Background noise!

[davekershaw]

Thanks Mojo.Just saw your post.I got the Firebox from the States, so the power unitis the wrong voltage for here.I'll see what I can do Monday. Maybe an adapter.Will get back to you then.Cheers,Dave.

[prez]

Sept 26, 2008, 7:59am, aimusic wrote:I do think he's talking about the general hiss you pick up from the pre in the firebox... I think anything over 12 starts to generate a hiss, the louder you get, the louder the hiss becomes, that's why I think he's gotta try and establish a decent level without having to boost the gain on the pre....lol! Just totally ignored this advice and it sounds like it may be the problem. Jude 2

[matthoggard]

Definately fix your voltage issue!!! I am an electrician and I deal with this problem alot. If your voltage is higher than the equipments rating you can severely damage the unit. Remember, the higher the input voltage the lower the amperage at the unit. BUT the sensitive circuit board may not handle that higher voltage. If your voltage is lower than than the rated input , then the amperage the unit uses goes up. This will overload resitors and diodes on the circuit board. When you increase the gain it increases the amperage that much more. Fix this before you do anything else or you might be buying a new unit!!!Make sure your electrical system is grounded. Im not familiar with the UK's power system but all systems work on the same principal. A grounded system will dissiapate harmonic and electromagnetic interference. Have you ever been in a club with neon lights and the amps and PA hum like crazy? Or get that shock when you touch your mouth to a microphone while playing your guitar? This is a perfect example of an ungrounded system. Consult with an electrician to find out if your system is grounded.

[mojobone]

Sept 27, 2008, 5:26am, prez wrote:Sept 26, 2008, 7:59am, aimusic wrote:I do think he's talking about the general hiss you pick up from the pre in the firebox... I think anything over 12 starts to generate a hiss, the louder you get, the louder the hiss becomes, that's why I think he's gotta try and establish a decent level without having to boost the gain on the pre....lol! Just totally ignored this advice and it sounds like it may be the problem. Jude 2Probably not the preamp itself, as the issue shows up in the monitors but not the recording.@Matt: He's powering the Firepbox from the firewire bus, so no voltage mismatch applies, but the bus power could be picking up interference from an internal fan or power supply.

[davekershaw]

Quote:@Matt: He's powering the Firepbox from the firewire bus, so no voltage mismatch applies, but the bus power could be picking up interference from an internal fan or power supply.It's Monday morning, an' I'm back on it!I was going to say the same Mojo, but thanks for your input Matt.And thanks Prez. I didn't ignore it. It's just not as simple as that; it happens at low volume too. That would come under: "novice, who doesn't know you'll get noise if you turn the volume too high". I'll try the mains power, if I can find a suitable adaptor.We're 240 volts here, so I gotta get it right, otherwise the problemwill be which interface to replace the Firebox with! Will let you know what transpires.

[aimusic]

I know this might sound daft, but any chance the hiss is coming from your speakers? I mean I know some speakers if you turn them up fully, they pump out a slight hiss sound? just a thought....

[davekershaw]

Sept 29, 2008, 2:59am, aimusic wrote:I know this might sound daft, but any chance the hiss is coming from your speakers? I mean I know some speakers if you turn them up fully, they pump out a slight hiss sound? just a thought....No, it's not daft Brad, but the sound also comes through the headphones!

[anthony34]

I'm out of my depth here - and I don't know the unit concerned BUT if you've got a volume control and a gain control on this device, GAIN higher than VOLUME ie pre-amp higher than main amp is ALWAYS distortion and often enough simply strong hiss. So, if there's two gains anywhere in the chain, ensure the main amp is the higher level. Michael W.

[davekershaw]

It's not the power fellas!In Sonar, as playback hits each separate track, the noise increases.Even though it's not recording, it's annoying when trying to mix.I don't get it!!

[audiogeek]

Sept 26, 2008, 11:24am, milfus wrote:yeah im thinking emi, its not possible to move it to like the other side of the desk to test it is it?If it's a hiss, it's not EMI. ElectroMagnetic Interference shows up in two audible ways. The UK uses AC power on a 50 Hz cycle, rather than the 60 Hz here in the US. So a 50 Hz hum indicates inductive coupling from an adjacent current source, or injection of a ground loop into the signal path. A 100 Hz buzz indicates one of three things - capacitive coupling from a voltage source, "dirty power," or in the case of a damaged unit, blowing of the filter caps in a power supply. Coupling from both the current source and voltage source can be a nearby electrical cable. Dirty power, or noise injection from the voltage source, can come from any other electrical item on the same circuit which generates a lot of harmonics on the neutral, such as fluorescent lights, like Matt said.Hiss (white noise) is created by ALL electrical components, even simple resistors. The circuit design of a piece of gear will make it hiss more or less than another model, at the same gain levels. If it's not present on the recording, but is present on the playback of the tracks, I would suspect either a noisy output stage of the interface (you can have an input stage that's quiet and an output stage that isn't, depending upon the circuit design), or the output gain structure.Just so we all understand the characteristics of the noise, is it hiss, hum, low frequency buzz, or a high frequency buzz (which can be generated by some computer/laptop power supplies (I have a problem with this and have to always record and mix with the laptop on battery power.Lots of rambling there. Hope this helps. If not, I'll try mulling over other possibilities.Brad