Balanced to Unbalanced Leads

[richie00boy]

Hoping Al is around...

There's three ways these leads can be done:

1) Stereo jack/XLR to phono plug, cold shorted to ground at jack/XLR end
2) Stereo jack/XLR to phono plug, cold shorted to ground at phono end
3) Stereo jack/XLR to phono plug, cold left unconnected at phono end

When you buy ready-made leads, which is generally the standard type out of the above?

[AndrewT]

Hi,
have you seen the RANE site for other combinations and switched ground lifts for experimenting (not mains ground lift).

Jensen also show a psuedo balanced output that costs very little to add and gains in some noise rejection.

Maybe that's not what you have.
Are you converting true balanced output to unbalanced input? Again Jensen's site shows some options that preserve the noise rejection.

D. Self has a good paper on balanced connections with unbalanced/pseudo ins/outs.

As for what is available retail, who knows?

[richie00boy]

Thanks Andrew, but I have studied in depth several times every single one of those items you mention.

Just awaiting 'real world' info from people as per my original specific request.

[moamps]

Hi,

There is a one more way (no. 4 ):

XLR+ to phono hot
XLR- to phono gnd
XLR GND n.c.

I don't know which way would be industrial standard, if any. The optimal choice of the wiring depends of the source output type (transformer output, electronicaly balanced etc.) and the design in question. I thus use types 2,3 and 4 in my wiring projects.

Regards,
Milan

[pinkmouse]

Originally posted by richie00boy
Hoping Al is around...

There's three ways these leads can be done:

1) Stereo jack/XLR to phono plug, cold shorted to ground at jack/XLR end
2) Stereo jack/XLR to phono plug, cold shorted to ground at phono end
3) Stereo jack/XLR to phono plug, cold left unconnected at phono end

When you buy ready-made leads, which is generally the standard type out of the above?

In my experience, 2) is most common, but most techs carry a soldering iron just in case something needs to be "adapted" on site. However, it's always a good thing to mark up altered leads with a bit of tape, so the lads and lassies back in the yard can put it back to standard before it goes out on the next job.

[sangram]

There's really no standard unfortunately, when it comes to this.

I've seen type 2 most often though, and 3 sometimes, but never type 1.

When doing my own connectors for this kind of application I always use type 2, however after reading through some of those papers I think that is wrong and the shield should be left unconnected, the signal coming off hot and cold, and find a way to plug the shield to the chassis ground (not signal ground as will be the case for all the above). Therefore not use a phono at all.

[richie00boy]

Good good, I was hoping type 2 would be most common. That means I can use the balanced output circuit I wanted to use and I will get ground loop rejection even with unbalanced inputs.

Thanks Al and Sangram.

[moamps]

Originally posted by richie00boy
That means I can use the balanced output circuit I wanted to use and I will get ground loop rejection even with unbalanced inputs.

Ahem...I don't think you can get ground loop rejection if pin1 of the XLR (ground) is connected to the groundpin of the RCA connector. But, you may get ground loop rejection using wiring no.4 in my previous post.

Regards,
Milan

[forr]

A circuit idea published in Electronics World, may 2006, by Marcel van de Gevel, is : "Electronic Audio Balun". It deals with the conversion of balanced to unbabalanced (and vice versa) audio signals and uses a common-mode loop. There are no CI's, only discrete bipolars.

[richie00boy]

Originally posted by moamps
Ahem...I don't think you can get ground loop rejection if pin1 of the XLR (ground) is connected to the groundpin of the RCA connector. But, you may get ground loop rejection using wiring no.4 in my previous post.

Regards,
Milan

Self says otherwise.

From Doug Self website
When an unbalanced output is being driven, the quasi- floating output can be wired to work as a ground-cancelling connection, with rejection of ground noise no less effective than the true balanced mode. This requires the cold output to be grounded at the remote (input) end of the cable.

Which makes sense to me.

Originally posted by forr
A circuit idea published in Electronics World, may 2006, by Marcel van de Gevel, is : "Electronic Audio Balun". It deals with the conversion of balanced to unbabalanced (and vice versa) audio signals and uses a common-mode loop. There are no CI's, only discrete bipolars.

I have not seen that. EW seemed to go quite downhill in recent years so I have not looked at it much. I'll try and get a copy of that one, thanks.