Behringer Tube Ultra-Q T1951 User manual

TUBEULTRA-Q® T1951
www.behringer.com
Version 1.1 November 2001
Users Manual
ENGLISH

2
TUBE ULTRA-Q T1951
This s mbol, wherever it appears, alerts
ou to important operating and mainte-
nance instructions in the accompan ing
literature. Read the manual.
SAFETY INSTRUCTIONS
CAUTION: To reduce the risk of electric shock, do not remove
the cover (or back). No user serviceable parts inside;
refer servicing to qualified personnel.
WARNING: To reduce the risk of fire or electric shock, do not
expose this appliance to rain or moisture.
DETAILED SAFETY INSTRUCTIONS:
All the safet and operation instructions should be read before the appliance is operated.
Retain Instructions:
The safet and operating instructions should be retained for future reference.
Heed Warnings:
All warnings on the appliance and in the operating instructions should be adhered to.
Follo instructions:
All operation and user instructions should be followed.
Water and Moisture:
The appliance should not be used near water (e.g. near a bathtub, washbowl, kitchen sink, laundr tub, in a wet
basement, or near a swimming pool etc.).
Ventilation:
The appliance should be situated so that its location or position does not interfere with its proper ventilation.
For example, the appliance should not be situated on a bed, sofa, rug, or similar surface that ma block the
ventilation openings, or placed in a built-in installation, such as a bookcase or cabinet that ma impede the
flow of air through the ventilation openings.
Heat:
The appliance should be situated awa from heat sources such as radiators, heat registers, stoves, or other
appliances (including amplifiers) that produce heat.
Po er Source:
The appliance should be connected to a power suppl onl of the t pe described in the operating instructions
or as marked on the appliance.
Grounding or Polarization:
Precautions should be taken so that the grounding or polarization means of an appliance is not defeated.
Po er-Cord Protection:
Power suppl cords should be routed so that the are not likel to be walked on or pinched b items placed
upon or against them, pa ing particular attention to cords and plugs, convenience receptacles and the point
where the exit from the appliance.
Cleaning:
The appliance should be cleaned onl as recommended b the manufacturer.
Non-use Periods:
The power cord of the appliance should be unplugged from the outlet when left unused for a long period of time.
Debris and Liquid Entry:
Care should be taken that debris and/or liquids do not enter the enclosure through openings.
Damage Requiring Service:
The appliance should be serviced b qualified service personnel when:
- The power suppl cord or the plug has been damaged; or
- Debris or liquid has entered the appliance; or
- The appliance has been exposed to rain; or
- The appliance does not appear to operate normall or exhibits a marked change in performance; or
- The appliance has been dropped, or the enclosure damaged.
Servicing:
The user should not attempt to service the appliance be ond that which is described in the operating instruc-
tions. All other servicing should be referred to qualified service personnel.
This s mbol, wherever it appears,
alerts ou to the presence of
uninsulated dangerous voltage inside
the enclosurevoltage that ma be
sufficient to constitute a risk of shock.

3
TUBE ULTRA-Q T1951
FOREWORD
Dear Customer,
We thank ou for expressing our confidence in BEHRINGER products b purchasing the BEHRINGER
TUBEULTRA-Q. It is one of m most pleasant tasks to write this preface, as our engineering team has made
it possible to enhance the traditional tube circuitr design (particularl for our VINTAGER series of products),
and adapt it to meet the high sound qualit and d namics requirements of modern, pro-level audio technolog .
The fact that we are still fascinated b antique tube radios and amps as well as the fine and warm tonal
character that we usuall associate with them, are the reasons wh vacuum tubes have kept their ground even
in state-of-the-art circuit topologies used especiall in professional audio technolog or high-end devices. We
are particularl proud that we have found an extremel effective s mbiosis between solid-state and tube
technologies making them affordable to an bod interested in audio technolog . As alwa s, our top-priorit
concern when developing this device was the demanding end user, in other words: ou. It was our major goal
to meet our demands. Sure, it meant a lot of hard work to develop such a product, but the fun has made it all
worthwhile. The shine in the e es of the man interested musicians at the Music Fair 1997, when the saw our
VINTAGER models for the first time, was a lasting incentive driving our development efforts.
It is our philosoph to share our jo with ou, because ou are the most important member of the BEHRINGER
famil . With our highl competent suggestions for new products ouve greatl contributed to shaping our
compan and making it successful. In return, we guarantee ou uncompromising qualit (manufactured under
ISO9000 certified management s stem) as well as excellent technical and audio properties at an extremel
favorable price. All of this will enable ou to full unfold our creativit without being hampered b budget
constraints.
We are often asked how we can make it to produce such high-grade devices at such unbelievabl low prices.
The answer is quite simple: its ou, our customers! Man satisfied customers means large sales volumes
enabling us to get better conditions of purchase for components, etc. Isnt it onl fair to pass this benefit back
to ou? Because we know that our success is our success, too!
I would like to thank all people whose help on Project TUBEULTRA-Q has made it all possible. Ever bod
has made ver personal contributions, starting from the designers of the unit via the man staff members in our
compan to ou, the user of BEHRINGER products.
M friends, its been worth the trouble!
Thank ou ver much,
Uli Behringer

4
TUBE ULTRA-Q T1951
T1951
TUBEULTRA-Q®
2 x 4-Band Parametric Tube Equalizer
s4-band parametric stereo equalizer with selected 12AX7 tubes
sULTRA-TUBE circuitr (UTC) adds desired amount of warmth without additional noise
sParallel filter architecture ensures minimal phase shifting
sPrecision state-variable filters with constant-Q characteristic
sUltra low-noise 4580 audio operational amplifiers offer outstanding performance
sSwitchable shelving filter functions remove unwanted frequencies
sEach band can be b passed and is full adjustable from notch filter to broadband equalization
sBroad frequenc band overlapping allows extreme boost/attenuation
sHigh-qualit detented potentiometers and switches with vintage-st le knobs
sCut-in dela to avoid switch-on thumps
sRela -controlled hard b pass with auto b pass function in case of power failure
sServo-balanced gold-plated XLR and 1/4" TRS inputs and outputs
sBEHRINGERs high-performance OT-1 output transformer retrofitable
sHigh-qualit components and exceptionall rugged construction ensure long life even under the most
demanding conditions
sManufactured under ISO9000 certified management s stem

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TUBE ULTRA-Q T1951
TABLE OF CONTENTS
1. INTRODUCTION..................................................................................................................... 6
1.1 The concept .................................................................................................................................... 6
1.2 Before ou get started ..................................................................................................................... 6
1.3 Control elements ............................................................................................................................. 7
2. OPERATION ............................................................................................................................ 9
2.1 Introduction ..................................................................................................................................... 9
2.2 The TUBEULTRA-Q in the signal path ........................................................................................... 9
2.3 Filter settings .................................................................................................................................. 9
2.4 Setting of the tube stage ................................................................................................................ 11
3. APPLICATIONS ..................................................................................................................... 11
3.1 Filtering out unwanted frequencies ................................................................................................. 11
3.2 Shelving filters and Roll Off .......................................................................................................... 12
3.3 Equalizers as creative audio tools ................................................................................................. 12
3.4 The TUBEULTRA-Q as tube interface ........................................................................................... 14
3.5 EQ-ing a P.A. s stem ................................................................................................................... 14
4. TECHNICAL BACKGROUND .............................................................................................. 16
4.1 Function ........................................................................................................................................ 16
4.2 The Constant-Q principle ............................................................................................................. 16
4.3 The concept of parallel filters ......................................................................................................... 16
4.4 On phase shift and time dela ....................................................................................................... 17
4.5 Tubes used in the TUBEULTRA-Q ................................................................................................ 17
4.5.1 Tube histor ........................................................................................................................ 17
4.5.2 Design and functional principle of tubes .............................................................................. 18
4.5.3 Properties of tubes .............................................................................................................. 19
4.5.4 The best of both worlds ....................................................................................................... 19
4.5.5 UTC circuit .......................................................................................................................... 20
4.5.6 Studio applications .............................................................................................................. 20
5. INSTALLATION ..................................................................................................................... 21
5.1 Rack mounting .............................................................................................................................. 21
5.2 Mains voltage ................................................................................................................................21
5.3 Audio connections ........................................................................................................................ 21
5.4 Transformer-balanced outputs (optional) ........................................................................................ 22
6. SPECIFICATIONS ................................................................................................................. 23
7. WARRANTY ........................................................................................................................... 24

6
TUBE ULTRA-Q T1951
1. INTRODUCTION
With the BEHRINGER TUBEULTRA-Q T1951 ou have purchased an innovative device. Parametric equalizers
represent the most advanced form of equalization s stems. With the TUBEULTRA-Q ou have purchased an
extremel musical and flexible device. Our ULTRA-Q range of devices has been a hit ever since we introduced
our first model some 5 ears ago. This high-end parametric equalizer is based on man ears of experience
and findings in equalizer technolog and is used throughout the world in renowned studios, sound reinforce-
ment s stems as well as in broadcast and television studios. Improving the legendar ULTRA-Q even further
was a real challenge, and we are proud of our success. The BEHRINGER TUBEULTRA-Q meets highest
requirements in terms of operation, sound, specifications and workmanship.
Even at the conception of the TUBEULTRA-Q it was clear that we had to combine the outstanding technical
specifications of our ULTRA-Q with a warm tube sound. We are therefore proud to be able to present the
TUBE ULTRA-Q, a device featuring our newl developed UTC vacuum tube circuit combined with a no-
compromise approach. The newl developed UTC circuit provides subtle sound enhancement rather than
show effects processing. In particular, digital workstations can be considerabl enhanced in their sound
character. You are free to use the TUBEULTRA-Q before the recording sessions or later when ou mix down
the music ou recorded. You can also use it to brighten up entire MIDI productions or even movie sound
recordings and thus give them their finishing touch.
The philosoph behind BEHRINGER products guarantees a no-compromise circuit design and emplo s the
best choice of components. The op-amps, t pe 4580, used in the TUBEULTRA-Q are chosen for their superior
signal-to-noise ratio, low distortion and linear performance. Additionall , the TUBEULTRA-Quses high qualit
resistors and capacitors with ver tight tolerances, high-grade switches as well other selected components.
The TUBE ULTRA-Q is manufactured under ISO900 certified management s stem.
With the exception of two 12AX7/ECC83 tubes, the TUBEULTRA-Q T1951 is based on SMD technolog
(Surface Mounted Device). These subminiature components known from aerospace applications ensure both
extreme packing densit and greater reliabilit .
+Please keep the manual after reading, in order to use it for future reference.
1.1 The concept
The heart of the TUBEULTRA-Q is an extremel low-noise and transparent sounding state-variable filter. In
combination with the Constant-Q principle, the 4580 op-amp and the newl developed ULTRA-TUBE
technolog , the TUBEULTRA-Q achieves extremel low noise and distortion figures together with an
incredible warm sound. With four full parametric bands, it offers ou trul professional signal processing.
In the TUBE ULTRA-Q, two selected 12AX7 / ECC83 vacuum tubes are used. These triodes are capable of
handling a large d namic range with little microphon . In addition to that their relative ruggedness and above
average life span and ou can see wh its one of the most popular and reliable pre-amp tubes on the market.
These features also ensure ou their availabilit for man ears to come.
Failsafe rela s have been incorporated into the design of the BEHRINGER TUBE ULTRA-Q, which auto-
maticall and silentl b pass the unit in the event of power suppl disconnection or failure. These rela s are
also active at switch-on to isolate the TUBE ULTRA-Q until the power rails have settled, thus preventing the
possibilit of a potentiall damaging switch-on thump.
1.2 Before you get started
Your BEHRINGER TUBE ULTRA-Q was carefull packed in the factor and the packaging was designed to
protect the unit from rough handling. Nevertheless, we recommend that ou carefull examine the packaging
and its contents for an signs of ph sical damage, which ma have occurred in transit.
+If the unit is damaged, please do not return it to us, but notify your dealer and the shipping
company immediately, other ise claims for damage or replacement may not be granted.
Shipping claims must be made by the consignee.
The BEHRINGER TUBE ULTRA-Q fits into two standard 19" rack units of space. Please allow at least an
additional 4" / 10 cm depth for the connectors on the back panel.
1. INTRODUCTION

7
TUBE ULTRA-Q T1951
Be sure that there is enough space around the unit for cooling and please do not place the TUBE ULTRA-Q on
high temperature devices such as power amplifiers etc. to avoid overheating.
+Before you connect your TUBEULTRA-Q to the mains, please make sure that your local
voltage matches the voltage required by the unit!
The mains connection of the TUBEULTRA-Q is made b using a mains cable and a standard IEC receptacle.
It meets all of the international safet certification requirements. Please make sure that all units have a proper
ground connection.
+Please ensure that only qualified persons install and operate the TUBEULTRA-Q. During
installation and operation the user must have sufficient electrical contact to earth. Electro-
static charges might affect the operation of the TUBEULTRA-Q!
For additional information please refer to chapter 5 INSTALLATION.
As a standard, the audio inputs and outputs on the TUBEULTRA-Q are full balanced. If possible, connect the
unit to other devices in a balanced configuration to allow for maximum interference immunit . The automatic
servo function detects unbalanced connections and compensates the level difference automaticall (6dB
correction).
1.3 Control elements
The BEHRINGER TUBEULTRA-Q has four parametric filters organized in 4 different frequenc bands. A
backlit VU meter shows the input or output level. Each channels comes with a Warmth control, and a tube
window.
Fig. 1.1: Control elements on the front panel
1The INPUT control determines the input level applied to the device and can be set within a range from
-15 to +15dB.
2When the PEAK LED above the INPUT control lights up, it means that a level of at least 18dBu is
present after the input stage. Adjust the INPUT control so that the PEAK LED lights up onl with signal
peaks, make sure that it never lights up all the time. When the PEAK LED is on, there is still some 5dB
of headroom left.
+Please note that extreme boost settings in combination ith a high input level can overload
the unit. In such a case, the input level must be reduced ith the INPUT control.
3The IN/OUT switch is used to enable/disable the entire equalizer section in the audio path. The switch
uses a rela -controlled hard b pass function, i.e. as long as it is not active or if the unit is switched off,
the inputs are directl connected to the outputs. The IN/OUT switch allows for A/B comparisons
between processed and unprocessed signals.
1. INTRODUCTION

8
TUBE ULTRA-Q T1951
4The FRE UENCY control selects the filters center frequenc , which can be freel chosen within the
frequenc range of the associated band.
5The LEVEL control determines the amount of level boost/cut. The setting range is from -15 to +15dB.
6The BANDWIDTH control determines the slope or qualit of the filter. Settings from 0.03 (Q = 43) to 2
octaves (Q = 0,67) are possible. A small bandwidth (high Q) means that the onl a small portion of the
total frequenc range will be affected while a wide bandwidth (low Q) means that a large part will be
affected.
7With the SHELF/PEAK switch the two outer bands can be switched from parametric (peaking
response) EQ to low and high pass (shelving EQ) filters respectivel . Use this feature to eliminate
rumble, plop and breathing noises from the bottom end and noise or hiss from the top end. When
switched to PEAK mode the filters operate identical to the other filters.
8The individual IN/OUT switches allow for enabling/disabling specific bands in the audio path. Use this
switch to check the influence of the separate filters and to switch unused filters of for maximum signal
integrit .
Fig. 1.2: Control elements on the front panel
9The WARMTH control determines the amount of harmonics the UTC circuit adds to the signal. This is
the amount of tube sound (WARMTH) that is added.
10 The WARMTH meter displa s the amount of added harmonics. This controls the amount of harmonics,
or tube sound (WARMTH), the UTC circuit adds to the signal.
11 Use the POWER switch to turn the TUBE ULTRA-Q on or off. When switched of the TUBE ULTRA-Q
automaticall switches to a hard b pass mode, the signal is then led directl to the outputs.
13 15
1412
Fig. 1.3: Rear panel elements of the TUBEULTRA-
1. INTRODUCTION

9
TUBE ULTRA-Q T1951
12 SERIAL NUMBER. Please complete and return the warrant card within 14 da s of the date of
purchase. Otherwise, ou will lose our right to the extended warrant . Alternativel , ou can register
online at our website under www.behringer.com.
13 FUSE HOLDER / VOLTAGE SELECTION. Before connecting the T1951, confirm that the voltage
displa matches our local mains voltage. When replacing the fuse, ou must alwa s use the same
t pe. In man units the fuse holder can be installed in one of two positions, allowing ou to switch
between 230 V and 115 V. If ou wish to operate a unit outside Europe at 115 V, then a stronger fuse
must be used (see chapter 6 SPECIFICATIONS). The mains connection is made via the IEC
receptacle. An appropriate mains cable is included.
14 AUDIO IN. These are the audio inputs of our TUBEULTRA-Q, available both as balanced 1/4" TRS and
XLR connectors.
15 AUDIO OUT. These are the audio outputs of our TUBEULTRA-Q. Matching 1/4" TRS and XLR
connectors are wired in parallel. The automatic servo function recognizes balanced or unbalanced
connection and automaticall compensates for the difference in level (correction 6dB). The BEHRINGER
OT-1 output transformer is optionall retrofitable.
2. OPERATION
2.1 Introduction
The BEHRINGER TUBE ULTRA-Q gives ou a combination of all technical properties both of parametric
equalizers and of narrow-band notch filters. With its excellent audio qualit and outstanding specifications it is
simpl better than an conventional equalizer. The ULTRA-Q can be used to make up for frequenc response
deficiencies and to creativel process an audio material, thus giving ou undreamed-of equalization flexibilit .
It is a highl efficient and all-purpose tool both in creative audio processing in broadcast and television studios,
in video post-production and on stage. Each of its four bands can be freel adjusted in qualit : from extremel
narrow to broad-band. The TUBEULTRA-Q is superior to graphic equalizers in all respects.
The BEHRINGER TUBE ULTRA-Q uses our newl developed ULTRA-TUBE technolog , a development
resulting from two ears of intensive research work b our engineering team. The ULTRA-TUBE technolog
overcomes the problems related to tube circuitr (see chapter 4) and generates upper harmonics even at low
levels to give our recordings more warmth and power.
2.2 The TUBEULT A-Q in the signal path
The best point to insert the TUBEULTRA-Q in the signal path depends on the task on hand: basicall , it can
be inserted in the main mix insert points of our mixing console, subgroup inserts, subgroup outputs, effects
paths or between signal processor(s) and mixing console/power amp, etc.
Due to its 2-channel architecture, ou can also insert the TUBEULTRA-Q in two independent channels of the
mixing console (if available). This wa the TUBEULTRA-Q acts as a high-qualit and versatile channel EQ.
Depending on the wiring of the inserts on the console, ou either need a special 1/4" stereo insert cable that is
routed to two mono jacks (send & return), or two separate cables for the send and return path. Connect the
insert sends of the subgroups to the inputs on the TUBEULTRA-Q, and the insert returns to the outputs.
You can even connect the two channels of the TUBEULTRA-Q in series to make one equalizer with 8 bands!
Connect the output of channel one with the input of channel two. Set the output of channel one as well as the
INPUT control of channel two at 0dB.
2.3 Filter settings
You ma find that getting to know a dual channel processor like the TUBEULTRA-Q is easier when ou
concentrate on one channel first. If ou have a mixer, connect the TUBEULTRA-Q to the insert of one channel
onl .
Alwa s start off b setting all controls to neutral. All gain controls at 0dB and bandwidth wide. This prevents
wasted time looking for non-existent problems or that settings with a gain higher than 0dB cause problems
2. OPERATION

10
TUBE ULTRA-Q T1951
like feedback. In live applications uncontrolled feedback can cause damage to loudspeakers and amplifiers.
B means of the INPUT control ou can adapt the sensitivit of the TUBE ULTRA-Q to the input level. The
sensitivit can be varied within a range of -15 to +15dB. Set the INPUT control so that the PEAK LED lights up
onl rarel , it should never light up constantl . If the LED lights up it means that the level directl after the
INPUT control is exceeding +18dBu, this means that there is still approx. 5dB headroom until the
TUBEULTRA-Q starts clipping.
+Please note that extreme levels can be achieved ith this unit. When a high input level is
combined ith an extreme setting or multiple filters boosting the same frequency range, over-
loading can occur even though the input level as set correctly. This can not be contributed to
a malfunctioning of the unit but is a consequence of the settings that ere chosen. If this
occurs please lo er the input level or choose less extreme settings.
+If extreme equalizer settings are necessary to achieve a usable frequency response, the alarm
bell should start ringing!
The shelving filters
In contrast to graphic equalizers with fixed frequencies and bandwidths ou can freel set all filter parameters,
center frequenc , bandwidth and gain, with a parametric equalizer. The two outer filters of the TUBE ULTRA-Q
can additionall be switched between shelving (SHELF) and bell characteristic (PEAK).
In the setting SHELF the filter resembles a normal tone control on a hifi amplifier, but with the possibilit to alter
the start frequenc and the slope of the filter. The frequenc can be set within a wide range with the
FREQUENCY control. With the BANDWIDTH control the slope can be altered. When the control is turned
counter-clockwise the slope becomes steeper, turning the other wa results in a more gentle slope. The
LEVEL control sets the amount of boost or attenuation. Use the shelving filters to control rumble, plop/
breathing noises and wind or tape hiss. With the freedom to set the frequenc , slope and gain, the
TUBEULTRA-Q can be tailored exactl to our needs giving ou much more flexibilit than an other standard
low-cut switch.
The parametric filters
When the first and the last filters are set to PEAK, the are identical to the two other filters. In that case the
filters have a peaking response or a bell curve. Start b boosting a fairl broad frequenc band to locate the
frequenc band ou want to adjust. It is easier to locate problem frequencies b boosting them first. When the
problem frequenc is located ou can adjust the bandwidth to isolate the correct range. Now ou can cut or
boost this range to suit our needs. The filters are set up in such a wa that the cover the entire spectrum from
20Hz to 20 kHz, while overlapping each other over a wide range. After finding the right setting ou can tweak
the setting of each band to achieve maximum results.
During operation ou can switch on and off the individual bands to make an A/B comparison between the
equalizer effect and the unprocessed signal. Due to the complex and partl difficult settings of parametric
equalizers such a facilit is indispensable. Still, most parametric EQs have no band-specific in/out switches
which makes it difficult to keep track of what the various switches and controls do.
Adjusting the overall level
It is possible that ou have to correct the overall level after setting the equalizer. It is possible that the effect of
the filters result in a higher or lower level than the original signal. Use the INPUT control to adjust the total level.
You can compare the processed and unprocessed level with the help of the IN/OUT switch.
+Please note that the IN/OUT performs a hard are bypass. The input signal is fed directly to the
output. The INPUT control has no influence.
2. OPERATION