CPXTM 3800 Power Amplifier Owner`s Manual CPX
Contents
1. must be sent in its original carton If improperly packed your amplifier may be damaged For replacement gi packaging call Crest Performance s Customer Service specifications CPX Series Rated Power Bridged 8 ohms Rated Power 2 x 4 ohms Rated Power 2 x 8 ohms Rated Power 1 x 4 ohms Rated Power 1 x 8 ohms Minimum Load Impedance Maximum RMS Voltage Swing Frequency Response Power Bandwidth T H D 2 x 4 ohms T H D 2 x 8 ohms Input CMRR Voltage Gain Crosstalk Hum and Noise Slew Rate Damping Factor 8 ohms Phase Response Input Sensitivity x40 Input Impedance Current Draw 1 8 Power Current Draw 1 3 Power Cooling Controls Indicator LEDs Protection Connectors Construction Dimensions Net Weight Gross Weight CPX 3800 2650 watts 1 kHz at lt 0 1 T H D 1300 watts per channel 1 kHz at lt 0 05 T H D both channels driven 775 watts per channel 1 kHz at lt 0 05 T H D both channels driven 1500 watts 1 kHz at lt 0 05 T H D 875 watts 1 kHz at lt 0 05 T H D 4 ohms 93 volts 10 Hz 100 kHz 0 2 dB at 1 watt 10 Hz 35 kHz 0 3 dB at rated 4 ohm power lt 0 1 1050 watts per channel from 20 Hz to 20 kHz lt 0 1 700 watts per channel from 20 Hz to 20 kHz gt 55 dB O 1 kHz x40 32 dB gt 55 dB 1 kHz at rated power 8 ohms gt 108 dB A weighted reference to rated power 8 ohms gt 15V us gt 500 12. uses warnen die von machen die Handhabung und Wartung des Produkts betreffen VORSICHT Risiko Elektrischer Schlag Nicht ffnen VORSICHT Um das Risiko eines elektrischen Schlages zu vermeiden nicht die Abdeckung enfernen Es befinden sich keine Teile darin die vom Anwender repariert werden k nnten Reparaturen nur von qualifiziertem Fachpersonal durchf hren lassen ACHTUNG Um einen elektrischen Schlag oder Feuergefahr zu vermeiden sollte dieses Ger t nicht dem Regen oder Feuchtigkeit ausgesetzt werden Vor Inbetriebnahme unbedingt die Bedienungsanleitung lesen IMPORTANT SAFETY INSTRUCTIONS WARNING When using electrical products basic cautions should always be followed including the following 1 Read these instructions C Keep these instructions Heed all warnings Follow all instructions Do not use this apparatus near water Clean only with a dry cloth Do not block any of the ventilation openings Install in accordance with manufacturer s instructions 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 plug The wide blade or third prong is provided for your safety If the provided plug does not fit into your outl
3. 00 32 00 14 5 00 10 00 20 00 12 3 20 6 40 12 80 10 2 00 4 00 8 00 SRE p 32 setup glossary of terms for setup RERERE PERFORMANCE Stereo Mono Crossover Bi amp Full Range Program Hi Pass Low Pass Mid High Sub Parallel Music with two separate channels usually a left and right channel Music with only one channel An electronic device that separates high and low frequencies and sends them to different outputs The sepa rate signals are usually sent to a high out and a low out The separation of high and low frequencies with a cross over using separate speakers and power amps for each Both high and low frequencies together in a single channel The signal that is plugged into the amplifier Allows only the high frequencies to pass blocking the low frequencies Allows only the low frequencies to pass blocking the high frequencies The speaker designed to play everything but the low frequencies The speaker designed for low frequencies only Both speakers or inputs have the same signal When referring to speakers this means plugging the second speaker into the first speaker and so on p 33 NOTES CREST AUDIO LIMITED WARRANTY Effective Date November 1 2000 What This Warranty Covers Your Crest Audio Warranty covers defects in material and workmanship in Crest Audio products purchased and serviced in the U S A
4. 20 Hz 1 kHz 5 to 12 degrees 20 Hz to 20 kHz 1 8 volts 3 for 1 kHz 4 ohm rated power 15 k ohms balanced 1185 watts 4 ohms 720 watts 8 ohms 2975 watts 4 ohms 1835 watts 8 ohms Two front panel temperature dependent variable speed 80 mm DC fans 2 front panel attenuators rear panel Mode switches 2 GCL gain comparator limiting 2 Signal presence 2 Active Status Thermal DC turn on bursts subsonic incorrect loads Per channel Combi XLR amp 6 3 mm phone input Speakon and Binding Post speaker output 15 amp IEC mains connector 14 ga steel with cast front panel and cast handles 88 9 mm x 482 6 mm x 376 3 mm 31 8 for rear support ears and connectors 3 5 x 19 x 14 81 1 25 38 1 mm 1 5 handle depth 19 5 kg 43 lbs 20 6 kg 45 5 lbs power measurements made at 120 VAC power transformer cold 4 ohm power is time limited by magnetic circuit breaker All power measurements made at 120 VAC power transformer cold 2 ohm power is time limited by magnetic circuit breaker RGRERE PERFORMANCE service and support CPX owner s manual standard cable lengh infoo u De Mood DORMIT Ud 18 9 1 58 3 16 16 50 1 00 2 00 14 31 62 L 12 20 40 80 10 125 25 50 10 18 1 58 3 16 6 32 16 1 00 2 0 4 00 14 62 1 25 2 50 12 40 80 1 60 10 25 50 1 00 4 0 18 8 00 12 60 2520 16 4 00 8 00 1 60 14 2 50 5 00 10 00 12 1 60 3 20 6 40 10 1 00 2 00 4 00 8 625 1 25 250 Q pa 16 8 00 16
5. Performance features and each indicator or control on the amplifier will appear as terms actions specific actions or selections the user can execute will appear as actions tasks are broken down into steps e e warnings Procedures not to attempt A Issues or hazards to keep in mind when operating the equipment indicators What to look for on the equipment display 5 Alerts indicators prompts that may appear tips Preferred methods gi Helpful hints Feature insights see see refers to other sections of the manual containing supplementary information on the current topic or a related issue note note supplementary feature information p 9 introd uction CPX owner s manual welcome For your safety A read the important Congratulations on your purchase of the CPX 3800 Series a power ampli precautions section fier designed for years of reliable flawless operation under rigorous use as well as input This amplifier offers the sonic superiority and unsurpassed reliability for output and power which Crest Performance is famous while remaining surprisingly compact connection sections Advanced technology and extensive protection circuitry allow operation with greater efficiency into difficult loads and power conditions The GCL Gain Comparator Limiting circuit ensures trouble free operation into loads as low as 2 ohms The Gain Comparator Limiting circuit protects drivers and ensu
6. activate the LOW CUT filter for the corresponding channel It is a push type switch that requires a small tool to activate The IN position routes the input signals through the 40 Hz LOW CUT filter while the OUT position bypasses the filter This filter will cut extremely low frequencies protecting speakers from the possibility of over excursion The filter low frequency rolloff is 12 dB per octave The LOW CUT filter for each channel will function independently of the crossover function Crossover Switch 100 Hz crossover This switch is used to activate the 100 Hz crossover for the cor responding channel It is also a pushpush type switch and requires a small tool to activate The CPX offers two 100 Hz crossovers These are specially designed features that enhance the response of most loudspeakers in a typical bi amped application Rather than having a flat output curve these crossovers use special filters to tailor the response and provide a flat acoustical output This type of crossover sounds more natural than conventional state variable crossovers With the switch IN the input signals are routed through the crossover and the low frequen cies are automatically sent to the corresponding channel At the same time the high frequencies are sent to the HIGH OUT 9 jack and must then be patched to the INPUT of the other channel of this amplifier or to another amplifier input to complete the bi amped system With the switch OUT the crossover i
7. be shipped to Crest Audio for warranty service the consumer must pay initial shipping charges If the repairs are covered by warranty Crest Audio will pay the return shipping charges How To Get Warranty Service 1 Take the defective item and your sales receipt or other proof of date of purchase to your Authorized Crest Audio Dealer or Authorized Crest Audio Service Center OR 2 Ship the defective item prepaid to Crest Audio 412 Highway 11 amp 80 East Meridian MS 39301 Include a detailed description of the problem together with a copy of your sales receipt or other proof of date of purchase as evidence of warranty coverage Also provide a complete return address Limitation of Implied Warranties ANY IMPLIED WARRANTIES INCLUDING WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE LIMITED IN DURATION TO THE LENGTH OF THIS WARRANTY Some states do not allow limitations on how long an implied warranty lasts so the above limitation may not apply to you Exclusions of Damages CREST AUDIO S LIABILITY FOR ANY DEFECTIVE PRODUCT IS LIMITED TO THE REPAIR OR REPLACEMENT OF THE PRODUCT AT CREST AUDIO S OPTION IF WE ELECT TO REPLACE THE PRODUCT THE REPLACEMENT MAY BE A RECONDITIONED UNIT CREST AUDIO SHALL NOT BE LIABLE FOR DAMAGES BASED ON INCONVENIENCE LOSS OF USE LOST PROFITS LOST SAVINGS DAMAGE TO ANY OTHER EQUIPMENT OR OTHER ITEMS AT THE SITE OF USE OR ANY OTHER DAMAGES WHETHER INCIDENTAL CONSEQUENTIAL OR OTHER
8. original factory packing If the shipping carton is unavailable contact Crest to obtain a replacement mounting CPX Series amplifiers will mount in standard 19 racks Rear mounting ears are also provided for additional support which is recommended in non permanent installations like mobile or touring sound systems connecting power CPX Series amplifier power requirements are rated at 1 8 power typical music conditions and 1 3 power extreme music conditions The maximum power rent draw rating is limited only by the front panel circuit breaker Consult the speci fications in the Appendices section for figures on the current that each amplifier will demand Make sure the mains voltage is correct and is the same as that printed on the rear of the amplifier Damage caused by connecting the amplifier to improper AC voltage is not covered by any warranty Unless otherwise specified when ordered Crest amplifiers shipped to customers are configured as follows Option North America 120 60 Hz Option 2 Europe Asia 230 240VAC 50 Hz Option 3 Australia 240VAC 50 Hz Option 4 South America 120 60 Hz or 240 50 Hz p 12 CPX owner s manual For replacement gi packaging call Crest Performance s Customer Service Department directly see service and support Always tum off and disconnect the amplifier from mains voltage before making audio connections A so as an extra precaution tum down t
9. remember to have the gain controls turned down during power up to prevent speaker damage if there is a high signal level at the inputs Whether you buy or make them use good quality connections input cables and speaker cables along with good soldering technique to ensure trouble free operation Most intermittent problems are caused by faulty cables Consult the Wire Gauge Chart to determine proper gauges for different load impedances and cable lengths Remember that cable resistance robs amplifier power in two ways power lost directly to resistance PR loss and by increasing the total load impedance thereby decreasing the power demanded of the amplifier Also make sure the mode switch is correctly set for the desired application See Sections on Stereo Parallel and Bridged Mono modes for more information Make certain that there is enough space around the front and rear of the amplifier to allow the heated air to escape suggestion In racks with closed backs allow at least one standard rack space opening for every four mounted power amplifiers Always turn off and disconnect the amplifier from mains voltage before making audio connections Also as an extra precaution turn the attenuators down during power up p 13 installation CPX owner s manual connecting inputs Input connections are made via the three pin XLR pin 2 or 6 3 mm plug Combi connectors on the rear panel of the amplifier The inputs are
10. terminal that is marked by the letter E the earth symbol colored green or colored green and yellow b The wire that is colored blue must be connected to the terminal that is marked with the letter N or the color black The wire that is colored brown must be connected to the terminal that is marked with the letter L or the color red 18 Exposure to extremely high noise levels may cause a permanent hearing loss Individuals vary considerably in suscep tibility to noise induced hearing loss but nearly everyone will lose some hearing if exposed to sufficiently intense noise for a sufficient time The U S Government s Occupational Safety and Health Administration OSHA has specified the following permissible noise level exposures Duration Per Day In Hours Sound Level dBA Slow Response 8 90 6 92 Ab 3 97 2 100 112 102 105 y2 110 1 4 or less 115 According to OSHA any exposure in excess of the above permissible limits could result in some hearing loss Ear plugs or protectors to the ear canals or over the ears must be worn when operating this amplification system in order to prevent a permanent hearing loss if exposure is in excess of the limits as set forth above To ensure against potentially dangerous exposure to high sound pressure levels it is recommended that all persons exposed to equipment capable of producing high sound pressure levels such as this amplification system be protected by hearing protect
11. SSSR AR CPX 3800 Power Amplifier Owner s Manual Intended to alert the user to the presence of uninsulated dangerous voltage within the product s enclosure that may be of sufficient magnitude to constitute a risk of electric shock to persons Intended to alert the user of the presence of important operating and maintenance servicing instructions in the lit erature accompanying the product CAUTION Risk of electrical shock DO NOT OPEN CAUTION To reduce the risk of electric shock do not remove cover No user serviceable parts inside Refer servicing to qualified service personnel WARNING To prevent electrical shock or fire hazard do not expose this appliance to rain or moisture Before using this appliance read the operating guide for further warnings Este simbolo tiene el prop sito de alertar al usuario de la presencia de voltaje peligroso sin aislamiento dentro de la caja del producto y que puede tener una magnitud suficiente como para constituir riesgo de descarga el ctrica Este simbolo tiene el prop sito de alertar al usario de la presencia de instruccones importantes sobre la operaci n mantenimiento en la informaci n que viene con el producto PRECAUCION Riesgo de descarga el ctrica NO ABRIR PRECAUCION Para disminu r el riesgo de descarga el ctrica no abra la cubierta No hay piezas tiles dentro Deje todo mantenimiento en manos del personal
12. WISE EVEN IF CREST AUDIO HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES Some states do not allow the exclusion or limitation of incidental or consequential damages so the above limitation or exclusion may not apply to you This Warranty gives you specific legal rights and you may also have other rights which vary from state to state If you have any questions about this warranty or service received or if you need assistance in locating an Authorized Service Center please contact Crest Audio at 201 909 8700 and ask for the service department Features and specifications subject to change without notice Logo referenced in Directive 2002 96 EC Annex IV x d RES X OJ L 37 38 13 02 03 and defined in EN 50419 2005 The bar is the symbol for marking of new waste and is applied only to equipment manufactured after 13 August 2005 SECRET http www crest performance com CPX Owner s Manual 01 18 2006 80303153
13. What This Warranty Does Not Cover The Warranty does not cover 1 damage caused by accident misuse abuse improper installation or operation rental product modification or neglect 2 damage occurring during shipment 3 damage caused by repair or service performed by persons not authorized by Crest Audio 4 products on which the serial number has been altered defaced or removed 5 products not purchased directly from Crest Audio or from an Authorized Crest Audio Dealer Who This Warranty Protects This Warranty protects only the original purchaser of the product How Long This Warranty Lasts The Warranty begins on the date of purchase by the original retail purchaser The duration of the Warranty is as follows Product Category Duration Amplifiers 5 years Consoles 5 years Signal Processing 2 years 1 year Enclosures 3 years 2 years Crest Performance 2 years 2 years Denotes additional warranty period applicable if optional Warranty Registration Card is completed and returned to Crest Audio by original purchaser within 90 days of purchase Denotes all products sold under the Crest Performance brand including amplifiers consoles signal processing enclosures and any other product category What Crest Audio Will Do We will repair or replace at Crest Audio s discretion products covered by warranty at no charge for labor or materials If the product or component must
14. actively balanced The input overload point is high enough to accept the maximum output level of virtually any signal source inputs CHANNEL INPUT outputs connecting outputs All models have two output speaker connections per channel Cables can be connected with banana plugs spade lugs or bare wire to the five way binding posts The preferred method is connection via the Speakon connectors p 14 RGRERE PERFORMANCE location of connectors and controls gt legend of panel symbols features overview front panel rear panel features overview CPX owner s manual AQ COC A pa gt SCREST bis CPX 3800 ameurien front panel switches and controls The power only breaks AC Power Switch Circuit Breaker one side of the AC mains Hazardous energy may be A The CPX Series amplifiers have a combination AC switch circuit breaker present in the PORC on the front panel If the switch shuts off during normal use push it when the power switch is in back to the ON position once If it will not stay on the amplifier needs tie OFF servicing Input Attenuators Whenever possible set the attenuators fully clockwise to maintain Winen in De mode both attenuators must optimum system headroom The input attenuator controls located at the be in the same position so the front panel one for channel A o
15. do el aparato ha sido da ado de alguna manera como cuando el cable de alimentaci n el enchufe se han da ado alg n liquido ha sido derramado alg n objeto ha caido dentro del aparato el aparato ha sido expuesto a la lluvia la humedad no funciona de manera normal ha sufrido una caida Nunca retire la patilla de Tierra Escribanos para obtener nuestro folleto gratuito Shock Hazard and Grounding Peligro de Electrocuci n y Toma a Tierra Conecte el aparato s lo a una fuente de alimentaci n del tipo marcado al lado del cable de alimentaci n Si este producto va a ser enracado con m s equipo use alg n tipo de apoyo trasero Nota para el Reino Unido solamente Si los colores de los cables en el enchufe principal de esta unidad no corresponden con los terminales en su enchufe proceda de la siguiente manera a El cable de color verde y azul debe ser conectado al terminal que est marcado con la letra E el s mbolo de Tierra earth coloreado en verde o en verde y amarillo b El cable coloreado en azul debe ser conectado al terminal que est marcado con la letra N o el color negro c El cable coloreado en marr n debe ser conectado al terminal que est marcado con la letra Lo el color rojo Este aparato el ctrico no debe ser sometido a ning n tipo de goteo o salpicadura y se debe tener cuidado para no poner objetos que contengan l quidos como vasos sobre el aparato La exposici n a altos niveles de ruido pu
16. ede causar una p rdida permanente en la audici n La susceptibilidad a la p rdida de audici n provocada por el ruido var a seg n la persona pero casi todo el mundo perder algo de audici n si se expone a un nivel de ruido suficientemante intenso durante un tiempo determinado El Departamento para la Salud y para la Seguridad del Gobierno de los Estados Unidos OSHA ha especificado las siguientes exposiciones al ruido permisibles Duraci n por D a en Horas Nivel de Sonido dBA Respuesta Lenta 8 90 6 92 4 95 3 97 2 100 1 102 1 105 vA 110 menos 115 De acuerdo al OSHA cualquier exposici n que exceda los limites arriba indicados puede producir alg n tipo p rdida en la audici n Protectores para los canales auditivos tapones para los ofdos deben ser usados cuando se opere con este sistema de sonido para preve nir una p rdida permanente en la audici n si la exposici n excede los limites indicados mas arriba Para protegerse de una exposici n a altos niveles de sonido potencialmente peligrosa se recomienda que todas las personas expuestas a equipamiento capaz de producir altos niveles de presi n sonora tales como este sistema de amplificaci n se encuentren protegidas por protectores auditivos mientras esta uni dad est operando GUARDE ESTAS INSTRUCCIONES important precautions Save the carton and packing materi als Should you ever need to ship the unit use only the o
17. ejos Siga todas las instrucciones No usar este aparato cerca del agua Limpiar solamente con una tela seca No bloquear ninguna de las salidas de ventilaci n Instalar de acuerdo a las instrucciones del fabricante No instalar cerca de ninguna fuente de calor como radiadores estufas hornos u otros aparatos incluyendo amplificadores que produzcan calor No retire la patilla protectora del enchufe polarizado o de tipo a Tierra Un enchufe polarizado tiene dos puntas una de ellas mas ancha que la otra Un enchufe de tipo a Tierra tiene dos puntas y una tercera a Tierra La punta ancha la tercera se proporciona para su seguridad Si el enchufe proporcionado no encaja en su enchufe de red consulte a un electricista para que reemplaze su enchufe obsoleto Proteja el cable de alimentaci n para que no sea pisado pinchado particularmente en los enchufes huecos los puntos que salen del aparato Usar solamente afiadidos accesorios proporcionados por el fabricante Usar solamente un carro pie tripode o soporte especificado por el fabricante o vendido junto al aparato Cuando se use un carro tenga cuidado al mover el conjunto carro aparato para evitar que se da e en un vuelco No suspenda esta caja de ninguna manera Desenchufe este aparato durante tormentas cuando no sea usado durante largos periodos de tiempo Para cualquier reparaci n acuda a personal de servicio cualificado Se requieren reparaciones cuan
18. enden Sie nur die vom Hersteller erh ltlichen Zubeh rger te oder Zubeh rteile Verwenden Sie nur einen Wagen Stativ Dreifu Tr ger oder Tisch der den Angaben des Herstellers entspricht oder zusammen mit dem Ger t verkauft wurde Wird ein Wagen verwendet bewegen Sie den Wagen mit dem darauf befindlichen Ger t besonders vorsichtig damit er nicht umkippt und m glicherweise jemand verletzt wird Trennen Sie das Ger t w hrend eines Gewitters oder w hrend l ngerer Zeitr ume in denen es nicht benutzt wird von der Stromversorgung Lassen Sie s mtliche Wartungsarbeiten von qualifizierten Kundendiensttechnikern durchf hren Eine Wartung ist erforderlich wenn das Ger t in irgendeiner Art besch digt wurde etwa wenn das Netzkabel oder der Netzstecker besch digt wurden Fl ssigkeit oder Gegenst nde in das Ger t gelangt sind das Ger t Regen oder Feuchtigkeit ausgesetzt wurde nicht normal arbeitet oder heruntergefallen ist Der Erdungsstift darf nie entfernt werden Auf Wunsch senden wir Ihnen gerne unsere kostenlose Brosch re Shock Hazard and Grounding Gefahr durch elektrischen Schlag und Erdung zu Schlie en Sie nur an die Stromversorgung der Art an die am Ger t neben dem Netzkabel angegeben ist Wenn dieses Produkt in ein Ger te Rack eingebaut werden soll muss eine Versorgung ber die R ckseite eingerichtet werden Hinweis Nur f r Gro britannien Sollte die Farbe der Dr hte in der Netzleitung dieses Ger ts nicht m
19. eral performance specifications are the same as in the Stereo Mode bridged mono Both amplifier channels can be bridged together to make a very powerful single channel monaural amplifier Use extreme caution when operat ing in bridged mode potentially lethal voltage may be present at the output terminals To bridge the amplifier depress the rear panel Amp Mode switch 11 to the IN position Direct the signal to channel A input and connect the speakers across pin 1 and 2 of the channel A Speakon output connector Only channel A s input attenuator is active while in Bridged Mono mode Both connectors are strapped together so either connector can be used with a patch cable to drive the input of another amplifier RGRERE PERFORMANCE When operating in the Bridged Mode both attenuators must be in the same position so the speaker load will be equally shared between the channels Unlike the Stereo and Parallel Modes in which one side of each output is at ground in he Bridged Mode both sides are hot Pin 1 is Channel side which is the same polarity as he input The minimum nominal load impedance in the Bridged Mode is 4 ohms which is equivalent driving both chan nels at 2 ohms Driving bridged loads of less han 4 ohms will activate GCL circuitry result ing in a loss of power and potential thermal overload p 23 rotection features CPX owner s manual gt description of protec
20. es not have a ground pin a suitable grounding adapter should B channel A stereo parallel be used and the third wire grounded properly Never break off the ground pin on any equipment It is provided for sm channel B stereo parallel your safety The use of extension cords should be avoided but if necessary bridged mene always use a three wire type with at least a 14 AWG wire size The five way binding post use of lighter wire will severely limit the power capability of this amplifier Always have a qualified electrician install any new electrical equipment To prevent the risk of shock or fire hazard always be sure that the amplifier and all associated equipment is properly grounded Dee bridged mono NOTE FOR ONLY If the colors of the wires in the mains lead of this unit do not correspond with the colored markings identifying the terminals in your plug proceed channel B stereo parallel as follows 1 The wire that is colored green and yellow must a channel A stereo parallel p 18 features overview be connected to the terminal that is marked by the letter E the Earth symbol colored green or colored green and yellow 2 The wire that is colored blue must be connected to the terminal that is marked with the letter N or the color black 3 The wire that is colored brown must be connected to the terminal that is marked with the letter L or the color red Low Cut Switch This switch is used to
21. et consult an electrician for replacement of the obsolete outlet DS QUE wo m 10 Protect the power cord from being walked on or pinched particularly at plugs convenience receptacles and the point they exit from the apparatus 11 Only use attachments accessories provided by the manufacturer 12 Use only with a cart stand tripod bracket or table specified by the manufacturer or sold with the apparatus When a amp 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 Never break off the ground pin Write for our free booklet Shock Hazard and Grounding Connect only to a power supply of the type marked on the unit adjacent to the power supply cord 16 If this product is to be mounted in an equipment rack rear support should be provided 17 Note for UK only If the colors of the wires in the mains lead of this unit do not correspond with the terminals in your plug proceed as follows a The wire that is colored green and yellow must be connected to the
22. ge or subsonic frequencies at its output terminals its output relay will immediately open to prevent loudspeaker damage RGRERE PERFORMANCE p 25 rotection features CPX owner s manual turn on turn off protection At power up the amplifier stays in the protect mode with outputs disconnected for approximately six seconds while the power supplies charge and stabilize While the output relays are open the GCL LEDs light When power is removed the speaker loads immediately disconnect so that no thumps or pops are heard AUTORAMP signal control Whenever a CPX Series amplifier powers up or comes out of a protect mode the AUTORAMP circuit acti vates While the speakers are disconnected the AUTORAMP circuit fully attenuates the signal and activates the GCL LED After the output relay closes the signal slowly and gradually raises to its set level The PWR LED will illuminate and the GCL LED will turn off when the signal is no longer attenuated The AUTORAMP Signal Control circuit has some important advantages over conventional instant on circuits If a signal is present during power up or when coming out of protect the speakers are spared a sudden potentially damaging burst of audio power 2 Because the gain is reduced until after the output relay closes no arcing occurs at the contacts This extends the contacts useful life p 26 safety gt protecting your speakers speaker protection gt the owner s r
23. he attenuators during power up installation cooling requirements The CPX Series amplifiers use a forced air cooling system to maintain a low con sistent operating temperature Air is drawn into the amplifier by fan s on the rear panel courses through the cooling fins of the tunnel configured channel heat sink s and then exhausts through the front panel grille If either heat sink gets too hot its sensing circuit will open the output relay disconnecting the load from that particular channel The CPX 3800 utilizes one common heat sink and a single fan but retains the separate circuitry NOTE Maintain an adequate air supply at the back of the amplifier and enough space around the front of the amplifier to allow the cooling air to escape If the amp is rack mounted do not use doors or covers on the front of the rack the exhaust air must flow without resistance If you are using racks with closed backs use fans on the rear rack panel to pressurize the rack and ensure an ample air supply operating precautions RGRERE PERFORMANCE Make sure the mains voltage is correct and the same as that printed on the rear of the amplifier Damage caused by connecting the amplifier to improper AC voltage is not covered by any warranty See the Connecting Power section for more information on voltage requirements Although the CPX Series amplifiers have AUTORAMP circuitry which raises the signal level gradually after the output relay closes
24. ically limit the duration of continuous square waveforms applied to the speakers The amplifier will however allow normal musical transient bursts to pass Some speaker systems are packaged with processors that have power limiting circuits and should not require additional external limiting Fuses may also be used to limit power to speaker drivers although as current limiting rather than voltage limiting devices they are an imperfect solution As the weakest links fuses only limit once before needing replacement Some poor quality fuses have a significant series resistance that could degrade the amplifier s damping of the speakers motion and may even deteriorate the system s sound quality If you elect to use fuses check with the speaker manu facturer to determine the proper current rating and time lag required Do not drive any low frequency speaker enclosure with frequencies lower than its own tuned frequency The reduced acoustical damping could cause a ported speaker to bottom out even at moderate power Consult the speaker system specifications to determine its frequency limits amplifier maintenance and user responsibility A CPX Series amplifier requires no routine maintenance and should never need any internal adjustment during its lifetime Your CPX Series amplifier is very powerful and can be potentially dangerous to loudspeakers and humans alike It is your responsibility to read the Important Precautions section in the front of thi
25. it den Klemmen in Ihrem Stecker bereinstimmen gehen Sie folgenderma en vor a Der gr n gelbe Draht muss an die mit E Symbol f r Erde markierte bzw gr ne oder gr n gelbe Klemme angeschlossen werden b Der blaue Draht muss an die mit N markierte bzw schwarze Klemme angeschlossen werden c Der braune Draht muss an die mit L markierte bzw rote Klemme angeschlossen werden Dieses Ger t darf nicht ungesch tzt Wassertropfen und Wasserspritzern ausgesetzt werden und es muss darauf geachtet werden dass keine mit Fl ssigkeiten gef llte Gegenst nde wie z B Blumenvasen auf dem Ger t abgestellt werden Belastung durch extrem hohe L rmpegel kann zu dauerhaftem Geh rverlust f hren Die Anf lligkeit f r durch L rm bedingten Geh rverlust ist von Mensch zu Mensch verschieden das Geh r wird jedoch bei jedem in gewissem Ma e gesch digt der ber einen bestimmten Zeitraum ausreichend starkem L rm ausgesetzt ist Die US Arbeitsschutzbeh rde Occupational and Health Administration OSHA hat die folgenden zul ssigen Pegel f r L rmbelastung festgelegt Dauer pro Tag in Stunden Ger uschpegel dBA langsame Reaktion 8 90 6 92 4 95 3 97 2 100 1 102 1 105 110 4 oder weniger 115 Laut OSHA kann jede Belastung ber den obenstehenden zul ssigen Grenzwerten zu einem gewissen Geh rverlust f hren Sollte die Belastung die obenstehenden Grenzwerte bersteigen m ssen beim Betrieb dieses Verst
26. ly and continuously when limiting occurs IGM impedance sensing The CPX Series amplifiers feature innovative circuitry that allows safe operation into any load When an amplifier sees a load that overstresses the output stage the Instantaneous Gain Modulation IGM circuit adjusts the channel gain to a safe level This method of output stage protection is far superior to conventional brute force type limiting found on other amplifiers The IGM circuit is sonically transparent in normal use and unobtrusive when activated thermal protection Internal fans keep the amplifier operating well within its intended temperature range under all normal conditions If a channel s heat sink temperature reaches 75 C which may indicate an obstructed air supply that channel will independently protect itself by disconnecting its load and shutting down until it has cooled During this time the POWER LED will go out the GCL LEDs will remain lit and the cooling fans will continue running at high speed short circuit output is shorted the IGM and thermal circuits will automatically protect the amplifier The IGM circuit senses the short circuit as an extremely stressful load condition and attenuates the signal protecting the channel s output transistors from over current stress If the short circuit remains the channel will eventually thermally protect itself by disconnecting the load DC voltage protection If an amplifier channel detects DC volta
27. n The equipment does not appear to oper ate normally or exhibits a marked change n performance The equipment has been dropped or the enclosure damaged To obtain service contact your nearest Crest Performance Service Center Distributor Dealer or Crest Performance at 601 486 2000 USA or visit www crest performance com for additional information email techserve crestaudio com detailed in documentation This symbol is used to warn opera tors that uninsulated dangerous voltages are present within the equipment enclosure that may This symbol is used to alert the operator to follow important procedures and precautions pose a risk of electric shock table of contents p 8 how to use this manual introduction installation unpacking mounting connecting power cooling requirements operating precautions connecting inputs connecting outputs features overview front panel rear panel operation modes stereo parallel bridged mono protection features GCL Gain Comparator Limiting IGM impedance sensing thermal protection short circuit DC voltage protection turn on off protection AUTORAMP signal control safety speaker protection user responsibility service and support support contact us specifications wire gauge charts CPX owner s manual contents appendices how to use this manual conventions SEREST PERFORMANCE terms official Crest
28. ndicates that its channel s output relay is closed and the channel is operational It lights under normal operation and remains on even when the channel is in Gain Comparator Limiting or GCL gain reduction These protection features leave the output relay closed If the Power LED goes off there is no signal at the output connectors 17 featu res overview CPX owner s manual NEL INPUT HIGH OUT DO NOT OPEN JARNING REDUCE THE RISK OF FIRE OR SHOCK DO NOT EXPOSE THIS EQUIPMENT TO RAIN OR MOISTURE AVIS RISQUE DE MADEIN CHINA 69 MOUNT IN RACK ONLY INSTALLER SUR SUPPORT DE MONTAGE SEULMENT rear panel legend input connection rear n XLR connector polarity IEC Mains Connector TRS connector polarity This is a standard IEC power connector An AC mains cord having the appropriate AC plug and ratings for the intended operating voltage is included in the carton U S DOMESTIC AC MAINS CORD The mains cord supplied with the unit is a heavy duty three conductor type with a conventional 120 VAC plug with ground pin It should be connected to an independent circuit capable bridged mono mode De spe parallel mode stereo mode gt D G gt gt of continuously supporting at least 15 amps This is particularly G output connection critical for sustained high power applications If the outlet used Speakon output do
29. ne for channel B adjust gain for speaker load will be equally their respective amplifier channels in all modes See the specifications shares e diem ele See the section on Bridged at the end of this manual for standard voltage gain and input sensitivity as information information and precautions p 16 features overview indicators CPX Series amplifiers feature three front panel LED indicators per channel GCL SIGNAL and POWER These LED indicators inform the user of each channels operating status and warn of possible abnormal conditions GCL Gain Comparator Limting LED A channel s GCL LED will light at the onset of clipping If the LEDs are flashing quickly and intermittently the channel is just at the clip threshold A steady bright glow means the amp is clip limiting or reducing gain to prevent severely clipped waveforms from reaching the loudspeakers See the Gain Comparator Limiting section for more information During ini tial power up the GCL LED will light to indicate that the AUTORAMP gain reduction circuitry is activated This prevents sudden signal bursts when the speaker relays are closed Signal LED This LED lights when its channel produces an output signal of about 4 volts RMS or more 0 1 volt or more at the input with 0 dB attenuation and standard x40 voltage gain This signal indicates whether a signal is reaching and being amplified by the amplifier Power LED The Power LED i
30. ole in amplifier safety user responsibility 27 safety CPX owner s manual speaker protection All loudspeakers have electrical thermal and physical limits that must be observed to prevent damage or failure Too much power low frequencies applied to high frequency drivers severely clipped waveforms and DC voltage can all be fatal to cone and compression drivers The Crest Performance CPX Series amplifiers automatically protect speakers from DC voltages and subsonic signals For more information see the section on Protection Features Mid and high frequency speakers especially compression drivers are highly susceptible to damage from overpowering clipped waveforms or frequencies below their rated pass band Be extremely careful that the low and mid bands of an electronic crossover are connected to the correct amplifiers and drivers and not accidentally connected to those for a higher frequency band The amplifier s clipping point is its maximum peak output power and can deliver more power than many speakers can safely handle Be sure the peak power capability of the amplifier is not excessive for your speaker system To ensure that the speakers never receive excessive power and that the amplifier never clips use a properly adjusted external limiter or a compressor with a ratio of 10 1 or higher to control power output In systems with active electronic crossovers use one for each frequen cy band The clip limiter will automat
31. ors while this unit is in operation SAVE THESE INSTRUCTIONS WICHTIGE SICHERHEITSHINWEISE ACHTUNG Beim Einsatz von Elektroger ten m ssen u a grundlegende Vorsichtsma nahmen befolgt werden 1 Q0 5 COS RE MD 10 11 12 13 14 15 16 17 18 19 Sie sich diese Anweisungen durch C Bewahren Sie diese Anweisungen auf Beachten Sie alle Warnungen Befolgen Sie alle Anweisungen Setzen Sie dieses Ger t nicht in der N he von Wasser ein Reinigen Sie es nur mit einem trockenen Tuch Blockieren Sie keine der L ftungs ffnungen F hren Sie die Installation gem den Anweisungen des Herstellers durch Installieren Sie das Ger t nicht neben W rmequellen wie Heizungen Heizger ten fen oder anderen Ger ten auch Verst rkern die W rme erzeugen Beeintr chtigen Sie nicht die Sicherheitswirkung des gepolten Steckers bzw des Erdungssteckers Ein gepolter Stecker weist zwei Stifte auf von denen einer breiter ist als der andere Ein Erdungsstecker weist zwei Stifte und einen dritten Erdungsstift auf Der breite Stift bzw der dritte Stift dient Ihrer Sicherheit Sollte der beiliegende Stecker nicht in Ihre Steckdose passen wenden Sie sich bitte an einen Elektriker um die ungeeignete Steckdose austauschen zu lassen Sch tzen Sie das Netzkabel sodass niemand darauf tritt oder es geknickt wird insbesondere an Steckern oder Buchsen und ihren Austrittsstellen aus dem Ger t Verw
32. osition de hauts niveaux sonores peut conduire des dommages de l coute irr versibles La suscep tibilit au bruit varie consid rablement d un individu l autre mais une large majorit de la population exp riencera une perte de l coute apr s une exposition une forte puissance sonore pour une dur e prolong e l organisme de la sant am ricaine OSHA a produit le guide ci dessous en rapport la perte occasionn e Dur e par Jour heures Niveau sonore moyen dBA 8 90 E ________________ _ 4 95 3 97 2 100 1 102 1 105 110 ou inf rieur 115 D apr s les tudes men es par le OSHA toute exposition au del des limites d crites ce dessus entrainera des pertes de l coute chez la plupart des sujets Le port de syst me de protection casque oreilette de filtrage doit tre observ lors de l op ration cette unit ou des dommages irr versibles peuvent tre occasionn s Le port de ces syst mes doit tre observ par toutes personnes susceptibles d tre expo s es des conditions au del des limites d crites ci dessus GARDEZ CES INSTRUCTIONS INSTRUCCIONES IMPORTANTES PARA SU SEGURIDAD CUIDADO Cuando use productos electr nicos debe tomar precauciones basicas incluyendo las siguientes 1 IIND 10 11 12 13 14 15 16 17 18 19 Lea estas instrucciones Guarde estas instrucciones Haga caso de todos los cons
33. owered on See the Operations Mode section for more information on Stereo Parallel and Bridged Mono Mode applications CPX owner s manual SO SEH m eration modes CPX owner s manual gt choosing the appropriate mode stereo gt switching between operation modes gt special considerations when using bridged mode parallel bridged mono p 22 operation modes stereo For stereo dual channel operation turn the amplifier off and set the mode select switches on the back panel to the OUT extended position In this mode both channels operate independently of each other with their input attenuators controlling their respective levels For example a signal at chan nel A5 input produces an amplified signal at channel A s output while a signal at channel B s input produces an amplified signal at channel B s output parallel For parallel dual channel single input operation turn the amplifier off and set the connector mode Conn Mode switch to the parallel position by depressing the switch Both input connectors are then strapped together and drive both channels with the same input signal Because both connectors are strapped together either connector can be used with a patch cable to drive the input of another amplifier Output connections are the same as in the Stereo Mode In Parallel Mode both input attenuators remain active allow ing users to set different levels for each channel Power and other gen
34. r amplifier output Crest Performance is not responsible for damage to loudspeakers for any reason Do not connect the inputs or outputs of amplifiers to any other voltage source such as a battery mains source or power supply regardless of whether the amplifier is turned on or off Connecting amplifier outputs to oscilloscopes or other test equip ment while the amplifier is in bridged mono mode may damage both the amplifier and test equipment Do not spill water or other liquids into or on the unit or operate the unit while standing in liquid Do not block fan intake or exhaust ports Do not operate equipment on a surface or in an environment which may impede the nor mal flow of air around the unit such as a bed rug weathersheet carpet or completely enclosed rack If the unit is used in an extremely dusty or smoky environment the unit should be periodically blown free of foreign matter Do not use the unit near stoves heat registers radiators or other heat producing devices The equipment power cord should be unplugged from the outlet when left unused for a long period of time Service Information Do not remove the cover Removing the cover will expose you to potentially dangerous voltages There are no user serviceable parts inside Equipment should be serviced by qualified service personnel when he power supply cord or the plug has been damaged The equipment has been exposed to rai
35. res that sonic integrity is maintained even in extreme overload conditions The CPX 38005 high efficiency design uses tunnel cooled heat sinks and variable speed DC fans This cooling topology maintains a lower overall operating temperature resulting in longer output transistor life For your safety read the important precautions section as well as input output and power connection sections Although the CPX Series amplifiers are quite simple to operate and are housed in ultra strong steel chassis improper use can be dangerous This amplifier is very high powered and can put out high voltages and sizable currents at frequencies up to 30 kHz Always use safe operating techniques when operating this amplifier Y RERERE PERFORMANCE what to do with the shipping carton proper rack mounting technique required AC line voltages keeping the amplifier cooled preventing amplifier damage installation unpacking mounting connecting power cooling requirements operating precautions connecting inputs connecting outputs installation unpacking Upon unpacking inspect the amplifier If you find any damage notify your supplier immediately Only the consignee may institute a claim with the carrier for damage incurred during shipping Be sure to save the carton and all packing materials Should you ever need to ship the unit back to Crest Performance one of its offices service centers or the supplier use only the
36. riginal factory pack ing For replacement packaging call Crest Performance s Customer Service Department directly Read all documentation before operating your equipment Retain all documentation for future reference Follow all instructions printed on unit chassis for proper operation Never hold a power switch or cir cuit breaker in the ON position if it won t stay there by itself Do not use the unit if the electrical power cord is frayed or broken The power supply cords should be routed so that they are not likely to be walked on or pinched by items placed upon or against them Always operate the unit with the AC ground wire connected to the electrical system ground Precautions should be taken so that the means of grounding of a piece of equipment is not defeated Damage caused by connection to improper AC voltage is not cov ered by any warranty Mains voltage must be correct and the same as that printed on the rear of the unit Do not ground any hot red terminal Never connect a hot red output to ground or to another hot red output Power down and disconnect units from mains voltage before making connections Do not drive the inputs with a signal level greater than that required to enable equipment to reach full output Do not run the output of any ampli fier channel back into another channel s input Do not parallel or series con nect an amplifier output with any othe
37. rkungssystems Ohrenstopfen oder Schutzvorrichtungen im Geh rgang oder ber den Ohren getragen werden um einen dauerhaften Geh rverlust zu verhindern Um sich vor einer m glicherweise gef hrlichen Belastung durch hohe Schalldruckpegel zu sch tzen wird allen Personen empfohlen die mit Ger ten arbeiten die wie dieses Verst rkungssystem hohe Schalldruckpegel erzeugen k nnen beim Betrieb dieses Ger ts einen Geh rschutz zu tra gen BEWAHREN SIE DIESE SICHERHEITSHINWEISE AUF INSTRUCTIONS IMPORTANTES DE SECURITE ATTENTION L utilisation de tout appareil lectrique doit tre soumise aux precautions d usage incluant Pe OS go 10 11 12 13 14 15 16 17 18 19 Lire ces instructions Gardez ce manuel pour de futures r f rences Pr tez attention aux messages de pr cautions de ce manuel Suivez ces instructions N utilisez pas cette unit proche de plans d eau N utilisez qu un tissu sec pour le nettoyage de votre unit N obstruez pas les syst mes de refroidissement de votre unit et installez votre unit en fonction des instructions de ce manuel Ne positionnez pas votre unit a proximit de toute source de chaleur Connectez toujours votre unit sur une alimentation munie de prise de terre utilisant le cordon d alimentation fourni Prot gez les connecteurs de votre unit et positionnez les cablages pour viter toutes d connexions acciden
38. s defeated and the input signal is routed directly to the respective power amp channel The crossover frequency is fixed at 100 Hz and cannot be changed The crossover configuration is a four pole Linkwitz Riley approximation High Out Jacks This 1 4 jack supplies high frequency output signals from the activated crossover for patching to this amplifier and or additional power amplifier inputs Unlike the low frequency crossover output that is automatically routed to the associated channel the high frequency output signal must be patched to some suitable input in order to complete the bi amped system This 1 4 jack also provides an unbalanced tip sleeve output to be patched with single conductor shielded cables SSSR p 19 20 features overview Conn Mode Select Switch Depressing the rear panel CONN MODE select switch connects both input connectors together in parallel This directs the same input signal to both channels and allows one connector to be used with a patch cable to drive another amplifier In the OUT position both input connectors operate independently Do not operate the CONN MODE select switch with the amplifier powered on See the sections on Stereo Parallel and Bridged Mono Mode for more information Amp Mode Select Switch The rear panel AMP MODE select switch determines if the amplifier is in stereo two channels or in Bridged Mono Mode Do not operate the AMP MODE select switch with the amplifier p
39. s manual and to make sure that the amplifier is installed wired and operated properly Many loudspeakers can be easily damaged or destroyed by overpowering especially with the high power available from a bridged amplifier Read the Speaker Protection section and always be aware of the speaker s continuous and peak power capabilities p 28 service and support gt when to get support support gt ways to contact Crest Performance contact us SRE p 29 service and support cht owners manual support In the unlikely event that your amplifier develops problem it must be returned to an authorized distributor or service center or shipped directly to our factory for service To obtain service contact your nearest Crest Performance Service Center Distributor Dealer or any of the worldwide Crest Performance offices For those with Internet access please visit the Crest Performance web site contact us customer service phone 601 486 2000 USA fax 601 486 1380 USA email customerserve crestaudio com technical support phone 601 486 2000 USA fax 601 486 1380 USA email techserve crestaudio com web site www crest performan ce com mail Crest Performance Inc 5022 Hwy 493 North Meridian MS 39305 USA p 30 Because of the complexity gi of the design and the risk of electrical shock all repairs must be performed by qualified technical personnel only If the unit needs to be shipped back to the factory it
40. t cnico cualificado ADVERTENCIA Para evitar descargas el ctricas o peligro de incendio no deje expuesto a la lluvia o humedad este apara to Antes de usar este aparato lea m s advertencias en la guia de operaci n Ce symbole est utilis dans ce manuel pour indiquer Putilisateur la pr sence d une tension dangereuse pouvant tre d amplitude suffisante pour constituer un risque de choc lectrique Ce symbole est utilis dans ce manuel pour indiquer Putilisateur qu il ou qu elle trouvera d importantes instructions concernant l utilisation et l entretien de l appareil dans le paragraphe signal ATTENTION Risques de choc lectrique NE PAS OUVRIR ATTENTION Afin de r duire le risque de choc lectrique ne pas enlever le couvercle Il ne se trouve l int rieur aucune piece pouvant tre repar e par l utilisateur Confiez l entretien et la r paration de l appareil un r parateur agr AVERTISSEMENT Afin de pr venir les risques de d charge lectrique ou de feu n exposez pas cet appareil la pluie ou l humidit Avant d utiliser cet appareil lisez attentivement les avertissements suppl mentaires de ce manuel Ausreichender Starke sind um einen elektrischen Schlag verursachen zu k nnen Dieses Symbol soll den Benutzer auf wichtige Instruktionen in der Bedienungsanleitung aufmerksam Dieses Symbol soll den Anwender vor unisolierten gef hrlichen Spannungen innerhalb des Geh
41. telles N utilisez que des fixations approuv es par le fabriquant Lors de l utilsation sur pied ou pole de support assurez dans le cas de d placement de l ensemble enceinte support de pr venir tout basculement intempestif de celui ci est conseill de d connecter du secteur votre unit en cas d orage ou de dur e prolong e sans utilisation Seul un technicien agr par le fabriquant est m me de r parer contr ler votre unit Celle ci doit tre contr l e si elle a subit des dommages de manipulation d utilisation ou de stockage humidit Ne d connectez jamais la prise de terre de votre unit Si votre unit est destin e a etre mont e en rack des supports arriere doivent etre utilises Note pour les Royaumes Unis Si les couleurs de connecteurs du cable d alimentation ne correspond pas au guide de la prise secteur proc dez comme suit Le connecteur vert et jaune doit tre connectrer au terminal not E indiquant la prise de terre ou correspondant aux couleurs verte ou verte et jaune du guide b Le connecteur Bleu doit tre connectrer au terminal not N correspondnat la couleur noire du guide C Le connecteur marron doit tre connectrer au terminal not L correspondant la couleur rouge du guide Cet quipement lectrique ne doit en aucun cas tre en contact avec un quelconque liquide et aucun objet contenant un liquide vase ou autre ne devrait tre pos sur celui ci Une exp
42. tion features GCL gain comparator limiting IGM impedance sensing AUTORAMP signal control thermal protection short circuit DC voltage protection turn on off protection features The CPX Series amplifiers incorporate several circuits to protect both themselves and loud speakers under virtually any situation Crest Performance has attempted to make the amplifiers as foolproof as possible by making them immune to short and open circuits mismatched loads DC voltage and overheating If a channel goes into the Gain Comparator Limiting or GCL gain reduction mode the speaker load remains connected but clipping percentage or output power are instantly reduced DC voltage on the output excessive subsonic frequencies or thermal overload will cause the channel s output relay to disconnect the speaker load until the problem is corrected or the amplifier cools down GCL gain comparator limiting Any time a channel is driven into hard continuous clipping the GCL circuit will automatically reduce the channel gain to a level just slightly into clipping guarding the speakers against the damaging high power continuous square waves that may be produced Situations that may activate the GCL circuit include uncontrolled feedback oscillation an improper equipment setting or malfunction upstream from the amplifier Normal program transients will not trigger the GCL only steady excessive clipping will The GCL LED will glow bright
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