................................20

BLOCK DIAGRAM......................................................................21

A R T TUBE CHANNEL SPECIFICATIONS ............................. 22

WE’RE ON-LINE! ........................................................................ 23

WARRANTY AND SERVICE INFORMATION......................... 23

IMITED WARRANTY

ERVICE

....................................................................................... 23

.................................................................... 23

Features

The Tube Channel is a unique product. It contains three independent award-winning circuit designs: one of the finest tube microphone preamplifiers available, one of the finest optical tube compressors available, and one of the most flexible EQs you’ve ever used -- all in one unit. Developed in partnership with studio and live sound engineers, the Tube Channel possesses a “sound” that is not available from any other product on the market -- at any price! The Tube Channel was designed and constructed with the best components, assuring a lifetime of quiet, reliable performance. The Tube Channel offers:- The award winning A R T “SOUND”! - A Tube-based mic/line preamplifier- An Electro-optical compressor design

- A Tube-based semi-parametric, four-band equalizer- Hand-selected preamp tubes- VCA-less compressor circuitry (i.e., transparent dynamics control)- Unique tube drive and gain reduction metering

- VU output level metering- Bypassable compression and equalization circuitry- XLR balanced inputs and outputs- ¼” TS unbalanced inputs and outputs- A Custom extruded aluminum chassis

- ¼” unbalanced insert points between the preamp and compressor and between the compressor and equalizer- +48V phantom

power- Phase reversal- Over 70dB of gain- Detented rotary controlsCompression and limiting ratios- Selectable release time settings>90dB dynamic range- An Internal power supply- A three year warranty- The Tube Channel was Designed and manufactured in the USA

Overview

Why use an external processing channel?

The shortest signal path is the best way to get a signal to tape. In most cases, the shortest path is: mic to preamp to compressor to EQ to tape deck. The signal doesn’t even go through the mixer! This isn’t a new concept, but it has become more relevant with the availability of affordable mixing consoles. As their name implies, most affordable mixers excel in signal routing and mixing capabilities. However, they are not necessarily your best option for the actual recording of tracks. While their onboard circuitry is nearly always clean and quiet, the simple truth is that the Tube Channel has a better sounding and more

flexible collection of circuits. Mixer manufacturers need to make trade-offs to keep prices down while keeping performance up. Imagine the price of your mixer if each channels’ EQ cost over $200 (and we’re not talking about those of you who have one of those $250,000+ consoles!) The use of external processing (equalizers, preamps and compressors) has sonic and practical benefits when you consider that most recording is done one or two channels at a time. For those of us on a budget, it just doesn’t make sense to spend a ton of money on a “Cadillac” console when a budget mixer and a few pieces of external gear is more cost effective. Even those engineers who regularly work on “big” consoles use external EQs, compressors and preamps!The goal of any recording is to get the sounds right before you commit them to tape. The Tube Channel exists to help you get it right so you don’t have to “fix it in the mix”.

Design Notes

The Tube Channel is a multi-purpose tool for audio engineering and recording. Enclosed in a one rack space (1U) chassis are three independent circuits featuring a tube-based analog preamplifier, a VCA-less, optical compressor, and a semi-parametric, four-band, tubebased equalizer. Used as a direct recording channel, a mic/line preamp, or a DI (direct) box, the Tube Channel is designed to work seamlessly with any recording, sound-reinforcement, or electronic instrument setup. A R T’s Tube Channel circuitry is a hybrid design utilizing the latest, most advanced, solid-state and tube technology. With a transformerless design, the Tube Channel maintains exceptional signal integrity and extremely low noise. The compressor circuit follows the preamp and the equalizer follows the compressor (although you can change the order of the circuits by utilizing the insert points). While the preamp is always active, the compressor and equalizer may be individually bypassed. The preamplifier’s active balanced solid-state input provides extremely low noise and excellent CMRR. The ¼” input has a high impedance, which prevents the loading of any device connected to it and makes the Tube Channel perfect for DI or line level applications. The preamplifier’s second stage 12AX7a tube runs on a regulated DC voltage providing an additional 40dB of gain. Our design enables the tube to overload before the input or output stage. This allows you to manipulate the tube gain to meet different sonic requirements.The compression circuit features a VCA-less design and utilizes optical (Vactrol) electronics for superior musical performance. The compressor is soft knee by design. Although it is capable of providing a thoroughly “squashed”

signal, it was designed to excel in areas where transparent and musical dynamics control is desired. The beauty of the optical design is its ability to apply heavy amounts of compression without pumping and breathing like VCA-based compressors. In many cases you will hear the results of the compression without hearing the compressor.

The tube-based equalizer was designed to help “fix” the instruments that give us the most headaches when we’re recording: kick, snare, bass, toms, guitar amps, voice, etc. The two sweepable parametric bands and selectable shelving bands have been optimized for musical instruments. The two sweepable bands overlap each other and also the high and low shelving bands, providing you with the ultimate in flexibility. This EQ design gives you all the control you need to effectively alter and dial in great sounds from even the poorest of sources.

Setting Up

Unpacking

Your Tube Channel was packed with care at the factory. The shipping carton was designed to protect the unit during initial shipment. Please retain this carton for use in transporting the Tube Channel, or in the unlikely event that you need to return your Tube Channel for servicing.

AC Power Hookup

The Tube Channel has an internal power supply designed to operate at 100 to 125VAC, 50 to 60Hz. Units manufactured for use outside of the United States have been modified to comply with the required electrical specifications. Under no circumstances should the power cable be altered. If the cable becomes cut or damaged, discontinue use and have it replaced before operating the Tube Channel.

Audio Connections

Audio connections to and from the Tube Channel are balanced XLR (Pin 2 = Hot (+), Pin 3 = Cold (-), Pin 1 = Ground) and unbalanced ¼” (Tip = Hot (+), Sleeve = Ground).

The insert points between the preamp and compressor and the compressor and equalizer are ¼” (Tip = Hot (+), Sleeve = Ground)

unbalanced connectors.

We recommend using only high-quality cables equipped with the appropriate connectors.

Installation

The Tube Channel may be employed in a number of setups including:Between a microphone and a mixer, digital multi-track recorder,

DAT machine, hard disk recorder, or analog recorder.- In a mixer’s channel insert points.- Between a microphone and signal processors.- Between electronic musical instruments (synthesizers, guitars, basses, samplers, acoustic instruments with pickups) and

other gear.

Safety Precautions

Warning: To avoid the risk of shock or fire, do not expose this unit to moisture. Do not remove metal panels or chassis parts. Removing any chassis parts exposes dangerous high voltages. There are no userserviceable parts inside. Refer all servicing to qualified personnel. Note: If your power cord becomes damaged and must be replaced, always replace it with the proper (3 prong) type.

Powering Up

When the power switch is turned on, the VU meter will illuminate. It is important to remember to turn the Tube Channel on before any monitoring levels or power amps are turned on. The Tube Channel has the ability to add over 60dB of gain to its input signal. This can cause the Tube Channel to produce a “thump” on power up and power down.Note: Like all tube-based equipment, the Tube Channel needs to warm up before being used. Allow one to two minutes for the tubes to reach proper operating temperature before using. If the Tube Channel fails to power up when the power switch is turned on, check to see that its power cord is plugged into an active outlet. If the unit still fails to operate properly, turn it off and unplug it. Then consult your dealer or A R T’s Customer Service department.

Front Panel Controls & Indicators

Preamp Circuit

Gain Control

The Gain control sets the amount of input gain of the Tube Channel.

Turn the control clockwise to increase gain and counterclockwise to

decrease gain. Selection of the gain range is made with the +20dB

gain switch. You may control two ranges of gain with this control, +9

to +50dB and -11 to +30dB. When setting the Gain control, refer to

the 4 segment Tube Drive Array for a visual reference to the Tube

Channel’s internal signal levels (applied gain).

for the Tube Channel is when the second” warm” Light Emitting

Diode (LED) in the Tube Drive array is lit.

Gain Switch

Use the Gain switch to set the range of the Gain control. When the

switch is in the out (0db) position the gain range is -11 to +30dB.

Depressing the switch adds 20dB of gain. With the switch in, the gain

range is +9 to +50dB.

you’ll find using the Tube Channel with the +20dB gain switch in is

needed. Use the setting that best fits your application.

Note:

With most microphone applications

Hint:

the “sweet spot”

Phantom Power Switch

The Tube Channel can power any microphone needing +48 volts DC

phantom power. Consult your microphone’s documentation to see if

phantom power is required to power it. Phantom power is turned on

and off with this switch and supplies power to pins 2 and 3 of the XLR

input jack.