Hmmm... Just happened across your post Schlieren

quote:

. . . also, there are rectifiers other than those which use diodes? Careful now, you're talking with someone who knows about electronics what they teach in aircraft systems

Brendan. +

What's is this about exactly?

A discussion on studio grounding techniques or how to kit out a 747 with home studio recording equipment, with a bit of personal defamation thrown in? I am of-course not talking about military rectifiers, and I would wager few home PC's would have them . However, I'm not an aircraft engineer but a designer of modern commercial and industrial equipment that is commonplace with 99.9% of electronic equipment used on the ground. Suffice to say, this includes the modern recording studio.

I have served the electronics industry for almost 25 years in a design capacity so I should know just a little of the basics. Currently I work for CSR plc (global leaders in Bluetooth) in a similar capacity, albeit a sort-of hands-on managerial one nowadays. Furthermore, designing out noise considerations involving sensitive bespoke equipment for manufacturing processes is a feat in itself. Did I also mention that I have written technical papers for the IPC?

You said a lot but you didn't say whether or not a grounding rod would help him out or if it was snake-oil to a problem inherent with PSUs. . .

You will note the previous threads here, extolling the virtues of transformer isolation and local grounding busbars, though as I say, the issues can be complex. With a little understanding it's often possible to identify the potential source of interference and apply (cheaper) localised corrective measures to isolate the worst offenders, hence the background on switched-mode PSU's as primary offenders in the presence of sensitive audio equipment and a few clues on probable noise characteristics.

Though not always inexpensive, I wholeheartedly agree with the largely-successful good practice exemplified by other posters here, and without doubt this is always the right approach by default. For some however, purchasing proprietary equipment may not always be possible as we talk of home recording studios as much as professional setups. Knocking huge stakes into the ground however will reduce impedance to Earth but only as a measure to potentially reduce an unguarded cause of interference, with questionable effectiveness. As I'm sure you will know, there is also the issue of ground wiring inductance and resistance (effective impedance) between your studio ground and the ground outside - a wildly varying factor that figures little in the discussions I've seen before on the effectiveness of grounding rods.

Talking purely hypothetically... if you're stood in a room on (say) a damp or ground-capacitive floor, holding a microphone and experiencing interference, then interfering loop current may be using your body as an alternate path to ground, thereby transferred through signal cables to the mic. By reducing the mains earth impedance (big stakes or otherwise) then you are effectively adding a parallel path to your body, reducing the signal current transferred through signal cables in such an event. However, as I say, this is not actually isolating the source of interference. Similar situations can arise with anything even stood on a floor offering similar paths to noise loop current - particularly where equipment is double isolated (without mains earth) but the chassis is still common to signal ground.

Snake oil? There's no answer to that as sometimes it may work and others may not - based on the source of interference, its nature and extent, and the complex paths introducing noise loop-current into sensitive audio equipment. In the professional environment I've always had the luxury of designing in "best practice", though as I say - not always within the realms of the cash-strapped home studio. If knocking a stake into the ground reliably works for you then that's fine, but I would suggest is not the right approach if you are (ideally) able to first identify and isolate the source of interference, in addition to employing best practice - which is not necessarily so expensive and far more likely to achieve the desired results.


Brendan.

ORIGINAL: losguy

If I was bothered enough to go outside and start sledgehammering a rod into the ground, I'd first go get an isolation transformer and use the output side for my studio. It's a lot like a balanced direct box for your studio's AC power, complete with a ground lift. So, rather than tring to find a better ground from the power company, you can use off-the-shelf technology and create your own. What you get in return is total control over the source and nature of that ground, and you are assured that it is completely clean. Not only that, but the hot side is completely clean, too. Way cleaner than almost any other solution, in fact.

For an example of what I'm talking about, you can look here.

This turned out to be a winner of a suggestion. I received a Tripp-Lite isolation transformer today, plugged it in, plugged my guitar amp into that and was immediately greeted with the lushest, warmest guitar tone I've heard in a long time. But wait, there's more... just for grins I decided to plug my Furman Power Factor Pro unit into the isobox and then ran the amp off the Furman and that improved things even more. The amp sounded tighter. What a winning combination. Wow.

I'm a believer now in these isolation transformers. I bought a 1000 watt unit for around $300 on Ebay (brand new). And if you haven't tried that Power Factor Pro unit, give it a spin. It makes an audible difference.

Thanks guys for all your suggestions.

ps - the last electrician who came here didn't know squat about audio or anything audio related and suggested all kinds of bizzare stuff (including a motor generator). He left and never came back. That's two electricians that came saw and ran screaming

ORIGINAL: krizrox
suggested all kinds of bizzare stuff (including a motor generator). He left and never came back. That's two electricians that came saw and ran screaming

Wow. I'm really glad that you didn't go that route! (Bet you are too!) Ironically, he was suggesting the equivalent of an iso transformer, except with a moving rotor! (plus loads of noise and vibration, and really poor line regulation) That's the transformer solution they used in about 1910, before Tesla first introduced AC power. You really would have had a museum piece!

...or buy one hospital-grade one that performs twice as well for half the price.

Outstanding, it's great to hear you've gone a long way in resolving.

Sounds like it may be all settled! I meant to keep checking in here to see how it was going, after offerring some comments up front, but time got away from me. Trying to slow down again.
I read some great advice here from others! Looks like you stayed away from "the most expensive answer is the best one", good going there.....sadly some will try to charge too much. And in grounding problems, sometimes it's not the cost, but the simple things to correct. For two the thousand dollars that was quoted, I would "volunteer"....just kidding!! Glad to hear all is well.

Joe

I don't know what it is with these guys. They all seem to have the same mindset - why build one when you can have two at double the price

Sounds like government work! (I'm allowed to say that, I work for a government contractor!)