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100m+ Line Level Runs

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nev23 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote nev23 Quote  Post ReplyReply Direct Link To This Post Posted: 18 March 2012 at 10:03pm
Depends how quiet the lines need to be.
Few modern pieces of equipment have truly balanced line outputs or inputs; most make do with "impedance balancing" meaning that the impedance of the hot and cold lines is the same. But because the amplifier configuration is not symmetrical, the actual voltages and currents in each  leg will usually not be the same. This will start to show up at quiet moments, especially if power cables are run close to the signal cables or if someone is using a mobile phone nearby.
Transformers are good from a safety perspective but poor on bass distortion.
Alice Matchpaks are handy for this sort of thing.
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audiomik View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote audiomik Quote  Post ReplyReply Direct Link To This Post Posted: 18 March 2012 at 10:51pm
Re: "Transformers are good from a safety perspective but poor on bass distortion."

Don't know where this idea came from, as properly designed transformers will perform very well at high signal levels easily down to 20Hz.  It is usually at high frequencies that problems occur if the 'wrong' material is used for the core.

Granted the low cost ones will saturate cores or suffer other non-linearity at both low and high frequencies compared with say 1kHz at a given signal level - but who, with the known limitations of these low-cost transformers, would actually use them for professional systems?

Mik
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shagnasty View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote shagnasty Quote  Post ReplyReply Direct Link To This Post Posted: 19 March 2012 at 12:06am
I have say Audiomik has a good point, the transformer option on most gear is £100 + per channel, most broadcast rigs I've worked on onlu run tranny balanced, I have to say the post is true but the bit about trannies is just plain crap, an alice match pack won't touch a simple hi-end tranny box..
 
That said for normal use the Art DTI....
 
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audiomik View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote audiomik Quote  Post ReplyReply Direct Link To This Post Posted: 19 March 2012 at 12:43am
You should find this Paper by Gavs Sowter of interest which relates to history and research on magnetic core materials used for Audio Transformers: http://www.sowter.co.uk/pdf/GAVS.pdf

I had numerous meetings with him over in Ipswitch for designing specific Audio Line transformers - a very interesting and clever man who is now missed by many.
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Grumpy View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Grumpy Quote  Post ReplyReply Direct Link To This Post Posted: 19 March 2012 at 10:56am

Yes had lots of long chats with Dr Sowter over the years and he has wound me some cracking transformers - his departure is a great loss to the industry

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