Behringer Ultracoustic ACX1800, Ultracoustic ACX450, Ultracoustic ACX900 User Manual 2.pdf

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User’s Manual

Version 1.1 June 2006



CAUTION: To reduce the risk of electric shock, do not remove the top cover (or the rear section). 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 and moisture. The apparatus shall not be exposed to dripping or splashing and no objects filled with liquids, such as vases, shall be placed on the apparatus.

This symbol, wherever it appears, alerts you to the presence of uninsulated dangerous voltage inside the enclosure—voltage that may be sufficient to constitute a risk of shock.

This symbol, wherever it appears, alerts you to important operating and maintenance instructions in the accompanying literature. Please read the manual.


1)Read these instructions.

2)Keep these instructions.

3)Heed all warnings.

4)Follow all instructions.

5)Do not use this apparatus near water.

6)Clean only with dry cloth.

7)Do not block any ventilation openings. Install in accordance with the manufacturer’s instructions.

8)Do not install near any heat sources such as radiators, heat registers, stoves, or other apparatus (including amplifiers) that produce heat.

9)Do not defeat the safety purpose of the polarized or grounding-type plug. A polarized plug has two blades with one wider than the other. A grounding type plug has two blades and a third grounding prong. The wide blade or the third prong are provided for your safety. If the provided plug does not fit into your outlet, consult an electrician for replacement of the obsolete outlet.

10)Protect the power cord from being walked on or pinched particularly at plugs, convenience receptacles, and the point where they exit from the apparatus.

11)Only use attachments/accessories specified by the manufacturer.

12)Use only with the cart, stand, tripod, bracket, or table specified by the manufacturer, or sold with the apparatus. When a cart is used, use caution when moving the cart/apparatus combination to avoid injury from tip-over.

13)Unplug this apparatus during lightning storms or when unused for long periods of time.

14)Refer all servicing to qualified service personnel. Servicing is required when the apparatus has been damaged in any way, such as power supply cord or plug is damaged, liquid has been spilled or objects have fallen into the apparatus, the apparatus has been exposed to rain or moisture, does not operate normally, or has been dropped.

15)CAUTION - These service instructions are for use by qualified service personnel only. To reduce the risk of electric shock do not perform any servicing other than that contained in the operation instructions unless you are qualified to do so.




Dear Customer,

Welcome to the team of BEHRINGER users, and thank you very much for expressing your confidence in us by purchasingthe BEHRINGER ULTRACOUSTIC.

Writing this foreword for you gives me great pleasure, because it represents the culmination of many months of hard work delivered by our engineering team to achieve a very ambitious goal: to present you with an outstanding acoustic instrument amplifier that

is at the forefront of what is technically possible and that offers you a vast variety of sound shaping options. The task of designing our new ULTRACOUSTICs certainly meant a great deal of responsibility, which we assumed by focusing on you, the discerning user and musician. Meeting your expectations also meant a lot o6f work and night shifts. But it was fun, too. Developing a product usually brings a lot of people together, and what a great feeling it is when all who participated in such a project can be proud of what they’ve achieved.

It is our philosophy to share our enjoyment with you, because you are the most important member of the BEHRINGER team. With your highly competent suggestions for new products you’ve made a significant contribution to shaping our company and making it successful. In return, we guarantee you uncompromising quality as well as excellent technical and audio properties at an extremely reasonable price. All of this will enable you to give free rein to your creativity without being hampered by budget constraints.

We are often asked how we manage to produce such highquality devices at such unbelievably low prices. The answer is quite simple: it’s you, our customers! Many satisfied customers mean large sales volumes enabling us to get better purchasing terms for components, etc. Isn’t it only fair to pass this benefit on to you? Because we know that your success is our success too!

I would like to thank all of you who have made the ULTRACOUSTIC Series possible. You have all made your own personal contributions, from the developers to the many other employees at this company, and to you, the BEHRINGER user.

My friends, it’s been worth the effort!

Thank you very much,

Uli Behringer


1. INTRODUCTION .........................................................


1.1 Before you get started ...................................................



Shipment ...............................................................



Initial operation ......................................................



Online registration ................................................



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


Front panel ......................................................................



Rear panel ......................................................................


3.APPLICATIONS ..........................................................



Connecting options for the ACX450 ..............................



Extended connecting options (ACX900 and ACX1800) 7

4. SOUND PROCESSING ...............................................



FBQ equalizer .................................................................



Digital effects processor ................................................



Compressor (only in ACX1800) .....................................


5. INSTALLATION ...........................................................



Audio connections .........................................................


6. SPECIFICATIONS .....................................................


7. WARRANTY ..............................................................





+ Please make sure that all of your equipment is

grounded at all times. For your own protection, you

Thank you for choosing the ULTRACOUSTIC amplifier. You have

should never tamper with the grounding of the cable

or the unit itself. The unit shall always be connected

purchased a modern 2-channel amplifier that guarantees

to a mains socket outlet with a protective earthing

excellent sound quality for various applications yet is easy to


operate. The ULTRACOUSTIC comes with a wide range of


features such as two integrated, 24-bit multi-effect processors

1.1.3 Online registration

or the FBQ Feedback Detection system which help you to

fine-tune your sound. Due to the many possibilities of connecting

Please, do remember to register your new BEHRINGER equipment

external effects units and playback feeds, the ULTRACOUSTIC

right after your purchase by visiting and

is a real all-rounder leaving nothing to be desired.

kindly read the terms and conditions of our warranty carefully.

+Please read this manual to familiarize yourself with Should your BEHRINGER product malfunction, our goal is to have the control elements of the unit and its functions. it repaired as quickly as possible. To arrange for warranty service, After you have carefully read this manual, keep it please contact the retailer from whom the equipment was

for future reference.

purchased. Should your BEHRINGER dealer not be located in


your vicinity, you may directly contact one of our subsidiaries.


Corresponding contact information is included in the original

1.1 Before you get started

equipment packaging (Global Contact Information/European


Contact Information). Should your country not be listed, please

1.1.1 Shipment

contact the distributor nearest you. A list of distributors can be

found in the support area of our website (

The ULTRACOUSTIC was carefully packed at the assembly plant

Registering your purchase and equipment with us helps us

to ensure secure transport. If the cardboard box is damaged,

please inspect the ULTRACOUSTIC equipment immediately for

process your repair claims quicker and more efficiently.

physical damage.

Thank you for your cooperation!


+ Damaged equipment should NEVER be sent directly



to us. Please inform the dealer from whom you


acquired it immediately as well as the trans-

portation company from which you took delivery.


Otherwise, all claims for replacement/repair may



be rendered invalid.


2.1 Front panel

+ If the unit needs to be shipped, please always use


The ¼" jack connector labeled INSTR(UMENT) is the input

the original packaging to avoid damage.

of the instrument channel of your ULTRACOUSTIC to

+ Never let unsupervised children play with the

connect your acoustic guitar. Use a commercially available

ULTRACOUSTIC or with its packaging.

mono jack cable. We recommend using a cable with impact

+ Please dispose of all packaging materials in an

sound insulation so as to avoid unpleasant incidences

during a rehearsal or concert.

environmentally-friendly fashion.

The PHASE switch (not included in ACX450) reverses


1.1.2 Initial operation

the instrument channel phase by 180°. Use this function

to eliminate feedback problems or phase errors of dual

Please make sure that your ULTRACOUSTIC is provided with

pickup systems.

sufficient ventilation, and never place it on other amplifiers or in

The GAIN controller is used to determine the volume of

the vicinity of a heater to avoid the risk of overheating.

the respective channel.


+ Before plugging your ULTRACOUSTIC into a power

With the TUNER switch (not included in ACX450),

socket, please make sure you have selected the

you can mute the channel. There is a permanent signal at

correct voltage:


connector at the rear of the unit. You

The fuse retainer near the power cord connector has three

have the option to connect an external tuner to this jack

(e.g. BTR2000, TU100).

triangular markings. Two of these triangles point in opposite

When the input signal overdrives the instrument channel,

directions. Your ULTRACOUSTIC is set up for the voltage

indicated near these markings, and can be altered by turning the

the CLIP LED located in the TUNER switch is on (only in

fuse mount by 180 degrees. ATTENTION: This does not apply

ACX1800). Reduce the input gain with the GAIN controller

to export models built for 120 V, for example!

until the CLIP LED is off. Occasional flashing of the CLIP

+ If you use your ULTRACOUSTIC unit with a different

LED caused by signal peaks is harmless though, as the

instrument channel has sufficient headroom.

voltage, you must change the fuses accordingly.

This is the FBQ EQUALIZER. Each sliding controller

The correct value of the fuses needed can be found

controls a specific frequency range. In position 0,

in the section “SPECIFICATIONS”.

the frequency is not adjusted. To boost a frequency range,


+ Faulty fuses must be replaced with fuses of

move the respective sliding controller up. To lower its

volume, move the sliding controller down. The maximum

appropriate rating, without exception! The correct

boosting or damping range is 12 dB.

value of the fuses needed can be found in the




Press the FBQ switch to activate the FBQ function. While

Power is delivered via the cable that was delivered with the

the FBQ is switched off, the controller LEDs are lit with

the same brightness. When the FBQ is on and you play

ULTRACOUSTIC. All mandatory safety precautions have been

your instrument, the LED’s brightness varies, depending

adhered to.

on the energy content of the associated frequency range.



This visual feature supports you in adjusting the sound


and eliminating feedback. The equalizer is always


activated, irrespective of whether the FBQ function is on.




The MIC jack is the balanced XLR microphone input of the microphone/line channel.

The balanced LINE jack (1/4") of the microphone/line channel can be used for line-level signals, e.g. from keyboards, drum computers, etc.

The COMPRESSOR controller is used to adjust the intensity of the compression (only in ACX1800, see chapter 4.3).

The compressor is switched on/off with the IN/OUT switch (only in ACX1800).

With the FX SELECT controller, you can select one of 16 effect programs. For a detailed description of the available effects, see table 4.1 in chapter 4.2.

With the PARAMETER controller (only in ACX1800) you can edit certain effect parameters. For details on the parameters that are adjustable for each effect, see table 4.1.

The IN/OUT switch (not included in ACX450) allows you to activate the selected effect. If an effect has been activated, the LED in the switch is on. Alternatively, you can switch the selected effect on and off with the foot switch.

The FX LEVEL controller is used to adjust the level (share) of the selected effect.

With the MASTER controller, you can adjust the overall volume of the ACX1800.

The PHASE switch reverses the phase of the mix signal by 180° (only in ACX1800). Use this switch to eliminate problems with feedback.



2.2 Rear panel





3.1Connecting options for the ACX450

Fig. 3.1: Cabling options of the ACX450

The above cabling is suitable for sessions in the rehearsal room or for practicing at home. Connect your guitar to the instrument input jack of channel 1. If desired, connect another instrument or a dynamic microphone to channel 2.

Connect the supplied FS112 foot switch to the foot switch input at the rear panel. With the foot switch, you can switch the effects units of both channels on and off, which is particularly useful during live performances.

To play along with a playback, connect a CD player to the CD input. Of course, a MD player or a computer can be used as playback device as well.

3.2 Extended connecting options (ACX900 and ACX1800)

Fig. 3.2: Extended connecting options (ACX900 and ACX1800)

Models ACX900 and ACX1800 offer a wide range of additional connecting options. The above figure shows only one of many possible installations:

The instruments, microphones, the foot switch as well as the CD player are connected as shown in figure 3.1. The tuner is connected to the tuner output where there is a constant instrument signal. If you wish to integrate external effects units, you can do this separately for each of the two channels. Connect the input of the effects unit to the INSERT SEND of one of the respective channels, and connect the effect output at the unit to the INSERT RETURN jack of the same channel. Instead of the two stage effects units shown here connected in series in the signal path, you can establish a parallel effects loop, e.g. by means of a 19" studio effects unit. In this case, connect the input of the effects unit to the MIC INSERT SEND or the INSTRUMENT INSERT SEND output, and feed the stereo output signal of the effects unit through the CD INPUT jacks. You can then use the CD LEVEL controller to mix the effects signal and your guitar signal. With this option, please note that the effects unit only returns the effects signal (100%Wet) and not the original signal.

Musicians who wish to play their instrument through a PA system during a live session normally need a DI box. A DI box prepares the signal for transfer through long cable lines, so that a higher output level for the mixing desk can be achieved. You will be delighted to know that your ULTRACOUSTIC comes with a builtin DI box! Connect the balanced LINE outputs directly to the mixing desk input or to the multi-core feeding to the mixing desk. Use a microphone cable (two-core shielded cable with XLR connectors).





The ULTRACOUSTIC offers many options for sound processing. The ACX1800 includes, for example, an FBQ equalizer, a multieffects unit and a compressor. The various processing options are explained in this chapter.

4.1 FBQ equalizer

A graphic equalizer with FBQ spectrum analyzer is available for sound adjustment and correction. If the sliding controllers are in neutral position (0), the signal is not modified.

sTo boost the frequency range, move the respective sliding controller up.

sTo dampen the range, move the sliding controller down.

sPress the FBQ switch to activate the FBQ display.

FBQ function: Each controller is equipped with a LED indicating the level of the associated frequency range of the controller by means of its brightness. This assists you in identifying the controller that must be used to edit the sound. If the sound is for example too dull or too droning, one of the LEDs is probably very bright, indicating the sliding controller that should be moved down to reduce the bass level. On the other hand, you can quickly identify frequency ranges whose level is too low (LED barely lit) to increase it.

+To emphasize certain frequency ranges, it might not be necessary to raise these, but to lower the levels of the other frequencies by moving the respective sliding controllers down. This approach prevents excessively high internal signal levels, thus retaining valuable dynamic reserves (“headroom”).

4.2 Digital effects processor

One of the key features of your ULTRACOUSTIC are the two built-in multi-effects processors that operate independently of each other in both channels. Each effects module offers a total of 16 different programs that are grouped in four categories.

sTo switch effects on or off, press the IN/OUT switch at the ULTRACOUSTIC or at the foot switch.

sTurn the FX SELECT controller to select a program. The effects are described in the following overview:
































































Chorus / Delay 400 ms

Delay Level






Flanger / Delay 400 ms

Delay Level






Chorus / Delay 300 ms

Delay Level





Flanger / Delay 300 ms

Delay Level




Delay 80 ms




Delay 300 ms













Delay 400 ms










Delay 500 ms


Table 4.1: Effects programs

sUse the FX LEVEL controller to make the effect audible.

sEdit the effect using the PARAMETER controller (only in ACX1800).

The reverb presets are effects that imitate the reverberation of various large rooms. Use the PARAMETER controller to adjust the reverberation time (decay).

1CHAMBER simulates the typical characteristics of a studio. This effect is useful in cases where you need unobtrusive reverb to liven up the signal.

2ROOM: Reverberation typical for rooms of medium size, with clearly audible reverb from walls.

3HALL: Simulation of a lively large hall with considerable echo.

4CONCERT simulates the prolonged reverb in a large concert hall.

This group includes four modulation effects that are generated in different ways. For each effect, you can adjust the depth and speed of the modulation.

5CHORUS give guitar signals more depth and width. This is achieved by means of a modulated delay of the input signal.

6FLANGER: Popular guitar effect achieved by constant modulation of the tone pitch.

7PHASER: The phase effect is similar to the flange, but somewhat subtler. It is achieved by superimposing a phase-shifted effects signal on the input signal.

8TREMOLO: Intensive variation of the volume at a preset rate.

This group includes a number of dual effects where for example a chorus or flanger effect is combined with a delay. In the ACX1800, you can adjust the volume of the delay effect.

9 CHORUS/DELAY with a delay of 400 ms.

10FLANGER/DELAY with a long delay (400 ms)

11CHORUS/DELAY with a short delay (300 ms).

12FLANGER/DELAY with a delay of 300 ms.

In this group you find delay effects with different delay times. The “Feedback” parameter determines the number of repeats.

13Short DELAY of 80 milliseconds (ms).

14Medium DELAY of 300 ms.

15DELAY of 400 ms.

16Long DELAY of 500 ms.




4.3 Compressor (only in ACX1800)

The compressor reduces the dynamic range of a signal. Volume peaks are lowered, and low signals are boosted, so that the difference between the loudest and the lowest tone of an instrument or voice is reduced. This results in a more expressive and homogeneous sound, and the sustain of long tones is prolonged.

sSwitch on the compressor (ON switch ).

sTurn the COMPRESSOR controller slowly in clockwise direction to increase the compression intensity.

sCompare the compressed and the original signal by switching the compression ON and OFF (at the ON switch).

If the input signal to the compressor is high, it operates at its optimum range. If the signal is low, the effect becomes only audible when the compressor controller is set to a very high position. If a compressor is switched on in this position, there is a risk of sudden level changes. If GAIN is set to a high value, the same compressor effect is achievable without having to set the controller to a high value. In this case, the COMPRESSOR controller does not have to be turned to a position near the stop in order to achieve any effect. We recommend that you try this out until you have found the best settings!


5.1 Audio connections

With the exception of the balanced LINE jack mono input, all inputs and outputs of the BEHRINGER ULTRACOUSTIC are unbalanced mono jack sockets. The LINE OUT connections are designed as balanced XLR outputs. The CD inputs are designed as RCA connectors.

+Please ensure that only qualified persons install and operate the ULTRACOUSTIC. During installation and operation, persons handling and using the equipment must be sufficiently earthed, as electrostatic discharge might affect the operation of the ULTRACOUSTIC!

Fig. 5.1: XLR connectors

Fig. 5.2: ¼" stereo TRS connector

Fig. 5.3: ¼" TS connector






















¼" TS unbalanced


Input Impedance




10 MOhm






XLR balanced


Input Impedance




4 kOhm






¼" TRS balanced


Input Impedance




40 kOhm






¼" TS unbalanced

Input Impedance




220 kOhm





¼" TS unbalanced

Input Impedance




220 kOhm








CD input






Input Impedance




>10 kOhm



















XLR balanced

Output Impedance




4.3 kOhm

Max. output level




>24 dBu










¼" TS unbalanced

Output Impedance




100 Ohm






Max. output level




>18 dBu





¼" TS unbalanced

Output Impedance




100 Ohm

Max. output level




>18 dBu










¼" TS unbalanced

Output impedance




33 kOhm






Max. output level




>6 dBu







Power rating


1 x 45 W / 4


2 x 45 W / 2 x 4


2 x 90 / 2 x 4









24-bit sigma-delta, 64/128-times oversampling

Sampling rate




40 kHz

















1 x 8"


2 x 8"


2 x 8"











BUGERA™ dual cone speakers




4 Ohm


4 Ohm


4 Ohm








Power handling


40 W


60 W


60 W










USA/Canada 120 V~, 60 Hz







Europe/U.K./Australia 230 V~, 50 Hz







Mains voltage




Japan 100 V~, 50 - 60 Hz










China/Korea 220 V~, 50 Hz







General Export model 120/230 V~, 50 - 60 Hz







Power consumption


max. 90 W


max. 135 W


max. 265 W

Fuses 100 - 120 V~


250 V


250 V


250 V








Fuses 200 - 240 V~


250 V


250 V


250 V

Mains connection




Standard IEC receptacle

















413 x455 x 212 mm


423 x 526 x 232 mm


427 x 526 x 242 mm

(H x W x D)


16.3 x 17.9 x 8.3"


16.7 x 20.7 x 9.1"


16.8 x 20.7 x 9.5"



29.1 lbs (13.2 kg)


37 lbs (16.8 kg)


40.6 lbs (18.4 kg)

BEHRINGER is constantly striving to maintain the highest professional standards. As a result of these efforts, modifications may be made from time to time to existing products without prior notice. Specifications and appearance may differ from those listed or illustrated.






1.This warranty does not exclude or limit the buyer’s statutory rights provided by national law, in particular, any such rights against the seller that arise from a legally effective purchase contract.

2.The warranty regulations mentioned herein are applicable unless they constitute an infringement of national warranty law.


Please do remember to register your new BEHRINGER equipment right after your purchase by visiting (alternatively and kindly read the terms and conditions of our warranty carefully. Registering your purchase and equipment with us helps us process your repair claims quicker and more efficiently. Thank you for your cooperation!


1.BEHRINGER (BEHRINGER International GmbH including all BEHRINGER subsidiaries listed on the enclosed page, except BEHRINGER Japan) warrants the mechanical and electronic components of this product to be free of defects in material and workmanship for a period of one (1) year* from the original date of purchase, in accordance with the warranty regulations described below. If the product shows any defects within the specified warranty period that are not excluded from this warranty as described under § 5, BEHRINGER shall, at its discretion, either replace or repair the product using suitable new or reconditioned parts. In the case that other parts are used which constitute an improvement, BEHRINGER may, at its discretion, charge the customer for the additional cost of these parts.

2.If the warranty claim proves to be justified, the product will be returned to the user freight prepaid.

3.Warranty claims other than those indicated above are expressly excluded.


1. To obtain warranty service, the buyer (or his authorized dealer) must call BEHRINGER (see enclosed list) during normal business hours BEFORE returning the product. All inquiries must be accompanied by a description of the problem. BEHRINGER will then issue a return authorization number.

2.Subsequently, the product must be returned in its original shipping carton, together with the return authorization number to the address indicated by BEHRINGER.

3.Shipments without freight prepaid will not be accepted.


1.Warranty services will be furnished only if the product is accompanied by a copy of the original retail dealer’s invoice. Any product deemed eligible for repair or replacement under the terms of this warranty will be repaired or replaced.

2.If the product needs to be modified or adapted in order to comply with applicable technical or safety standards on a national or local level, in any country which is not the country for which

the product was originally developed and manufactured, this modification/adaptation shall not be considered a defect in materials or workmanship. The warranty does not cover any such modification/adaptation, irrespective of whether it was carried out properly or not. Under the terms of this warranty, BEHRINGER shall not be held responsible for any cost resulting from such a modification/adaptation.

3.Free inspections and maintenance/repair work are expressly excluded from this warranty, in particular, if caused by improper handling of the product by the user. This also applies to defects caused by normal wear and tear, in particular, of faders, crossfaders, potentiometers, keys/buttons, tubes, guitar strings, illuminants and similar parts.

4.Damages/defects caused by the following conditions are not covered by this warranty:

simproper handling, neglect or failure to operate the unit in compliance with the instructions given in BEHRINGER user or service manuals.

sconnection or operation of the unit in any way that does not comply with the technical or safety regulations applicable in the country where the product is used.

sdamages/defects caused by force majeure or any other condition that is beyond the control of BEHRINGER.

5.Any repair or opening of the unit carried out by unauthorized personnel (user included) will void the warranty.

6.If an inspection of the product by BEHRINGER shows that the defect in question is not covered by the warranty, the inspection costs are payable by the customer.

7.Products which do not meet the terms of this warranty will be repaired exclusively at the buyer’s expense. BEHRINGER will inform the buyer of any such circumstance. If the buyer fails to submit a written repair order within 6 weeks after notification, BEHRINGER will return the unit C.O.D. with a separate invoice for freight and packing. Such costs will also be invoiced separately when the buyer has sent in a written repair order.


This warranty is extended exclusively to the original buyer (customer of retail dealer) and is not transferable to anyone who may subsequently purchase this product. No other person (retail dealer, etc.) shall be entitled to give any warranty promise on behalf of BEHRINGER.


Failure of BEHRINGER to provide proper warranty service shall not entitle the buyer to claim (consequential) damages. In no event shall the liability of BEHRINGER exceed the invoiced value of the product.

* Customers in the European Union please contact BEHRINGER Germany Support for further details.

Technical specifications and appearance subject to change without notice. The information contained herein is correct at the time of printing. The names of companies, institutions or publications pictured or mentioned and their respective logos are registered trademarks of their respective owners. Their use neither constitutes a claim of the trademarks by BEHRINGER nor affiliation of the trademark owners with BEHRINGER. BEHRINGER accepts no liability for any loss which may be suffered by any person who relies either wholly or in part upon any description, photograph or statement contained herein. Colours and specification may vary slightly from product. Products are sold through our authorised dealers only. Distributors and dealers are not agents of BEHRINGER and have absolutely no authority to bind BEHRINGER by any express or implied undertaking or representation. No part of this manual may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying and recording of any kind, for any purpose, without the express written permission of BEHRINGER Spezielle Studiotechnik GmbH. BEHRINGER® is a registered trademark.

ALL RIGHTS RESERVED. © 2006 BEHRINGER Spezielle Studiotechnik GmbH,

Hanns-Martin-Schleyer-Str. 36-38, 47877 Willich-Muenchheide II, Germany.

Tel. +49 2154 9206 0, Fax +49 2154 9206 4903