Sennheiser ASP 2 Antenna Splitter

[Sound Man]

Hello

 

I currently have four Sennheiser EW100 belt pack radio mic systems and I’m undecided whether to purchase an ASP 2 Antenna Splitter unit for the receivers and fit them into a rack. When I use them I tend to position them near each other and set up the aerials so that they are not touching one another. What puts me off buying the Splitter is that after reading the spec on the Sennheiser Website I found out that as the unit is passive and that it would attenuate the RF by 14dB, the last thing I would of thought that needed to happen when the belt packs are buried beneath the actors costumes. I realise that there are aerial booster units available such as the AB 2 of which I would need to purchase two to get around this attenuation problem.

 

The question I’m asking is that what are the advantages of the Antenna Splitter over positioning the receivers near each other like I’ve been doing apart from the fact of being able to fit the whole system in a rack with the addition of the GA 2 Racking Adaptors.

 

Thank you

 

Dave

[Bobbsy]

You've mostly answered your own question. The major advantage is the ability to place your four receivers in a compact rack unit and not have to worry about having a total of 8 extendible antennae sticking out getting in the way. With four channels, it's a bit of a toss up whether or not it's worth it. As your system grows (my last show used 22 channels of radio mic) it becomes pretty well impossible NOT to have rack mounts and splitters.

 

However, the other thing to consider is that, when using a dividing network, you can also place your antennae remote from the receivers and get them as close to the TX packs as possible. Clearly, for this to be an improvement you need to use antennae with sufficient gain and high quality cable, otherwise losses in the run can outweigh gains from getting the antennae closer. Done properly though, carefully positioned and/or high gain antennae can make a useful difference.

 

Bob

[ben.suffolk]

Clearly, for this to be an improvement you need to use antennae with sufficient gain and high quality cable

 

The ASP also provides power on the antenna feeds, so you can put an amplifier with the antennae to over come any losses on the cable runs.

 

Regards

 

Ben

[paulears]

14dB sounds a lot, but putting the receivers foh as so many people do can be far worse. A properly designed splitter, like the sennheisers wouldn't be so popular if they were poor performers. FOH, you often get close to full strength on the meters, so moving them closer to stage produces levels that can easily cope with a bit of attenuation. Remoting the aerials also enables the diversity switching to be much more decisive. Two aerials close together often are both in nulls, making you think it's a distance problem - which in most cases, it isn't.

[soundo26]

There are other makes of active splitters out there, we use a prosplit which works well with 6 Sennheiser mics in a rack with the sennheiser paddle antennae via the Sennheiser active converters ( 1 for each antenna).

There are other makes also but I haven't tried any of those yet!!

[tall_phill]

See the Lectrosonics Wireless Microphone Systems Guide for an excellent explanation of how the systems work, and a thorough treatment of all aspects of wireless mic systems:

http://www.lectrosonics.com/wg/wg2000.pdf

 

See also Jim Brown's Audio Systems Group Articles:

Wireless Mics & The Audio Professional

http://www.audiosystemsgroup.com/wireless.pdf

 

And tangentially, Which Coax for Wireless Microphone Antennas

http://www.audiosystemsgroup.com/Which_Coa...reless_Mics.pdf

 

Cheers,

 

Phillip

[Bobbsy]

I can heartily recommend the two Jim Brown links above...he'd very knowledgeable in the RF area. Two slight caveats: first, he's written from the US point of view so the regulatory scene (and therefore the problems of finding frequencies) is quite different and, on the cable choice post, some manufacturers and designations don't cross the Atlantic too well.

 

I notice that people have mentioned line amps and active splitters. I use these regularly but would just like to throw in that they have to be used with care. A couple of points: first, cheap ones can often introduce phase errors into the RF signal which can be responsible for lots of hard to trace "funnies". Over the years, I've earned a reasonable amount of money "consulting" on radio mic systems and, quite often, my fix has been to REMOVE active electronics from the antenna system. The official Sennheiser accessories should be fine from this point of view--it's the cheapie TV distribution stuff that many try to use that is to be avoided.

 

Also, when using RF amps in the antenna feed, please remember that these have to be as near the antenna end of the line as possible. Placing them near the receivers has the effect of raising the noise floor as well as the wanted signal. This can have the effect of giving you a display that shows a high strength signal...but one that's not usable by the receivers. Again...funnies...(which are anything but funny during a show.

 

Bob

[basilbrush1982]

We use the EW500 G2 system at work and use ASP2's in nearly all our systems. However, we have found that the performance of the Sennheiser aerials relative to that of the Shure ones is not as good. We therefore use the ASP2's and the Shure directional aerials - UA870WB. These have amplifiers built into them so you don't have to buy (and rack) the aerial amplifiers.

[Bobbsy]

Yeah, the most basic Sennheiser antennae are pretty...er...ordinary, though their more specialist stuff is okay. I've never played with the Shure antennae but have always had excellent results using the Sony active antennae plus their active splitter.

 

You've just reminded me that the last show I worked on used a mix of Sony and Sennheiser mics and both rental houses sent along antennae. There was no comparison in terms of performance and I ended up using the Sony "sharks fins" and their splitter to drive both racks of receivers.

 

Bob

[Andy Channel_Zero]

My original system used a single ASP2 to drive four ew100 receivers, using the passive omnidirectional antennae and ab1 booster all supplied by Sennheiser. The current rig has a single ASA3000 active splitter, which will take two diversity feeds and drive 8 outputs each. Feeding the input of this I have a pair of A12D active antennae, which are connected via RG213 cable (much better for longer runs than RG58). The ASA3000 drives seven EW100 & 300 receivers directly, whilst the last pair of outputs drives a pair of ASP2s via the original AB1 boosters, in an attempt to minimise the passive splitter loss.

 

Not sure how effective using the ASP2s and AB1s in this configuration is, but it seems to work ok, with the A12Ds being on average ten metres from the stage.

 

I would definately advocate the use of pouches/belts for the transmitters, as I've had no end of trouble in the past with performers stuffing transmitters down their trousers/pants/etc. and very little RF signal being able to get out!

 

As some of the previous posts have mentioned, it makes a difference to the rig having it driven by a single pair of antennae rather than multiple ones, and of course enables you to get them closer to the stage. The only time I had difficulty with the active rig was when the A12Ds were too close to the transmitters, causing desensitisation of signal, and transmitters on adjacent frequencies were interfering with one another.