Knoll Systems MR1250F Manuale Utente

 

Installing the 

MR1250f

 should be relatively easy. With a bit of 

planning, the 

MR1250f

 will give trouble free service for years. 

The MR1250f amplifier does not contain any user serviceable parts 

inside. If you suspect a problem that may require servicing, contact us 

at www.knollsystems.com/contact.html, or by phone at 800 566-5579.  

 

 

1. The most important consideration when installing the 
MR1250f is cooling. The 

MR1250f

 has a lot of power packed 

into a small chassis size. When installing it in an equipment 

stack, it should be the top component. It needs at least 3"-5" of 
space above the amplifier to allow for adequate convection 

cooling.  

Troubleshooting 
If a problem is encountered with the 

MR1250f

, the most 

expedient procedure is to locate the problem and if possible 
repair it before requesting service. Be sure to carefully check 

other system components such as controllers, CD players, 
volume controls, wiring, speakers, etc. that may be at fault. 

Problem   Action 

2. Amplifiers should always be the top components in system.  

Power LED does  

1. Check that the 

MR1250f

 is plugged in.  

not light - no sound  2. Test the AC outlet with a lamp. 

3. If 

MR1250f

 channels frequently shutdown due to overheating, 

install a fan directed up from the 

MR1250f

 bottom center.  

 

 

 

3. If remote on/off is used, check that  

 

 

 

    the trigger voltage is at 12 VDC. 

 

 

 

4. Check 

MR1250f

 power button on (in). 

4. Never operate the 

MR1250f

 on its side, as the cooling potential 

drops significantly when operated on the side. 

 

Sound cuts out 

1. Verify speaker impedance is 4-16 ohms. 

 

 

 

    Changing speakers may be required. 

 
5. Connect the 

MR1250f

 inputs to the source component outputs 

with good quality, short as possible RCA jack cables. Connect 
each channel individually.  

   2. 

Check 

if 

the 

MR1250f

 feels hot. If it's  

 

 

 

    hot increase cooling - see Installation. 

 

Sound is distorted 

1. Turn the volume down. 

6. Connect the 

MR1250f

 speaker outputs to speakers using good 

quality speaker wire. Minimum 16 gauge copper wire is 

recommended with 14 gauge minimum for runs over 30' (10m). 

 

 

 

2. Check speakers for damage. 

 

 

 

3. Check inputs for proper levels. 

 

 

 

    

MR1250f

 gain and source output level 

  

 

 

    may have to be adjusted. 

    Note: Ideally the 

MR1250f

 likes 6-8 ohm loads. Connecting 

 

 

 

4. Speakers may be less than 4 ohms. 

    to 4 ohm loads won't hurt the 

MR1250f

 but those channels 

 

    connected to 4 ohm loads may occasionally shutdown due 

MA1250 does  

1. Push 

MR1250f

 power switch off (out)  

    to overloading. Never connect the 

MR1250f

 to less than 4 

not turn off    

2. If trigger is being used, power switch 

    ohms. 

  

 

 

    needs to be set to off (out) position  

 

 

 

 

    or amp is on all the time. 

7. Individually adjust the channel gains as required. Ideally, all 

gains are fully on (fully clockwise). 

 

 

 

3. Try disconnecting trigger jack. 

 

Trigger does not 

1. Measure trigger voltage with a volt 

8. Make sure the speakers in each room are connected in phase 
with the amplifier + going to the speaker + . Out of phase 

speakers give unstable imaging and poor bass response.                        

work   

 

    meter. It needs to be 11-15 volts DC  

 

 

 

    to work (current is about 35mA total 

  

 

 

    per amp). See page 5 for details.  

9. Connect trigger if being used to a 12 VDC source (about 
35mA) using a 3.5mm mono jack. 5 VDC triggers will not work. 
 

 
Speaker pops when  1. Speaker may need resistor placed 
amp turned on or off     across terminal. Suggest 2k0 1/4 w. 
 

 

 

      Discharges speaker internal cap.