The Patchbay Blog

On Aug 4, 2017, at 6:57 PM, Chris Mehalso wrote:
Hi Mister Patch Bay –

I am having trouble. Possibly more than one problem. I have 8 outputs on my sound card, so I created 8 outputs on my TT patch bay. One of those stereo pairs is normalled to a pair directly below it that goes to a little headphone amp. The headphone amp accepts TRS input, so I had to build a cable that takes the two balanced channels and combines them onto one TRS that I could plug into the headphone amp.

Problem #1 is that I simply cannot get the normals to make sound. I assume this is a problem with the patch modules or my cables from the sound card. I will address this myself. But I tested it by simply using patch cables to grab sound from a known working output. More problems then . . .

I am getting a loud hum. I also noticed that the click track sounds clear and appears on BOTH EARS when I only have one of the two patch cables connected. Then I connect the second cable the sound volume drops significantly and the quality is really poor. This seems like a phase error because I built the cable wrong. Here’s how I built it:

The TRS end:

T – both red conductors from two cables
R - both black conductors from two cables
S - both ground conductors from two cables

The patch bay end:
Left cable
Black conductor – T
Red conductor – not connected
Ground conductor – S

Right cable
Red Conductor – T
Black conductor – not connected
Ground conductor – S

I thought by doing this I would be creating a stereo unbalanced feed from two mono balanced feeds . . . but I appear to be doing something wrong. Can you help??


Chris Mehalso, CTS COHERENT MEDIA SYSTEMS SPECIALIST BTX TECHNOLOGIES, INC. // // // Direct Line: 904.885.0054

Hey Chris,

The input to your TRS headphone amp should be as follows: Left channel hot goes to the tip of your 1/4” TRS cable that plugs into your headphone amp. The Right channel hot goes to the ring of your 1/4” TRS cable that plugs into your headphone amp. The ground on the 1/4” TRS cable that plugs into your headphone amp can come from either left or right channel ground.
That’s it. It is two mono channels that drive the stereo headphones.

Bobby Hickey
Visit Bob Land Below
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