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pedrop  
#1 Posted : Sunday, December 18, 2011 9:08:11 PM(UTC)
pedrop

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Hi Guys,

I just completed build of the Legato 3.1 unit (with buffer) and was able to integrate successfully to the Buffalo II.
It's making music as I'm writing this.

I am only using the balanced output for now as was able to zero out the voltage per the manual.

I tried to zero out the SE output voltage by adjusting VR3 and VR4, but are non-responsive and both voltages at 14 VDC (left and right). Reason that I won't use because I think 14VDC is kinda too high? I would appreciate any advise on this one?

Hint: When I initially powered up the Legato 3.1, I had the IC1(LM4562)backwards. Do you think it might have fried it causing this problem? Thank you.

Pedrod'oh! d'oh! d'oh!
avr300  
#2 Posted : Monday, December 19, 2011 1:52:11 PM(UTC)
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Yes, it might very well be the reason. If you have any other double OPAMP (pin and voltage compatible) you could try swapping.

You could post a picture, both top and bottom side. Also look for solder bridges (less likely since you're having this problem on both channels).
pedrop  
#3 Posted : Tuesday, December 20, 2011 12:07:47 AM(UTC)
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I'll try finding a direct replacement... Thanks avr300. Would NE5532 be ok.?

Pedro

Russ White  
#4 Posted : Tuesday, December 20, 2011 6:06:10 AM(UTC)
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Yes, NE5532 should work just fine.
Russ White  
#5 Posted : Tuesday, December 20, 2011 6:07:32 AM(UTC)
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One thing to consider is that it may not only be the opamp that is dead. It could also be the buffer. In fact it could be an either/or both proposition.
avr300  
#6 Posted : Tuesday, December 20, 2011 11:57:08 AM(UTC)
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Replacing the opamp would be easiest by quite a margin, especially if it's socketed.
pedrop  
#7 Posted : Tuesday, December 20, 2011 5:26:02 PM(UTC)
pedrop

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I have an NE5532 on hand and replaced the LM4562. I was then able to adjust the SE putput voltage to zero.

Is it safe now to hook up to the preamp(rca input)? I'm certainly hoping the buffers are ok. My next question also is, how much am I missing in terms of sonic now that I have the NE5532 in the circuit instead of the LM4562?

Let me hear your thoughts. Thanks.

Russ White  
#8 Posted : Tuesday, December 20, 2011 7:36:54 PM(UTC)
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Its a perfectly fine opamp I doubt there will be any appreciable difference.

If you can get the output to zero then things are likely just fine. :)
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