Talkback units on e-bay

have you got a proper spec for these? 

Do they have clearcom / rts / 2wire outputs for use with normal beltpacks? Or are they 4 wire only? The advert is very unclear and i can't find the manufacturers website. 

A question I would also like to know Tom but sorry I have also not been able to find any info about them.

 

I suspect they will be four wire only but once mine arrives I will do some further testing with my prospect 4wire/IFB/2wire beltpacks.

NESS don't seem to even  have a web presence now, making me wonder if they went bust - no products of any kind seem to be being talked about. I'm assuming that in essence it's 8 inputs tagged to 8 outputs in the normal way, so not really much use as a 2 wire master station, but as a 2 wire features sidetone reduction, it should be fairly simple to interface using a Tecpro/Clearcom pack, and then being able to monitor other sources and send stuff. For my theatre work with video, it's quite handy I think - being able to get access to cable comms, radio comms and other sources. Worth the money I think - tempted to buy another too? If he has any left and I get to test the capabilities of the first one.

 

Well the box arrived this afternoon and it is a very good box for the money, it is 19inch rack mount or stand alone with the small feet that flip out.

 

Basically eight line level GO or talback send outputs with individual key to talk via internal or ext mic source with the added ability of selecting several outputs or all of them and then a keyed talk to the pre sets, you can also tap twice to latch the multi talkback key.

 

Eight return or FB (foldback) line level inputs and the red led lights on each return key flash to show signal present.

 

The connectors are quite flexible with XLR's plus screw down terminals and I think push wire connectors for each of the GO and FB circuits, there are also trim pots for each GO and FB and an overall trim control which then feeds the internal speaker or headphone socket.

 

It's mains operated but you can also pop four AA batteries in the back panel to make it stand alone.

 

The final switch is for LINE or MIC which is changed by pressing it whilst powering up the unit, if the unit is in LINE mode the two XLR connectors on the front panel then come into play and you can then feed the LINE input source to any of the eight GO sends or feed any of the eight FB circuits to the LINE output socket.

 

It does not have two wire capability but I am sure Paul will report further on this type of operation.

 

For £100 delivered from France it is an absolute bargain and I could have done with one of these for the Olympics to test all the four wire circuits in the mixed zone position so it will be going to Moscow and Rio with me and it is a useful cheap coms box. It could even have applications as a selectable distribution amplifier system or sending multiple line level signals in press or conference situations.

 

Will post some pics later. 

I'd back up all Gary's comments. As for two wire, then you can use it by taking the headphone level feed from the 2 wire packs (I'm using Tecpro gear). Each input has a gain control, so it's easy to match the level. The output from the channel (on the 'go' outlets) then feeds the 2 wire pack - Tecpro make a proper 4 wire convertor, but they're rare on ebay and new cost a fortune. I use an old pack with a broken volume pot for this kind of thing. The unit mixes all the incoming audio feeds, and provides, as Gary said, switched outputs back to the users. I'm going to use this I think to interface with a 2 - 2 wire systems, for a project after christmas, where I shall have lighting and sound on one communal 2 wire system, and video on another - somebody needs to speak to both of these, but the two don't need to hear each other, or have that facility. On top the person using the unit also has the facility to speak to the people on stage - via one of the balanced XLR outputs to the sound mixer, the audience via another and possibly the back stage system to talk to dressing rooms. In theatre the stage manager usually has PA facilities to backstage, front of house areas and maybe even stage door, plus has listen/speak input to the technical ring for cueing the show. This normally means using two systems, this, I hope might be able to do everything from one single unit. The only thing not tried is the 2 wire interface. I need to do this (maybe tomorrow if I get a job or two out of the way). It's very straightforward BUT the Tecpro audio input is very intollerent of impedance, and is of course unbalanced. So linking pins 1 and 3 and turning the output level down might do odd things - and getting it wrong usually makes the Tecpros burst into feedback! I'll need to check this one.

I did a quick test using an XLR splitter with a C1b prospect box that can be used as a two wire but it didn't work properly, the green connectors are very good and allow screw wire terminals or push in wire connectors that can also be removed, maybe they could be wired as jumpers to link pins to enable two wire operation for some channels as that is what you can do with the prospect units to re configure them.

 

Need to do more work regarding the pin allocations for the two wire interfacing on my boxes but if all else fails they are full four wire battery units so will work better that way. 

 

Will be interested to see your findings Paul but I already have a use for mine as on premiership matches I need to listen to multiple incoming sources and talk to RT and four wires as well so it will be ideal as it is a battery powered unit and more extensive than a glensound box.

 

Shame it hasn't got front level pots for the incoming sources like the pospect type but I may look into just adding a small passive pot to some of the inputs or using one of these: http://www.absolutemusic.co.uk/catalog/product/view/id/22611?gclid=CI6hn5fVqbMCFSbMtAodqjYA3Q

Only just noticed the battery aspect Gary! Thanks. For 2 wire the biggest issue is power on a pin normally used for balanced audio - which might be a snag. I'll have a go and see how they work unbalanced and send receive linked across maybe different channels?

I'm quite interested in getting one or two of these. 

 

Does anyone have a link to affordable (ish) 4wire belt packs? At the moment we have a custom built 2wire system (which we got from a retired radio engineer, its really lovingly designed and built, but looks a little sketchy due to the 80s die cast project boxes which house the belt packs) I'm trying to work out if there is an affordable upgrade path from this system, or if it makes more sense to go from here to wireless comms. 

I just bought a job lot of as new ex olympic C1b prospect boxes, they are still die cast project boxes and were £150 each, around half price but still not cheap.

 

To be honnest if you just need keyed talkback you are probably better off getting one of these and going wireless using cheap walkie talkies such as the baofeng UV-5RC: 

http://www.sinotel.co.uk/amateur-radio-handheld-c-1/baofeng-uv-5rc-2m-70cm-dualband-handheld-transceiver-with-dual-frequency-display-p-67

 

Ofcom PBR licence is £75 for five years.

 

I don't like motorollers - it's hard enough to hear wired comms without the hiss factor and hassel of linking into other systems. (everytime i've tried to use 2way radios for camera directing it has gone badly wrong!) The lack of any duplex is also a massive issue - if the director mic is open then nobody else can speak at all making it a bit too one way for use as a camera comms system.

 

I've used Clearcom Tempest (very good) and HME DX200 (OK) both these are proper comms systems with the Clearcom having the edge due to more robust construction and compatability with standard Peltor headsets.  Both these systems run to in excess of £1000 per station, but I could forsee getting a reasonable amount of hires for such a system as there seems to be a national shortage of quality wireless comms systems (like half the time i've tried to rent a system nobody has had stock) 

 

I breifly glanced at an IP based system which looked very interesting, i've forgotton its name now though (beltpacks were green IIRC) That would seem like the modern approch but i'd want to try a system in the field before being convinced it was a good idea. 

Yes know what you mean there Tom we tend to abandon RT systems on sports as they are just too unreliable, those baofengs are semi duplex though so can listen across two frequencies at the same time, they are also VHF and UHF so a bit more flexible.

 

Interesting you mention IP based systems as that seems to be the way things are going.

 

I just did the Olympics and all the commentary systems were IP based using CAT 5 cable with a software driven front end with DSP etc, the trilogy system is also superb but at a cost that is sadly way beyond most of us at this end. 

 

We discussed a USB based four wire coms system or bluetooth interfacing during the games but we had a lot od problems with USB headsets dropping out and the IP engineering coms system we had was just too unreliable so we used old fashioned four wire boxes such as these for our own talkback circuits to the IBC. 

 

A good friend has just got the blackmagic vision mixer and camera system and that uses two of the 16 channels of SDI audio for it's talkback circuits so everything is going down the fibre chain but it is still not a hugely flexible system.

I note the ad carefully includes the words

The BMD Camera Converters would be a good basis for a modern system were it not for a few stupid design mistakes. 

in summery the issues with them are.. 

30 Ohm heaphone output - doesn't match with normal peltor headsets (results in very low volume) 

Crappy connections - only the BNC connections are standard, everything else is domestic crap. (LC fibre, minijack, quarter inch jack(!!wtf?)) 

Hard / impossible to link into proper comms systems

No way to mount the system on camera 

Fibre is still expensive. 

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Having spent the last decade wishing for Sony to put basic studio facilites on their smaller cameras they have finally seen the light and put Genlock and Timecode on the PMW200/150 - now i'm finding myself saying arrgh would it be that hard for someone to do a small camera with tally and comms? 

 

Why is there still no replacement for the DSR570? The JVC system comes close but it's expensive, and still lacks some features. 

Ah yes but the manufacturers now have to chase the 5D cinematic shallow DOF side of the market and us ENG type broadcast users get forgotten, sorry couldn't resist cross bitterness from the cine alta camp!

 

Yes I agree with all the black magic domestic crap but you would be horrified to see what crap I was using to send full HD pictures from the Q ball to Abu Dhabi at the weekend, a BNC HD SDI into a thin fibre link with a plastic terminator into a yellow brick 3 inches by 2 run off a 12v DC wall wart!

 

At least I take all my own audio and coms kit now and whilst it's not the most expensive it uses tried and tested technology.

 

Even the CAT 5 and coms on the olympics was remarked at being very call centre domestic based technology but hey ho that's progress for you and I just end up being bitter and twisted!   or maybe I just need to drink more Bitter and Twisted???

 

We had a saying in't the old days at Tyne Tees TV that " you can get a man on the moon but you can't get a stable talkback feed out of studio 2 "

 

and we work in a communications industry but coms and tallies are seldom an option on most kit??? 

 

 

The little yellowbriks are not too bad really, they do quite a nice rackmounting solution for 8 or so of them complete with a neat inbuilt PSU thing. 

 

Fibre is networking tech really so the LC connector type isn't really designed for field use. But then you look at the cost of an opticon connector and it all makes a little more sense. 

 

Compared to audio and lighting which actually has touring reliablity in mind then even oldschool broadcast kit looks like a load of fragile junk. 25pin Dsub for tally and comms on the back of a CCU is classic broadcast - ok in a studio install but horrible for any portable setups (excluding coach built OB trucks!) 

 

Tests so far seem to show that it's not that simple to get it talking to a two wire system without some simple electronics.

 

By unbalancing an output and using the variable gains, I can speak to a 2 wire loop - however, the common systems (Tecpro and Clearcom) add a signalling voltage to the audio line and this gets shunted with a direct connection, so the signalling doesn't work. A capacitor should provide enough DC isolation to sort this one, but haven't had the chance to try it yet. The lack of sidetone is a big problem, as if you bridge the GO and the FB channels together, you can talk to the comms line, and hear it - but through the speaker, it feedback unless the volume is kept very low. I've tried using a pack and splitting the 4 wire to the headphone into two XLRs and this works fine - so I shall use the system like this.

 

They're nice pieces of kit. 

Paul