How to tame 50hz with a 1' depth

Stuart - This really is the wrong forum to talk about star grounds. But, good as a star ground is, it's not the only good ground system and in some studios it may not be the best choice.

I don't see how it can be the wrong forum, when that's where the thread has gone in tracking down the original poster's problems with 50 Hz.! In any event, what other grounding system would you recommend for a studio? And under what circumstances would star grounding NOT be a good idea for a studio? - Stuart -

To make it simple if you looked at the sine wave of the two power legs they are out of phase in the case of 220-240.

Out of phase as compared with what??? Neutral? Ground? Each other? That would only be the case if you are talking about three-phase power, which is unlikely to be the situation in a home studio. In normal single-phase 220 volt systems, such as those used in South Africa, Chile, and most likely India too, you have a "live" or "hot" or "phase" conductor, and you have a neutral conductor, which is usually tied to ground at the distribution panel. So there is no "out of phase" situation across live and neutral, nor from live to ground.

You need a line conditioner to correct this if it is coming in that way.

A line conditioner is not necessarily going to fix phasing issues when deriving single phase from 3-phase. A simple isolation transformer can do the job just as well, and probably much cheaper.

there is a certain amount of distortion that is "to spec" per the power company so they won't do anything about it so that's why we are installing a HUGE conditioner where I work.

If you have serious waveform distortion problems with your mains supply, then probably the best you can do is to go for a true on-line dual-conversion UPS. It takes in pretty much any garbage you feed it, over a very broad range, and simply uses that to charge the batteries. Then the battery power is used to run an inverter that creates a brand new pure clean sine wave for the output. Nothing better. Cleans up power like you wouldn't believe. Beats a simple conditioner hands down, and they aren't all that expensive at all. A decent one for an average home studio shouldn't cost no more than a thousand dollars or so. (Or maybe around two grand, if you have a lot of heavy equipment). I use a simple 1 kVA or 3 kVA UPS for live sound gigs regularly, if I have any suspicions about the feed I'm getting.

I doubt it's a grounding issue since it's at 50hz

Sorry to disagree, but the fact that it is at 50Hz indicates that it most likely IS a grounding issue! What else would it be, if it isn't a grounding problem? 50 Hz hum in your audio is a pretty certain red flag that you have a grounding issue somewhere. (Or perhaps a poor quality pick-up on a guitar or something....) - Stuart -

Hey guys, Glad to see people willing to help... the true spirit of these forums. Here's a link to the complete thread, if anyone is interested: http://www.gearslutz.com/board/studio-b ... eeded.html It's a pretty long read, sorry. Amit has run some measurements from a battery powered UPS, and the spikes are gone. He has said that there is no audible interference, it only shows up on the graph. I had wondered if it isn't the checkmate spl meter he is using for the rta mic.

Soundman2020 wrote:

I doubt it's a grounding issue since it's at 50hz

Sorry to disagree, but the fact that it is at 50Hz indicates that it most likely IS a grounding issue! What else would it be, if it isn't a grounding problem? 50 Hz hum in your audio is a pretty certain red flag that you have a grounding issue somewhere. (Or perhaps a poor quality pick-up on a guitar or something....)

You are right......I finally pulled out all my material when I got home and I think my brain has gotten overloaded with single phase/three phase/sine wave/blah blah phase electrical info that IT short circuited. If there was dirty power it would usually be appearing at the higher harmonics or even other frequencies depending on the interference and not at exactly 50 Hz. Something is not grounded or there is a ground loop. At first I was thinking that it would have to be audible to be a grounding issue but it doesn't have to be. Bad mic cable picking up electrical interference???? Sorry for talking out my ass....back to school.

Ah yes, but it does appear at the harmonics as well. Look back at the waterfall I posted earlier. 50hz is the main culprit, but there are other ridges as well. The new graphs Amit has posted on the other site appear to have been smoothed.

Actually it is hard to tame 50hz with a 1' depth. If you are a professional you can do that. I've tried that before but it doesn't work. I went to a professional and he is the one who help me but didn't taught me what exactly to do. may be you can consult to an expert one dude.