HK Audio CTA 208 Mid/High - Manual (Page 19)

19
E. Service
Regularly check the vents to ensure air flows freely
in and out. Clean the foam rubber filters whenever
necessary. Remove the vent grille on the back to do
this.
2. ConTour Array™
Spare Parts
Note:
• If your equipment needs service, please turn
to your HK AUDIO dealer or the HK AUDIO
distributor in your country. They stock the
required spare parts.
• In the event of a defect, always indicate the
defective device’s serial number. This way the
HK AUDIO service team can immediately find out
if an update is available for your product.
• Use only original HK AUDIO replacement speakers
and parts! Most were developed especially for HK
AUDIO products and are not available direct from
speaker manufacturers!
3. Replacing Loudspeakers
and Voice Coils
3.1 1", 8" and 18" Speakers
Proceed as follows to replace the given speaker:
• Unfasten and remove the Phillips screws holding
the grille in place. Remove the grille. These screws
are on the CT 118 Sub’s front panel and the
CTA 208’s side and bottom panels.
• Unfasten and remove the hex head bolts holding
the speaker in place.
• The speaker is now detached. Disconnect the
speaker wires.
Caution: When installing and connecting a
replacement speaker, ensure the polarity is correct!
Red= positive, black = negative
1. Maintenance
3.2 The Drivers’ Voice Coils
Proceed as follows to replace the drivers’ voice coils:
• Remove the front grille as described above.
• Unfasten the four screws holding the horn yoke
and remove the horn and driver from the baffle.
Disconnect the wires connecting the driver. Ensure
correct polarity when installing and connecting
a replacement speaker! Red= positive, black =
negative
• Unfasten the voice coil housing’s hex head bolts
using a 3 mm wrench.
• Take the lid off the voice coil housing.
• Replace the voice coil.
Important note: Replace the voice coil in a clean
working environment only. Be sure to keep dust
and dirt out of the open driver. If despite your
precautions particles manage to get in, use a strip
of adhesive tape to remove them or carefully blow
compressed air into the back of the driver to whisk
the particles out. When installing the new voice
coil, ensure it is centered properly. Proceed as
follows to check this:
Close the cover of the voice coil housing and
reconnect the cords (red = positive, black =
negative). Feed a sine wave signal with a frequency
between 1000 Hz and 1500 Hz into the mid/high
enclosure’s input. Sweep through the frequency.
If you hear abrasive noises like crackling or
scratching, the voice coil is not centered properly.
Reopen the voice coil chassis and turn the voice coil
a bit until it renders the signal cleanly!
4. Checking Speakers’ Phase
As a precaution, always check the components’
phase using a suitable phase-checker after replacing
speakers. To do this, connect the CTA 208 mid/high
unit to the CTA 118 Sub using a Speakon
® cord.
Note: If you are checking the CTA 208 mid/high
unit in passive mode with an external power amp,
you will get a different phase reading! Therefore
always use the CTA 118 Sub for phase checks.
Connect the phase-checker to the CTA 118’s signal
input. It may be advisable to lower the input level on
the DDO-Pro™ Controller!
The speakers’ phases should read as follows:
With CTA 118 Sub:
18" woofer:
In phase (+)
8" speaker: Out of phase (-)
1" driver: In phase (+)
CTA 208 passive:
8" speaker:
In phase (+)
1" driver: Out of phase (-)
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