pin 1 connection for multi channel component set up

[prasanth.nath]

Hello,

I have recently built a Hypex based system with DLCP (a DSP) in 1 metal chassis and the Hypex UCD amps (and their power supplies) in another chassis.

I wanted to know - what is the technically correct way to handle pin 1 in a multi component build?

I have followed the wiring guidelines from Hypex, and from Bruno's paper on pin-1.

In pre-amp:
* Each signal cable from dsp board has a shield, which is connected to pin 1 of XLR-out on one end, and the shield pin on the DLCP-channel-out on the other end.
* pin-1 of XLR-out is connected to chassis also.

The above connections are made for all 6 channels in the pre-amp chassis.

In amp:
* Each signal cable from XLR-in to amp has a shield, which is connected to pin 1 of XLR-in on one end, and the shield-pin of the amp's audio-in on the other end.
* pin-1 of XLR-in is connected to chassis also.

The above connections are made for all 6 channels inside the amp chassis.

I would like to double check if this is the correct way to connect components.

Q1: It is not clear to me if I need to do this for all 6 channels or only 1.
Q2: In the amp, 4 of the amps are powered by 1 common SMPS power supply, while each of the other two have their own power supplies. I read somewhere that when 1 power supply is feeding more than 1 amp, the signal-shield needs to be connected to only 1 amp. Is there any science to this?

Thanks.
PS: I don't understand electronics, I just wanted to build a system so that I can hear great music.

 

[House de Kris]

In my opinion, this is one of those times where you need to pick a philosophy and stick with it. As I recall from my early days of audio, with balanced connections you can choose "shields go forward" or "shields go back." Or, you can choose to use the standard commercially available "shields connect at both ends." One of the beauties of balanced connections is that it enables you to completely break ground loops, but only if you opt for one of the first two philosophies. The nice thing about using XLR connectors is that they are directional by design, thus enabling you stick with your chosen philosophy without screwing yourself up.

Personally, I chose "shields go forward." Thus, all my cables have no connection at all on pin 1 at the destination end of the cable. Recently I've noticed a trend with some amps not having pin 1 connected to anything, this allows you to use commercial XLR cables and have a "shields go forward" philosophy.

Tour answer your questions,
1. Yes, do the same for all channels, not just one.
2. I see this as applying only to unbalanced systems, not balance.

 

[prasanth.nath]

Thank you.