Soundcraft ui24 and Sennheiser EW300 IEM Lots of Hiss

[ozone7]

Hi. First post here I hope you guys and gals can help.

I've got a couple of Sennheiser EW300 transmitters to run wireless IEM and a Soundcraft ui24 mixer.
I'm running the mixer aux outputs linked stereo for a number of foldback pairs, two of which go to the Sennheisers.

The problem I'm having is with massive white noise in the IEM.

At the moment I'm checking backing tracks into the mixer from Laptop via EVO8 interface. For the gigs we will replace all the instruments except the keys with live playing (Axe FX, Bass Pre, Roland TD17 and OH mic plus two vocals). But at the moment it's pretty much all from the laptop.

I'm assuming this is a gain structure problem, and I'd really be grateful for some help.

I was always of the school that what comes into a mixer should be a healthy level to prevent pushing noisy mic/line amps.

So my EVO8 is pretty much at max. If I plug my IEM headphones into the EVO8 hp op (and turn it down to around 11 o'clock) there's decent level and no appreciable noise.

If I plug the IEM cans into the EE300 hp output (with EVO 8 back up at full), I get some hiss, but not enough to be a problem.

But the moment I turn on the receiver with the IEM connected, the hiss is unbearable. over ear cans have much less hiss, if connected to the wireless receiver.

I do live right under a powerful radio transmitter which can PUSH RFI onto any amplified signal so I kind of wonder if that might be a factor. Changing the wireless frequency seems to have no effect.

Turning IEM pack levels up almost full doesn't affect the noise floor until right at the end. Tried adjusting the EW300 sensitivity with no useful outcome.

So I'm stumped. If you could steer me in the right direction that would be so appreciated!

 

[ozone7]

Hi. First post here I hope you guys and gals can help.

I've got a couple of Sennheiser EW300 transmitters to run wireless IEM and a Soundcraft ui24 mixer.
I'm running the mixer aux outputs linked stereo for a number of foldback pairs, two of which go to the Sennheisers.

The problem I'm having is with massive white noise in the IEM.

At the moment I'm checking backing tracks into the mixer from Laptop via EVO8 interface. For the gigs we will replace all the instruments except the keys with live playing (Axe FX, Bass Pre, Roland TD17 and OH mic plus two vocals). But at the moment it's pretty much all from the laptop.

I'm assuming this is a gain structure problem, and I'd really be grateful for some help.

I was always of the school that what comes into a mixer should be a healthy level to prevent pushing noisy mic/line amps.

So my EVO8 is pretty much at max. If I plug my IEM headphones into the EVO8 hp op (and turn it down to around 11 o'clock) there's decent level and no appreciable noise.

If I plug the IEM cans into the EE300 hp output (with EVO 8 back up at full), I get some hiss, but not enough to be a problem.

But the moment I turn on the receiver with the IEM connected, the hiss is unbearable. over ear cans have much less hiss, if connected to the wireless receiver.

I do live right under a powerful radio transmitter which can PUSH RFI onto any amplified signal so I kind of wonder if that might be a factor. Changing the wireless frequency seems to have no effect.

Turning IEM pack levels up almost full doesn't affect the noise floor until right at the end. Tried adjusting the EW300 sensitivity with no useful outcome.

So I'm stumped. If you could steer me in the right direction that would be so appreciated!

Just to add a relevant note: If I unplug the XLR inputs from the back of the EW300s, the noise is unaffected. So I guess (although I probably could still look at gain structure later), this is an issue with the two EW300 units and how they work with my IEM.

Anybody else had issues?

Thanks!

 

[Mike Caldwell]

What do you have the level set at in the IEM transmitter?
What mode are you operating them in?
If you turn off the transmitter do you still have the noise at the receiver pack?

I have older EW300's and use them for IEM's as well as wireless audio links without noise issues.

 

[ozone7]

What do you have the level set at in the IEM transmitter?
What mode are you operating them in?
If you turn off the transmitter do you still have the noise at the receiver pack?

I have older EW300's and use them for IEM's as well as wireless audio links without noise issues.

I’ve got them in stereo mode with pilot on. Did one more test last night and turned off the rig completely.

Still getting hiss with just the receiver. And with the volume at lowest setting. Squelch adjustment does nothing, as I’d expect.

The thump on power on is a bit uncomfortable.

So I’d say this is definitely exacerbated by IEM with a low impedance. Will check the specs but they’re ultimate ear UE7’s.

At least I can take a receiver and the in-ears out of the house easily and check if it’s atmospheric RFI.

 

[Mike Caldwell]

As for the noise when using the IEM system run the level at the transmitter fairly high.

 

[s0c9]

Senn wireless IEM has always had a noise floor, but generally manageable to where its only noticeable when nothing is going thru it.
Both my prior Senn IEM systems did - I'm now using Mipro, but NOT because of Senn noise
One has to "gain stage" IEM's as with any other signal chain.

• Too much output to the xmitter.. noise.
• Too little output and xmitter and receiver gains increase - noise.
• Too much gain on transmitter and not enough signal from mixer - noise!
• And so on, as there are other "noise" combinations.

It's important to do the gain staging in advance to minimize the noise floor (hiss).

 

[kittywithabanjo]

I like to carry a few Behringer P1 and P2 packs, this would be another quick way to check where the noise was, as it would eliminate the UI24R

 

[s0c9]

I like to carry a few Behringer P1 and P2 packs, this would be another quick way to check where the noise was, as it would eliminate the UI24R

We carry a couple of P2's.. They work great for the $$

 

[ozone7]

Thanks. It’s not the Ui24.

The UE7 IEM are super sensitive and the raised noise floor is present even with no transmitter power to the Sennheiser receiver pack.

I ruled out RFI with a field trip out of range of the local transmitter tower. No change.

So as of yesterday I’ve lowered the output of the receiver with an iFi IEMatch+.
Tried this approach with a couple of cheap in line volume adjustment cables but the HF roll off was unacceptable, as I suspected it would be.

Now I have much more usable travel on the Sennheiser volume and the hiss is reduced to significantly more reasonable levels.

Next step will be checking the different IEM of the two musicians who are also going to be on the Sennheisers. Might be lucky. Might not.

Appreciate the help.

 

[s0c9]

The UE7 IEM are super sensitive and the raised noise floor is present even with no transmitter power to the Sennheiser receiver pack.

Are you saying that you had hiss in the UE7's when connected to the [I'm assuming powered up] receiver, even with nothing being transmitted from the Senn base unit?
If so, adjust the receiver "squelch" setting to minimize the noise!