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#77229 - 03/17/06 07:33 AM Re: hum from 7500 but not ground loop?
Ritz Offline
Desperado

Registered: 07/03/05
Posts: 547
Loc: NJ/Beijing
Papa,

That seems like an awful lot of effort to go through because one componenet in jrlouie's system is succeptible to transformer buzz and/or hum. A number of people are complaining about this so perhaps the ultimate problem may be ground loops or line sags or whatever, but why is the 7500 so much more succeptible to that? A consumer audio device shouldn't require laboratory quality conditioned input power to operate properly since most homes don't have anything close to that. 8-)

Cheers,
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#77230 - 03/17/06 07:37 AM Re: hum from 7500 but not ground loop?
gonk Offline
Desperado

Registered: 03/21/01
Posts: 14054
Loc: Memphis, TN USA
If there are a number of people complaining, I suspect the variation they are seeing is significant - well outside the typical variation that equipment is designed to deal with.
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#77231 - 03/17/06 08:56 AM Re: hum from 7500 but not ground loop?
Ritz Offline
Desperado

Registered: 07/03/05
Posts: 547
Loc: NJ/Beijing
Which is counter-intuitive. You'd think people who are able to afford a $1500 amplifier for their home theater system would likely also be able to afford a newer house with newer wiring in an area with a more stable power grid, etc. So I'd expect to see less variation of this nature. Of course, that might just mean that my expectations are wrong. But I don't recall seeing much in the way of griping about hum and ground loops with previous incarnations of Outlaw amps.

Cheers,
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#77232 - 03/17/06 09:24 AM Re: hum from 7500 but not ground loop?
jrlouie Offline
Gunslinger

Registered: 03/05/06
Posts: 118
Loc: Missouri
Except in my case, purchasing a house just hasn't happened, although I can afford one. I am currently choosing to rent a loft downtown and I appreciate the walk to work wink

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#77233 - 03/17/06 10:01 AM Re: hum from 7500 but not ground loop?
gonk Offline
Desperado

Registered: 03/21/01
Posts: 14054
Loc: Memphis, TN USA
By "number of people complaining" I meant the other tenants in jrlouie's building - not all of whom (presumably) are hooking multichannel amps up smile - and that the reason for all the complaints was a valid issue with the electrical service to the building.

As for affording newer homes with newer wiring, that can depend some on the region. Around here, some of the most expensive homes (relative to lot size and square footage) are in older parts of town, where wiring is 50+ years old and upgrades to bring it up to modern standards can be a real bear - if the owner realizes why such upgrades might be beneficial.
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#77234 - 03/19/06 08:12 AM Re: hum from 7500 but not ground loop?
rectilineariii Offline
Gunslinger

Registered: 03/06/06
Posts: 29
Loc: Honolulu, HI
I just had exactly the same thing happen to me. My 7700 was dead silent then this mysterious hum emulated from the unit. We have a small space heater that we use occasionally downstairs and that was the little culprit. The weird thing is that it's not on the same circuit.

We are having an electric guy come over and put our HT toys on a separate circuit.

This forum is great! I am finding out that just about every "problem" has been discussed at least once and a solution is usually found. It's nice to know that there is a good chance a solution will be found 24/7.
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Zone 1: Outlaw 990, Outlaw 7700, Panasonic Plasma, Apple TV, 24" Intel iMac, ReVox A77, Mission 77 Series, Mirage LF-150
Zone 2: McIntosh MA1650, Dual 1219, Smaller Advent Speakers
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#77235 - 03/19/06 10:20 AM Re: hum from 7500 but not ground loop?
jrlouie Offline
Gunslinger

Registered: 03/05/06
Posts: 118
Loc: Missouri
So I tried a test. Outlaw suggested I try various outlets and if possible, outlets on a different line. When I tried, I thought the different line cleaned it up. But, I was using an extension cord and when I tried it on other outlets on the original line, I couldn't hear it then either. So, I used a power strip to different outlets on the original line, and I could hear it. So, essentially somehow this one extension cord is masking the test.
Now with the power strip, I can hear the hum from the 7500, from 2 other outlets on the same line, with or without a cheater plug. I also was able to find a different extension cord that still allowed me to make the 7500 hum. Using that extension cord, going to a different line, the 7500 still buzzes/hum.
So, I guess it isn't really this one line. It is in my apartment at various locations. I wonder if the electrical stuff in this building is just noisy. I know the light flicker a lot. I wish I could find a loner DC filter, just to try it out and see.

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#77236 - 03/31/07 02:30 PM Re: hum from 7500 but not ground loop?
Supertom Offline
Gunslinger

Registered: 01/12/06
Posts: 33
Loc: Syracuse
Hi Jrlouse

Hope i'am not bothering you.
I was just wondering if you ever figured your buzz problem out
I seem to have the same problem with my new 7500
it comes and goes i did the ex-cord thing and it seemed to help ...... so i put in a separate 20amp circuit JUST for the Amp (its Better but it still comes around every once and awhile)
I Hate it ...... like tou said its "NOT LOUD" but it is there and not part of the Movie/Music
Thanks
SUPERTOM

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#77237 - 05/21/07 09:37 PM Re: hum from 7500 but not ground loop?
cp1966 Offline
Gunslinger

Registered: 04/20/07
Posts: 221
Loc: Minneapolis
My 7700 makes almost a whirling noise when it first turns on, but then it gradually goes down. It is audible, but only if you are right next to it.

I also had a ground loop, but was able to determine it was caused by having a digital coaxial audio cable plugge din. I am only using opticals now, and it sounds great. If I put my ear right next to the speaker, I can hear a faint noise coming it.
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