Digitial clipping in Interface

soapfloats 11 September 2009

This is a new issue that has reared its ugly head a few times.

Here is the signal chain:
Kick > Beta52 > Focusrite ISA 428 > PreSonus Firestudio (Insert Ch1) > PC (Cubase SX3). I run an XLR > 1/4" from the 428 to the FS insert.

Periodically and randomly the level of the signal from the preamp will more than double. I hear this in the monitors (no DAW necessary), and it shows in the recorded waveforms. It literally sounds like the kick head is being blown open w/ each hit. It randomly comes and goes, sometimes w/in the same track/song.

I've traded out the 52 for a CAD kick mic; mic cables, and cable connecting the the 428 to the FS. No luck - it comes and goes on a whim.

The levels on the ISA428 seem to be fine (peaking @ -10db or lower). I get no visual indication of a clip from the preamp, the Firestudio (and Control Console), or inputs on Cubase - only audio indications.

Trying to get ahold of the folks at PreSonus as I type, but thought someone here might have a clue.

Thanks,
Ben

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Comments

XLR->TS or XLR->TRS? When using an insert it makes a huge diffe

TheJackAttack Fri, 09/11/2009 - 17:11

XLR->TS or XLR->TRS? When using an insert it makes a huge difference.

I'm pretty sure I put a TRS back there. I'll check for sure when

soapfloats Sat, 09/12/2009 - 16:37

I'm pretty sure I put a TRS back there.
I'll check for sure when I'm in on Monday.

You can't use a pure XLR->TRS if you are going into an insert po

TheJackAttack Sat, 09/12/2009 - 17:20

You can't use a pure XLR->TRS if you are going into an insert point. Usually the tip=send and ring=return. Check with your specs to be sure. A custom converter cable then needs to be used.

Thanks Jack - I've got a bevy of different cables lying around,

soapfloats Sun, 09/13/2009 - 21:53

Thanks Jack - I've got a bevy of different cables lying around, so I have the necessary XLR>TS cables. I'll make the switch.

However, I use the same type of cable to go into both inputs 1 and 2. This is only a problem w/ 1, and only w/ the kick drum. Input 2 is usually dedicated to an OH mic. I also use both channels for voice, acoustic and electric guitar mics, and direct box, but have had no issues w/ these sources.
The frequency and randomness of the noise is what makes this most confusing for me...

It isn't that you need an XLR->TS cable, you need an XLR that go

TheJackAttack Mon, 09/14/2009 - 08:03

It isn't that you need an XLR->TS cable, you need an XLR that goes from pin 2 to the ring on the TRS and then tie pins 1 and 3 together on the XLR going to the sleeve of the TRS. The tip of the TRS won't be connected to anything in this scenario.

At least that is my memory of this particular conversion cable.

If the insert is wired T (send) R (return) S (shield/common/grou

Codemonkey Mon, 09/14/2009 - 14:39

If the insert is wired T (send) R (return) S (shield/common/ground/whatever)...
I'd ditch the T on the jack end.
Which is what TheJackAttack said.

Tying the other XLR output that has the inverted signal to the shield shouldn't matter, unless the state of it being connected affects the tone/electrics of it all?