802VLZ4 introducing noise into signal chain

[JordanDoyle]

I've had a decent setup for close to a year now consisting of an SM7B, 286s and a 2i2 and this has worked really well for me. I've recently "upgraded" my setup and bought a 802VLZ4, 131s and a PRO-XL MDX2600.

My signal chain looks like this:

SM7B
↓             → (insert on 802VLZ4)
802VLZ4                   ↓
↓                       286s
2i2                       ↓
                       MDX2600
                          ↓
                         131s

Because the inserts are now mounted in a rack they're ~6 meters away, I decided to gain closer to the mic so I'm not running a low voltage over a "long" run (I've tried gain at the 286s but there is a LOT of noise). I noticed there was a nice big electromagnetic hum when speaking (this is how I figured out it was at the 802VLZ4 - because the 286s was gating out the EM hum whenever I wasn't talking). I took the insert out and there was a lot of buzzing when the Mackie was turned up to 60db gain. Plugging the microphone directly into the 2i2 with gain on full yielded a nice clean signal.

The mixer is connected to the interface using 2 individual TRS cables so I don't have to mess about with any virtual stuff to convert my mono signal to stereo. I'm convinced the noise is not introduced between the mixer and the interface because the noise gets gated out by the channel strip.

Has anyone had this problem with Onyx preamps on Mackie mixers before? Any solutions? This happens on every channel.

I guess now would be the time to invest in a nice preamp... I've wanted to have some sort of tube in my signal chain for a while now to colour my signal. Are there any nice affordable tube preamps (£100-£200? Or is this too low...) that could drive an SM7B out there?

Cheers

 

[arcaxis]

Possibly a couple things going on that are giving the noise.

- Your inserts are unbalanced. It might be that a 6 meter run of unbalanced cables to and from the racked gear is susceptible to picking up hum.
- A ground loop issue between the computer, interface, mixer, and/or rack gear.
- Gain staging of different devices may not be set optimally(?)
- If you plug headphones into the mixer with and without the insert of extra gear how does the mic sound?
- More is less. The more devices you stick in the signal chain, the more likely to have problems.

If you insist on having all that gear, try a different connection...
SM7b > 286s > MDX2600 > 131s > 802VLZ4 (line in) > 2i2 (Use TRS balanced cables from the 286s through to the inputs of the 2i2)

I do have an SM7b and the 286s. Personally I don't see the need to add on the extra gear as you have done, as the 286s by itself does a decent job shaping the sound with its own processing.

So far as a 'tube' preamp/channel strip, take a look a ART Pro Channel , possibly used. I think I've run my SM7b through the one I have.

 

[JordanDoyle]

Possibly a couple things going on that are giving the noise.

- Your inserts are unbalanced. It might be that a 6 meter run of unbalanced cables to and from the racked gear is susceptible to picking up hum.
- A ground loop issue between the computer, interface, mixer, and/or rack gear.
- Gain staging of different devices may not be set optimally(?)
- If you plug headphones into the mixer with and without the insert of extra gear how does the mic sound?
- More is less. The more devices you stick in the signal chain, the more likely to have problems.

If you insist on having all that gear, try a different connection...
SM7b > 286s > MDX2600 > 131s > 802VLZ4 (line in) > 2i2 (Use TRS balanced cables from the 286s through to the inputs of the 2i2)

I do have an SM7b and the 286s. Personally I don't see the need to add on the extra gear as you have done, as the 286s by itself does a decent job shaping the sound with its own processing.

So far as a 'tube' preamp/channel strip, take a look a ART Pro Channel , possibly used. I think I've run my SM7b through the one I have.

Thanks for that mate. I've figured out it's actually the _cable_ running between the microphones and the mixer which is introducing the noise, I wiggled the cable about a bit and found out the noise gets a LOT louder the closer it gets to the CPU (I would've guessed the PSU to be honest but that's not the case...). I didn't have this problem with the Scarlett because the cable doesn't have to run past my computer. The XLR cable is a cheapo cable that came with my cheapo boom arm, the cable flows down the arm itself and isn't replaceable.

I actually figured this out when I knocked the XLR cable while I was unplugging the insert...

Looks like I'm going to have to pick up a new XLR cable!

Cheers