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Issue with CTs 4200 and CTs 1200


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#1 bigkids

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Posted 26 July 2012 - 09:05 PM

Hi,

Please have a look at the attached pic and let me know why we see all these warning lights (RED) appearing.
The sound is low even if the volume controller knob is up. The sound is also "crappy" and screechy. Speakers are JBL Control 25 (5 of them). Source is a DVD player I believe.

PS: Click on picture for full zoom.

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#2 joust

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Posted 27 July 2012 - 04:00 PM

The CTS4200 has a Clip light on: This may indicate two things: either the amp is clipping normally or the amp is limitting (thermal condition). We'll go with the assumption that the signals are appropriate and of program material (NOT SINE GENERATED!). Verify that the loads (min 4 ohms in dual, 8 ohms bridge, distributed) are appropriate for the output (speakers or distributed). Reduce input levels until the Clip condition is removed (cool unit off). Then, bring input levels until you start to have Clip events and reduce levels until no more Clip is seen and bring down the levels a notch.

Same thing for the CTS1200: Hopefully you're not testing with Sine! That doesn't bode well with SMPS supplies. There areoutput  Thermal and Clip events that must limit output current and input signals to the max! Again, start off by reducing input levels and cool off the amp. Then gradually increase levels until Clips events start to appear and reduce levels until no more Clips are seen. Then reduce one notch.

There is a new calibration protocol for the JTS circuit (CTS1200) that seems to have a better thermal tolerance. I would perhaps make an appointment with an authorized Crown service center to have the JTS re-calibrated.

Hope this helps!

#3 bigkids

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Posted 27 July 2012 - 04:57 PM

Source is a DVD player, no volume control for it.

#4 joust

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Posted 02 August 2012 - 11:03 AM

Well, you can use the amplifiers's level controls! :) Or, pass the DVD signal with a small mixer.