UPS, Power and Hum/Noise

I spent several hours this weekend trying to track down a significant hum/noise/whine in my recording/playback equipment, and ultimately I tracked down the source of 90% of the problem to a failing UPS.   The whine was present while using headphones off my audio interface, but it became worse when routing the audio interface output back through my computer speakers.   At that point it was unbearable, it was even showing up in my recordings during playback. 

But, as I said, I tracked down the major problem which was a UPS near the end of its life cycle.    Once I removed it from my system, the whine/noise was completely eliminated during recording and playback if I use my headphones.  However, I still get a slight high pitch whine over my speakers when I route the output through them.  The whine does not show up in the recording, at least not noticeably.  So, a few questions;

- Do I need to run separate monitors for my recording playback vs. a sound output for my computer?
- I am routing the sound back from my audio interface using the headphone out jack and plugging it into the mic input on my sound card. (volume controller actually on a Bose sound system, but it is effectively the same thing)
- I need a new UPS and was wondering if there were features that I should include that would benefit my audio recording.  For example, is there any benefit to the "Pure Sine Wave" type of UPS?  I know that "pure" is just a marketing term, but it is a more consistent (smoother maybe) source of backup power.  I would if this also does a better job filtering power.

Thanks.

SR

if you really are plugging the lambda into your computer soundcard then you're completely defeating the purpose of having the lambda.  you might as well record using the onboard soundcard.

also, this is very likely a source of problem for the buzz/hum.  you're probably creating a ground loop between the lambda and the computer that way.

you can set up your lambda to be the only output if you want (that's the way I do it - I have my DAW soundcard act as the ONLY soundcard and I have my onboard soundcard disabled).  or you can leave your onboard soundcard and computer speakers connected and use that separate from the DAW.  either way will work fine.

the UPS does not matter much to the DAW as long as it isn't noisey or creating ground loops.  pure sine wave to the computer doesn't hurt, but it doesn't benefit much either unless you're using power that is already very "noisey."  (noisey as in harmonics and or frequencies other than the 60Hz intended for power).

most UPS's are not really "UPS" - this is a pet peeve with me and the consumer type UPS's will literally have no affect on the computer as far as sound recording goes unless it's designed poorly and doesn't have good ground design.

UPS = "Uninterruptable Power Supply" and for consumer UPS's they are not "uninterruptable."  I like to go to Best Buy or CompUSA and ask the sales drones if the models on the shelf are true UPS systems and of course they say they are.  then I ask them what the "switching time" is and they will rattle off some low number.  BBBBUUUUZZZ!!!  wrong answer!  you lose!

a true UPS does not "switch" - a switch is an interruption in power - however "negligable" they say it is - it doesn't matter, it's still a switch and it's still a period of time which gets converted from one source to the other.

a true UPS has the system running on the battery ALL the time and the 60Hz AC is used to constantly charge that battery.  it might give DC power directly to the computer (best scenerio, but highly unlikely especially for consumer use) or it might use an inverter to convert the DC battery current to AC for the computer's power supply which converts it back to DC for the computer to use.  ugh.  what a stupid scenerio that is!  all of that transferance is inefficient, noisey and loses too much power in the translation in the form of heat.

however, a true UPS which sends DC current directly to the computer would be the ultimate way to achieve quiet operation for a recording device.  but you're not going to find a UPS for consumer use which will deliver DC power directly to the computer (by-passing the computer's power supply and plugging directly into the motherboard and peripherals).

so after that rant of my pet peeve - all that to say:  consumer "UPS" systems only matter if they are designed poorly.  most any of them are fine.