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[Frederik Rosenkjær]

I have 32 channels of Mipro ACT7 wireless which I'm very happy with, but for various reasons (Dante, better software control, streamlined rechargeable battery system etc.) I'm beginning to buy Shure ULX-D with a plan to replace the Mipros eventually. I'm now up to 8 channels of ULX-D, but I'm experiencing a problem:

I would like to find a cheap (/expendable with a minimum of tears) lav mic that I can use on the cheeks of actors, which is what I currently do with Mipro's own omni lav mic (MU55LS) and I'm very happy with this. But all options I've so far tried on the ULX-D have been distorting very ungracefully at higher vocal levels (nothing extreme at all). I've tried the Microphone Madness housebrand omnis, an omni and a cardioid from PointSource Audio (the former of which is supposed to take 148 dB SPL before distorting). Then I found out that my source for the Mipro-mics could easily solder Shure-wired plugs on them, so I've just had 8 of those done - after all this is a mic that has proven to work for me....but it too distorts quite badly on the Shure ULX-D bodypacks....in a way it doesn't do at all on the Mipro packs.

I have two DPA headsets and they're the only ones that do not distort on the ULX-D body packs - so it is possible.

What could be the problem? I'm not overdriving the input of the belt packs - they are quite a bit away from overloading and engaging the input pad does nothing to help the problem. Is the supply voltage too low or something?

Any experiences or suggestions would be appreciated!

[Steve Alves]

Have you adjusted the input on the packs? I have both my mics and packs at -6

[Frederik Rosenkjær]

Yes, the -12dB pad makes no difference (other than the obvious). The pack is not clipping either way, and the DPA mics that do not distort have much higher input into the body pack (yet, do not distort). Something is going on in the mics that does not happen when they're on Mipro packs.

[TJ (Tom) Cornish]

I have 32 channels of Mipro ACT7 wireless which I'm very happy with, but for various reasons (Dante, better software control, streamlined rechargeable battery system etc.) I'm beginning to buy Shure ULX-D with a plan to replace the Mipros eventually. I'm now up to 8 channels of ULX-D, but I'm experiencing a problem:

I would like to find a cheap (/expendable with a minimum of tears) lav mic that I can use on the cheeks of actors, which is what I currently do with Mipro's own omni lav mic (MU55LS) and I'm very happy with this. But all options I've so far tried on the ULX-D have been distorting very ungracefully at higher vocal levels (nothing extreme at all). I've tried the Microphone Madness housebrand omnis, an omni and a cardioid from PointSource Audio (the former of which is supposed to take 148 dB SPL before distorting). Then I found out that my source for the Mipro-mics could easily solder Shure-wired plugs on them, so I've just had 8 of those done - after all this is a mic that has proven to work for me....but it too distorts quite badly on the Shure ULX-D bodypacks....in a way it doesn't do at all on the Mipro packs.

I have two DPA headsets and they're the only ones that do not distort on the ULX-D body packs - so it is possible.

What could be the problem? I'm not overdriving the input of the belt packs - they are quite a bit away from overloading and engaging the input pad does nothing to help the problem. Is the supply voltage too low or something?

Any experiences or suggestions would be appreciated!

Possibly a difference in the bias voltage supplied between the Shure and the MiPro packs?  Brief Googling doesn't give me the bias voltage specs for either the ULX-D or the MiPro.

[Keith Broughton]

This is probably not a mic clipping issue but the output of the mic is clipping the input to the pack.
I had a similar problem with Rode headset mics on Sennheiser EW300 packs. Couldn't pad the inputs down enough to stop clipping on singers.
Turns out, some of the mics were the first generation and the newer mics were designed with less output.
The new mics worked perfectly. (Rode replaced the old ones at no charge)
Seems to me that the Sennhieser mics come with different outputs as well.

[Jens Palm Bacher]

Are you sure the plugs are wired correctly?

[Scott Helmke]

Are you sure the plugs are wired correctly?

That would be my guess too. Same connector is not a guarantee of same pinout.

[Steve Anderson]

I know you're talking about different mics, this is for a MiPro MU23, which is a headset. But if it's the same sensitivity and needs the same bias then this could work.
Can't remember where I found the info though, but it seemed to work and I heard no complaints about distortion etc

** didn't mean to revive old thread, but it didn't seem to be resolved publicly **

[Frederik Rosenkjær]

I know you're talking about different mics, this is for a MiPro MU23, which is a headset. But if it's the same sensitivity and needs the same bias then this could work.
Can't remember where I found the info though, but it seemed to work and I heard no complaints about distortion etc

** didn't mean to revive old thread, but it didn't seem to be resolved publicly **

Thanks, Steve!

I have not resolved the issue yet, no - so it's great to get some suggestions.
I'll try that out first chance I get (probably in 2017 or something...

[Hayden J. Nebus]

That would be my guess too. Same connector is not a guarantee of same pinout.

^-This.

Signal overload is highly improbable.

Maximum Input Level
1 kHz at 1% THD
Pad Off 8.5 dBV (7.5 Vpp)
Pad On 20.5 dBV (30 Vpp)

[Frederik Rosenkjær]

Finally got around to trying out various solutions. First, I tried wiring it as suggested by the schematic posted by Steve Anderson (thanks again!). Unfortunately it made no sound at all in that configuration, so apparently the pinout is different on that headset, oddly enough.

I then tried the approach outlined in the DPA adaptor schematic from Jens (thanks for that), and this works quite well! I ended up connecting both the white and red wire from the mic to the "hot" wire and the shield to pin 1 as suggested, and now the mic handles higher SPL and clips much more gracefully - the harsh distortion they had before when overloading is gone. Also the signal is much hotter, so now I have to engage the PAD on the transmitter, but then it's fine. I'm not sure if the mics are handling exactly the same SPL as they do on a MiPro beltpack, but it's at least close if not identical.

Incidentally, I measured the Shure bodypacks providing 5.2V of bias and the MiPros give 5.9V, so that's pretty close.

Thanks to all who chimed in! The problem is pretty much solved now.

[ProSoundWeb Community]