Hum issue - driving me more crazy


Page 1

Not sure if this should be here, Tech talk or Cables...

Audio Research Ref 2 Preamp, Pass labs electronic Xover, Bryston 4B ST amps (2), MAGGIE 20.1 speakers. All eqpt working OK.

Pre source eqpt left rear of room
spkr amp & XOVER left front of room
spkr amp right front of room

Separate 20 amp circuit for hifi eqpt. Other plugs in rooms for lamps, etc. Many of lamps on dimmers

Singlended IC's (now double shielded)are "under" flooring (pier and beam construction) & has been moved away from other wiring & cross at right angles

Initially some hum from dimmers (on separate circuit), etc. Have learned to leave them off.

But there is constant low level hum - right side only EVEN with preamp and XOVER turned off.
imdoc
If you haven't run a ground from pre to amp, you need to try that and maybe with xover. If the gear doesn't have a ground terminal, loosen a cabinet screw and attach.
Try lifting the grounds on the amplifiers by using a two-prong adapter. You have the perfect setup for ground loops -- all equipment plugged in multiple outlets spaced far apart on the same circuit along with interconnects running the length of the room.
You really need to run the system balanced if possible.
Connect the A/C grounds along the same path the pre to amps interconnect goes. if it fixes the problem you can leave it that way permanently.
Even try the the neutral line same way. (but do not leave it, if it 'fixes' the problem, then you need to do some A/C rewiring) just leave the hot wire alone.
Sometimes electricians use the neutral wire in wrong ways and connect it up to other stuff instead of a pure separate wire. just the neutral A/C wire. (My refrigerator circuit neutral is connected to my separate 20 amp circuit neutral. Grrrr. But it does not seem to be a problem for me.)
Other possibilities: one of the items is wire wrong internally? hot and ground reversed?
Then also: run extension cords from ONE outlet at the preamp to both amps to test for buzz. If gone, then it is the A/C wires to that side are somehow currupted. IF no change with the extension cord, then it is not the A/C wire.

A comment about dimmers: some are great, and some are 'dimmer from hell'. I had one dimmer that would burn out bulbs in less than a two months. All the time. then another that the bulbs last for YEARS. same usage.
My understanding is some cut the current wave vertically and completely slicing it, bad lots of RF, some horizontally with a hard cut, OK, and some horizontally with a soft cut, (probably they just add a resistor, or a cap in the thing) and those are good, not so much hash.
None of them tell you what type they are. just from replacing bulbs you may know which are the bad type, as they kill bulbs faster. I took the good ones with me when I last moved!! (four years for the bulbs in the one room with the 'perfect' dimmer, and I use them every day!!)
Finally with your stuff you should get a pair of 14B-SST2 for those 4B-ST.(even 2 of the 4B-SST2 used would be great)
I have a 4B-SST2 with my 3.6s and it is really good. (I almost bought an ARC REF 3 used, but bought a Bryston BP-26 preamp.
Anyway, I like your stuff, and have similar stuff, so i 'more than usual' wish you well.
Good luck!
But there is constant low level hum - right side only EVEN with preamp and XOVER turned off.

I agree with Gs5556. Try some ground cheaters.

Just because you turned off the preamp and xover that would not break the ground loop current path through the right channel amp.

Have you tried to isolate the right channel amp from all other equipment? Nothing connected to the input of the amp... That would tell you if the low level hum is caused by the amp or not.
One other thing to do, swap the amps. leave everything else the same and swap them. If it follows the amp, time for a repair.
Page 2 (Continued)
I have used cheaters in all possible combinations with resolution of most of the hum BUT not the residual in the right channel only.

I have disconnected the dimmers from the circuits in room->no help
Reversing amps and XOVER outputs -> no help
Ground lift change on amps->no help
Preamap powered off and XOVER powered off -> no help
Electrician has reevaluated wiring and says all is OK
Separate 20 amp circuit has its own ground
No lights are plugged into stereo circuit

Unplug interconnect at right amp -> RESOLVES HUM
" " " RIGHT XOVER OUT -> RESOLVES HUM

Bringing the IC to the right amp TO ABOVE the floor-> RESOLVES NOISE. In my unknowing frog brain, this implies something is inducing noise in the right sided IC (when under the floor - down about 12-16" is all though). But nothing can be identified so far

As I know not enough about electronics:
Unplugging or turning off preamp or XOVER does not help - > are these eliminated as issues causing ground loops etc when OFF? Or are they still part of a system with potential "current flowing" (even though "off")

Does disconnecting IC from AMP (or at XOVER) TELL SOMEONE WASSUP?

Perhaps, as a (sort of) simple solution - > Would balanced from XOVER to AMP resolve the issue regardless of cause?

Thanks
When you say you bring IC to above floor, the same IC?
Or just another one.
I will assume you actually bring the same physical interconnect up.
Then you have some wierd stuff in the floor.
Something is causing a field of some kind in there under the floor. Could be even something in ground under the house?

A way to cut the field would be to run a armoured cable sheath (like used for A/C armoured wires) and run that under the floor with the interconnect inside. and ground that shield to the A/c ground.
that would cost about a buck a foot.
If that did not work, or only partially then:
Then if you can use a balanced connection, you should. A balanced connection will (Hopefully) not be affected by that.
I would see if you can borrow a suitable cable from a cable place or your dealer, and try it, Even if you can borrow several shorter ones and chain them together just to try out if it cuts the hum. Then you can buy a correct one if it works.
Then even both the armoured cable shield ,and the balanced wire.
If you use it for one channel, and it works, i would do it for both (the balanced wires).

No guarantee.. but other stuff to try
Also: Non contact voltage detector: From Amazon: Greenlee GT-16 ($22) it goes off if a electomagnetic field is around, or something is spewing out a field. IF you can actually get under (a basment? or crawlspace?) and use the detector and it will go off if a field is present. it may be just in one spot. Or a big area.
http://www.amazon.com/Greenlee-GT-16-Adjustable-Non-Contact-Detector/dp/B001QIJOW0/ref=sr_1_1?ie=UTF8&s=hi&qid=1306389698&sr=8-1
Well worth checking out.
Bringing the cable above the floor may be moving them away from fluorescent ballasts. Speaking of lights, do you have any low voltage LED or decorative lighting that feeds off a DC transformer? These introduce DC into the wiring that get into ground loops.

To answer your question: yes, balanced IC's are the best way to go because the shields are tied to the chassis instead of signal ground. But somewhere, there is something that is amplifying your problem -- computers, improper CATV or Telco grounding, etc.
Elizabeth-> same IC. My cables are well and DOUBLE shielded.

Gs5556-> No fluorescent under the floor. No LED

Balanced appeals to me as best easiest possible solution. Should help with noise anyway

Now if I had only made the holes in the floor for the IC's bigger.... but who knew?

Can one build a balanced cable (for a trial anyway)?

If so one can someone tell me what to get at Altex or Frys or online. I can easily pull another cable behind the IC but balanced XLR connector will be problematic right now due to hole circumference.

Thanks to all for help, psychiatric consult, etc
In most cases, when components are all using the 3 prong cords, each component in the system has its own ground. Unless all of these grounds are routed back in the electrical system through one point, you get can a ground loop. This is because the components are also grounded by way of the ICs through the other components' ground as well.

If you are going to lift the ground (cheater plugs) try to do that on the preamp and let everything ground through the amps. This is how I get my amp and preamp to play nicely, but my pre has a switch for doing this. I do run a cheater on the QSC amp that runs my bass horns to eliminate a ground issue there.

If you haven't already, try to plug both amps into the same outlet and see if the hum is diminished. Matter of fact, you may need to plug everything in your system into one outlet to see if this helps even more. Use extension cords and/or power strips to get everything plugged into the same outlet and see what happens.

Interesting that you also have one side worse than the other. Try swapping the ICs between amps and see if the hum follows the change. It happens. Just last week I helped a customer with what turned out to be a bad IC, but in this case it was causing the input protection fuses to blow on his amp. Now that's a bad cable!

When you can, try turning off all of the breakers in the house except the one feeding your system and see what happens. This may tell you if the problem is coming in from outside.

Good luck! YOu have my sympathies. I don't think anything is as frustrating as finding solutions to ground issues.
You can probably remove the RCAs from the cables and replace them with XLRs. Most ICs have three wires inside anyway. If they do it's pretty simple if you can solder to attach XLR's. You don't even have to be able to solder with some of the new clamping XLR connectors.
Neutric solderless XLR
"Bringing the IC to the right amp TO ABOVE the floor-> RESOLVES NOISE. In my unknowing frog brain, this implies something is inducing noise in the right sided IC (when under the floor - down about 12-16" is all though)."
05-26-11: Imdoc

Imdoc,

*How long is this IC cable?
*What type of cable supports are used under the floor? Plastic? Metal?
*How often is the cable supported, distance between supports?
*What is the area, space, under the floor? Basement? Crawlspace?
The dimmers must go, off is not good enough.
Have replaced components, cables, used cheaters,aligned cables, changed conditioners and surge, replaced tubes, replaced power cables.
As soon as I took out the dimmer switches, problem solved.
I had the same issue with my Dynaco pas 3 preamp. All I had to do to eliminate the hum was to twist the rca connectors from the phono in the socket until it made good contact. Try this first with all of your rca plugs and see if that solves the problem. It did it for me, no more hum.
You don't have a TV or tuner connected to cable or satellite whic is connected to your system do you?

Cable and dish installations are often grounded in a different location than your mains ground which almost always creates a ground loop though your audio system.
Make sure the cables are plugged in all the way.
Dan_ed

If you are going to lift the ground (cheater plugs) try to do that on the preamp and let everything ground through the amps. >>>>>>>>Will try but I think this worsens other hums

If you haven't already, try to plug both amps into the same outlet and see if the hum is diminished.>>>>>>NO help

Matter of fact, you may need to plug everything in your system into one outlet to see if this helps even more.>>>>>>>>Will try

Try swapping the ICs between amps and see if the hum follows the change. >>>>>>No help

When you can, try turning off all of the breakers in the house except the one feeding your system and see what happens. >>>>Have tried without obvious source as I recollect but will try again

Jea48

*How long is this IC cable? >>>~ 15'
*What type of cable supports are used under the floor? Plastic? Metal? >>>>>>>>Blue flex hose supported with plastic hangers
*How often is the cable supported, distance between supports?
>>>>>>>>About 5' apart as I recollect
*What is the area, space, under the floor? Basement? Crawlspace?
Space is under entire first floor of house ~ 1800' I guess
Room is 15X20 -sort of isolated from other parts of house Crawl space is ~ 18" dirt to bottom of rafter

Magnumpi205 - > I don't disagree and will try this
Shayl123 - I have -> no help
Rwwear -> I have -> no help

BUT I replaced right channel with balanced IC's tonite AND SO FAR NO NOISE. Can even use the dimmers in room that were clearly problematic. Able to remove the cheater plugs without hum (which was an issue before)

Not ready to declare victory (as there was variation in level of hum) but things are looking up so far.

MAGIC SO FAR
Has the system always hummed or did it start when something was changed?
Hello Imdoc, Hope my obsessively detailed response was helpful in your quest to rid the hum. I am a firm believer now-a-days in running things balanced. Took years of trial and error, and a whole hell of alot of gear, cable, and subwoofer swapping. But balanced is the thing for me.

A suggestion for you regarding balanced cables. Before you go out and start dumping your hard earned cash on stuff, try some "professional" grade stuff. For whatever it's worth, I don't have any idea how $90 balanced mic cable from Guitar Center can be referred to as "professional", but I tried some of their "house" brand balanced cables, and also some MOGAMI brand. Didn't set me back much at all, and worked just fine for a long time, (until eventually upgrading to shit that cost 40 times as much for the same length.) Try it out. If it doesn't work out, or degrades your sound at all, you won't feel suicidal for for emptying your bank account. That cheap stuff ain't all that bad sometimes.

As for lights on dimmers- Elizabeth is oh so right. Not all dimmers are created equal, with some of them really causing more problems than they're worth. I have 800 watts of halogen lights on tracks, illuminating various pieces of artwork in my listening room. I too had hum because of them- once. Not anymore. Lutron, and Leviton make something called a (I KNOW I will screw up the spelling on this, but...) Colloidial coil?? something like that? It's essentially a "anti-buzzing" coil that is wired into your electrical supply line, between the dimmer and the fixture, lamp, etc. Works like a champ and completely kills the buzz caused by dimmers, and halogen bulbs. Lamps Plus sells them, or at least they used to. Try your local electricians supply house.
Unplug any cables (RCA, F connector, etc.) from your Cable TV/Sat/Antenna and see if the humm disapears.
Rwwear - hum started at time of new XOVER. BUT this was also same time that I "buried" the IC's under the floor and got new IC's. Thus multiple simultaneous changes. IC's above floor are great.

Ozzy - No TV or SAT in system - LP, DAC and CD player are only sources

BALANCED cables has fixed all issues even allowing me to use the dimmers in the room without a peep. Even slight hum in Vinyl subsystem (2 chassis phono preamp) is gone.

I don't know enough electronics to understand what "I fixed" (or more likely unbroke) but the end results are outstanding for about $120.00 worth of cable and connectors. All I can say is in my application/room/system -> Balanced IC's are great.

Thanks to all. Have a memorable Memorial weekend
Yeah, if going balanced fixes it, go for it. It could take a long time to figure out what is happening. Enjoying music is much more fun. ;-)
Always use balanced mode when possible. More equipment should be balanced.
PS Audio has something called a Humbuster (now version 3).
Never tried it.
Humbuster is specifically for removing DC from your AC line. So it will solve problems of transformer hum coming from the chassis of an amp, etc. But doesn't address the sources of hum that come out of speakers.

Great device if DC on the line is your problem, as it was for me at my old apartment.
All the posts that I have read try to assume a particular problem. However, this is similar to auto repair shops not doing a detailed diagnostic and simply replacing components until the problem is fixed. First, under no circumstance do you lift any ground by using cheaters. People do this often to eliminate potential ground loops, but a) This simply mask the problem but does not fix it, b) you have now created a situation whereby you, your family, pet, etc. may become a better ground when there is a fault and someone could get seriously hurt.

What I usually post for this problem is time consuming, but detailed. I am an Electrical Engineer and found that whenever I try to piecemeal something, I always run into problems.

1. Turn off every component.
2. Unplug all power connections.
3. Unplug all interconnect connections.
4. Connect the speakers to the amp. Nothing else.
5. Turn on the amp only. Noise? No. continue. Yes, amp is the problem, or speaker cables. Turn off amp. Disconnect right speaker cable, turn on amp. Noise? no. continue. yes, interesting. Try different cables or raise them from the floor. If no change, amp is the problem.
6. Turn off the amp.
7. Connect pre-amp to amp, (speakers already connected).
8. Turn on pre-amp and amp. Noise? No. Continue. Yes, pre-amp or interconnect cable is the problem. Turn off components. Disconnect right interconnect cable. Turn on components. Noise? no. continue. Yes, change interconnect cables and try again. Noise? yes, try rerouting the cables away from noise making components. power cables, power supplies, etc.

The point here is to systematically connect one component at a time, until the hum begins to determine which component, cables, etc is causing the problem. Start with everything disconnected first and connect one thing at a time.

You will eventually find which component is causing the problem. Also, remember, that running interconnect cables anywhere near power sources or power cables is asking for hum trouble. If cables must cross, do so at ninety degree angles.

I run interconnect cables down one path, power cables down another and speaker cables down a different path and try hard to not have any close to the other or cross.
Also, I have run separate power feeds from my circuit breaker box for amps and for low level components. If you have a raised foundation, it is relatively easy to do this. But, a skilled electrician will not charge an arm and a leg for this. A few hundred dollars. Small change when you consider the cost of your equipment. So, my two amps have totally separate power outlets each independent to the power panel. My low level components (pre-amp, turn table, cd player, tuner, music server, crossover, DACs,) all feed into a power conditioner and that has its own power outlet that is independent to the panel as well. The benefits? Noise floors substantially dropped. No hum, no impact from dimmers or refrigerator, etc.) dead quiet.

But again, please, please, please do not use cheaters and lift the ground. you or your kids will become the ground and that is not good. Find and fix the problem.

enjoy.
Mnorl: I also have a ground loop hum that I have traced to my Directv dish; but only on my main system; the bedroom system using an Integra receiver has no hum...I've checked and made sure the dish is grounded properly; and have used some cheater plugs; but still have hum....hummm...how to fix that I wonder? ideas? Knowing which piece is causing the hum; then fixing it are two different sides to the same puzzle...thanks.
Mribob, Purchase a Iso-Max VRD-1FF made by Jensen Transformers Inc.
Ozzy,

I don't think the Iso-Max VRD-1FF will work on a SAT dish
system.
Yea, I think that Sat systems run DC power through the cable along with the signal. Any transformer in the path would block the DC and my saturate the core due to the DC, making it act like a short circuit.
...I've checked and made sure the dish is grounded properly;
05-31-11: Mribob
Mribob,

Properly.... Please explain.
jim
Jea; I had electrician come out to house and attach dedicated ground wire to a grounded piece of metal on house; ie; electrical conduit. I did try to put a piece of steel rod in the ground to a depth of 5', and attach copper grounding wire; but that proved a bit problematic. What ideas do you have about properly grounding a sat dish? how come my bedroom sat system has no ground hum; only my more sensitive main listening area when I switched out my Meridian 861 processor for a Marantz 7005 processor;(no hum before with same sat box and connections) and added a VAC tubed preamp. System stone quite in 2 channel listening mode; only hums when Marantz is powered up; and attached to Directv dish; take away the hdmi cable from sat dish to marantz; no hum...hummmm; any help would be appreciated. Added a ARTcessary DTI (dual transformed isolator) running as rca plugs instead of balanced to connect Marantz to VAC for front channel for home theater rig; and made a big reduction in the hum; so at least is only mildly anoying, but not eliminated.bought from MCM electronics catelogue...
I would appreciate any and all helpful tips on this problem...sure others have similiar issues with Directv dishes; since the Jensen product works by eliminating the hum; but if fails to allow the video/audio signals to be sent thru as well....
Mribob,

how come my bedroom sat system has no ground hum;
More than likely the associated equipment is two wire cord and plug. Is that correct?

I switched out my Meridian 861 processor for a Marantz 7005 processor;(no hum before with same sat box and connections)
Marantz uses a two wire cord and plug. Does the Meridian 861 processor use a three wire cord and plug?

I had electrician come out to house and attach dedicated ground wire to a grounded piece of metal on house; ie; electrical conduit.

Does not meet NEC code......

Good chance what you have with the metal conduit is a poor lightning grounding conductor at best. Every fitting, connectors and couplings, could be adding resistance to the length of the conduit run.

NEC code says the cable grounding block shall be bonded, connected, to the main grounding electrode system of the main electrical service by means of a ground wire. NEC code is bare minimum safety standards.....

How far is the SAT cable grounding block from the main electrical service panel?

For a test, test only, disconnect the existing pipe ground wire from the SAT cable ground block. Check for hum and post back.

Note:
The ground block must be earth grounded for lightning protection. For the test you will not cause any harm....