DI Killing 1/4" output

3506string · #1 01-12-2013, 04:12 PM

I run a Art tube channel preamp and IPR3000DSP power amp. Last night during a soundcheck/rehearsal I plugged into to the snake for the house. I got a loud pop and silence from my speaker. The house was getting sound but my power amp was not. So I unhooked the xlr out and I got signal back to my power amp. So I used a 1/4" to XLR adapter from the sound man to use the Thru output from my IPR3000. Same thing, house is getting sound but my power amp is not.

I run a balanced 1/4" from the Art preamp to the IPR. I vaguely recall having this problem once before.

Any Ideas to what's going on.

I think it has something to do with the balanced connections but not really sure what the problem is.

M. Owen Santy · #2 01-12-2013, 10:29 PM

Are you using an incompatible 1/4 plug (TRS ~vs~ TS). Sounds silly but it's the silly little things that cause crap like this. Also check phantom power.

If all else fails contact ART and ask - I think ART was absorbed by Yorkville Sound years back and their service is top notch.

3506string · #3 01-12-2013, 10:43 PM

The cable from my pre to my power amp is TRS to TRS. Sound guy said he wasn't running phantom.

The show was tonight. I decided to bring my art tube pac to run as a DI. I ran my bass to the tube pac. The tube pac to the house and to my rack preamp. With this setup I got sound to the house and to my cab but the signal was very noisy(humming and popping). Finally we decided I had enough cab to carry the venue.

I just checked with my interface to be sure I could still get signal to both the 1/4" and XLR, and sure enough, it is working just fine. I'm thinking it was something with the snake or the board. I'm not sure about this one. The only other thing I can think of is I was plugged into a power conditioner with the house power amps per sound man's request. Doubt that had anything to do with it but, who knows?

beans-on-toast · #4 01-13-2013, 09:01 AM

Just to be sure, from the back of the Art tube pac, you are running a TRS cable from the unbalanced 1/4" output of the Art to the 1/4" balanced input (center of the XLR) of the IPR. Since this has worked, I assume that there are no issues in doing this. Sometimes you need a 1/4" unbalanced to balanced cable. You can run from the Art's balanced output XLR connector to the mixer. You were plugged into the left hand side at the back of the Art, not the right which is an input.

When running just from the Art to the IPR, it would be better to use an XLR cable. The connection is better and you are running balanced to balanced. The specs are typically different for 1/4" and XLR inputs and outputs. They have different impedances and different signal levels. In general, if you can, go XLR to XLR.

A hum at the mixer would indicate that the ground needs to be lifted, pin-1 on cable connected to the Art's output XLR disconnected. Some mixers have a switch for this, otherwise you can use a ground lift patch cable. This breaks a ground loop and eliminates the hum.

3506string · #5 01-13-2013, 09:21 AM

You are right, The output of my art is unbalanced. I am still using the TRS 1/4" cable because my last preamp had balanced 1/4" outs. I never really checked to see if the art was balanced or not. I will have to go ahead and switch out that cable to a standard TS.