how do i get OPA134/lm6171 to replace a TL071 in trident?

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leigh
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Post by leigh » Wed Apr 24, 2013 12:33 pm

Jim Williams wrote:Got scope?

You'll need one.

The LM6171 as mentioned in the original post is a 100 mhz part. When stable it sounds good but is a bit noisy.
Ah, sorry Jim, didn't catch that the 100MHz figure was a reference to the IC named in the original post.

I do in fact have a scope. Would I see these types of troublesome oscillations while the board is in an "idle" state, or would I have to send some clicks/impulses into the board to really find trouble spots (to see if circuits are ringing unreasonably long after an impulse)?

The master strip and 4 of the channels on this Trident 65 were reportedly upgraded by you, by the way. That was at least 2 owners ago, and I don't have any paperwork to prove it, but that's what I was told.

cheers,
Leigh

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Post by Jim Williams » Wed Apr 24, 2013 9:01 pm

First check without signal, rotate the pots. Then feed a sine wave and rotate all the pots. It should remain clean. OPA1641's are a good choice, easy to tame.
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leigh
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Post by leigh » Thu Apr 25, 2013 10:50 am

Jim Williams wrote:First check without signal, rotate the pots. Then feed a sine wave and rotate all the pots. It should remain clean. OPA1641's are a good choice, easy to tame.
OK, I'll give that a whirl with the scope.

The OPA1641 looks like it has nice specs, but it's not available in a DIP package (surface mount only). So that would add a de-soldering (to take out the old DIP IC socket), an adapter, plus a surface-mount soldering job to each IC replacement. Repeat x100 or more, and that doesn't make for an attractive option for the Trident.

Do you no longer favor the LT1357?

Leigh

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Post by Jim Williams » Fri Apr 26, 2013 8:06 am

The BB part is lower noise, fet input (no bias current to deal with) and low current draw, same as an TL071 opamp. It's also a rail to rail device that will output more voltage increasing headroom without increasing supply voltage.

Yes, SOIC only, but so are most of the newer parts. Brown Dog sells adaptors for about $2.50 each, less in quantities.

If you want to go DIP package, the LME49710 is an excellent part under a buck each. Both are precision devices so you may be able to replace the electrolytic coupling capacitors with a wire.
Jim Williams
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