dougdrake2 Posted September 16, 2001 Share Posted September 16, 2001 Calling all EE's!!! Trying to get rid of a ground hum and hoping you can point in the right direction. Here's the situation. I have a new amp that is giving me a ground hum, but only when the interconnects are hooked to my Denon receiver. The hum goes away when I put a cheater plug on the amp, but I don't want to leave it that way. The Denon uses a 2-prong plug. I've plugged the amp and the Denon into several different outlets on different circuits and the hum persists. I also removed, from one source at a time, the interconnects from the Denon to other devices and the hum did not go away. How can I trace this down further and remove it? Thanks in advance - Doug ------------------ Denon AVR-3300 Acurus A200x3 NAD 7155 Receiver Pioneer PD-F19 CD Changer Sony CDP-C8ESD CD Changer Denon 3000 DVD Toshiba M784 VCR B&O Beogram 1800 TT Klipsch Chorus Klipsch KV-3 Center Klipsch SS-1 Surround Klipsch KG4 Klipsch KG3 Klipsch Forte (2pr) Velodyne CT120 Sub Sony KP-43T75 RPTV Monster HTS2000 AudioQuest Copperhead Interconnects AudioQuest Slate Speaker Wire Various other interconnects/cables Quote Link to comment Share on other sites More sharing options...
chickey Posted September 16, 2001 Share Posted September 16, 2001 Doug, 1. Make sure both units are plugged into the same AC circuit. Plugging them into different circuits can definitely create a ground loop. Sounds like you already tried this, but just in case. 2. I've had good luck eliminating ground loops using Jensen Transfomers (http://www.jensentransformers.com). I do no work for them, nor am I affiliated with them in any way, just a satisfied customer. Click on audio isolators, and check out model CI-2RR. I've had great success with these devices, and no degradation in sound occurs (and I'm pretty picky). Hope this helps, Colin Quote Link to comment Share on other sites More sharing options...
boa12 Posted September 16, 2001 Share Posted September 16, 2001 thanks doug, as u may have seen, I got it w/ the new acurus also. more of a real nasty buzzz. i too used the cheater on the acurus which took it away but would also like to solve it elsewise. same thing, disconnecting interconnects didn't work, but when I disconnected the cable tv cable from the cable box & tv it vanished (try that yet?). chickey was helping me out on my past postings. wondered then if I had a quasi-ground loop w/ some of that movie playback distortion but never solved. then again never had anything connected w/ a 3 prong ground before the acurus. i had an electrician put in a 3-prong outlet on the side wall. he ran the ground to a water pipe in the crawl space. wanted him to run it to the common ground but it was 2 far away(costly) & this old house has very few grounded outlets anyway. so on the side wall w/ the grounded outlet I have the monster hts2500 powercenter (grounded) & the dvdp, receiver & acurus power amp. only the acurus has a 3 prong plug & currently has that cheater plug. on the front wall w/ the old ungrounded plug is the tv, digital cable box, vcr, & powered sub (has a 3 prong plug but have always used the cheater on the plug in anyway. from the cable box to receiver i have s-video, digital audio & analog audio connections. from the receiver i have an s-video connecton to the tv & the line connection to the powered sub. gosh, looks like i'm the poster boy for a ground loop problem i also tried removing the outside ground on the cable connection but that didn't work. the only things that work are the cheater plug on the power amp or disconnecting the cable tv. the 1st & easiest thing to try would be a ground loop isolator. i'll try the f-pin isolator like jensen's cable line isolator for $59, but i'm not gung-ho on spending $100s for s-video, sub, analog isolators. is it possible i am or have been getting a ground loop even without anything being plugged in with a 3 prong plug? iow, can u get electrical noise like a ground loop with only 2 prong plugs into either a 2 or 3 prong grounded outlet? my electricical knowledge is limited & i know these GLs are very tricky & mileage will vary, but could there be some way to solve this in the home electrical sys? what really causes a ground loop? could a solution be to ground the cable tv & both or all of the outlets i'm using for the av sys all to that same common ground/pipe? whew! ------------------ Klipsch KLF 30 (front) 2-KLF C7 (front center & rear center) Cornwall I (rear) Velodyne HGS-18 sub woofer Marantz SR-8000 receiver Acurus A200X5 power amp Sony DVP-C650D 5-disk cd/dvd player Sony Trinitron 27" stereo tv Toshiba hi-fi stereo vcr Scientific Atlanta Explorer 2100 digital cable box Monster HTS2500 & HTS1000 powercenters Boa's Listenin Lounge: Klipsch RF-3, RC-3 Sony STR-DE935 a/v receiver Kenwood KR-9600 AM/FM stereo receiver (vintage 1975) Russound AB-2 receiver switch to RF-3 Teac PD-D1200 5-disk cd changer Technics SL-1950 turntable/AT LS500 cartridge Technics dual cassette deck rock on! This message has been edited by boa12 on 09-17-2001 at 12:34 AM Quote Link to comment Share on other sites More sharing options...
dougdrake2 Posted September 17, 2001 Author Share Posted September 17, 2001 Colin - Thanks for the tips. Yes, I have both the amp and the receiver (and the sub, which is giving me a hum also) all plugged into a Monster HT2000 strip. Like boa, the amp is the only 3-prong device I have, although the HT2000 has a 3-prong on it. I looked at the Jensen items. Interesting. Since I have a 3-channel amp and a subwoofer exhibiting these symptoms, that looks like 4 channels of problems which would require 2 CI-2RR's to solve at $178 a piece, plus 4 more interconnects. Yikes!! We're looking at over $400 to knock out a ground loop? I downloaded their Troubleshooting Guide which I think I'll attempt first. Boa - I don't have cable, so that's not an issue. I actually unhooked everything, one device at a time, including aerial antenna feeds, and still the hum persisted (at least as long as the interconnects from the amp to the receiver were in place). DD2 ------------------ Denon AVR-3300 Acurus A200x3 NAD 7155 Receiver Pioneer PD-F19 CD Changer Sony CDP-C8ESD CD Changer Denon 3000 DVD Toshiba M784 VCR B&O Beogram 1800 TT Klipsch Chorus Klipsch KV-3 Center Klipsch SS-1 Surround Klipsch KG4 Klipsch KG3 Klipsch Forte (2pr) Velodyne CT120 Sub Sony KP-43T75 RPTV Monster HTS2000 AudioQuest Copperhead Interconnects AudioQuest Slate Speaker Wire Various other interconnects/cables Quote Link to comment Share on other sites More sharing options...
boa12 Posted September 17, 2001 Share Posted September 17, 2001 doug, from all i've read, theoritically u should have no ground loop. all i can think is somehow your receiver is getting a ground somehow & it's different from the ground on the outlet. assuming everything is plugged in directly to the powercenter. maybe try grounding the receiver chassis. just talking out of my A## though. don't know as i've found many electricians don't know on audio either. u may want to call adam at mondial. 800-544-1482 X8661 good luck! This message has been edited by boa12 on 09-17-2001 at 01:16 AM Quote Link to comment Share on other sites More sharing options...
J M O N Posted September 17, 2001 Share Posted September 17, 2001 Is there any reason you guys don't want to use cheater plugs? They are cheap and they solve the problem. I use them myself. A ground loop is essentially when you have multiple components grounded, then when you connect them together via interconnects (or cable -- the TV cable is also grounded), you create a "Loop" which causes the noise. By using cheater plugs, you are breaking the loop, but each of your components are still grounded via the interconnects (or TV cable). Just make sure you have at least one component grounded to protect all your equipment. Quote Link to comment Share on other sites More sharing options...
Mike Lindsey Posted September 17, 2001 Share Posted September 17, 2001 I just ordered an A200x3 and it should be here in a week or so. Can someone pleas explain what a cheater plug is? Thanks, Mike ------------------ Family Room ----------- Hitachi 43UWX10B HDTV (16:9) Denon AVR-4800 Panasonic DVD-RP91K (Progressive Scan & DVD-Audio) Dual CS-5000 Turntable w/Shure V15V-MR DBX 3bx Series III Range Expander Klipsch Chorus (mains) Klipsch KLF-C7 (center) Klipsch Epic CF-2's (rears) Klipsch RS-3's (rear surrounds) SVS 20-39CS Sub w/Samson S700 Amp Monster HTS-3500 Line Conditioner Scientific Atlanta Explorer 2100 Digital Cable box Monster M-500 Component Video cables Monster Datalink 100 Digital Coaxial cables Radio Shack Gold Series for all other audio interconnects Bedroom ------- Mitsubishi 31" TV Yamaha M-4 Amp Yamaha C-4 Preamp Yamaha T-7 Tuner Teac DVD Player Dual CS-721 Turntable w/B&O MMC2 Looking for a pair of Heresy's Quote Link to comment Share on other sites More sharing options...
Ray Garrison Posted September 17, 2001 Share Posted September 17, 2001 A "cheater plug" is a something that lets you put an electrical cord that is terminated with a three-prong plug into a two-prong outlet. The electric cord plug with the hot, neutral and ground connectors plugs into one side of the adaptor. The other side has only two prongs, one hot and one neutral. Carried to the extreme, the two prongs may be the same size (not polarized), allowing the adapter to be plugged into an outlet either way 'round. Here's an interesting article on why this can help break ground loops, and some of the safety issues, from the PS Audio website: http://www.psaudio.com/articles/hum.asp Ray ------------------ Music is art Audio is engineering Quote Link to comment Share on other sites More sharing options...
dougdrake2 Posted September 17, 2001 Author Share Posted September 17, 2001 JMon - If, by "have at least one component grounded," you mean have at least one 3-prong plug directly plugged into an electrical outlet, that may be my challenge. I have only one device with a 3-prong plug (the Acurus), so if I put a cheapter plug on it, I will then have no devices that are grounded, right? All devices are plugged into a Monster HT2000, which DOES have a 3-prong plug on IT. Would that cover it? The reason I'm trying to not use a cheater plug is because Mondial said not to (maybe that's not a good enough reason ). Also, a troubleshooting guide at http://www.jensen-transformers.com/an/ts_guide.pdf advises against it, and points out that most cheater plugs are designed to have a 3rd connection grounded to the electrical outlet via the cover plate screw. Maybe I'm just paranoid... DD2 Quote Link to comment Share on other sites More sharing options...
chickey Posted September 17, 2001 Share Posted September 17, 2001 Doug, Glad you picked up on the link to the troubleshooting guide on Jensen's site - it's a very informative source. As you've indicated, you can spend loads of money on solving these problems if you're not careful. In my case, after a lot of troubleshooting, I discovered that the connection between my TV and preamp/pro was the source of the ground loop, so inserting a single Jensen transformer into the signal path solved the problem. As such, you don't necessarily need to isolate all paths into or out of a given device - just those that create the ground loop in the first place. Also, as you and may others have correctly surmised, cheater plugs, while temporarily correcting the problem, can create a dangerous situation, and as such should be avoided. I've battled ground loop gremlins in my system for years (10 separate components plus a TV are a breeding ground for such problems). As such, if I can be of any further assistance, please let me know. Sounds like you're off to a good start. Colin Quote Link to comment Share on other sites More sharing options...
boa12 Posted September 17, 2001 Share Posted September 17, 2001 i just ordered the magic box cable tv ground loop isolator by mondial from www.audioadvisors.com per keith. will see what it does. i have no problem keeping a cheater plug on the acurus though. the hts2500 powercenter & the cable tv will still be grounded. Quote Link to comment Share on other sites More sharing options...
eq_shadimar Posted September 17, 2001 Share Posted September 17, 2001 Ack you guys are killing me with these prices. If you want to break the ground loop from the cable system (a very very common problem) try this out. http://www.hometech.com/video/atten.html Look for XA-63400 Ground Breaker it is around $7 or so. I have no comment on the audio stuff but I guess it is worth it if it does not affect the sound any. EDIT - I had the same hum problem with my Hafler when I plugged it into the system to power the SVS Woofer but it had a switch on it to change the chassis to a floating ground. That fixed the fixed the problem. I am guessing that it works basically the same way as using a cheater plug. Laters, ------------------ FOR SALE OR TRADE COMPLETE R*3 SYSTEM FOR 3 HERESY'S Main System - Cornwalls (L/R main) RC-3 RS-3's (white) SVS 20-39CS Harman Kardon AVR 510 Hafler P505 (running sub) ProMedia 4.2 v400 for PC This message has been edited by eq_shadimar on 09-17-2001 at 02:35 PM Quote Link to comment Share on other sites More sharing options...
boa12 Posted September 17, 2001 Share Posted September 17, 2001 eq, without going into all the tech details & probably embarrasing my self , those cheapies can & probably will degrade both audio & video quality from the cable feed & may not even do a good job of isolating the ground. & w/ klipsch speaks & quality reproducers which can magnify a problem such as this, i'm going w/ a quality piece. just my rationalizing Quote Link to comment Share on other sites More sharing options...
eq_shadimar Posted September 17, 2001 Share Posted September 17, 2001 Boa - Ah very true. I keep forgetting I am a lofi dude in a hifi world. Anyhoo here is another great link for ground loop information: http://www.smr-home-theatre.org/Ground-Loops/index.html Laters, ------------------ FOR SALE OR TRADE COMPLETE R*3 SYSTEM FOR 3 HERESY'S Main System - Cornwalls (L/R main) RC-3 RS-3's (white) SVS 20-39CS Harman Kardon AVR 510 Hafler P505 (running sub) ProMedia 4.2 v400 for PC Quote Link to comment Share on other sites More sharing options...
T2K Posted September 18, 2001 Share Posted September 18, 2001 Ran across the below in my notes while looking for something else.Don't remember what it is,but anyone interested can do the homework. Radio Shack ground loop isolator #270-054 $14.99 each Keith ------------------ KSP-300 FL/R KSP-C6 CENTER SW8II C/SUB KSP-S6 SURR KSP300 SB SW12II SONY KP53XBR35 RP DENON 3801 DENON DVD3300 DVD-AUDIO SONY MDP455 LDP ACURUS 125X5 ACURUS 100X3 MONDIAL M.A.G.I.C. BOX PANAMAX MAX 1000 PANAMAX COAXMAX (2) AQ SLATE AQ COPPERHEAD AQ SIDEWINDER AQ VSD TRIBUTARIES S-VIDEO MONSTER INT.400MKIII Quote Link to comment Share on other sites More sharing options...
dougdrake2 Posted September 21, 2001 Author Share Posted September 21, 2001 Well, I've crawled through the entire system, and discovered that 3 components are introducing hum into the system -- the DVD, the VCR, and the TV. I disconnected ALL inputs from my receiver and the hum went away. I then hooked up, one at a time, the various other components and noted which ones created hum. I disconnected any upstream devices from the components so I had each one isolated (e.g. removed the DVD connection to the TV so I just had an audio connection in the receiver). Keith, I looked at the Radio Shack item on their web site, and I cringe looking at those interconnects. Kind of makes Copperheads superfluous, doesn't it? But if I use them only on the connections from the TV (a single composite video used only for OSD from the Denon and a VCR signal) and the VCR (again, no big loss if those aren't the greatest interconnects) and switch the audio connection from the DVD from coax to fiber, that should isolate the hum sources. The key interconnects are the ones from the CD player, DVD, and the amp, and those would all be on good cable or fiber. Just musing aloud... DD2 This message has been edited by dougdrake2 on 09-21-2001 at 01:05 AM Quote Link to comment Share on other sites More sharing options...
Mike Lindsey Posted September 21, 2001 Share Posted September 21, 2001 Doug, I too have noticed a slight crackling noise (hum?) coming out of my speakers when there is nothing playing, but the source is turned on to something (DVD, CBL, etc). If I have the receiver volume set to anything (-60 to 20) it makes the noise. If I turn the volume to where the 3 dash lines appear instead of a digital number (one click above -60), it goes away. I noticed this long before I hooked up the Acurus. Is this the hum you speak of? It's not very noticeable until you walk up to the speakers but it's there. Do I have a ground problem also? Thanks, Mike Quote Link to comment Share on other sites More sharing options...
Guest BobG Posted September 21, 2001 Share Posted September 21, 2001 Mondial Magic Box is a distributed capacitance device which eliminates cable-related ground loop problems. Also Magic Splitter. These work and don't degrade audio or video performance. They can be purchased on this web site. Dougdrake's problem will not be corrected by either of these devices, but just saw an opportunity to get in a plug (no pun intended ;-)) Quote Link to comment Share on other sites More sharing options...
dougdrake2 Posted September 21, 2001 Author Share Posted September 21, 2001 Mike - The hum I am getting is new, since the Acurus acquisition (due to the 3-prong plug). It hums even when the preamp (Denon) is off, and all other sources for that matter. In other words, the hum happens with only the Acurus turned on feeding idle-level juice to the speakers. BobG - Plug away!!! It's your web site and bulletin board, no need to be shy! Actually, someone else (Keith, I believe) already put in a plug for the plug. DD2 ------------------ Denon AVR-3300 Acurus A200x3 NAD 7155 Receiver Pioneer PD-F19 CD Changer Sony CDP-C8ESD CD Changer Denon 3000 DVD Toshiba M784 VCR B&O Beogram 1800 TT Klipsch Chorus Klipsch KV-3 Center Klipsch SS-1 Surround Klipsch KG4 Klipsch KG3 Klipsch Forte (2pr) Velodyne CT120 Sub Sony KP-43T75 RPTV Monster HTS2000 AudioQuest Copperhead Interconnects AudioQuest Slate Speaker Wire Various other interconnects/cables Quote Link to comment Share on other sites More sharing options...
boa12 Posted September 21, 2001 Share Posted September 21, 2001 mike some noise like crackling is typical when changing the volume or any switching w/ the receiver. even w/ the receiver or other components idle some hiss or noise is common & usually can't be heard when playing material. jmo, but sounds like some line or component noise which the acurus is amplifying & the klipsch are reproducing as they do quite well ground loop noise tends to be a very obvious hum or buzz. nothing subtle on the buzz i get from the cable tv connection. if u have that cable tv connection, just unhook the f-pin cable coming into the house at the 1st point & see if that noise u speak of goes away. Quote Link to comment Share on other sites More sharing options...
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