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neb001  
#1 Posted : Saturday, April 25, 2009 11:56:59 PM(UTC)
neb001

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Posts: 31

Hooked up the CP's today, checked the power supply and it was putting out 12v, jumpered the resistors on the LCBPS and the voltage went up to 14.2v; good enough for now I guess.

There was a horrible hum which I eventually removed by connecting the mains ground. The DAC is currently mounted to a wood plank for testing, which is why it wasn't connected.

Checked the DC offset, I got the following:

Ref'd to ground:
out-: -78mv
out+: -32mv
between out- and out+: 30mv

out-: -88mv
out+: -14mv
between out- and out+: 35mv

I'm not sure what steps I should take to try to fix the offset, any help would be great.

I hooked up the dac to a set of cheap amp/speakers, and it sounds pretty good aside from some faint buzzing.

edit: the buzzing seems to be related to mounting locations and wire routing, will try to reroute some of my wiring.

Edited by user Sunday, April 26, 2009 2:57:17 PM(UTC)  | Reason: Not specified

Russ White  
#2 Posted : Sunday, April 26, 2009 3:11:03 PM(UTC)
Russ White

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If you have that much offset I would recommend you use output caps.

The Humm/buzz definitely sounds like a GND loop or maybe EMI.

Cheers!
Russ
neb001  
#3 Posted : Monday, April 27, 2009 2:56:47 AM(UTC)
neb001

Rank: Advanced Member

Groups: Member
Joined: 7/30/2007(UTC)
Posts: 31

For output caps I simply hook them in series from the terminal block to the wire, correct? I know it's probably obvious, but I just want to double check before I do it.

For grounding wiring, whats the best way you have found to wire the grounds?

Edited by user Monday, April 27, 2009 2:59:50 AM(UTC)  | Reason: Not specified

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