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[Andrew Roberts]

The Sennheiser IEMs have different intermod products than the Audio-Technica mics.

You really should just download (it's free!) Shure's Wireless Workbench. It's not that hard to use, and can save you a huge amount of RF trouble.

Scott,
I suspect you are probably right about the variant in intermod products across brands causing the problem.  However, I was assuming (perhaps wrongly) that generated harmonics would be the same across brands, determined by the root frequencies, rather than the brand of transmitter.

I used the AT frequency algorithm because the majority of the product being used was from them. I will download WWB but I don't have any shure product. Does it compute for other brand products as well?   

[Bob Charest]

Scott,
I suspect you are probably right about the variant in intermod products across brands causing the problem.  However, I was assuming (perhaps wrongly) that generated harmonics would be the same across brands, determined by the root frequencies, rather than the brand of transmitter.

I used the AT frequency algorithm because the majority of the product being used was from them. I will download WWB but I don't have any shure product. Does it compute for other brand products as well?

I use IAS from Professional Wireless Systems. It has a number of model numbers from various manufacturers. I've gotten great results with it, though I seldom have to coordinate devices other than my Sennheiser IEMs and mics.


Sent from my iPhone using Tapatalk

[Erik Jerde]

Does it compute for other brand products as well?

Yes.  If a product isn't listed you can create a custom entry if you have all the necessary information.

[brian maddox]

Scott,
I suspect you are probably right about the variant in intermod products across brands causing the problem.  However, I was assuming (perhaps wrongly) that generated harmonics would be the same across brands, determined by the root frequencies, rather than the brand of transmitter.

I used the AT frequency algorithm because the majority of the product being used was from them. I will download WWB but I don't have any shure product. Does it compute for other brand products as well?

WWB does have presets for most of the major wireless products out there, including the AT 5000 series and the Sennheiser IEMs that you have.

I do find it to be a little bit confusing to learn at first, but it's a fantastic tool.  Worth spending an hour or so finding your way through it.  If you don't have Shure products you do have to ignore a good bit of the program, but the intermod calculation is spot on.  I use it all the time.

[Scott Helmke]

That is AT's frequency compatibility computational software. It definitely maps harmonic interference.

It is the nature of the various manufacturers and devices themselves that they produce different intermod products. IEMs in particular use stereo FM transmission vs. microphones.

I looked at the WWB presets for AT 5000 series and Evolution IEM, and they're different.

[Jim McKeveny]

The Sennheiser IEMs have different intermod products than the Audio-Technica mics.

Thinking mathematically, how could one manufacturers intermod products differ from another's?

It may be that the tolerance-stack of the collective center frequencies are at range limits, skewing intermod calculus. This is where predictive software fails, and a trusted analyzer is helpful. (I miss my TTI).

When talking about unseen/unheard RF, what should be in the environment can be very different from what is in the room.

[Mac Kerr]

Thinking mathematically, how could one manufacturers intermod products differ from another's?

It may be that the tolerance-stack of the collective center frequencies are at range limits, skewing intermod calculus. This is where predictive software fails, and a trusted analyzer is helpful. (I miss my TTI).

When talking about unseen/unheard RF, what should be in the environment can be very different from what is in the room.

Talking about just the specified center frequency there would be no difference, but the transmission is not just that center frequency, it is a narrow band of frequencies, so has as you say, tolerance specs. The frequencies shown that the AT software found all look too close together to me. I would want at least 400KHz between devices, and 1 MHz between mics and IEMs, more is better. Others have pointed out that neither WWB nor IAS accepts those numbers as working together, I would suggest trying other software for better results.

Mac

[Scott Helmke]

Thinking mathematically, how could one manufacturers intermod products differ from another's?

I am not an expert, but...

Typically a transmitter generates a fixed lower frequency, modulates that with the audio signal, then does some RF voodoo to push it up to a tunable frequency in the appropriate range.  Other (outside) frequencies leaking into those different stages is what cause intermod products.  Also mics typically use a 32kHz pilot tone while IEMs typically use a 19.2kHz pilot tone, because of the stereo multiplexing needed for IEMs.

[Lyle Williams]

Your IEM transmitters appear to be at the bottom of the available band.  More frequency separation is always good.

What happens if you turn off particular IEM transmitters?  Does anything change?  If you have access to an RF attenuator, try putting that in from of your receivers.  If the interference falls of faster than the attenuation you are putting in front of the receivers, the receiver chain is probably being overloaded by the nearby transmitter.  If not, the transmitters are probably generating the junk.  My bet is on receiver overload.  Possible solutions, getting rid of excessive preamp gain (if you have a preamp...) maximising MHz separation between TX and RX, and adding low-pass filters to the receiver antenna inputs.

[Lyle Williams]

... there is nothing on earth with better bang-for-buck in isolating interference problems than in-line attenuators.

If you have diversity receivers, you'll probably want two.  Something around 3dB to 6dB.

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