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#72540 - 01/11/07 07:21 PM Annoying hum
AARONMADLER Offline
Gunslinger

Registered: 12/12/06
Posts: 169
Loc: Needham, MA
Good evening fellow Outlaw people - I had been listening to my 990/7700 with two front speakers and all sounded well. The other day, I added 4 rear speakers and a subwoofer. Now I have an annoying hum constantly. Does anybody have any advice for ridding myself of this buzz and hum?

On a side note: I emailed Outlaw tech support several days ago at 7:40 pm and Steve got back to me with a solution to the problem via email and by leaving a message on my cell phone at 9:01 pm the same night... an hour and twenty one minutes later. Now that is incredible service!
_________________________
Outlaw 990/7700, Oppo DV-981HD, Gallo S.A.Amp, Nucleus Ref. 3.1, AV C, AV M, TR-2, Paradigm Atom, Pioneer PDP-4214HD, Mtrola DCT6200/2005

Outlaw 990, Aragon 8008X3, 8008, Denon 3930CI, Dahlquist DQ20, Outlaw LFM-1+, Paradigm Atom, Mtrola DCT3416 I

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#72541 - 01/11/07 07:34 PM Re: Annoying hum
gonk Offline
Desperado

Registered: 03/21/01
Posts: 14054
Loc: Memphis, TN USA
That's some quick service!

Since the hum cropped up when the rears and sub arrived, there are two possibilities. One is that one or more of the surround speaker cables and/or subwoofer interconnect are getting too close to a power cable and picking up some noise from that. The other (and probably more likely) is a ground loop due to a grounding issue between where the sub is plugged in and where the rest of the system is plugged in.
_________________________
gonk
HT Basics | HDMI FAQ | Pics | Remote Files | Art Show
Reviews: Index | 990 | speakers | BDP-93

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#72542 - 01/11/07 07:54 PM Re: Annoying hum
AARONMADLER Offline
Gunslinger

Registered: 12/12/06
Posts: 169
Loc: Needham, MA
gonk - now that you mentioned it, the sub, amp and 990 are all plugged into the same surge protector as the outlet is too far away. What do you recommend? Do you have any experience with line conditioners? Will that make a difference? Thanks for your help.
_________________________
Outlaw 990/7700, Oppo DV-981HD, Gallo S.A.Amp, Nucleus Ref. 3.1, AV C, AV M, TR-2, Paradigm Atom, Pioneer PDP-4214HD, Mtrola DCT6200/2005

Outlaw 990, Aragon 8008X3, 8008, Denon 3930CI, Dahlquist DQ20, Outlaw LFM-1+, Paradigm Atom, Mtrola DCT3416 I

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#72543 - 01/11/07 08:57 PM Re: Annoying hum
Lizard King Offline
Desperado

Registered: 08/30/06
Posts: 425
Loc: NY
Try using the Belken PureAV series!
_________________________
Outlaw 1070, Anthem MCA5 II amp.
Sony Ps3
Alon 2 Mk2 Loudspeakers
HSU VTF-2 Mk2 sub x2
VAC PA100/100 Tube Amp
ARC SP16-L tube Preamp
Audio Note Dac 2.1 "B" signature
Furutech E-TP80,
Ascend HTM-200, 340C
Sony KDS-55A2020

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#72544 - 01/11/07 08:59 PM Re: Annoying hum
palmer Offline
Gunslinger

Registered: 05/13/01
Posts: 121
Loc: South San Francisco, CA USA
I'll weigh in as I had a very similar experience in my system when I re-installed it after a massive remodel. I had a loud and annoying hum when my Sub was attached to the system. I did a little research and discovered that the most common source of a ground loop hum (based on reports in this forum and others) appears to be an improperly grounded cable connection.

I tested this by disconnecting the coax line from my cable box. The hum went away.

I checked the point of entry and found that the cable line was not properly grounded. I attached a copper ground wire from the cable point of entry to my houses' earth ground and this ALMOST completely eradicated the hum. Disclaimer: unless you have experience working with electricity, you will probably want to engage an electrician.

I killed the rest of the hum with a Jensen ground loop isolator model VRD-1FF. The isolator gets installed inline between the coax from the wall and the cable box/TV.

It costs about $50-$60. You can read about it here:

http://www.jensen-transformers.com/iso_vid.html

Incidentally, I had the same hum trouble when I added a sub to my bedroom system and I found a ground loop isolator from Dayton (Model VIT-1) on PartsExpress.com for about $10 that also killed the hum completely. I wish I had found the $10 model first!

The main difference that I can find between the two devices is the bandwidth that they purportedly pass. The Jensen specs state that it passes 2MHz-1300MHz while the Dayton specsheet says it passes 100MHz-1000Mhz. In my experience both units pass all digital cable channels with no problem and both killed the hum equally well.
_________________________
Outlaw 976, Outlaw 7700, Pro-Ject Phono Box S
Sonus Faber Domus Grand Piano (F&C), Niles HDFX (Surr. & Rear Surr.), Outlaw LFM-1 Plus, Velodyne SMS-1
Sonos multi room audio
Video: Sony KDL-46V2500, OPPO BDP-103, TiVo Premiere XL4
2-channel: Outlaw RR2150, SF Concerto Home, Outlaw LFM-2

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#72545 - 01/11/07 10:51 PM Re: Annoying hum
gonk Offline
Desperado

Registered: 03/21/01
Posts: 14054
Loc: Memphis, TN USA
Palmer describes what is probably the absolute best place to start with isolating a ground loop hum, and the Jenson is probably the most sure-fire solution I've heard about in the event that the cable service is the culprit.
_________________________
gonk
HT Basics | HDMI FAQ | Pics | Remote Files | Art Show
Reviews: Index | 990 | speakers | BDP-93

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#72546 - 01/12/07 03:49 PM Re: Annoying hum
AARONMADLER Offline
Gunslinger

Registered: 12/12/06
Posts: 169
Loc: Needham, MA
Lizard King - I googled Belkin PureAV and they have so many models. Which model were you referring to?

Palmer - Your advice is excellent! There is still some minor hum, but it is better than it was prior to installing the VRD-1FF. I ran to "U-Do-It" Electronics today and picked up the Jensen CATV isolator VRD-1FF for $49.90 and it works! Of course, I tried to buy the Dayton VIT-1 for $9.85, but they never heard of it even after I showed them the print out from Parts Express...figures, why sell me something for $10.00 when they can charge $50.00. Now for some more advice. I read that this is only for cable tv, not satellite. The guy at the electronics store, said that satellite is digital and cable is analog, therefore, the Jensen VRD-1FF would not help with my satellite system at home, where I also have some hum and buzz. Is this correct and do you also have some advice for me to prevent the hum and buzz from my Direct TV satellite system? Thanks again for all of your help.

I am going to have my electrician install a separate 20 amp circuit in the hope that this does something to further reduce the hum as well as properly grounding the cable line.

Gonk - Thanks as always.
_________________________
Outlaw 990/7700, Oppo DV-981HD, Gallo S.A.Amp, Nucleus Ref. 3.1, AV C, AV M, TR-2, Paradigm Atom, Pioneer PDP-4214HD, Mtrola DCT6200/2005

Outlaw 990, Aragon 8008X3, 8008, Denon 3930CI, Dahlquist DQ20, Outlaw LFM-1+, Paradigm Atom, Mtrola DCT3416 I

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#72547 - 01/12/07 08:23 PM Re: Annoying hum
palmer Offline
Gunslinger

Registered: 05/13/01
Posts: 121
Loc: South San Francisco, CA USA
There are numerous sources of information on ground loop hum on the net (Google is your friend). Here's one that has good information (if not the best spelling or grammar):

http://www.epanorama.net/documents/groundloop/

I would recommend a component by component, connection by connection test to definitively determine the source of the hum. Start with external connections(CATV, Satellite Antenna, etc.). In the case of the satellite box, first disconnect the coax antenna cable coming from the satellite dish to the receiver. Is the hum still there? If it's gone, the dish may not be properly grounded. Try reconnecting with the isolation transformer, but even if that fixes the hum, HAVE THE DISH PROPERLY GROUNDED. If the hum persists, the source is downstream and possibly isolateable with a line level isolation transformer available from Blue Jeans Cables. You'll need to test each component individually where it connects to your processor, removing the line level connections one component at a time.

Take a look at this thread on Audioholics; it seems that Hughes satellite receivers have been known to induce hum due to some issues with their power supplies. A properly grounded, dedicated circuit may help, but there may be more to it. I'm sorry I can not be more helpful but ground loop hum is hands down the most frustrating thing I have EVER had to troubleshoot in my systems due to the huge number of potential variables. Also, I have no first hand experience with Satellite TV.

This time I got off easy thanks to two factors: New, properly grounded construction and a single source of hum (CATV).

Be persistent, be safe, and don't give up. Hum is almost always completely correctable.
_________________________
Outlaw 976, Outlaw 7700, Pro-Ject Phono Box S
Sonus Faber Domus Grand Piano (F&C), Niles HDFX (Surr. & Rear Surr.), Outlaw LFM-1 Plus, Velodyne SMS-1
Sonos multi room audio
Video: Sony KDL-46V2500, OPPO BDP-103, TiVo Premiere XL4
2-channel: Outlaw RR2150, SF Concerto Home, Outlaw LFM-2

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#72548 - 01/16/07 09:57 PM Re: Annoying hum
TooMuchActions Offline
Deputy Gunslinger

Registered: 11/23/06
Posts: 10
Loc: Los Angeles
try this one...PureAV Home Theater Power Console (PF60)

http://www.ecost.com/ecost/shop/detail.asp?dpno=501009&store=ecost&source=ECOSTDEAL&srccode=cii_13736960&cpncode=07-20334864-2&adcampaign=email,ECOSTDEAL

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#72549 - 01/16/07 11:36 PM Re: Annoying hum
AARONMADLER Offline
Gunslinger

Registered: 12/12/06
Posts: 169
Loc: Needham, MA
Palmer and TooMuchActions, Thank you for your advice. I actually got on google and searched for prices for the pf60 and it was at least $300 everwhere else, so I bought two from Ecost. Thanks again.
_________________________
Outlaw 990/7700, Oppo DV-981HD, Gallo S.A.Amp, Nucleus Ref. 3.1, AV C, AV M, TR-2, Paradigm Atom, Pioneer PDP-4214HD, Mtrola DCT6200/2005

Outlaw 990, Aragon 8008X3, 8008, Denon 3930CI, Dahlquist DQ20, Outlaw LFM-1+, Paradigm Atom, Mtrola DCT3416 I

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