Is this ground loop? - AVS Forum
Audio Theory, Setup, and Chat > Is this ground loop?
atdamico's Avatar atdamico 07:57 AM 07-15-2007
Never having experienced ground loop hum...I received my new tt and phono preamp yesterday. Set up the tt and connected it to the input of the phono preamp. Connected the outputs of the phono preamp to the analog inputs on my Anthem AVM30 which outputs to my Sherbourn 5/5210a amp. I have had this system for years with NO hum or buzz. Connected to it are a DVD player, a SACD player connected via analog, and sattelite. Since connecting the tt there is a horrible buzz/hum that is more than a hum...its loud. You can hear the LP playing but the sound is completly lacking any sort of dynamics and at any volume over
-45 the hum/buzz threatens to harm the speakers. The phono preamp is a Parasound Zphono. I do not have cable tv anywhere in the system.

Is this a ground loop hum? Any suggestions or ideas? I'm thinking a bad phono preamp.

Thanks,

Rupert's Avatar Rupert 08:03 AM 07-15-2007
Does your tt have a ground wire?
atdamico's Avatar atdamico 08:11 AM 07-15-2007
Quote:
Originally Posted by Rupert View Post

Does your tt have a ground wire?

No. The tt is a Rega Planar 2.

Everything is plugged into the same surge suppresor with the exception of the tt which is plugged into a seperate wall socket. The analog inputs that the tt is plugged into are the same ones that I had my CD player plugged into without any noise. I plugged the tt directly into the anthem and while the sound was very low, as to be expected, there was sound from both channels and no hum. Its only when I introduce the phono preamp into the mix that I get the hum. But, as I said, never haveing experienced this before this is more of a VERY LOUD buzz/hum and the music, while you can hear it, is very compromised.

There is a ground connection on the phono preamp, but no ground wire from the tt attach to it.

I just disconnected the tt by unplugging it. I left the phono preamp plugged in and connected that the buzz is still there. So its not the tt, its the preamp. Now the question still is:

Do I have a bad phono preamp or do I have a ground loop hum from it?
Rupert's Avatar Rupert 09:05 AM 07-15-2007
It's probably just a ground loop and not a defective device.

Have you tried the AC Polarity switch on the phono pre-amp?

Also, is it possible to connect everything to the same surge protector?
atdamico's Avatar atdamico 09:08 AM 07-15-2007
Quote:
Originally Posted by Rupert View Post

It's probably just a ground loop and not a defective device.

Have you tried the AC Polarity switch on the phono pre-amp?

Also, is it possible to connect everything to the same surge protector?

Yes, I tried the polarity switch. And everything is connected to the same surge protector. Except the tt, which is not plugged in at all right now and I still have the buzz/hum.
4DHD's Avatar 4DHD 11:01 AM 07-15-2007
Quote:
Originally Posted by atdamico View Post

Yes, I tried the polarity switch. And everything is connected to the same surge protector. Except the tt, which is not plugged in at all right now and I still have the buzz/hum.

Is the tt still connected to the preamp. Even tho the tt is unpluged from the AC it could still be causing the hum if the L/R audio is still connected.
It sounds to me like the tt needs a ground.
sprung2's Avatar sprung2 12:21 PM 07-15-2007
Your anthem AVM30 has balanced outputs and your Sherbourn 5/5210A has balanced inputs, you should be using them. A 14ga or better wire between the ground lug of the parasound zphono and that of the AVM30 would futher lower the ground noise.
sprung2's Avatar sprung2 12:31 PM 07-15-2007
Sweet system BTW
trekguy's Avatar trekguy 03:42 PM 07-15-2007
Quote:
Originally Posted by sprung2 View Post

A 14ga or better wire between the ground lug of the parasound zphono and that of the AVM30 would futher lower the ground noise.

I am curious as to why you suggest 14 AWG or better for supplemental ground connection between the phono amp and the AVM30? It will never be the safety ground route for the power circuit.
atdamico's Avatar atdamico 05:50 PM 07-15-2007
Quote:
Originally Posted by sprung2 View Post

Your anthem AVM30 has balanced outputs and your Sherbourn 5/5210A has balanced inputs, you should be using them. A 14ga or better wire between the ground lug of the parasound zphono and that of the AVM30 would futher lower the ground noise.

I am using the balanced XLR connections between the prepro and amp. Everything is plugged into the same surge supressor, and I have no cable TV.

But what would a ground between the phono preaamp, and the preprocessor get me?

By the way, I play guitar and have for a long time. I love single coil pickups so I am VERY familiar with the 60hz humm that exists. This is NOT anywhere near that buzz. This is LOUD enough at -40 (and my system is calibrated for 0 to be reference level) that my speakers couldn't take much more. (Vandersteen 2CE)

That's why I am asking if what I described is even a ground loop hum at all.
4DHD's Avatar 4DHD 07:03 PM 07-15-2007
About the only thing left to do is try another phono preamp. And get a tt that has a ground wire to run to the phono amp.
But first I'd be contacting both the tt manufacturer and the phono amp company to see if they have a clue.
sprung2's Avatar sprung2 07:39 PM 07-15-2007
Quote:
Originally Posted by atdamico View Post

I am using the balanced XLR connections between the prepro and amp. Everything is plugged into the same surge supressor, and I have no cable TV.

Then there is no loop between the amp and pre/pro though your satellite could cause the same issue as the cable tv

Quote:
Originally Posted by atdamico View Post

But what would a ground between the phono preaamp, and the preprocessor get me?
.

Nothing if there is no loop between the zphono and the AVM30.
The Rega's ground via their l/r outputs. The zphono may have a problem with that.

Quote:
Originally Posted by trekguy View Post

I am curious as to why you suggest 14 AWG or better for supplemental ground connection between the phono amp and the AVM30? It will never be the safety ground route for the power circuit.

Force of habbit mostly, Both the chassis' of the zphono and the 5/5210A are grounded , by converntion so should the chassis of the AVM30 which is not grounded as Anthem uses a soft ground for its amps and pre/pros.
atdamico's Avatar atdamico 06:29 AM 07-16-2007
So, as I said from the beginning. I'm not even sure I have a ground loop problem. As I have never heard one, I envision it a a low 60 cycle hum in the background of the media. Not a loud buzz/hum that threatens the speakers and 99% overrides any media played.

Is this even a ground loop problem??
4DHD's Avatar 4DHD 10:16 AM 07-16-2007
Quote:
Originally Posted by atdamico View Post

So, as I said from the beginning. I'm not even sure I have a ground loop problem. As I have never heard one, I envision it a a low 60 cycle hum in the background of the media. Not a loud buzz/hum that threatens the speakers and 99% overrides any media played.

Is this even a ground loop problem??

As I said in an earlier post, you need to contact the two companies that built the units, to see if they have a solution to the problem.
That's what I did when I had a problem with my H/K receiver and the problem got solved, as in getting a new receiver.
soundlovr's Avatar soundlovr 11:31 PM 07-16-2007
It is NOT a ground loop problem since you're running everything off the same outlet (except the turntable which you've excluded from the system and still had the problem). Period.
atdamico's Avatar atdamico 07:19 AM 07-17-2007
Quote:
Originally Posted by soundlovr View Post

It is NOT a ground loop problem since you're running everything off the same outlet (except the turntable which you've excluded from the system and still had the problem). Period.

A very direct answer to a very direct question, thanks!

That's the conclusion I came to as well, I sent the phono preamp back yesterday. I get a new one today, so I'll see if I have the same issue.
atdamico's Avatar atdamico 09:27 AM 07-17-2007
FYI:

Received my new phono preamp today, simply switched it with the Parasound one and the system is dead quiet. Not buzz, hum, or noise at any volume level. The Parasound Zphono preamp was DOA. Went with a Pro-ject SE. It was not a ground loop hum.
Chu Gai's Avatar Chu Gai 10:13 AM 07-17-2007
Which one did you get? BTW, I'm somewhat surprised there isn't a ground wire that comes from the turntable and then gets attached to someplace on the back of your pre.
atdamico's Avatar atdamico 11:00 AM 07-17-2007
Quote:
Originally Posted by Chu Gai View Post

Which one did you get? BTW, I'm somewhat surprised there isn't a ground wire that comes from the turntable and then gets attached to someplace on the back of your pre.

I got a Pro-ject SE phono stage. About $300 and it works fine. Rega's ground is in one of the Coax cables so there is not a seperate ground wire. I haven't had a chance to critically listen yet, but I did listen to side B of Janis Joplin, Big Brother and the Holding Company. Ball and Chain sounded great. And the entire system is dead quiet. I was going to post on one of the vinyl threads once I have a chance to really listen to some good material and switch back and forth between CD and Vinyl. I have a new copy of Eva Cassidy's Songbird and Let It Bleed by the Stones, both on 180 gram vinyl that I am going to use for my comparrison.

I'm also going to experiement with blending my sub into the mix. Up till now I only listen to music via two channel (except for SACD) so I want to see what my Vandersteens sound like in two channel and with a sub.
Chu Gai's Avatar Chu Gai 01:44 PM 07-17-2007
I think incorporating the sub is an excellent idea. While going 'old-school' is fun, there's nothing fun about using old-school thinking when it comes to low frequencies having to come from two speakers.
sprung2's Avatar sprung2 10:52 AM 07-18-2007
If you don't mind me asking, which cartridge are your using with the p2, According to Rega it comes standard with the red bias2 which is a mm. Did you try the mm/mc switch on the parasound ??. The project audio SE is also mm/mc but it uses dip switches.
atdamico's Avatar atdamico 11:52 AM 07-18-2007
Quote:
Originally Posted by sprung2 View Post

If you don't mind me asking, which cartridge are your using with the p2, According to Rega it comes standard with the red bias2 which is a mm. Did you try the mm/mc switch on the parasound ??. The project audio SE is also mm/mc but it uses dip switches.

As noted in my post above, the problem was solved. The Parasound Zphono was DOA. I know its not logical to blackball a brand due to one bad product, but I won't buy Parasound equipment again. I remember many years ago when a bunch of people died eating Jack In the Box food. I just don't get why I still see people eating there. I'll give anybody one chance, but not two.
Chu Gai's Avatar Chu Gai 12:41 PM 07-18-2007
Gee, Jack in the Box. I haven't had one of those in years. I remember when they first opened by me. Must've been in the late 60's or so and while the food was so-so, the tacos were pretty damned big. My favorite place was the old drive up A&W root beer place where they'd come to your car. A pitcher of root beer and 4 mama burgers for $2. Those were the days
atdamico's Avatar atdamico 02:50 PM 07-18-2007
Quote:
Originally Posted by Chu Gai View Post

Gee, Jack in the Box. I haven't had one of those in years. I remember when they first opened by me. Must've been in the late 60's or so and while the food was so-so, the tacos were pretty damned big. My favorite place was the old drive up A&W root beer place where they'd come to your car. A pitcher of root beer and 4 mama burgers for $2. Those were the days

I remember A&W rootbeer stands. There was also Original Hotdog. Same gig, came to your car and delivered the best hotdogs in town! As I haven't eaten red meat in over 20 years the Jack In the Box scare didn't really apply to me. But I still can't fathom ingesting a product from a company that killed people due to its lack of standards. Sorry, but I don't take Tylenol, eat red meat anymore, or cater to companies that have either buned me personally or killed people due to contaminated products. In our consumer society, there are just way too many options to do business with quality companies that stand behind their products and employ good busines practices. But that's just my opinion.
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