Sennheiser paddles compatibility

[sunray]

4 hours ago, paulears said:

This has always surprised me a little - the communication industry stack or bay directional antennas as a matter of course, but it's mainly to increase gain and decrease beam width, so I'd always linked that to not having any real multiparty reduction advantage, apart from the one gained by the increased focus of a two, or four coupling of antennas. Multipath reduction was the version I'd always thought was primarily to do with different paths to the same working area. Odd that Shure have sort of 'commandeered' gain boosting as a multiparty solution, when they occupy almost the same space. With typical paddle designs, ¼ wave side by side baying is quite possible, and is the most efficient, ¾ wavelength apart baying doesn't seem to offer and advantages (or disadvantages) over ¼ and I just struggle to see the close spacing really doing anything for multipath problems. I'm not sure if somewhere in a dim memory there was an issue with baying log-periodic - something about parasitic elements of one having an impact on the other antenna as distances are very similar. Jaybeam, before they morphed into Amphenol had a version of their 4 stack antennas that were horizontal across a boom, vertically polarised, with the standard power splitter harness, but it didn't last long - I wonder if this is the same issue, and why vertical stacking works best, but of course gain is their primary purpose. Interesting. Trantec always used to recommend wide spacing.

The communications industry is a different situation to radiomics. Stacking/baying is used for antenna gain to give long distance comms, however one has to also consider the effects of nulling which can happen at 1/4 wave. My own experience has shown me the effect of 1/4 wave nulls is more noticeable on shorter range systems than longer range.

I once placed a line of Trantec RXs along a table all on the same frequency and performed a walk test, watching the bargraphs (just 4 LEDs) and the A/B switching bobbing around tells a big story. I'd like to repeat it with non diversity RX's (or RXs with one aerial not fitted) If I have enough 4.16s still I may try it in the better weather and put some pics here.

[sunray]

Just now, chelgrian said:

You also have to be careful to not overload the input stage of he receiver. One venue I was involved with had terrible problems because they had installed boosters on medium length but high quality cable runs. This was providing so much signal it was saturating the receivers.

Removed boosters everything worked perfectly.

Ah yes.

A local hotel had problems, I found:

Pair of paddles mounted just below the suspended ceiling, F type twin wall plate about 4m lower, Senheiser pre-amps (directly on back of ADA), S5000 ADA & 3x S5000 RX, second S5000 ADA fed from the +10dB o/p of the first and 5x S5000RX, one being from +10dB.

To put this into perspective, I estimate the room holds around 600 theatre style.

Their tech was with me and explained they'd had their CH69 kit Shure kit replaced with the 8x Trantec S5000's and In a bid to resolve the problems the installer had added the pre-amps. He also showed me the Shure kit consisting of 4x 2CH RX's and a pair of Labgear style passive aerial splitters which he still used as they 'sound right'.

The very first test I tried with the Trantecs was to unplug the aerial leads from the ADA and instantly a 1,2 test sounded clear. He looked at me as if I had 3 heads, took the mic and started talking into it and moving away. Of course it soon ran out of range with no aerials. Removing the pre-amps made a slight improvement but not enough.

Within the ceiling I found mast head amplifiers (something like Labgear 25dB style) and a local DC injector. Removing those and moving RX8 onto ADA1 the system worked properly.

It was something like this with about 55bB of gain for RX8, only one aerial shown for simplicity:

My Solution:

 

Original CH69 Shure system:

 

 

 

[paulears]

Yes, concur on too much signal. I’m convinced signal strength is rarely the issue, it’s those big cancellation zones, the black holes where a full scale signal just vanishes, only to reappear full scale as soon as the person takes two steps to the left!

 

I’m not convinced on the side by side issue, the physics remains the same despite it being radio mics and not comms. Is the process of two antennas and two cables and two receivers different from a combiner, two antennas, one cable and one receiver? I don’t think so? At least not in terms of what happens to the polar pattern. Side by side distorts the pattern to be more directional. I’m not sure that’s a good problem solver. 
 

even worse, now we’ve gone digital and the damn things don’t hiss, all we can rely on are the signal strength displays and they don’t show trends. You can hear tint amounts of receive signal strength changes on analogue, but the digital meters seem sort of ‘averaged’ with going up or going down very difficult to see.

[Keith_]

Sorry I'm late here, but wondering what is inside the Senn A1031-U that justifies the ~£120. I have always been puzzled by the price of directional log periodic paddles, but these passive omnis are surely just a copper dipole sandwiched between two bits of plastic. What am I missing?  Otherwise I'll just keep using the wee whips. I also note my efforts to fabricate antennas for UHF bands were not particularly impressive, but maybe that's my skills, ha ha.

[Stuart91]

I'm wondering the same as Keith, but coming from a different angle. I have one A1031-U and one of the A2003 directional paddles that are "broken". They are demonstrably not working (reception doesn't improve any compared to having nothing at all plugged into the receiver) but I can't see any physical damage. Continuity on the BNC connector perhaps?

[Keith_]

I've been thinking about this. To achieve the rather broad bandwidth, it is likely to be something very like a bow-tie antenna inside ( https://antenna-theory.com/antennas/wideband/bowtie.php ). The plastic lolipop shape is a weak clue.

It is passve and the only thing I can think of is that the solder connection between its feed and the foil has failed, which I suppose might happen with a heavy knock or bend (e.g. if someone actually used it as a table tennis bat).

As with all these sort of things, there is a small, highly specialised, enthusiast circle devoted to home brew antennas (URL above is an example). I expect the £120 is for developing the exact shape and use of well manufactured parts, but really it is stretching willingness to pay to the absolute limit (the thing itself probably costs less than a fiver to make).

I am going to muck about with some copper foil and see if I can get anything resembling decent performance (just out of interest). By the way I see broad band mobile phone paddle antennas for about 1/10 the price, but unfortunately now 1 and 2G are gone, they start above 700MHz. I guess Sennheiser correctly believe if you want Sennheiser, you have to pay Sennheiser prices (or substite your preferred RM kit maker).

[sunray]

5 hours ago, Keith_ said:

I've been thinking about this. To achieve the rather broad bandwidth, it is likely to be something very like a bow-tie antenna inside ( https://antenna-theory.com/antennas/wideband/bowtie.php ). The plastic lolipop shape is a weak clue.

It is passve and the only thing I can think of is that the solder connection between its feed and the foil has failed, which I suppose might happen with a heavy knock or bend (e.g. if someone actually used it as a table tennis bat).

As with all these sort of things, there is a small, highly specialised, enthusiast circle devoted to home brew antennas (URL above is an example). I expect the £120 is for developing the exact shape and use of well manufactured parts, but really it is stretching willingness to pay to the absolute limit (the thing itself probably costs less than a fiver to make).

I am going to muck about with some copper foil and see if I can get anything resembling decent performance (just out of interest). By the way I see broad band mobile phone paddle antennas for about 1/10 the price, but unfortunately now 1 and 2G are gone, they start above 700MHz. I guess Sennheiser correctly believe if you want Sennheiser, you have to pay Sennheiser prices (or substite your preferred RM kit maker).

I have some log periodic TV antennas, possibly these: TRIAX F TX20L Log Periodic W/B (Bag) from Alltrade which have served me very well.

[Keith_]

Oh yes, Sunray, I remember we discussed them before. Good for Ch38, but their rejection at 862MHz to stop mobile phone intereference would probably put the damper on Ch70.

I might have a play with some bits and pieces this weekend if it is not raining.

Thanks.

[GaryNattrass]

I did a very good radio mic training course at Sennheiser a few years ago when I worked for Sky and if you can get a hold of their book it is excellent too at explaining the effects of cabling and gain structure for aerials.

I also used the 9000 and 6000 ser digital radio mics and they are far superior to the analogue ones.

We also had the Shure digital radio mics at Sky and we have 16 channels of them here in Salford for BBC sport and they are superb too with none of the problems you get with analogue radio kit. They pretty much sound like a cabled mic now and the digital filtering means you can get a lot more channels per air space and I have never heard one of them drop out in the five years I have used them. 

 

[sunray]

3 hours ago, Keith_ said:

Oh yes, Sunray, I remember we discussed them before. Good for Ch38, but their rejection at 862MHz to stop mobile phone intereference would probably put the damper on Ch70.

I might have a play with some bits and pieces this weekend if it is not raining.

Thanks.

I primarily use them on CH70 with good results, the reason they are listed as 862 is that is the top of the TV band or CH68 and there is no rejection/filtering built into them. CH69 & 70 have (I believe)  never been TV channels in UK (just checked an elderly Sony TV and it only goes to 68). I believe the analogue phone frequencies started well above 900MHz (915 comes to mind) and wouldn't have been an issue at the time. I recall a few TV stations changing frequency, somethng like CH66/7 to make way for experimental channels quite early on. IIUIC it might have been as recent as 4G which I'll hazard a guess was only 10 years ago that crept closer to 865MHz, bear in mind radio mic CH69 was only finally vacated around 2010/11 (in plenty of time for huge amounts of compensated kit to be used at London olympics). Digital phones filled in many of the gaps when analogue was closed down, and that was a lot more recently than people think, I guess it was well within the last 10 years I did a few jobs replacing old handsets used for telementry/control at water/sewage pumping stations.

 

All of this is from memory And I'm happy to accept I have things wrong.

Edited April 14, 2023 by sunray

[Keith_]

I just tried one of these https://www.farnell.com/datasheets/1641049.pdf and got 30 on the signal meter of my Senn G2 receiver with an skp100 placed 80m down the road, on the ground with parked cars in the way. I paid £50 +VAT for it about two years ago, they are £93 on CPC now. I bought it for communicating between speaker towers (for RX end only of course) - line of sight it is brilliant, but its beamwidth is too narrow for radio mic work. The smaller ones, I found not that great, so will continue experimenting. I have not made a cone antenna yet - will keep you posted.

[cedd]

While we're talking about tv channels and using tv aerials, it's worth a note saying that some theatres (particularly smaller, community run ones) still use modulators and coax to distribute their backstage video feeds. One in particular caused me no end of issues. They had a top loader VCR sat in the lighting box with composite video in from a camera, being distributed to the displays (mixture of old flat screen tv's and CRT's) via the VCR's modulator. They'd removed a screen for this particular show and left the coax to it open circuit. Caused me no end of issues all week until I tracked it down. 

Not particularly of relevance to the discussion about aerials, but we were vaguely on the topic and it might bail somebody out of a hole sometime! 

[sleah]

2 hours ago, cedd said:

While we're talking about tv channels and using tv aerials, it's worth a note saying that some theatres (particularly smaller, community run ones) still use modulators and coax to distribute their backstage video feeds. One in particular caused me no end of issues. They had a top loader VCR sat in the lighting box with composite video in from a camera, being distributed to the displays (mixture of old flat screen tv's and CRT's) via the VCR's modulator. They'd removed a screen for this particular show and left the coax to it open circuit. Caused me no end of issues all week until I tracked it down. 

Not particularly of relevance to the discussion about aerials, but we were vaguely on the topic and it might bail somebody out of a hole sometime! 

Interesting!

So I'm second guessing here and without any expert knowledge of RF. Was it tuned to something which directly clashed with radiomics/iems? Possibly it was on Ch36 (IIRC Ch36 was one of the 'defaults' for VCRs etc - my memory maybe failing though..) and causing co-channel interference on Ch38?

Got it in the back of my head some uhf modulators were set to Ch69 as default - again memory dodgy!

For anyone not familiar, uhf modulators on VCRs / Computers (Yes! Many had rf only display outputs!) / video games etc could often be re-tuned to anywhere from Ch21 to Ch69.

[cedd]

I can't remember which of my mics had the issue. I run ch38, ch65 and ch70, so could have been any of them! The guy who set it up also liked to tinker, so can't even guarantee it was on a default channel - could well have been directly on my mic channel. 

[Keith_]

Finally got round to real-life testing antennas (I have been off with a total rupture of the quadriceps tendon, which put me in hospital for a week, now on crutches).

What I found was that for Ch70 this thing works splendidly: https://www.rfsolutions.co.uk/antennas-c8/wall-mounting-gain-antenna-for-gsm-3g-and-wifi-p161

It only costs £37.

Unfortunately, with my injury, a lot of work I had in the diary is up the spout - you never know what will happen next.