Knoll Systems service information
Installation
Installing the MA1250 should be relatively easy. With a bit of
planning, the MA1250 will give trouble free service for years.
The MA1250 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
MA1250 is cooling.
The MA1250 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 MA1250, 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.
2.
Amplifiers should always be the top components in system.
Problem Action
Power LED does
1. Check that the MA1250 is plugged in.
3.
If MA1250 channels frequently shutdown due to overheating,
install a fan directed up from the MA1250 bottom center.
not light - no sound 2. Test the AC outlet with a lamp.
3. If remote on/off is used, check that
the trigger voltage is at 12 VDC.
4.
Never operate the MA1250 on its side, as the cooling
potential drops significantly when operated on the side.
4. Check MA1250 power button on (in).
Sound cuts out
1. Verify speaker impedance is 4-16 ohms.
Changing speakers may be required.
5.
Connect the MA1250 inputs to the source component outputs
with good quality, short as possible RCA jack cables. Connect
each channel individually.
2. Check if the MA1250 feels hot. If it's
hot increase cooling - see
Installation
.
6.
Connect the MA1250 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).
Sound is distorted
1. Turn the volume down.
2. Check speakers for damage.
3. Check inputs for proper levels.
MA1250 gain and source output level
Note:
Ideally the MA1250 likes 6-8 ohm loads. Connecting
may have to be adjusted.
to 4 ohm loads won't hurt the MA1250 but those channels
4. Speakers may be less than 4 ohms.
connected to 4 ohm loads may occasionally shutdown due
to overloading. Never connect the MA1250 to less than 4
MA1250 does
1. Push MA1250 power switch off (out)
ohms.
not turn off
2. If trigger is being used, power switch
needs to be set to off (out) position
7.
Individually adjust the channel gains as required. Ideally, all
gains are fully on (fully clockwise).
or amp is on all the time.
3. Try disconnecting trigger jack.
8.
Make sure the speakers in each room are connected in phase
with the amp going to the s . Out of phase
speakers give unstable imaging and poor bass response.
Trigger does not
1. Measure trigger voltage with a volt
work
meter. It needs to be 11-15 volts
DC
to work (current is about 35mA total
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.
per amp). See page 5 for details.
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.
