+ve AND -ve Demux

[peternewman]

Hi all,

 

At school we have recently finally moved to DMX, having got a Sirius 48 and 4 Betapacks to replace our ageing strand gear. We would however like to be able to reuse some of our old stuff and some of the stuff from the drama department.

 

Hence does anyone know of a demux (or a demux and voltage invertor used together) that will do the following:

 

24 channels

positive on some and negative on others, so we can do either of these combinations:

3 +ve and 1 -ve or 3 -ve and 1 +ve

 

 

Being a school we want to do everything as cheaply as possible.

 

 

 

Thank in Advance

 

PN

 

PS Why isnt DMX in the dictionary? <_<

[richard]

Hello

 

You could buy the Zero88 demux48 and one negative output card, you could fit the neg output card to ways 25-48, meaning that ways 1-24 are +ve and 25-48 -ve, alternativelivy you could connect the neg card to a new set of sockets, meaning that you could run either pos/neg on 1-24 and just pos on 25-48 (I think I would prefer the former approach)

[tjkerr]

Dont talk about demux guys I was sent to a panto last week to Op the show (cinderella) by my boss. So I am sittin there "nice and happy" (yeah right) and the great line "cinderella you shall go to the ball" was said and with a pop and sparkle the demux unit in the control room where I was sitting died!!!! not the best night for me I hate that feeling so much went theres little you can do!

[peternewman]

Hi all

 

Bad luck tjkerr, we had a wierd problem with a demux at a diff school, but thats another story.

 

 

Has anyone ever used the Botex ME-72. Whats it like, can it do +- at the same time?

 

Found one on sale cheap before but now cant find where it is sold, so if anyone knows that as well <_<.

 

Any cheaper options than the z88, or cheap places to get one. Also if we had first 4 sockets +ve and other four negative, wud we have to softpatch to get our run of dimmers on consecutive channels?

 

Thanks in advance

 

PN

[richard]

Hello

 

Yes, you would have to soft-patch your desk (although that is very easy on the sirius).

 

The botex one is, I believe, exactly the same as the strand one (only with different labels) I know that terrallec (www.terralec.com I think) sells them.. Don't know about +/-ve stuff though..

 

You could remove the need to softpatch the sirius while using the z88 one by wiring both the pos and neg cards to the same set of outputs (ie 1-24) - meaning that the top row of sockets would do ch 1-24 +ve, and the bottom set 1-24 -ve, then if you set your start address to 25 it will just work.. It's easy enough to do but does mean that if you need to use 48 ways on it you would have to open the top..

[peternewman]

Hi all,

 

Thanks for the advice richard, I like the sound of the +ve and -ve socket for each group of six, sounds very good. There is very little chance we will need more than 48 channels total as we just don't have the power for it (6 32a feeds, 2 alpha packs and sometimes a rack off a 13a socket).

 

Had a look at Terralec and that may well have been the site where I found it before, I can't remember.

 

One issue with the Botex is that it outputs on 25way D plugs, so does anyone know where we could buy some short 25way D to 8pin locking din leads, I had found some 10m ones (but now can't find them again) and we don't need anything that long.

 

Thanks in advance

 

PN

[richard]

You may find that strand do some (as the strand demux is the same) or the strand demux may have different socket - I dunno. I think that the strand one is cheaper than the Z88 one as well (although I may be wrong) so you could give a dealer a ring and see what they can do price wise.

 

Just be aware that if you plug a pulsar rack into a demux without using the correct adaptor lead some damage will occur (they use the same plugs but in typical pulsar ways are wired differently!!

 

Richard

[peternewman]

Hi,

 

No Pulsar gear, currently thinking the strand or botex with a half printer cable bodged up to some din sockets.

 

I wud prefer the z88 one, but best price ive found is over 500 quid with the negative kit. Whereas I can get 3 times more channels from a pair of strand/botex ones??? <_< Is this more expensive than normal, if so where can I get it cheaper.

 

Thanks in advance

 

PN

[Ike]

Is there anyone at your school who could knock up a few simple voltage inverters? Simply 0 to 10V to 0 to -10V based round an op amp or something? This would allow you to use the cheeper demuxs.

 

Ike

[peternewman]

Hi,

 

There are people at school. But the Botex/Strand one is cheapest and does +ve and -ve, only thing is we will need to softpatch on desk to get all the dimmers channels in a row. Im not sure whether we would be able to persuade the tech teachers to make up say eighteen copies of one circuit <_<. Also it wouldnt really be worth the effort just to avoid the softpatch. Its the different connectors which will be more of a pain.

 

OR do you mean there are even cheaper demux's which only do +ve or only -ve, if so please give me some more information on them.

 

Can someone confirm £500 is the rough usual price for a Z88 demux??

 

Thanks for the idea, hopefully looking forward to some info.

PN

[Brian]

Can someone confirm £500 is the rough usual price for a Z88 demux??

List price is £435 plus £80 for each 24-channels of -ve output (excl VAT).

[Ike]

Hi,

 

There are people at school. But the Botex/Strand one is cheapest and does +ve and -ve, only thing is we will need to softpatch on desk to get all the dimmers channels in a row. Im not sure whether we would be able to persuade the tech teachers to make up say eighteen copies of one circuit :P. Also it wouldnt really be worth the effort just to avoid the softpatch. Its the different connectors which will be more of a pain.

 

<snip>

sorry - didnt read the problem correctly <_<

[MarcT]

Has anyone ever used the Botex ME-72. Whats it like, can it do +- at the same time?

Hi Peter,

 

I own a Strand version of the Botex ME-72 demux, which they call the S72.

 

Its a great little unit for its price, but be aware that the output polarity and voltage settings apply to all of the analogue outputs. In other words you can't have a mixture of +ve and -ve channel outputs, or different voltages at the same time.

 

Also, you cannot change the dimming curve (the scaling between the DMX value and analogue level) - although this is only an issue if you have other dimmers or demux using a different scaling.

 

The 25way DIN to 8 way cables should be easy enough to make up yourselves, and unless your dimmers have BLEECON plugs you can gets all the parts you need from RS.

 

More info on the Strand S72 is here:

S72 Demultiplexer

 

Edit: Can't make the above link work. Cut & Paste it instead...

 

Regards,

Marc

[egw]

Hi,

 

The Zero88 betapacks will accept either a 0v to 10v or a 0v to -10v input. You need to swop a jumper around on the control board. Then you only need the demux to output one set of voltages.

 

cheers,

Ed

[Rob]

The Zero88 betapacks will accept either a 0v to 10v or a 0v to -10v input. You need to swop a jumper around on the control board. Then you only need the demux to output one set of voltages.

 

Very good point that we all managed to miss! The Betapack II's have it switchable on the front panel IIRC.