Warranty
Knoll Systems warrants MA1250 amplifiers sold in the USA and Canada by
authorized Knoll dealers to be free of defects in materials and workmanship. This
warranty extends for three full years from the date of purchase by the original
consumer. Any products returned to Knoll Systems and found to be defective by
Knoll Systems within the warranty period will be repaired or replaced at Knoll
Systems decision, at no charge. Knoll Systems will not be responsible for the
actual cost of installation or removal of the product, nor for any incidental or
consequential damages. Some states do not allow the exclusion or limitation of
incidental or consequential damages, so the above limitation may not apply to
you. This warranty gives you specific legal rights. You may have additional legal
rights that vary from state to state.
4K and 6K Amplifier
8 and 12 Channel Amplifier
Installation Instructions v1.3
Warning: To be installed and/or used in accordance with appropriate
electrical codes and regulations.
Description: The 4K and 6K are members of the long line of Knoll
multi-channel amplifiers. Designed primarily for the custom install
industry, they are used to power speakers with different or similar
sources in multiple rooms. With 8 or 12 channels rated at 50 watts per
channels at 8 ohms, these amplifiers pack some serious punch. Each
channel has a gain control. The amplifier can be turned on and off via
the front panel power switch or via the 12 VDC trigger. 4K channels 3-8
can be linked to channel 1-2 individually using the link switches. 6K
channels 3-12 can be linked to channel 1-2 individually using the link
switches. 4K and 6K amplifiers designed to meet the amplifier needs of
custom installed systems where high-quality sound is a specific
requirement.
Specifications: 4K (eight channel)/6K (twelve channel)
Inputs
8/12 Gold RCA jacks with adjustable gain
50k ohms
Input impedance
Outputs
Gold 5 way binding posts
Output power
Peak output power
Ideal impedance
Frequency response
S/N ratio
50 watts RMS per channel (8 ohms)
100 watts per channel (8 ohms)
4 - 8 ohms
10 Hz - 40 kHz +/- 1dB (1w)
over 105 dB A weighted (50 watts)
less than 0.1% 20 Hz to 20 kHz
less than 0.01% 60 Hz 7 kHz 4:1 (SMPTE)
12 VDC 35mA on 3.5mm mono jack
17" x 3.5" x 11.5" (432 x 89 x 292mm)
quiet 26 dBA
Key Features:
1. Size efficiency. The 4K has eight power amplifiers and the
6K has twelve power amplifiers each in one 3-1/2” high
enclosure. Each power amplifier channel can deliver 50 watts
RMS into an 8-ohm load.
2. Automatic protection circuitry. Each amplifier channel is
individually and fully protected against low impedance,
overheating, overloading, overvoltage and undervoltage. The
protection circuitry automatically restores the amplifier channel
as soon as its parameter returns to the safe operating area.
3. Individual input gain adjustment. Each channel features
an rear chassis input gain adjustment pot to adjust each channel
for gain and speaker sensitivity variations.
THD distortion
IMD distortion
Trigger control
Dimensions
Fan Noise
Power
550/750 watts at 117 VAC or 230 VAC
21 lbs (9.5 kg)
Weight
Note: Specifications subject to change without notice.
4. External power on/off. The 4K and 6K can be turned off
and on by external controllers using the 12 VDC trigger jack.
5. Stackable 17" chassis with 19” EIA rack version option.
6. Link Feature. Certain installations require that some or all of
the stereo channels play the same content. Instead of using Y
cords, "link" cascades any or all of channels 2-6 to channel 1
(l/r) on model 6K. With 4K link channels 2-4 to channel 1 (l/r).
Knoll Systems
145 Tyee Drive Point Roberts, WA 98281
12140 Horseshoe Way, Richmond, BC V7A 4V5
Tel: (604) 272 4555, fax (604) 272 5595
Made in Canada
Knoll Systems service information
The 4K and 6K amplifiers do not contain any user serviceable parts
inside. If you suspect a problem that may require servicing, contact us
Installation
Installing the 4K or 6K should be relatively easy. With a bit of
planning, the 4K or 6K will give trouble free service for years.
1. The most important consideration when installing the
4K or 6K is cooling. The 4K or 6K 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 4K or
6K, 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
Power LED does
Action
2. Amplifiers should always be the top components in system.
1. Check that the amp is plugged in.
not light - no sound 2. Test the AC outlet with a lamp.
3. If remote on/off is used, check that
3. If 4K or 6K channels frequently shutdown due to overheating,
install a fan directed up from the amplifier bottom center.
the trigger voltage is at 12 VDC.
4. Check 4K or 6K power button is on (in).
4. Never operate the amplifier 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.
2. Check if the amp feels hot. If it's
hot increase cooling - see Installation.
5. Connect the 4K or 6K inputs to the source component outputs
with good quality, short as possible RCA jack cables. Connect
each channel individually.
Sound is distorted
1. Turn the volume down.
6. Connect the 4K or 6K 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.
4K or 6K gain and source output level
may have to be adjusted.
Note: Ideally the 4K or 6K likes 6-8 ohm loads. Connecting
to 4 ohm loads won't hurt the 4K or 6K but those channels
connected to 4 ohm loads may occasionally shutdown due
to overloading. Never connect the 4K or 6K to less than 4
ohms.
4. Speakers may be less than 4 ohms.
MA1250 does
not turn off
1. Push 4K or 6K power switch off (out)
2. If trigger is being used, power switch
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
work
1. Measure trigger voltage with a volt
meter. It needs to be 11-15 volts DC
to work (current is about 35mA total
per amp). See page 5 for details.
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.
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.
10. Connect the AC power into an outlet that supplies at least
six amps (750 watts) dedicated to each 6k (four amps to 4K).
Caution: Never listen to sound that is distorted. If distorted
sound is heard, turn the volume down immediately or speaker
and/or amplifier damage could occur that is not covered by the
warranty. If this problem persists, contact your dealer.
The trigger is 12 VDC (35mA per 4K or 6K) via 3.5mm
mono jack. 5 VDC trigger outputs will not work. To
connect the trigger to a receiver use a 12 VDC power
supply (we suggest Knoll PS1202 power supply with an
adaptor). Plug the power supply into the switched outlet
on the rear of the receiver. Connect the 12 volt wire to a
3.5mm mono jack. Plug the jack into the rear of the 4K or
6K. 12 VDC polarity is not important. Make sure the
amplifier power switch is off (out). When the receiver is
switched on, the 4K or 6K amplifier is switched on.
User adjustments and service: Other than a gain or volume
adjustment, there are no user adjustments on the 4K or 6K.
Your installer may make certain gain level adjustments on the
rear panel.
Caution: The 4K or 6K contain no user serviceable parts, so do
not attempt to open or repair the 4K or 6K. Refer servicing to a
qualified technician only or contact the factory for information.
12 VDC
Trigger
Output
Output
Output
L+
L-
L-
L+
L+
L-
L-
L+
L+
L-
L-
L+
Input
1
Input
3
Input
5
2
4
6
L
L
L
2
1
5
6
3
4
R
R
R
120 VAC
8 Amps
R+
R-
R-
R+
R+
R-
R-
R+
R+
R-
R-
R+
1L 1R 2L 2R
3L 3R 4L 4R
5L 5R 6L 6R
Gain
Gain
Gain
6K Amplifier
Caution: NEVER connect the 4K or
6K to impedances less than 4
ohms or amplifier damage not
covered by the warranty may
occur.
The Link button is normally set to the in
position to give all six stereo inputs individual
sources. When the Link button is set to the
out position, that input Left/Right is linked or
cascaded to input #1 (without the use of Y cords). Any or
all combination of linked inputs 2 to inputs 6 are possible.
When all inputs are linked to input 1 the input impedance
is about 4000 ohms.
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