Focusrite ISA 828. Wierd noise on DI inputs.

[punkrockdude]

I get some wierd noise when I use the DI inputs on my Focusrite ISA 828. It is not present when I switch over to mic input on the same channels. I have attached an mp3 of how it sounds.

I have used the internal ISA ADC going to my Multiface II correcly clocked so that should not be a problem. I have amplified the mp3 with 41.7 dB so that you don't have to turn up your monitors. When using distorted guitar amplifier emulators the noise is very loud. What is causing this? Regards.

interfearingsounds.com/blandat/isa828dicrackling.mp3

[punkrockdude]

I would really appreciate any thought on this matter. Regards.

[boid]

hey man,

I run into the same problem with some of my guitaramps every now and then.
it's usually just dirt in the jack, unplug everything, use a qtip maybe with some ethanol and clean it, then use a new one to "dry" it

it's weird though... it appears at random times and doesn#t matter if unplugged or not
cleaning has helped most of the times though

try it and if not we'll figure it out

[punkrockdude]

hi boid!
I actually noticed today that I hear it on the mic inputs too. Really wierd and it bothers me since the unit cost a lot of money.

[boid]

ok easy
i'd still try the cleaning

i understand it's a multichannel unit
which/how many channels behave like that?

and also does the same crackling noise appear *simultaneously* on all channles or on each one independently?

[punkrockdude]

Bois, I will try that out but removing the input TS jacks from the unit will some work but maybe that will fix the problem. Seems wierd though. Regards.

[boid]

no that's not what i meant!!
you don't have to remove anything!
just take a q-tip and clean the contacts, you can access them pretty easily, i mean if you can fit a guitar cable in there a qtip should fit just nice

is the unit still under warranty?

also to further circle the cause of this malfuntion it's important to know:
which/how many channels behave like that?
does the same crackling noise appear simultaneously on all channles or on each one independently?


there's a number of things that could be causing what you've described
from my experience most of the time it's diry jacks, dirty pots
but sometimes it's bad caps on the board or psu, or dead solder joints

[punkrockdude]

Thanks boid.

The noise seem to be on at least two to four channels. I will try your advices tomorrow and see what happens.

[punkrockdude]

I have taken the isa 828 out of the rack and placed it on top of the rack's plastic top cover, removed the isa 828's metal cover and done some testing and I hear no noise/crackling what so ever. I wonder why it crackled before. I will place it in the rack again and see if it starts to crackle again. Regards.

[Nick Sevilla]

I have taken the isa 828 out of the rack and placed it on top of the rack's plastic top cover, removed the isa 828's metal cover and done some testing and I hear no noise/crackling what so ever. I wonder why it crackled before. I will place it in the rack again and see if it starts to crackle again. Regards.

Hi,

1.- Is the crackling present when the unit is not plugged into anything at all? Or only when using something plugged into it?

2.- The fact that it does not make the crackling when not physically touching other gear might mean that the audio ground is connected to the chassis ground on your Focusrite unit. You may need to have it live elsewhere in your rack, or simply not in your rack at all.

Cheers

[punkrockdude]

I have placed it back in the rack and it does not make the noise anymore on any channel (so far). Could something have been loose that got back in its place when I took it out?