Power supply filter/conditioner strip or outlet

[bangerang101]

Hi, I was wondering if anyone knows of a schematic or layout for a power filter and/or conditioner, outlet and/or strip that you could plug into a wall outlet, to get clean, stable power... Example: your playing at a venue that's in a very old building and the grounding is bad or non-existent and you plug your amp/pedals in, and you get excessive hum through your guitar amps. If someone does have a schematic, I  would also need some help w/ what capacitor voltage ratings, types of transformers, model #'s to use, ect... If anyone could give me any info on the best way to do this, it would be very appreciated.

[petemoore]

, I was wondering if anyone knows of a schematic or layout for a power filter and/or conditioner, outlet and/or strip that you could plug into a wall outlet, to get clean, stable power...
  To what extent..what's the load, what's the variance..there are plenty of schematics for entire power supplies, how much capacitence do you need? for instance.
Example: your playing at a venue that's in a very old building and the grounding is bad or non-existent and you plug your amp/pedals in, and you get excessive hum through your guitar amps.
  Nope, I use grounded outlets only on amps. Hum is a multifacted, non-static series of events, getting hum out of audio signal is a matter of finding it by way of complete elimination or dealing with it as you go along. Floating/regulated supplies for effects, solid ground for sure on the amps.
If someone does have a schematic, I  would also need some help w/ what capacitor voltage ratings, types of transformers, model #'s to use, ect... If anyone could give me any info on the best way to do this, it would be very appreciated.
  Figure out what you need as far as voltage so the transformer can be chosen to get you into the ballpark v after AC/DC conversion and load are considered, then figure out what the current requirements will be and exceed them by 10% or better.

[R.G.]

Pete is correct. Hum is with us always, and creeps in many ways.

There are no good, inexpensive, DIY ways to make a line power filter/conditioner that will clean up hum. The frequency is too low and the power is too big. what is possible is filtering out fluorescent light and other spiky/RF noises.

Beyond that, whenever you wire anything that's AC-power-line connected, you are literally betting your life and the lives of others around you for the entire history of the equipment that you've done it safely. Stop and think about that one for a minute.

There is a good, if heavy and expensive way to condition power. Buy a "harmonic neutralized" or "sine wave output"  constant voltage transformer. This thing takes in junk from the AC line, and has a heavy duty enough filtering action to clean it. A 50-75lb constant voltage transformer can do amazing cleanups. You can get this for on the order of $50 - $400 surplus, depending on how desperate the seller is. Ebay has them all the time.

[Pablo1234]

You Could also Make a Converter/Inverter. Rectify the Signal to a DC and then PWM it Back to 60Hz/115VAC. Its overkill IMO but it would work for what your asking.

[bangerang101]

Ok yeah, I didn't mean a "power supply" per say, I think I made it sound more complicated than I meant to... I was thinking of something more along the lines of, something that could possibly isolate the ground of my amp and/or pedals and get rid of ground loop hum... Exactly like what this thing claims to do, http://www.ebtechaudio.com/humxdes.html, but I wanna know if it's diy-able, if anyone knows how it might work, and if it's cheaper than buying a couple of those things (there like $60, I believe).

Thanks for the quick reply's BTW, guys... also, sorry I'm lacking in alot of electrical knowledge/application, alot of stuff just goes over my head at this point

[R.G.]

I don't know what's in the ebtech. It is likely that it breaks the ground connection and puts in the break a pair of back-to-back high current diodes paralleled with a small value resistor and maybe a cap. I've seen things like that. Could be a signal isolation transformer too, I guess.

However:
There is a reason that third wire ground is there. It's part of a concerted plan to keep you alive. Be really, really sure you know what you're doing before "lifting" the ground.

In addition, I mentioned that there are a lot of places to get hum. The old two-wire amps didn't have a ground wire at all. This was kind of the ultimate ground lift, right? Yep, they hummed. In fact, an amp by itself that is properly grounded internally has a lower hum with the third wire connected than if it's lifted. Where you get into issues is when you connect multiple things with and without ground, and they all have slightly different bits of capacitive leakage. It only takes one power supply connection anywhere in your signal chain with a little AC power leakage to hum. Or a dirty sleeve connection on one of the signal jacks. Or a jack/switch/control bushing that has dirt and corrosion between it and the chassis. Or a real, no-fooling magnetic hum loop pickup. Or a poorly wired *building* that you're plugged into for power.

Getting hum free is really hard. It requires careful work on all the pieces in your signal chain, from guitar all the way to the speaker, and everything that is electrically connected to that chain. Every rig is different, and so is every building.

All that being said, if the ebtech is an isolation transformer, it may make your rig better. Be sure you try one before you buy one, because if the hum is caused by something an isolator doesn't fix, you're out the money and still have hum.

My web site has a transformer isolator intended for two-amp rigs that might help. It's DIYable and there is a PCB and maybe a kit from General Guitar Gadgets. But the same advice applies - be sure the fix you apply is the fix for the problem you got. Antibiotics won't fix either the common cold or a broken leg. 

[bangerang101]

Wow, thats some useful information... thanks alot

I do understand the risks and hazards of electricity in a house/building and importance of grounding, and yeah... it's obviously there for a reason. So, I don't think I'm going to do any ground lifting.

I just wanted a diy alternative to something like that ebtech thing, so I'm going to give your transformer isolator method a look and check ggg for a pcb transfer or kit, as well. Thanks!

Also, you said "Where you get into issues is when you connect multiple things with and without ground, and they all have slightly different bits of capacitive leakage."... well, how can I find out what is causing the capacative leakage and what are some of the more non-obvious steps I could take to fix any issues inside my amp (vox ac30cc2, 2005), since that seems to be where most of the hum is comes from in my "rig".

[boogietone]

Getting hum free is really hard.

Actually, getting "hum free" is pretty easy. It has never cost me a red cent.