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2—5 

2  Safety instructions, warnings 

2.1  Basic precautions 

WARNING - When using electrical products, basic precautions should be followed, including the following: 
Read all the instructions before using the product. 
Do not use this product near water – for example, near a bathtub, washbowl, kitchen sink, in a wet basement 
or near a swimming pool. 
This  product may  cause  permanent  hearing  loss.  Do  not  operate  for  long  periods  of  time  at  a  high  volume 
level or at any level that is uncomfortable. 
Make sure nothing interferes with the ventilation of the product when in use. 
The product should be located away from heat sources such as radiators, heat registers, or other products 
that produce heat. 
The product should be connected to a power supply of the type described in the operating instructions or as 
marked on the product. 
The power supply cord of the product should be unplugged from the outlet when left unused for a long period 
of time. 
Care  should  be  taken  so  that  objects  do  not  fall  and  liquids  are  not  spilled  into  the  enclosure  through 
openings. 
The product should be serviced by qualified personnel when: 

The power supply cord or the plug has been damaged; or 

Objects have fallen, or liquid has been spilled into the product; or 

The product has been exposed to rain or moisture; or 

The product does not appear to operate normally or exhibits marked change in performance; or 

The product has been dropped, or the enclosure damaged. 

10. Do not attempt to service the product. All servicing should be referred to qualified service personnel. 
11.  For  continued  protection  against  the  risk  of  fire,  replace  fuses  only  with  those  of  the  same  type  and 
rating. 

2.2  Warnings used on the amp 

The lightning flash with the arrow head symbol 
within  an  equilateral  triangle  is  intended  to 
alert  the  user  to  the  presence  of  uninsulated 
‘dangerous  voltage’  within  this  product’s 
enclosure  that  may  be  of  sufficient  magnitude 
to constitute a risk of electric shock. 
 
The exclamation point within an equilateral triangle is intended to alert the user to the presence of important 
operating and maintenance (servicing) instructions in the literature accompanying this product. 

2.3  Grounding instructions 

This product must be grounded (earthed). If it should malfunction or break down, grounding provides a path 
of  least  resistance  for  electric  current  to  reduce  the  risk  of  electric  shock.  This  product  is  equipped  with  a 
supply cord having an equipment grounding conductor and a grounding plug. The plug must be plugged into 
an  appropriate  outlet  that  is  properly  installed  and  grounded  in  accordance  with  the  local  codes  and 
ordinances. 
DANGER - Improper connection of the equipment grounding conductor can result in a risk of electric shock. 
Check  with  a  qualified  electrician  or  serviceman  if  you  are  in  doubt  as  to  whether  the  product  is  properly 
grounded. Do not modify the plug provided with the product – if it will not fit the outlet, have a suitable outlet 
fitted. 

2.4  CE mark for European harmonized standards 

The  CE  mark  which  is  attached  to  these  products  means  it  complies  with  the  EMC  Directive  (89/69/EEC), 
CE mark directive (93/68/EEC) and Low Voltage Directive (72/23/EEC). 
 

Summary of Contents for KO750

Page 1: ...PROLUDE AMPLIFICATION KO750 KO750 KO750 KO750 Bass amplifier User s manual ...

Page 2: ...1 2 ...

Page 3: ...IC PRECAUTIONS 2 5 2 2 WARNINGS USED ON THE AMP 2 5 2 3 GROUNDING INSTRUCTIONS 2 5 2 4 CE MARK FOR EUROPEAN HARMONISED STANDARDS 2 5 3 SPECIFICATIONS 3 6 4 INFORMATION FOR INSTALLING 4 7 5 CONTROLS AND FUNCTIONS 5 8 5 1 THE FRONT PANEL 5 8 5 2 REAR PANEL 5 11 5 3 BLOCK DIAGRAM 5 12 5 4 OTHER FUNCTIONS PROTECTIONS 5 12 6 MAINTENANCE CLEANING 6 14 ...

Page 4: ...ape and role within the music have all contributed to my enthusiasm To start with my studies and my sphere of interest have both moved me to the direction of electronics As a result PROLUDE AMPLIFICATION was born at the beginning of the new millennium My goal is to provide bass players with the best possible sound quality Being an electrical engineer I m doing it mainly with a technical mindset Ho...

Page 5: ...l servicing should be referred to qualified service personnel 11 For continued protection against the risk of fire replace fuses only with those of the same type and rating 2 2 Warnings used on the amp The lightning flash with the arrow head symbol within an equilateral triangle is intended to alert the user to the presence of uninsulated dangerous voltage within this product s enclosure that may ...

Page 6: ...aker output connectors Neutrik Speakon Jack combo NLJ2MD H Instrument input connectors Neutrik 6 3mm Jack NMJ4HFD2 Input impedance Passive 500kohms Active 43kohms FX Return 15kohm Active Equalization Low 12dB 40Hz Low Mid 12dB 500Hz Mid 12dB Mid freq 800 3200Hz High 12dB 6kHz shelving type Line out 500mVp 600Ohms Phone 1 5Vp 50Ohms Working temperature range 0 40 C Storage temperature range 25 60 C...

Page 7: ...aker cabinets Use high quality Neutrik SPEAKON SPEAKON speaker cable with at least 2x1 5mm2 or more cross section They are reliable robust and have less influence on the sound Use a speaker cable in good condition and connect the speaker cabinet to the amplifier before you switch on the amplifier Try to minimize the number of power strips used to connect the amplifier to the mains Use high quality...

Page 8: ... will not cause any problem In such a case you get a larger signal level with some drive In some situations this can sound good At this point you have to consider the power handling of your speakers because the overdriven sound strains them more If you set the Gain too low the preamp section will not send enough signal to the power stage and the output power may be not enough and may also detain t...

Page 9: ...Out If the button is pressed the red LED is bright Note This Mute LED gives you additional information too see section 5 1 16 5 1 11 Phone Phone output drives stereo headphones in mono mode Its volume can be controlled by the Gain potentiometer 5 1 12 Foot Sw Footswitch input You can connect a two buttons footswitch here via a stereo jack cable You can activate the Boost channel or Shape function ...

Page 10: ... speakers connected It is normal Important Please avoid switching on and off the amplifier too often especially after playing at high volume level After playing at high volume level give the ventilator a few minutes to cool down the amplifier before switching it off 5 1 15 Mute LED Multifunctional feedback LED Bright when the Mute button is pressed Or if unpressed after switching on during the ven...

Page 11: ...if you have one instead of jack Avoid long speaker cables and low quality plugs in order to maintain sound quality and volume The amplifier can be used without speakers as well Warning There is dangerous voltage on the speaker output Connect the cabinets to the amplifier before switching on and do not touch the hot pole of the speaker jack 5 2 3 Ventilation cutouts Do not cover the ventilation cut...

Page 12: ...ventilator fault or too high environment temperature while playing at high volume overheating may occur In such a case the protection circuit detaches the speaker cabinets until the temperature of the power stage cools down This is being displayed by the Mute LED Input stage Preamp Boost Shape Comp Speaker Prot Volume Control Power Amp Level Det Line Buffer Phone Amp Fan Control Active Passive Act...

Page 13: ...he DIP switch located on the bottom of the amplifier The settings are described in section 5 4 7 if your electronic does not support phantom power you have to disconnect the battery and make a short circuit on the battery clip in the bass Note The phantom power can supply 14 5V and max 6mA You get more headroom compared to the use of one 9V battery before Make sure that your electronic circuit can...

Page 14: ...he amplifier has no need for particular maintenance Occasionally check the starting of the ventilator when you switch on the amplifier Use only soft and dry or dampened cloth for cleaning Avoid aggressive caustic cleaning materials ...

Page 15: ...6 15 Budapest 2014 03 27 ...

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