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input RC

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Hi everyone:

I've had to take a very long extended break, but now am ready to try to finish up some work on my Chipamp LM3886 dual mono project.

Question: What are the components at the beginning of the circuit? IT was marked as a Zobel network, but IIRC, Allan from (the now defunct) Chipamp.com said it was an input RC filter. Is that correct? Is it a LP filter? HP filter? Does anyone know?


Thanks
 
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Joined 2011
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Thanks. The cap, Cz appears to be a Vishay 100nF 63V. I'm guessing (no knowledge at all of electronics) that this is a "small" value?

I have almost no knowledge/experience with electronics, so I'm having a hard time being sure of the resistor (Rz) colours. It looks to me like Orange Violet Gold Gold. When I tested it on two diff. boards with a DMM, it measured 2.8 ohms. As for ground, the two components were never added to the Chipamp.com schematic. And I don't know how to tell just by looking at the PCBs.

Can anyone confirm these values?

Is that a LP or HP filter? (I don't know what high or low values would be, due to my lack of knowledge).

Thanks
 
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Is this the resistor you're talking about? It's a 2.7 Ω. 1 W or 2 W type (should really be at least 2 W).

That's on the output. It's part of the Zobel network.

Tom
 

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Yeah, no schematic. I was told by Allan @ Chipamp that in spite of the designation "z" for Zobel, neither of these components constituted a Zobel network, that they were an input RC filter, but my knowledge level is zero. Can anyone else be sure?

It seems Allan has given you bad information. those two components (Rz and Cz) are a Zobel on the output.
Those chipamp boards do not have a spot for an input RC filter. However, you could substitute a capacitor for R1 and form one. The lead spacing might be an issue though.

The miniDSP units have an output capacitor anyways, so you would not need this RC input filter for DC blocking. But, I assume you know that.

Dave.
 
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