Dull/muddy output on J99 with 990c's

[codeman015]

I'm getting a dull/muddy output on my J99 with 990c's. It is knowhere near as bright as the other J99 I built. I've double checked all of the components. Could it be the opamps? Or something else? Any thoughts? Thanks!

[codeman015]

A little update. I tried the 797's and they do sound better, and like the other J99 I recorded with 797's. So I guess it's either the 990c's or the C8/C9 caps? Anyone?

[craigmorris74]

From my experience, the 990c's are rather easy to blow during the installation testing phase. Once you've got them installed, they're fine, but I've blown a couple just trying to make a pre work. This could of course be attributed to my shaky hand causing a short.

[tpryan]

Try testing each JH990C in U1 without anything installed at U2. With the regulators adjusted for +/-18V to +/-24V and the input at CONN1 shorted, what DC voltage do you measure at U1, pin 6? Let us know what you find.