When connecting a single ended source, you often see that the single ended hot line is connected to the balanced hot line (XLR pin 2), and the ground of the singe endsed source is then connected both to the cold line of the balanced input (XLR pin 3) as well as to the ground of the balanced input (XLR pin 1).
ground at the receiver end.
I believe this last connection, to receiver ground, is not required (assuming you have enough headroom), but I'm not sure.
What do ye think?
Jan
ground at the receiver end.
I believe this last connection, to receiver ground, is not required (assuming you have enough headroom), but I'm not sure.
What do ye think?
Jan
You mean like this https://neurochrome.com/pages/pseudo-differential-cable
I'm not sure how much time you save not terminating this way?
I'm not sure how much time you save not terminating this way?
IMO it depends a bit on how the receiver is wired. A fully differential receiver will definitely require Pin 3 connected (or at the minimum, grounded which is the same thing i this case). A transformer with no galvanic connection to pin 1 will also need a reference for pin 3. In the case of a 'bridged' power amplifier, it becomes mandatory.
There are peudo-balanced outputs that drive only one side of the output and balance only the impedance at the driving end with a terminating resistor. This does result in a fully balanced input at the receiver end as it sees the same effective impedance on both lines.
Some receivers like the ones on soundcards and interfaces tend to not care, as they use the power supply ground reference anyway for both inputs (being based on simple opamps, as they tend to be).
There are peudo-balanced outputs that drive only one side of the output and balance only the impedance at the driving end with a terminating resistor. This does result in a fully balanced input at the receiver end as it sees the same effective impedance on both lines.
Some receivers like the ones on soundcards and interfaces tend to not care, as they use the power supply ground reference anyway for both inputs (being based on simple opamps, as they tend to be).
Pin 1 is supposed to be the shield, connected straight to the chassis or enclosure, if the balanced equipment is AES-48 compliant. Connecting it has the advantage that you get a continuous shield around both devices and the cable, and that you can't get excessively large common-mode potential differences if there is no other ground connection. A disadvantage is that it may become part of a ground loop if the grounds are already connected via some other path.
I usually connect it by default. If needed because of ground loop issues, I either open it or put a resistor of 220 ohm or so in parallel with a 100 nF capacitor in series with pin 1. You then keep the shielding for high frequencies and still have a soft connection between the grounds when the other connection gets interrupted.
Attachments
Do you have complete knowledge of the receiving side? Certainly even whitlock mentions only grounding at one end so I suspect you would see no issues.
Yes the receiving side is also my design.
I was doubting it because Bruno P recommends to connect pin 3 and pin 1 together with the se ground when using a se source for the Purifi 1ET400 amp.
But what you guys are saying convinces me that that is not necessary.
Jan
I was doubting it because Bruno P recommends to connect pin 3 and pin 1 together with the se ground when using a se source for the Purifi 1ET400 amp.
But what you guys are saying convinces me that that is not necessary.
Jan
I know that article. I originally published it in Linear Audio ;-)
But as far as I can see, it doesn't address my question ...
Jan
But as far as I can see, it doesn't address my question ...
Jan
Pin 3 tied to pin 1, tied the ground is the most common way of doing it because often the grounds are tied together via the power ground.
I’ve tried leaving out pin 1 when one of the devices doesn’t have a power ground. Results were mixed. It’s not too difficult to try both.
I’ve tried leaving out pin 1 when one of the devices doesn’t have a power ground. Results were mixed. It’s not too difficult to try both.
We used to use a 10k 10 turn pot centered at 5k then use pin 2 of the pot for the unbalanced in and pins 1 and 3 as balanced out. They go to the xlr pins 2 and 3 while the unbalance ground goes to pin 1 of the xlr. You can adjust the pot to balance the + and -.
