mcasen wrote:

It seems like the issue is that the input on the mixer is shorting the ring to ground

That’s exactly what I thought as well! So I’ve now dug into the mixer, and careful  inspection shows there’s no contact to the ring. It’s leaving the ring floating that is causing the degradation in sound.

I was able to verify this with the following experiment:

1. Take TRS out of the H9000 (it doesn’t matter which one. I verified from the analog DB25 and XLR outs)
2. Run that into a breakout adapter.
3. We now have a black TS plug with V+ on its tip and common ground on its sleeve, and a red TS plug with V- on its tip and common ground on its sleeve.
4. Plugging the black TS plug into pretty much any jack yields a thin phasey sound — so long as the red is left untouched.
5. The moment I ground the ring by connecting the red plug’s tip to its sleeve with some wire, everything returns to normal and sounds glorious. The moment I break that connection (leaving the ring floating), the phasey sound returns.

So feels like something about the way balanced signals are implemented in the H9000: either both V+ and V- must be loaded, or V- must be grounded out. Leaving V- to float causes a noticeable degradation in sound.

Maybe this is a problem with my unit? [Actually, after running the same test with my Omnipressors 2830Au, I’m seeing the same thing. So I’m guessing this is expected behavior? Thought with them it’s a way easier fix because their outs are TRS jacks. So plugging a TS cable into one grounds the ring automatically.] But the problem is I don’t think a DB25->TS cable will fix this as it will leave all the rings floating, not grounded. So throwing 8 couplers + TS patches onto the nest behind my rack seems like the fix. Not ideal, but what can you do.

But this isn’t how any other balanced gear (differential or otherwise) I’ve used has worked. It caught me pretty off guard and I imagine there’s some decent number of people who’ve (knowingly or not) run H9000 outs into unbalanced ins and thought “This thing is trash!” not knowing what they were missing. So might be worth some investigation and a callout in the manual?

Many thanks!