URGENT

[ceecrb1]

Urgent problem to fix.. long story

 

I am connecting a normal standard intercom base to an OB truck and the buzzer is on all the time..

 

What causes the buzzer to engage?

 

If I remove one of the 3 cable cores in the XLR the intercom does not work (cant communicate) at all..

[david.elsbury]

Check all cabling is correctly wired, I.e pin 1 to pin 1, 2 to 2, 3 to 3, and with no shorts between anything or to the chassis/shell of the XLR connector.

[paulears]

All the same kind? Clearcom? Some OB systems use Drake internally and to the ccus, then convert internally to whatever conventional comms system is in operation. There are subtle differences between them - but are you sure that you're not double powering? Your base station supplying dc at it's end, and then the truck doing the same outside?

[ceecrb1]

its a base system made by a spanish company..

I´m connecting to a standard base via convertor from 4 to 2 core systems..

 

Tried putting diodes etc to prevent "backflow" etc.

 

yes pin 1 goes to 1 2-2 and 3-3.

[paulears]

Ah -then it's by no means certain the two systems are compatible. Clearcom, tecpro and others, let alone TV 4 wires all seem to have subtle difference to how the signalling is carried out. I've come across systems where the audio line has DC applied to make the signal work, while others change voltage. Some have mic kill facilities and some have tone to autoswitch speakers on.

 

In your case, you'd want to use capacitors to isolate lines that carry audio and DC. Diodes will not necessarily stop DC problems if you have multiple powering issues.

 

The first thing to do when trying to connect different systems is establish which line is the audio, then check to see if it carries DC too. If it does, then remove that and connect them. audio could appear, although you may lose various signalling options as it's doubtful the exact protocol for making them work would then exist. Likely problems could be that one make has different line impedance characteristics, and connecting them together could raise or drop gain, or mess up the side-tone rejection. Tecpro are quite sensitive in this area - unterminating the comms circuit producing severe feedback style tone in the headsets.

 

The 4-wire to 2-wire unit is also sensitive to levels. what you're going to need to do is knock up an in and out box that allows you to block/unblock/isolate and adjust levels. Converting signalling systems is much more complex - getting audio to work is bad enough. Do you have the spec for the Spanish design?

[ceecrb1]

unfortunately no spec..

and the company who fabricate it were completely useless and just sent me a photocopy of the relevant page of the manual... which I am following and isnt working...

 

Oh well capacitors I will try,....

When I reach Lisbon at 1am (or so).

[j_b]

You're likely to have one of these types of system:

 

Clear-Com

Pin Function

1 Common for Audio, Power, & Shield

2 DC power: 30 volts nominal

3 Unbalanced Audio

 

Audiocom

Pin Function

1 Common for Audio, Power, & Shield

2 Audio + DC Power

3 Audio + DC Power

 

RTS TW

Pin Function

1 Common for Audio, Power & Shield

2 Channel 1 Audio + DC Power

3 Channel 2 Audio

 

You're less likely to have success with the call signal, Audiocom and RTS systems use a (inaudible) 20 kilohertz signal for the call signal, whereas Clear-Com systems use a DC voltage added to the audio signal.

 

For audio though, just bring the ground and a capacitor in series with the audio line - the systems are usually quite high impedance (in the region of 10k) so you shouldn't need a huge capacitor. 100nF would be plenty big enough for general purpose voice comms.

[mackerr]

its a base system made by a spanish company..

I´m connecting to a standard base via convertor from 4 to 2 core systems..

 

Please explain a bit more about this. On the 4 wire side it is just balanced audio in and balanced audio out. It is unlikely that any signaling would pass through that conversion. Are you using a 2 wire system in the venue and the truck has a 4 wire interface? The 4 wire interface should have nulling controls on it that will need to be adjusted after all the stations are wired up on the 2 wire side. This will keep the system from going into electronic feedback. You may also have to adjust the input and output of the 4 wire interface to get the audio levels to match between the 2 systems.

 

With Clear Com (and compatibles) the signal light being on all the time usually means a shorted cable somewhere. This puts voltage on the audio line which is how the signal is activated. Try to isolate the problem by unplugging one branch circuit at a time from the system. This kind of problem is the reason it is better to home run as much as you can rather than "daisy chaining" user stations. It is much harder to troubleshoot a system that is all on one branch circuit.

 

A lot of intercom information can be found on the Best Audio Downloads page. Pete Erskine's gift to the world of production comm.

 

Mac

[ceecrb1]

Thanks to all for your help!

 

In the end we went for the easy option and added a 2nd intercom base, purly for director - sat truck coms... nice and easy, did what it needed to do.

 

I'm looking into this with a little more depth now. I THINK I have the solution to try tomorrow but I'm having a brain fart and not seeing how to connect.

 

The intercom base is a base from KROMA a spanish brand.

Page 28 of this manual shows the pinout I will need (its not this intercom, and older version but htey have not changed the pinout.)

http://www.marcotec.pl/media/00000007194.pdf

 

Now what confuses me, is that this will give me a male and female XLR. which will open and close as an operator selects that channel in one of the trucks coms bases.

However... excuse me for seeming a little "newbie-like" but all the 2 core coms units I have have just ONE XLR... so what do I do with the male and female (in and out) this pinout gives me?!!?!?!

 

 

 

Ta muchly

 

p.s. forgot to add. the 2core base is an Altair ...

[paulears]

This connection isn't to go to a common audio theatre style comms system, it goes to a radio duplex tx/rx system. Comms audio is broadcast to everyone continuously. Walkie talkie style portables then transmit back on a different frequency, which is fed as an input into the comms line (and goes back out of the transmitter again). Pretty common with OBs for the mobile production team - most of the time they are just listening to production talkback, but have the facility to add to the comms talk if they need to. It's really called semi-duplex. Two channels being used, but still with press to talk. Basically, back to 4 wire - so you could use this output with a 2 wire to four wire converter to feed your normal comms system.

[ceecrb1]

Ok now I've managed to get my memory into gear....

 

I can tell you I have exactly this system in the ob truck:

http://www.kromatelecom.es/en/manual/tb6000.pdf

 

I have all components listed except the belt pack.. its "magically dissapeared"

 

And I need this to connect to an altair

http://www.showcomms.co.uk/altair-wbs200-w...cks-p-1091.html

 

 

Note in the kroma manual.. Last table on page 26..

This is the pinout for an external source.

If anyone can shed any light on what kroma's idea of "group A B or C" might mean AHAHAH

 

 

I'm getting the idea that it means I must make a dub 9 to 2 XLRs.. one being audio out and one being audio in...

What I dont like is that it means that the input to the altair is passed to "program in" and then out via "audio out"

Possibly whats ment to happen but I'd rather keep the program in... for the day that a director demands I send program audio down coms.. (however I can just tell him to run and jump and send audio down an XLR from the main distro)

[dbuckley]

Groups A,B,C I think are "paths" in the cabling. Your six core intercom cable should have three "paths": two screened balanced pairs (thats A and B), and one unscreened pair for the power (group C).

 

Ok, the good news is I think you can connect these together

 

CONNECTION to a MATRIX or 4 wire System

 

connect via Program input (switched to line level) and OUTPUT switched to PARTY LINE. Please note the input will be on the OUTPUT

 

Take an standard XLR mic cable and chop it into two halves.

 

Join earths of both cables together (pin 1 on the XLRs) and solder to both pins 3 + 4 for the EL6000. (yes, link the pins)

 

Wire the female XLR to pins 1 + 2 on the EL6000 (audio from wireless to EL6000)

 

Wire the male XLR to pins 11 + 12 on the EL6000 (audio from EL6000 to wireless)

 

Use the same colour of XLR cable core for EL6000 pin 1 and pin 11.

 

Should work.

 

If you blow it all up its not my fault!

[ceecrb1]

If you blow it all up its not my fault!

 

On the plus side I wouldnt have to keep trying to make this work :D

 

 

aside from this I am making some headway..

With an altair intercom.... At the base unit I can talk to all beltpacks and the ob truck, & vice-versa

HOWEVER from a beltpack, you can hear the truck but the truck cant hear you!

 

Its getting irritating!!

[ceecrb1]

In the end dbuckley is totally correct, and this is the cable arrangement I souldered up at 9am this morning using a manual from another Kroma intercom..

 

HOWEVER my altair intercom will only take an input from the kroma..

The "output" Is actually a Paging mic, only transmited from the altair's base station headset!!

 

As so, anyone with a beltpack can hear the truck... but the truck cant hear the belt packs!!!

 

 

I'm toying with the idea that there MUST be a way to extract the audio from the coms line of the altair.......

 

Its getting seriously irritating..... a whole day and nothing acheived!!

 

A concurrent post has been automatically merged from this point on.

 

UPDATE.. PROBLEM SOLVED

 

Thought I'd just add a wee note here as I've solved the problem.. incase there are any others who search for this

 

In this case and Altair 4w2-200 is needed.. Its a 4 wire to 2 wire convertor!

http://www.altairconsoles.com/index.php?op...200&lang=en

 

This will connect to my male and femals XLRs with audio in and out from the kroma (4wire) system and then give me another 2wire/ party line XLR to connect to a standard 2 wire base station.

 

In My case I'm going to order 2 as I have 2, 4 wire ouputs giving the directors in the truck the option to send individual coms lines to 2 places. (Eg stage manager and Sat truck) rather than have to talk to a sat truck and a SM etc at the same time.

 

Ta muchly for all involvement.

[mackerr]

its a base system made by a spanish company..

I´m connecting to a standard base via convertor from 4 to 2 core systems..

 

UPDATE.. PROBLEM SOLVED

 

Thought I'd just add a wee note here as I've solved the problem.. incase there are any others who search for this

 

In this case and Altair 4w2-200 is needed.. Its a 4 wire to 2 wire convertor!

http://www.altairconsoles.com/index.php?op...200&lang=en

 

This will connect to my male and femals XLRs with audio in and out from the kroma (4wire) system and then give me another 2wire/ party line XLR to connect to a standard 2 wire base station.

 

In My case I'm going to order 2 as I have 2, 4 wire ouputs giving the directors in the truck the option to send individual coms lines to 2 places. (Eg stage manager and Sat truck) rather than have to talk to a sat truck and a SM etc at the same time.

 

I thought you said you had the 2W to 4W adapters from the get go. What converter from 2W to 4W were talking about in your first post?

 

Many 2W to 4W interfaces come as a 2 channel unit. It generally does not matter what manufacturer it comes from as long as it can work with the system you have. Since these get used to interface to a variety of 2W systems they can generally be set for whichever 2W system you have. As has been mentioned earlier the 2 main 2W types are Clear Com or ASL compatible, and RTS compatible. All the interfaces I am familiat with will work with both of those standards.

 

For a completely manual system the Clear Com is easy to use and sounds quite good. Perhaps the best sounding and easiest to use it the Studio Technologies. The Studio Technologies uses digital control of an analog hybrid to achieve the best null. Just push a button and 15 seconds later you're done.

 

Mac