Slight Hum Using Rack Rider Power Conditioner?

John Moss · Post by **John Moss** » 24 Jul 2001 10:25 am

I just bought a new Rack Rider power conditioner to go in my 3 space rack for use with my ProFexII. I noticed a slight hum when using the Rack Rider as opposed to using just my floor power strip which produces no hum at all.
I have not tried the hum-frees that you can buy to isolate the units from the rack.
When I took the Rack Rider out and placed it on top of the rack the hum was gone.
I just wonder if the hum-frees will solve the problem or if the power conditioner just being to close to the ProFexII inside the rack is the problem.
Please Help.
Thanks,
John

Jack Stoner · Post by **Jack Stoner** » 24 Jul 2001 10:59 am

It's easy to tell. Put the power conditioner back in the rack, but set something non conductive between the power conditioner and the rack rails (cardboard will isolate it) - don't use the mounting screws. If that fixes it then the humfrees will probably do the trick. If not then it's too close to the Profex II and you'll have to try and rearrange your rack.

Steve Feldman · Post by **Steve Feldman** » 24 Jul 2001 5:31 pm

I bought replacement power cords for the components that I plug into my power conditioner and then I cut them short (~8 in). That took care of the last little bit of hum that I had.

LARRY COLE · Post by **LARRY COLE** » 24 Jul 2001 6:17 pm

John, if you run your power cords and your line level cords together you will get hum. Run you power cords down one side of the rack, and your line level cords down the other side. This will minimize the hum. When the line level cords pick up the 60 cycle hum, the power amp amplifies it along with your sound. If you have to cross them, do it at right angles(90%).

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LC. WILLIAMS U12, SHO-BUD PRO1,CARVIN TL60

[This message was edited by LARRY COLE on 24 July 2001 at 07:18 PM.][This message was edited by LARRY COLE on 24 July 2001 at 07:19 PM.]

Donny Hinson · Post by **Donny Hinson** » 24 Jul 2001 7:25 pm

Just curious...why are you using a power conditioner? (I've had a couple EE's tell me they're, more or less, unnecessary...unless you're building a recording studio!)

gary darr · Post by **gary darr** » 24 Jul 2001 7:54 pm

what Larry said John,I dont know if i ever told you about this but down at the V I had routed the power supply line for my RP-5 along with the lines coming from my foot pedal. took me about fifteen minutes of running circles to find out where the hum was coming from. Allso do you remember putting together the PA rack for restless native,we were picking up a 60 cycle hum from the tranformers of the crown amps through the EQ or cross-over or something. WE wound up making a divider of plywood lined with galvanized flashing to to seperate the two. sounds kinda drastic but it fixed the problem. hope this helps,( Gary McGuyver)

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sho-bud,session 500,american standard strat,shecter tele,peavy classic 50

John Moss · Post by **John Moss** » 25 Jul 2001 4:29 am

Thanks for the info guys. I tried it all and I just went back to the power strip on the floor. No hum at all with it.
Gary I remember that little hum with our sound equipment now and also the problem you told me about at the VFW.
I guess sometimes things are best left alone. HaHa.
Thanks Again,
John

Jack Stoner · Post by **Jack Stoner** » 25 Jul 2001 5:15 am

AC shouldn't bother speaker leads. I have my rack case wired with a plug for the AC and the panel with the 1/4" speaker jacks next to each other. I don't get any AC hum feeding into the speakers. I also have a surge type AC power strip mounted on the bottom lid of the rack case and no problems with AC hum from that either. I have a Peavey Transtube Fex and a MosValve 500 power amp mounted in the rack case.

Lee Baucum · Post by **Lee Baucum** » 25 Jul 2001 2:13 pm

I have a question about 60 cycle hum. What note is 60 cycles? I get a low hum in the little room I practice in. It's about a low B natural. Is that 60 cycles?

Lee, from South Texas

Jack Stoner · Post by **Jack Stoner** » 25 Jul 2001 3:31 pm

55Hz (cycles) is an A note. I'm not sure what a B would be.

Steve Feldman · Post by **Steve Feldman** » 25 Jul 2001 3:55 pm

...why are you using a power conditioner?

Set up the rack and plug in only one cord. All the rack components are plugged in to the power conditioner. Cuts down on the spaghetti.

Blake Hawkins · Post by **Blake Hawkins** » 25 Jul 2001 5:07 pm

Lee, you are correct. B is 61.735 Hz
Jack is also right on it. A is 55.000Hz

Blake[This message was edited by Blake Hawkins on 25 July 2001 at 06:09 PM.]

Donny Hinson · Post by **Donny Hinson** » 26 Jul 2001 5:04 pm

Steve, if I have a lot of cords to plug in (as at my computer workstation) I just use an outlet strip. A real "power conditioner" is heavier, larger, more expensive, and more prone to problems than a simple outlet strip.

Steve Feldman · Post by **Steve Feldman** » 27 Jul 2001 4:39 am

Semantics, Donny -

I admit that alot of what are called power conditioners are not much more than glorified power strips. I have a rack mounted (which is handy in and of itself) Furman 'power strip' that has one outlet in the front, and 6 in the back. It claims to do some line voltage regulation, although I wonder about how well it really does that. And then there are the fancy lights that indicate when you exceed acceptable fluctuation limits.

I've used a 'Dranitz Meter' several times to monitor and record voltage fluctuations - in real time - over a period of weeks, both in my home and in other places (e.g., various laboratories where a lot of sensitive analytical equipment is on-line). RARELY, if ever, have I seen much of anything in the way of harmful voltage spikes (or low voltage events, which can be worse). So, I agree that with most places that meet electrical code, there's not much problem. However, you never know what you're plugging into. Just try checking the outlets at your next gig with a simple polarity tester and see how whacky the grounding conditions can be.

So, in short, for me, it's a justifiable expense to at least try to give yourself SOME type of line protection short of full-blown line conditioning (however effective it may [or may not] be...).

Steve [This message was edited by Steve Feldman on 27 July 2001 at 05:42 AM.]

Jack Stoner · Post by **Jack Stoner** » 27 Jul 2001 4:55 am

The only way to be sure, if someone is paranoid about the AC line is to carrry aroud a big UPS. It would take care of the problem, but it's really not practical.

A "good" grade surge protector will suffice for processor type effects units. And a "good" grade is not the $9.95 models or even the $19.99 or $39.99 models. You have to go to a high end commercial model to really get any protection. I've seen the specs on the Furman "conditioners" but I've never seen any unbiased evaluations of them so I can't comment on whether they are effective or not.