LP-->MOTU Ultralite-->Logic Studio connection problem

tele-pet · Post by **tele-pet** » Sun Mar 08, 2009 8:13 pm

As soon I connect the Little Phatty into the MOTU Ultralite, the LP changes from 'PRESET ACTIVE' to 'PANEL ACTIVE'. In addition to that, the sound changes significantly, sounding nothing like the preset. Using the same cable, I connected the LP to an amp with no problems.

I have a hunch I'm overlooking the obvious. Or, perhaps it's an advanced setting on the Phatty (or the Ultralite) that I need to change. For the time being, I will re-read the manual. Of course, it would be awesome if anyone had any ideas on this.

Amos · Post by **Amos** » Mon Mar 09, 2009 12:41 am

plug the cable into the ultralite but leave the other end unplugged.
measure between the tip and the sleeve of the unplugged end with a volt meter; test for AC and DC volts.

Normally I would not expect any voltage to appear here; this is a cable plugged into an input so there should be no signal.

however, if there is a fault of some sort, you may have a stray voltage on this cable; a stray voltage on the audio cable can cause odd behavior on the LP such as you are reporting. So, it's certainly something to check.

Cheers,

Amos

Najati · Post by **Najati** » Mon Mar 09, 2009 2:25 am

And just to be clear, you're talking about this happening when you plug a TS cable into the Phatty, right? Not a MIDI cable? Is the panel still responsive and well behaved? How do you hear the change in sound coming out of the Phatty? More info, please

tele-pet · Post by **tele-pet** » Mon Mar 09, 2009 7:29 am

I've tried multiple cables-- two different 1/4" guitar cables (not MIDI cables). Both of them cause the same problem. In addition to never getting a PRESET ACTIVE status, when I change to a different preset various settings adjust by themselves just after switching to the new preset. For example, when I switch to the Vaguely Vocal preset, the modulation, oscillators, and envelope knobs all slowly move a few knotches upwards.

There are not problems when I plug a cable into just the Phatty. It's only when there is a cable connected to the MOTU and the Phatty. I will borrow a voltage meter from work today and do some measurements. I think it's odd that I see the same problem with two cables though.

I wonder if I need a different kind of cable?

Voltor07 · Post by **Voltor07** » Mon Mar 09, 2009 11:37 am

tele-pet wrote:I've tried multiple cables-- two different 1/4" guitar cables (not MIDI cables). Both of them cause the same problem. In addition to never getting a PRESET ACTIVE status, when I change to a different preset various settings adjust by themselves just after switching to the new preset. For example, when I switch to the Vaguely Vocal preset, the modulation, oscillators, and envelope knobs all slowly move a few knotches upwards.

There are not problems when I plug a cable into just the Phatty. It's only when there is a cable connected to the MOTU and the Phatty. I will borrow a voltage meter from work today and do some measurements. I think it's odd that I see the same problem with two cables though.

I wonder if I need a different kind of cable?

I'm thinking the MOTU is sending some kind of voltage to the LP, as Amos stated. You are using the right cables...I use guitar cables to connect stuff as well.

tele-pet · Post by **tele-pet** » Mon Mar 09, 2009 12:12 pm

It sounds more and more like the Motu is the culprit. That could be challenging because MOTU's help site is very difficult to navigate.

For the time being, I will try to stay positive. I've gotten a new surge protector and a new balanced cable. I also have have a voltage meter. I will test this later tonight.

tele-pet · Post by **tele-pet** » Mon Mar 09, 2009 7:15 pm

Problem solved.

I replaced my surge protector.
I attached the three prong extension for my Macbook's power adapter.

I wish I knew exactly why it works but, honestly, I'm just thrilled that it does.

Thanks all for the advice!

Voltor07 · Post by **Voltor07** » Mon Mar 09, 2009 9:51 pm

That's awesome! The old surge protector most likely had a bad ground connection. Congrats on getting your rig to work properly.