Problems with Presonus TubePre

S

silentman

New member
Hello all,

I'm having problems with my presonus Tubepre. I'm attempting to record my bass guitar through the tube pre and into my UA-1000. The only problem is that the bottoms of my waveforms look chopped off (not good), but the transients look fine on the top of the waveform. Does anyone know what might be causing this?

Thanks,
Jamie
 
silentman said:
Hello all,

I'm having problems with my presonus Tubepre. I'm attempting to record my bass guitar through the tube pre and into my UA-1000. The only problem is that the bottoms of my waveforms look chopped off (not good), but the transients look fine on the top of the waveform. Does anyone know what might be causing this?

Thanks,
Jamie
Click to expand...

don't know.......
maby big-ass dc off-set?
and turn down?

not trying to be a wise ass, but noone's said it yet.
 
I second the DC offset theory. It sounds like the pretube may be adding some bias current to the soup.

G.
 
I think that you might be on to something with the DC off-set thing. I have the drive on the tubepre at about 12 o'clock and the gain at about 9 o'clock with the pad on. I have the pre on the UA-1000 turned all the way down. Also, the AC wall-wart that powers the TubePre is plugged into a different outlet than the rest of my equipment which is plugged into a Furman power conditioner. Do you think that a grounding problem between the conditioner and another socket in the room would cause this problem?

-Jamie
 
Last edited:
silentman said:
I think that you might be on to something with the DC off-set thing. I have the drive on the tubepre at about 12 o'clock and the gain at about 9 o'clock with the pad on. I have the pre on the UA-1000 turned all the way down. Also, the AC wall-wart that powers the TubePre is plugged into a different outlet than the rest of my equipment which is plugged into a Furman power conditioner. Do you think that a grounding problem between the conditioner and another socket in the room would cause this problem?

-Jamie
Click to expand...
Yeah, you may want to plug the pre into the power conditioner with your other equipment...
 
A quick check is to record some signal through the whole signal chain without actually playing the instrument. If your "flatline" in your DAW software is riding above or below the zero centerline, you have a bias current present.

Remove the TubePre from the chain and see if that current disappears. If so, you know it's in the TubePre. If not, then it's coming from elsewhere in the chain and you'd have to track that down.

If stuff like changing outlets fails to remove the problem, it can be attacked via software. Many DAW software packages have a "DC offset" setting built in, search the Help files for "DC offset" for more.

If your software does not have a DC offset option, there are free plugins available on the Internet including the one from Analog X.

G.
 
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