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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 D750 The Little Brick

Page 1: ...PROLUDE AMPLIFICATION D750 User s manual for the tube preamplifier version ...

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 HARMONIZED 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 10 5 3 BLOCK DIAGRAM 5 11 5 4 OTHER FUNCTIONS PROTECTIONS 5 11 6 MAINTENANCE CLEANING 6 11 ...

Page 4: ... 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 However a...

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: ...r amplifier Class D Speaker output connectors Neutrik Speakon Jack combo NLJ2MD H Input 1 connector front panel Neutrik 6 3 mm Jack NMJ4HFD2 Input 2 connector back panel Neutrik 6 3 mm Jack NMJ6HFD2 Input impedance Input 1 1 Mohm Input 1 with 12dB pad 48 kohm Input 2 57 kohm Preamplifier tube 1 pc 6N2P EV 6Η2Π ΕΒ Line out 500 mVp 600 Ohm Working temperature range 0 40 C Storage temperature range 2...

Page 7: ...er cabinets Use high quality Neutrik SPEAKON SPEAKON speaker cable with at least 2 x 1 5 mm 2 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 quali...

Page 8: ...clock position This setting gives you the most linear transmission of your instrument s sound 5 1 4 Volume Controls the overall volume of the Speaker Outputs The DI Out is not affected by this knob 5 1 5 Mute Mutes the Speaker Outputs and the DI Out If the button is pressed the Mute LED is red Note This Mute LED gives you additional information too see below 5 1 6 DI Out Balanced DI Out with Neutr...

Page 9: ...Lights green when the amplifier is switched on Lights red during the ventilator test when the power stage is overheated or short circuit on Speaker Outputs Lights green but flashing red power section is reached its maximum level the limiter is active ...

Page 10: ...s and Treble controls 5 2 3 Speaker Outputs Neutrik Speakon Jack combo outlets They are connected parallel inside the amplifier Both of speakon or 6 3mm jack plugs are suitable to connect speaker cabinets The minimum load impedance should not be less than 2 66 ohm Note The speakon connector is a more stable robust and reliable solution Use this if you have one instead of jack Avoid long speaker ca...

Page 11: ... high speed when the temperature reaches 50 C and switches itself back to low speed when temperature decrease below 40 C Do not cover the ventilation cutouts 6 Maintenance cleaning The amplifier has no need for particular maintenance Occasionally check the starting of the ventilator when you switch on the amplifier The preamplifier tube is a long life type probably you will never have to replace i...

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