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| Re: Grounding, dirty power or whatever it is... [message #318537 is a reply to message #316820 ] |
Sun, 24 February 2008 16:47   |
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 Mike Cleaver
Messages: 258
Registered: August 2004
Location: Vancouver, BC, Canada |
Active Member |
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So the next thing I'd try is a UPS that passes enough power to run your two pieces of equipment used in the last experiment.
In Canada and the US, it's possible to buy a unit and then return it if it doesn't do the job.
Hopefully, it's the same in Italy.
From your experiment, it's definitely coming in on the power line, likely from some equipment used in the factory.
You must isolate your power from theirs if you're to get any satisfaction.
If the UPS works, buy one big enough to run all your audio equipment plus 25 per cent for growth.
Mike Cleaver Broadcast Services
Vancouver, BC, Canada
Broadcast Studio Design and Consulting
Voiceover Talent
Newscaster
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| Re: Grounding, dirty power or whatever it is... [message #322606 is a reply to message #316820 ] |
Fri, 07 March 2008 14:41 |
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Brian Kehew
Messages: 2344
Registered: January 2005
Location: North Hollywood |
Platinum Member |
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There are surplus shops with SMALL isolation transformers (or used - don't forget your UPS could be MUCH cheaper if you buy it used from an old factory or office).
I am having a similar/different problem and will start a new thread for it...
Relax and float downstream...
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| Re: Grounding, dirty power or whatever it is... [message #333563 is a reply to message #317935 ] |
Mon, 14 April 2008 17:00 |
Stephen Anderson
Messages: 14
Registered: March 2005
Location: Los Angeles |
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1.5 V between Neutral and Ground is unacceptable, and is likely the primary source of noise. As you are sharing a Ground/Neutral bond with the neighbor, it makes complete sense that the load changes when his business shuts down.
You need an Iso transformer, not from Equitek (IMHO)) and an additional ground rod after the Iso, which should be sunk at least 10' feet away from the main building ground.
This will give you a new Ground/Neutral bond, giving you a good clean Ground that is, while still connected to service entrance, is some distance away, closer to your gear load. You'll wind you with less than 50 mV between Ground & Neutral, which will be much better. And you will be isolated by the transformer from the other business.
And on-line UPS is never a bad ides, but, be aware that many of them, and virtually all the line-interactive ones, have 2 problems:
1. Non-sinusoidal outputs
2. Noise reflecting back into electrical service.
#1 is because most cheap UPSs were designed to drive switching power supplies in computers, which don't care about waveform purity.
#2 is basically the same answer: a business desktop machine doesn't gove a crap about hash on the incoming AC feed. Linear supplies in most analog recording gear do care, however.
AC system design isn't sexy, but it's pretty predictable. It all depends on what you're willing to put up with. That said, there are studios that churn out hit records where you can hear snats coming from the speakers when the coffee pot heater cycles on and off. Some people can overlook such problems.
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| Re: Grounding, dirty power or whatever it is... [message #339154 is a reply to message #316862 ] |
Mon, 05 May 2008 15:49 |
Dusk Bennett
Messages: 51
Registered: November 2005
Location: Los Angeles |
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| drknob wrote on Tue, 19 February 2008 15:05 |
You could also get yourself an MGE Pulsar EXRT 2200 ups. It is a true online ups, regenerating perfect sinusoidal 120V 60Hz power with, I believe, power factor correction. It will make power line disturbances irrelevant and protect you from outages as well. At 2200 watts, it can run a lot of stuff. You wont get that with (shudder) Equitech.
Oops....they have 220V products too.
BTW, be careful - not all ups units are on line. Some just switch between mains power and battery backup when needed. An on line ups constantly regenerates power, with the added benefit that there is no switching transient when moving to battery mode.
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Dr. Knob,
Funny you mentioned that. I purchased an MGE Pulsar years ago for a problem room I was in. It never did everything the salesman said it would. I have been in several other rooms since with it and all it does is act as a UPS. It has not filtered out any AC problems in and of itself. It was quite a disappointing purchase, actually. The Equi-tech actually seems to be worth investigating.
BTW, the system I am currently on is a 20 amp IG. Plenty of headroom but every time someone turns on the paper folding machine or copier downstairs I have to stop tracking and wait till they are done. It's a mess.
I also had a bear of a time getting rid of the random ground loops that popped up with my previous "Neve'esque" mic pre's when combined with older tube mics that used outboard PSU's. Selling off the "neve's" and getting Chandlers solved part of the problem. Chandlers A/C wiring is less noisy than unshielded A/C traces etched on a motherboard next to audio lines.
The MGE has been helpful to a degree but not helpful enough.
Dusk
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Their (and my) experience of beating hum and noises into the hiss can be of use if you tell us more.
