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Noisy CTS-2000/USP-3/CN


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#1 jljohnson

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Posted 22 August 2006 - 04:35 PM

I have a system that will have 20 CTS-2000's with USP-3/CN's.  I an using a soundweb london as my analog input point and HP switches for the network duties.  I plugged in 1 of the amps and the soundweb today and found a lot of noise on the output of the amp.    If I unplugged the cobranet connector from the amp it would go away.  If I unplugged the cobranet from the london it would go away.  If I turn down the analog pots on the back of the amp it goes away.  If I Mute the outputs in IQwic it DOES NOT go away.  So to me it seems that there is junk getting into the analog signal chain between the USP-3 card and the amp??  and it is triggered by connection of the network to the card.  Is this possible?? if so how do I get rid of the noise.  It sounds like digital hash.  I would hate to have all 20 of these doing this...Jim...

#2 DGlass

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Posted 22 August 2006 - 04:58 PM

Try switching the amp sensitivity to 26 db. This should lower the noise floor.

#3 jljohnson

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Posted 23 August 2006 - 12:06 PM

QUOTE(DGlass @ Aug 22 2006, 04:58 PM)
Try switching the amp sensitivity to 26 db. This should lower the noise floor.
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Thanks David,
Here is an update, I have isolated it down to 2 different issues:
1.  The CTS seems to have a bad channel,  without the usp-3 card in it (a standard FXQ card in it's place)  channel 2 has a distinct noise issue.  (sounds like a leaky cap in the audio chain)
2.  The Buzz or clocknoise that the USP-3 seems to be making.  I moved the USP-3/CN to a CTS-600 and hooked it up. even without anything else connected, there is still a very audible buzz (120hz) in the speaker.  it is the Mid/high of a JBL PD-5322.  Switching the sensitivity did reduce it some but it is still quite plain. we are talking maybe 50db from the speaker (up close at 3 feet maybe).  I would guess its about 30 db up from the Hiss of the amplifier.  Of course the other 19 amps like this are already at the jobsite 300 miles away so i don't have anything to compare it with.  

it just seems that looking at the specs of the amps and cards the noise level his higher than it should be.  Any other ideas???
...Jim...