RE: arsclist question about XLR/RCA connections, pads, etc.

["George Brock-Nannestad" <pattac@xxxxxxxx>]

I am only in partial agreement with Dave Meyers on this:

>  There are 2 main problems you are dealing with when going from XLR to
>  RCA.
> Number 1 is that a typical XLR connection is a Balanced signal,
> meaning both wires are HOT one has a negative polarity, the other
> positive (like 220V in a house) then there is GND. An RCA jack is
> unbalanced, meaning there is a hot and a ground.

----- to reduce cross-Atlantic confusion: what is described is the US 
type of 2-phase (180 deg phase difference), where zero is a centre 
tap on the transformer, and both ends will give the usual 110 V, but 
higher power may be drawn between the ends, giving a full 220 V. 
In Europe we have 3-phase (120 deg between phases) also in 
houses, not only in industrial installations.

> so you need some type
> of ACTIVE device to do the balancing or unbalancing for you.


----- now, this is obviously not true: a transformer will work for audio 
as well as for mains, and indeed, transformers were the rule before 
active devices became dirt cheap.

>  Number 2 is that there is a Signal level difference. typical XLR type
> signals are +4 typical unbalanced signals are -10, once again, you
> need some type of active device to adjust this signal level difference
>  Number 3 (ok I lied, there are 3) there is also an impendence
>  difference in
> the signals, Balanced signals are typically 600 ohms, and unbalanced
> signals are typically 10-50K ohm.
> 

----- again I stress that all three problems may be solved either 
actively or passively by means of a transformer, as I said in an 
earlier mail:


either a Sonifex Redbox No. RB-BL2 Unbalanced-to-balanced bi-
directional converter (www.sonifex.co.uk). This will make a 
complete input and output connection to unbalanced apparatus.

or a minimum of two Lundahl transformers w. connectors 
(www.lundahl.se, or in the US from K&K Audio 
www.kandkaudio.com)

Kind regards,


George Brock-Nannestad
Preservation Tactics
Denmark

----------------------------------
Original message:
> To: ARSCLIST@xxxxxxxxxxxxxxxx
> Subject: arsclist question about XLR/RCA connections, pads, etc.
> 
> 
> Can someone lead me to info about how to go from XLR outputs on
> professional recording equipment to RCA phono jacks on consumer
> equipment like CD burners, computers, cassette dubbing decks, etc.? 
> Do I need a matchbox?  Cable or adapter w/pad??  Thanks! Don Share
> Curator George Edward Woodberry Poetry Room Harvard College Library
> Harvard University Cambridge, MA 02138
> 
> Telephone: (617) 495-2454
> Fax: 	    (617) 496-3692
> E-mail:    share@xxxxxxxxxxxxxxx
> Website for policies and schedule of events:
> http://hcl.harvard.edu/houghton/departments/poetry.html

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