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Author Topic: Extending range of Sennheiser EW100 radio mic  (Read 2319 times)

Miguel Dahl

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Re: Extending range of Sennheiser EW100 radio mic
« Reply #10 on: February 05, 2020, 01:20:28 pm »

You want to keep the noise floor as low as possible for best performance especially as the tx/rx distance increases. The goal when adding an active device to the antenna feed is to have a net result of unity gain by matching the amount of active gain to the cable loss.

Try switching an active antenna from 0db or 3db of gain to 10db on a short (10m or less) cable and watch the rf meters on your receivers.
Previously "dark" meters start to show a bit of rf activity. That is the noise floor that you have just raised.
When you get to the fringe areas of reception...your transmit signal may get buried in the higher noise floor.

I'm sure others have a more eloquent explanation.

But.. Still don't get it..bummer. The same signal to noise ratio is still there? As it will boost every incoming signal with the same amount. The only "extra noise" would be from the booster unit itself due to design?

If I use a 10dB booster, then I'd boost "everything" by 10dB, also the Tx signal. But if that signal is crap then it will still be as crap with or without the booster, wouldn't it? One has raised the noise floor, but the Tx signal will be equally stronger at the receiver, but there's more noise (and also Tx) in the chain?
« Last Edit: February 05, 2020, 01:25:41 pm by Miguel Dahl »
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Caleb Dueck

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Re: Extending range of Sennheiser EW100 radio mic
« Reply #11 on: February 05, 2020, 03:22:05 pm »

Maybe it's just me, but if your antennas are already overhead (so line-of-sight is being maintained) I feel like 35m from RX to TX shouldn't be any problem on half-wave whips. Is the mic tuned to a clear frequency? Are the antennas actually half-wave? I'm sure I've seen those mics work reliably over that distance without any trouble, even on the stock whips attached directly to the TX.

-Russ

Agreed, I've used a similar wireless (A-T 4k) hand held around 60m outdoor, line of sight, without issues.  The spectrum was pretty clear though, out in the country. 
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Ike Zimbel

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Re: Extending range of Sennheiser EW100 radio mic
« Reply #12 on: February 05, 2020, 03:33:44 pm »

But.. Still don't get it..bummer. The same signal to noise ratio is still there? As it will boost every incoming signal with the same amount. The only "extra noise" would be from the booster unit itself due to design?

If I use a 10dB booster, then I'd boost "everything" by 10dB, also the Tx signal. But if that signal is crap then it will still be as crap with or without the booster, wouldn't it? One has raised the noise floor, but the Tx signal will be equally stronger at the receiver, but there's more noise (and also Tx) in the chain?
While this is essentially correct logic, in practical terms it falls down because there is an upper limit to how much of your wanted signal you can use. So, what you are effectively doing is a) raising the noise floor and, b) limiting the dynamic range. For example, the LED's on a Shure AD top out at -70dB. If you have full bars, and add 10dB of gain, you are raising the noise floor by 10db, and while your signal is now -60dB, it's not really doing anything for you except putting you 10dB closer to an RF overload.
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Miguel Dahl

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Re: Extending range of Sennheiser EW100 radio mic
« Reply #13 on: February 05, 2020, 04:25:32 pm »

While this is essentially correct logic, in practical terms it falls down because there is an upper limit to how much of your wanted signal you can use. So, what you are effectively doing is a) raising the noise floor and, b) limiting the dynamic range. For example, the LED's on a Shure AD top out at -70dB. If you have full bars, and add 10dB of gain, you are raising the noise floor by 10db, and while your signal is now -60dB, it's not really doing anything for you except putting you 10dB closer to an RF overload.

Thank you! Perfect! This was exactly the kind of answer I was looking for with my "teaspoon-question".

And just to ask one more. Shure has an OL LED for RF as far as I know. Sennys do not. I've not been able to see if im close of wherever I'm at for RF overload on Sennheiser G3. How do I see that, even in WSM?

In WSM I use the RF Level Recorder and walk around the coverage area, and look at the screen after the walk, I can see that the reception is in the ceiling of the graph, but I don't see if it has ever been overloaded.
« Last Edit: February 05, 2020, 04:32:20 pm by Miguel Dahl »
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Dave Garoutte

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Re: Extending range of Sennheiser EW100 radio mic
« Reply #14 on: February 05, 2020, 04:46:45 pm »

I have a church looking to increase the range of their Sennheiser EW100 handheld microphone.  I have attached a rough layout of the church with the location of the two existing aerials. The radio mic is a bit patchy down at the back of the church at the main doors. The church want to extend the coverage down to the back of the church for meeting funerals and Easter ceremonies. The existing antenna are half wave whips. Without adding an antenna splitter I am confined to passive antenna. Would either the A1031 or A2003 antenna provide much of an improvement?
Or would I be better installing an antenna splitter and installing an antenna booster be a better bet?

Cheers

Just double checking that they aren't 1/4 wave whips, which need a ground plane.
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Mac Kerr

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Re: Extending range of Sennheiser EW100 radio mic
« Reply #15 on: February 05, 2020, 08:15:31 pm »

While this is essentially correct logic, in practical terms it falls down because there is an upper limit to how much of your wanted signal you can use. So, what you are effectively doing is a) raising the noise floor and, b) limiting the dynamic range. For example, the LED's on a Shure AD top out at -70dB. If you have full bars, and add 10dB of gain, you are raising the noise floor by 10db, and while your signal is now -60dB, it's not really doing anything for you except putting you 10dB closer to an RF overload.

In addition to what Ike explained clearly, any active stage (amplifier) is a potential source of intermodulation effects, which can cause interference.

Mac
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Russell Ault

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Re: Extending range of Sennheiser EW100 radio mic
« Reply #16 on: February 05, 2020, 11:23:42 pm »

In addition to what Ike explained clearly, any active stage (amplifier) is a potential source of intermodulation effects, which can cause interference.

...and in addition to that, most amplifiers also produce some non-harmonic distortion (noise) as well, further lowering CNR.

-Russ
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Keith Broughton

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Re: Extending range of Sennheiser EW100 radio mic
« Reply #17 on: February 06, 2020, 06:13:17 am »

Just double checking that they aren't 1/4 wave whips, which need a ground plane.
Just what I was thinking!
If these are the antennas that came with the Sennheiser kit, they are probably 1/4 wave.
Sennheiser does sell a 1/2 wave but it's not a "whip" antenna.
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Henry Cohen

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Re: Extending range of Sennheiser EW100 radio mic
« Reply #18 on: February 06, 2020, 09:53:55 am »

...and in addition to that, most amplifiers also produce some non-harmonic distortion (noise) as well, further lowering CNR.

Only if in saturation, or otherwise damaged. As long as the resulting composite amplified RF energy is below the amp's P1, it should still be linear with no discernible distortion, though there will be the inherent noise figure of the component.
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Russell Ault

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Re: Extending range of Sennheiser EW100 radio mic
« Reply #19 on: February 06, 2020, 10:34:24 pm »

Only if in saturation, or otherwise damaged. As long as the resulting composite amplified RF energy is below the amp's P1, it should still be linear with no discernible distortion, though there will be the inherent noise figure of the component.

I might have this wrong: won't an amplifier in saturation produce harmonic distortion?

The non-harmonic distortion I was thinking of is the inherent noise you mentioned.

-Russ
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Re: Extending range of Sennheiser EW100 radio mic
« Reply #19 on: February 06, 2020, 10:34:24 pm »


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