[Seth Diamond]

I’m tentatively optimistic here! With a test of effectively disconnecting Pin 1 (by jumping the Pin 2 and Pin 3 pairs respectively — but not Pin 1) between the MZA14 and the SKP100, I think I created a ground lift – which has quieted things down. As the mic works, the +48 phantom power is in fact being passed through.

Would a solution of using a transformer instead of a ground lift do the same thing here? Would that be a quieter solution than a ground lift?

Assuming I just go pick up a ground lift (as a permanent solution to the first problem here), I now need to get rid of the rest of the hiss and FM signals that I’m picking up. Any thoughts? What’s the next step?

[Seth Diamond]

Thanks for the updates so far, everyone! I’ve been away for the past week and away from my gear; I’ll do some more testing now that I’m back. Here’s the update:

@Richard Crowley – Yes. It’s a Sennheiser EK100 G3 receiver, and an SKP100 G3 transmitter. The AF OUT line-level is what I meant. Thanks for the positive support! I have definitely played with the sensitivity settings/preamp on the FS7/squelch settings/different cables. The MD46 is a dynamic (and unpowered) mic, so it didn’t need an XLR cable there. I’m getting plenty of signal, so it seems like it’s a high noise floor issue. More on all this in a bit.

@BruceWatson – Thank you so much for both your replies here and on Gearslutz, Bruce! I really appreciate it. Per the hiss, this definitely seems to be some sort of an RF thing going on here instead of mismatched levels; read below to see what I mean. (Meanwhile, there’s no argument from me about getting the levels right – but something is definitely causing ridiculous noise where the hiss is as loud as the mic input – not something more subtle like background hiss from inexpensive preamps.) Trust me – I’d Love (with a capital L) an SD MixPre-D if I could snag one at about $350 on eBay, but unfortunately it’s not an option right now. I spent my next-to-bottom dollar to get my hands on a used AT4053b (rare as hen’s teeth as used) and was lucky to get my hands on the MZA14 for stupidly cheap when I realized that my SKP100 didn’t provide +48V phantom power. It’s on my wish-list, to be sure!

@RobNeidig – Sorry for not being clear. The mics go into the SKP 100 (not a EW100 transmitter), but it transmits to the EW100 receiver. Sorry about the confusion. Please see what I wrote above per Bruce.

*********************

Here’s an update after a bunch of testing this afternoon, which will hopefully help rule things out. It looks like I have two separate problems here:

(1) RF SPRAY FROM THE SKP100 TRANSMITTER?: Check out the following picture of my setup. When I hold the SKP100 just like this, with my three fingers fully wrapped around the XLR connection and with the palm around the body of the SKP100 transmitter, almost all the noise goes away. Can I put something in there (ferrite RF chokes?) to shut down what may be RF Spray?

I’ve pulled the mics themselves out of the equation; the noise happens regardless of whether a mic is connected to the chain. Stripped down, it happens when the MZA14 is directly connected to the SKP100.

(2) FM RADIO INTERFERENCE: Once I hold the grip that way, most of the noise is gone. But in certain circumstances I’m now picking up variably slight broadcast radio noise. What’s weird is that I am in fact picking up FM (not AM) signals. At its worst, the sound is a couple of FM stations playing all at once. The clearest of the radio station signals is WBMX 104.1 FM, which is a powerful FM radio station (21,000 watts) broadcasting from the Prudential Tower exactly two miles away.

By the way, as far as cable quality goes, I’m planning to return the brand new 8” one (shiny cable ends) to Amazon — but neither cable seems to do anything to significantly solve the main hiss problem. I think the coiled black cable (Pearstone, with Neutrik ends) picks up less of the lower FM signal, but there’s higher handling noise when the coil moves around – so I’ll likely have to replace both cables for this application.

Thanks again in advance!