Line in from PC?

[fatrod]

Hi there,

I am looking for advice on the best way to set up multiple PCs / or if that is even possible.

The scenario is that I use two PCs regularly, and want both to be available as separate channels on my model 12.

I have one set up via USB on channels 1 and 2, and another going into channel 4 via a 3.5mm to TRS cable. The problem is with the latter - I am noticing that certain sound ranges on channel 4 are really quiet, and sound like they are either clipping or compressed to almost nothing.

For example the vocals or lead guitar on a track might completely disappear on the 3.5 to TRS channel.

Pressing the INST button helps, which makes me think it is a signal/gain issue, but does not "fix" the sound fully. It still clips badly for certain sound ranges.

Is there a correct way to do this, or its not actually possible? Really I'm just trying to do an Auxiliary in from a 3.5mm.

 

[-mjk-]

Not possible by USB. Only one PC can connect to the Model 12.

If you have a USB audio interface you could connect whatever you need for I/O from the Model 12's analog I/Os to the interface and get it in and out of the second PC.

 

[Mark Richards]

...going into channel 4 via a 3.5mm to TRS cable...
...certain sound ranges on channel 4 are really quiet...
...sound like they are either clipping or compressed to almost nothing...
...Pressing the INST button helps...

This is what I see happening:
1. By connecting computer #2's 3.5mm stereo out signal to the Model 12's Channel 4 TRS balanced mono input, you're randomly cancelling out those aspects of the incoming signal that make it stereo, creating the "certain ranges really quiet to almost nothing" problem.
(n.b. Compression, is different. It reduces the dynamic range of the audio, squeezing the audio signal together by raising the soft audio levels and reducing the loud audio levels.)

2. Computer #2's 3.5mm stereo output jack is likely the low impedance amplified headphone circuit.
a. Pressing the INST button converts the Channel 4 circuit to Unbalanced, converting the 3.5mm jack's stereo signal to mono, which addresses the "certain ranges really quiet to almost nothing" problem.

b. Pressing the INST button raises the unbalanced circuit from an impedance of 22kOhm to 1MOhm, which helps with but does not directly control the "clipping" problem. The way to control that is by lowering the signal output at the computer, and if that isn't enough, use the Gain knob to retard the signal coming into the Model 12.

Perhaps the better course might be to use the Talk/Music function on Channel 9/10.

 

[fatrod]

Thank you @Mark Richards , I did not even realise that Talk/Music input existed!

That is working perfectly

 

[shredd]

MR is amongst "the smart guyz" I so often invoke. Even I understood that going from stereo 3.5mm to mono TRS was a routing/connection problem; but I could no more articulate it that well than could a politician act with integrity or tell the truth...
@Mark Richards yew rawk!

 

[Max Relic]

@Mark Richards hats off!

 

[-mjk-]

1. By connecting computer #2's 3.5mm stereo out signal to the Model 12's Channel 4 TRS balanced mono input, you're randomly cancelling out those aspects of the incoming signal that make it stereo

One of those things that when you read it, you say "of course!" and then wonder why that didn't immediately come to mind. Excellent call Mark. You earned your check this week.