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JonG

SRb + PSC Rf Multi SMA?

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JonG   

I have recently decided that having so many single channel receivers in my bag:

 

a- doesn't work because of limited space in the bag

b- hurts my back

 

Most of my work consists of being in the same room with the talent, or being really far away from them. When Im really far away, I use the PSC Rf Multi SMA, which gives me outstanding range (environment/obstacles not counting...). Im wondering if I will get the same performance out of SRb's hooked up through the same system? Or will I get less performance because the SR receivers are dual receivers, and are not the same kind of diversity and have a lack of front end tracking as lets say a 411 receiver?

 

Before anyone says anything, I know it depends. Now that we have that out of the way, I would like to hear form anyone with experience in this sort of setup and can draw from having tried both scenarios in long distances from their transmitters.

 

To be clear, I have had to deal with very unrealistic expectations when it comes to range, and have somehow managed to get what I need when using SMQVs pumping out 250 mW in a non polluted RF environment in conjunction with 411 systems and the PSC box, but even then my clients tend to need more than that at times, which is where I tell that that it is not possible and they get what they get at that point. But regardless, the better performance, the better for me. I would just like to hear other peoples experiences before I make the move. 

 

Thanks!

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If only the SRb had the same tracking front ends as the 411s. I believe it's to do with RF physics, seriously ;)<br /><br />It is possible to get good results with SRbs, just not as good as the 411 when the RF gods are angry.

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If only the SRb had the same tracking front ends as the 411s. I believe it's to do with RF physics, seriously ;)<br /><br />It is possible to get good results with SRbs, just not as good as the 411 when the RF gods are angry.

I think it's got more to do with the size. The SR series case is a LOT smaller than the 411 is. To fit all the components for dual tracking-front-end receivers into a box the size of the SRb is probably just not possible. Also, the point of a tracking front end is to eliminate a lot of frequencies outside the one you're tuned to, which is exactly the opposite of what you're doing when tuned to two different frequencies....it'd have to be dual tracking middles?

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JonG   

So would using the PSC box help with the overall performance or would it simply increase rf garbage?

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It only does 2 things.

1. Reduces antenna clutter.

2. Allows you to use external antennas and RF amplifiers to compensate for long cable runs.

I assume it would not increase RF garbage, but not eliminate it either

So would using the PSC box help with the overall performance or would it simply increase rf garbage?

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JonG   

OK. So I currently use the PSC box with individual single channel receivers (IE 411s). I want to move to SRs due to bag weight/ how many I can fit into my bag. Will I get the same kind of performance out of the SRs or will my range be cut considerably?

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OK. So I currently use the PSC box with individual single channel receivers (IE 411s). I want to move to SRs due to bag weight/ how many I can fit into my bag. Will I get the same kind of performance out of the SRs or will my range be cut considerably?

Your range will not be cut relative to using the same receiver with whips. It's hard to tell if your range will decrease using SR's rather than 411's 'cause you're using them in your situations. Why not test a single 411a against a single SR with whips only? The difference in range you experience between the two units will be indicative of what will happen when you use the distro, which is really just an amplifier after all...

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You said you are mostly in the same room with the talent.  Why then do you need an antenna distro system at all?  The only reason I can see for using that unit in a bag is so you can utilize high-gain antennas that can be remoted from your bag, because the TX are working at some distance from you.  The SRA/Bs are a nice idea though.  Check Pascal's newest rig with his 664--very elegant w/ lotsa horsepower.

 

philp

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LarryF   

In our walk tests with 8 transmitters, SRb is very similar in range to a 411a and definitely better than an SRa. In very tough RF environments, 411a is still superior.

Best,
Larry F
Lectro

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JonG   

Thanks for your input.

 

Phil: I said that most of my work consists of being in the same room with the talent, OR being VERY far away from them. In the event that I am far away from them, I use the PSC RF Multi SMA, which has enabled me to get amazing range (with antennas mounted on my boom pole), and meet my producer's unrealistic expectations (see my post in the General Discussion board).

 

I suppose I will have to just rent em and try em here in Los Angeles, where every situation is rough on wireless (a joke, but still kinda true).. and decide from there.

 

The idea is to get more wireless into my bag without having to use a bigger bag, or compromise the performance of my wireless. But if the SR series cant compete just yet, I may have to wait till the SRx comes out.

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Are your long-distance shots such that you could just get the RX closer and cable back to you?   I ask because the RF thing and all the cable and antennas are more weight, power consumption and complication, esp for the days when you ARE close the talent.   Or do you have two rigs, one w/ the RF box and one without?

 

philp

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JonG   

When I dont need the RF rig, I dont use it. When I do need it, usually I can't put the RX closer since most of my work at this point is out of a bag and not cart based. I used to do a lot of features where working from a cart was more practical, but lately Ive been working more reality shows, which means I need to be mobile, and out of the shot. When they start adding cameras pointing every which way, out of the shot usually means REALLY out of the shot, and a lot of these shoots are hiking through wilderness and things, so Im moving too. 

 

I know the logical thing to say is that they (production) are asking too much, but I cant change the way they see things, even though I have spoken to them many times about it. The problem that I am seeing more and more of is that they create a show and sell it, then staff up without thinking things through from a logistical standpoint, which makes my job even more difficult than it already inherently is. But this is the world we live in now, and us guys who havnt been in the biz for many many years have to take these sorts of jobs before we get pro wardrobe, DPs and gaffers that know how to work with sound, and productions that take our technical advice. Not that Im complaining or anything, I am grateful for the opportunities that I am given. I just need to work around the problems that come with this sort of a job, and needing to fit more wireless into a bag and increase the range is one of them. Which brings me around to the main question at hand, being: will an SR coupled with an RF box such as the PSC give me the same performance as a bag full of 411s with the same RF box? Or are we still light years away from such a thing?

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I suppose I will have to just rent em and try em here in Los Angeles, where every situation is rough on wireless (a joke, but still kinda true).. and decide from there.

Let us know how it goes. I want to build the same set-up, but am piecing it together over the next few months. I have tested my SRb's against my SRa's, and was amazed at the increased range, but Larry is right, 411s are still better. Connencting a PSC unit could be a game changer though. Hopefully one of us will find out soon.

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As Jason pointed out, you may be falsely attributing your increase in range to the RF Multi, which is just an amplified antenna splitter.  The increase in range you experienced is most likely due to better antenna placement (high in the air with clear line of sight) and posibly high gain antennas like sharkfins or similar.

 

I have moved from a bag using all 411s to now using all dual channel recievers, and I'm happy with the range.  I use an RF Multi, which I installed to allow me to remote antennas for cart work, and it works fine.  I do find that in high rf environments having a wideband amplifier inline increases the noise floor above the whips alone, but that noise floor is a much smaller degredation than the improvement gained by remoting antennas.  In low rf environments, I don't really notice the difference, so I leave it hooked up for convenience, and only use single set of whips.

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JonG   

Thanks, you may be right. I have gotten great range when I hooked up my antennas (PSC passive shark fin and Lectro dipole) directly to my 411 Rx. That definitely has a lot to do with it. But I wonder if I lose anything with dual channel receivers that lack front end tracking when I employ them in the same system.

 

I think that I might just rent an SRb and take a couple of my boom ops out on a field trip this weekend to try it out.

 

Also, and this is off topic, but can you use a 200 series Tx with an SR Rx? I keep a couple of older systems around because I have things like my CUB mics wired for them, and it might be nice to ditch the Rx for those if theyll work with an SR system. Just a thought...

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Jon,

 

How well do your 411A's perform with your external antennas compared to whips? I would say if this is a significant boost with a little room to give up a bit of performance, the SRb's could do fine. If it's still "on the edge" of what you would consider usable, then you may just need every little bit you can get.

 

I don't consider SRa's with whips extremely usable in very RF cluttered zones, and I when video transmitters, 788T RF emissions and hops transmitters are involved, even 411A's cringe more than I would like. Hence, why Lectro has taken the initiative to improve their SR design.

 

I would consider the SRa to the 411a to be a couple of steps down in performance, but I would consider the difference between running in a fairly clean RF environment vs. camera transmitters, hops, etc. to be a giant leap down in performance. If you would consider adding a directional antenna to be recovering a fair amount of ground in terms of performance, I think the SRb would probably be a great candidate for bag work. Also, if you have 250mW capability, the antenna coupling does reduce the overall signal of everything -- your transmitters and your surrounding noise. As long as the 250mW is not overloading your receivers with RF, being able to reduce the entire signal while improving signal to noise ration would be ideal.

 

The SRa's can select compatibility mode per channel, so you can set channel 1 to 200 mode and channel 2 to hybrid mode or whatever you want.

 

-Scott

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Also, in the realm of helping your back in a troubling RF environment, the 664 I'm told is very clean as far as how much RF pollution it delivers to nearby receiver antennas and is also quite lightweight and not as power-hungry as the 788T. If you can justify the unit, it may also make your life easier. I find the 788T RF emissions in blocks 19-21 to be pretty bad, especially if I hook an external drive to the firewire port.

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Great read.

Something we don t discuss as much is working on transmitter placement on "talent". It improved range more drastically than anything i ve tried yet. The biggest usual obstacle is talent's own body when pack is at waist. Putting it down on ankle helped me bunch or high up head level if he/she s wearing a helmet/hat. I know pascal is using a a plastic tube aroun the antenna to prevent it to touch skin. I haven t tried that yet.

As often discussed too the zaxcom solution is also a workaround to all the range issues. I have a hard time to picture myself transfering bunch of cards at wrap everyday though. If i could have the system to transfer back files to a single polywav on my nomad it would be pretty slick. Deva does it i think. That s another subject anyway..

Cheers

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LarryF   

Since transmitter placement to improve range came up, we have the swivel antenna for SMA connectors

http://www.lectrosonics.com/459-AMJ-Specify-Block/View-details.html

and it can be used to get the antenna away from the body.  The ones we have now are a little fragile but once we use them up we will design a stronger one. Being a bit fragile, they are free at the moment if you email me, larryf@lectrosonics.com with the usual name and mail or shipping address.

Best Regards,
Larry Fisher
Lectrosonics

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Since transmitter placement to improve range came up, we have the swivel antenna for SMA connectors

http://www.lectrosonics.com/459-AMJ-Specify-Block/View-details.html

and it can be used to get the antenna away from the body. The ones we have now are a little fragile but once we use them up we will design a stronger one. Being a bit fragile, they are free at the moment if you email me, larryf@lectrosonics.com with the usual name and mail or shipping address.

Best Regards,

Larry Fisher

Lectrosonics

Wow i didn t know those even existed. Could i use them on my sr receivers? Would be nice to be able to fold them when i put my rain cover.

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LarryF   

Wow i didn t know those even existed. Could i use them on my sr receivers? Would be nice to be able to fold them when i put my rain cover.

Yep.

LEF

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" Or will I get less performance because the SR receivers are dual receivers, and are not the same kind of diversity and have a lack of front end tracking as lets say a 411 receiver? "

without saying it depends,  you are asking for a specific answer that may not really exist,  and seem to misunderstand a few of the things and  terms involved.

The first paramount fact is that the antenna is the single (actually multiple) most important factor; this includes the TX antenna, and the RX ant's... Improving the antenna  (TX and/or RX) and antenna location(s) will provide the greatest, easiest, improvement in reliable range.(including even better than raising power on TX's)

diversity is not as much about increasing range as it is making the system perform more reliably over its usable range, and tracking front ends are about reducing signals on frequencies not being tuned to, more than about increasing sensitivity or range. 

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