Noise on 192 when tracking.

[XPERIMENT]

Hi.
My set up is G5 dp2.7g, 6 gig memory, pt 7, single 192, o2r.
I am tracking all my midi outputs directly into 192 through db25 to trs connector.
When I turn on the the input monitor of the track that I want to record, I hear buzz like noise when I turn up the volumes on pt mixer. I checked with o2r if I had noise from midi but it was fine.
The noise isn't loud but it kinda bugs me.

Is this normal? Or I'm doing something stupid?
Please help!

[francois]

check your that your db25 is not loose ,happened to me once
Francois

[crizdee]

Hi,

Have you tried the different +4/-10 inputs on the 192! then from within the HW setup page you can select which one you use. there is also trim pots on the back of the 192 for each input!?

Also try unplugging your midi instrument outputs from the 25way multicore and plug them back in 1 at a time to see if one of them is causing noise.

Have you got your midi instuments output levels up high enough! if they are too low then you will get a low signal to noise level coming into the 192!

Chris

[XPERIMENT]

Thank you for the help.
Francois, I checked all the cables and they were connected securely. I don't think it is the connection problem.
Chris, I tried +4 and -10 and it seems -10 sounds a little louder on the input. But the noise went louder as well. I tried trim pots. Sound went louder as well as the noise .
All my midi instrument's output level is on the max. I tried turning down the midi output level, but noise didn't go down with the sound.
It is such a subtle noise that you can't hear if you turn the audio volume lower than 0. But I want to track midi gears as clean, noiseless and loud as possible. If you set up your midi gear directly inputting to 192 like my setup, is there certain way to do this?

[Monte McGuire]

Thank you for the help.
Francois, I checked all the cables and they were connected securely. I don't think it is the connection problem.
Chris, I tried +4 and -10 and it seems -10 sounds a little louder on the input. But the noise went louder as well. I tried trim pots. Sound went louder as well as the noise .

You have a grounding problem. There's really nothing related to the computer or the 192 that will change this. There are two possibilities:

1) you're not effectively using the balanced inputs of the 192 since you used the wrong type of connection. To effectively float your keyboards (and break the ground loop) you can wire the keyboard such that the tip of the 1/4" connection from the keyboard (the unbalanced signal output) goes to the "signal +" pin of the 192 and the sleeve of the 1/4" connection (ground) goes to the "signal -" pin of the 192's input. Leave the 192's ground pin unconnected. Right now, depending on your cabling, you could have the ground connection of the keyboard connected to the ground pin of the 192's input, causing a hum loop. There are some el-cheapo 1/4" tip-sleeve to DB-25 harnesses out there (Cable-Up) that probably do this. You want to use a proper balanced connection using a 1/4" tip-ring-sleeve connector, and you can float pin 1 (sleeve) when you do this.

-or-

2) you need to get some sort of an isolation transformer in series with your keyboards to isolate their grounds. Go from the unbalanced output of your keyboard into an isolation transformer and then (using a balanced connection) from the transformer to the 192 input. This will allow the 192's ground to be isolated from the keyboard's ground, breaking the hum loop. Jensen, Ebtech, Rolls and others make boxes with isolation transformers in them.

Many older keyboards were very poorly designed. They used 2 wire power cords, so the chassis would float. If you connect them to a properly grounded system, hum currents from the power supply travel through the audio signal ground, rather than being safely dumped to the green wire of the power inlet. An isolation transformer (like a passive direct box) will solve this problem completely.


Best of luck,

-monte-

[XPERIMENT]

Thank you very much Monte!!
I tried your options and problem solved!!

[Monte McGuire]

Great!

Nice to hear you've got it working....


Regards,

-monte-