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New TT new hum


Harleywood

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Need some pointers please. Just set up the new 1200gr and AT VM740sh cart. Used my Audioquest RCAs and ground from previous table and separated power and signal cables as before. Powered up amp only and hum in mains. Powering up sub yielded same result. Hum is in all inputs but louder in phono input. It's late  so I just unplugged the TT and thought I'd ask for some tips here on where to start tomorrow before hitting the sack tonight. Thanks guys!

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3 hours ago, Schu said:

1200gr is wonderful...

Is the hum gone without those audioquest cables?

Thanks for the reply. I haven't checked the cables yet. I read the manual and am having a hard time believing that I have to use the provided interconnects and ground. I did however remove the headshell and cart and when I powered up without them installed on the arm the hum was gone and it's dead quiet everywhere. I figure if it was an interconnect issue it would still hum without headshell installed. What's your thought on that? Headshell wires look good. No contacts or bare wire touching headshell but the leads do rest against it. Any suggestions on what/how to troubleshoot this? Thanks!

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Ho hum. Swapped cables and ground no luck. Moved power cords around no luck. Plugged tt into a cheater two prong plug and hum moved to right channel only. Running now without cheater plug and hum still only in right channel and only noticeable when volume is past 45. Before all this the hum was much louder and in both channels. I've also removed the headshell and reinstalled a few times and sometimes the hum got quieter and sometimes louder. Scratching my head. Headshell/cart issues?  Oh, I've also put the old table back in line and dead quiet with that table. Any input greatly appreciated! 

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If you have a separate grounding cable (TT chassis to amp or pre-amp) plus a plug prong ground - it's a ground loop. I suspect some sort of liability laws require them to supply 3-prong power cords, but this sets up a grounding loop by default when using a separate ground. Use either the third ground prong or the external grounding wire - not both at the same time. Your TT is grounded in either case.

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Ugh... Hum issues are the worst.  Sorry to hear.

 

I had hum issues and resolved them by plugging my TT, phono pre-amp, and Integrated amp into the same 4-outlet receptacle.  Voila.  Gone.  It's certainly worth giving that a try.

 

As an aside, although my Integrated has a phono-pre, I use an outboard phono pre-amp because my TT is too far away for 6' interconnects to reach the Int. amp.  By placing the phono pre-amp b/w the TT and Int. Amp, I have about 12' feet of total cable distance. 

 

Once you get it resolved, you'll love the 1210GR.  I have a GAE and it's a joy.

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On 3/12/2022 at 7:09 AM, chassell said:

If you have a separate grounding cable (TT chassis to amp or pre-amp) plus a plug prong ground - it's a ground loop. I suspect some sort of liability laws require them to supply 3-prong power cords, but this sets up a grounding loop by default when using a separate ground. Use either the third ground prong or the external grounding wire - not both at the same time. Your TT is grounded in either case.

Thanks for the input! I never was much of an electrician but isn't the small ground wire a signal ground where the three prong plug is a power supply safety ground? Two different paths? 

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6 hours ago, ODS123 said:

Ugh... Hum issues are the worst.  Sorry to hear.

 

I had hum issues and resolved them by plugging my TT, phono pre-amp, and Integrated amp into the same 4-outlet receptacle.  Voila.  Gone.  It's certainly worth giving that a try.

 

As an aside, although my Integrated has a phono-pre, I use an outboard phono pre-amp because my TT is too far away for 6' interconnects to reach the Int. amp.  By placing the phono pre-amp b/w the TT and Int. Amp, I have about 12' feet of total cable distance. 

 

Once you get it resolved, you'll love the 1210GR.  I have a GAE and it's a joy.

Yes I have a power strip and the TT, amp, sub and cd are all plugged into it. I'm going to invest in a better power strip though. I think the current one is a 9.99 wally world special. Also going to move my power amp down to bottom shelf in the rack giving more space between the two. I've already had to move my sub due to feedback issues at volume. Never affected my last tt. Funny that when you get new better components they always seem to amplify the shortcomings of other pieces in the chain. 

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Do you have a grounding wire connected from turntable to the preamp?  Ground loops are caused by the two chassis grounds having slightly different potentials and the current develops across the interconnects modulating the signal. Don't always rely upon the power receptacles being plugged into the same outlet because that's a much longer loop. You want a short loop directly connecting the TT to the amp.

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5 hours ago, Harleywood said:

Funny that when you get new better components they always seem to amplify the shortcomings of other pieces in the chain. 

 RE-plug the older TT , if the hum is gone , there's an issue with the new TT -

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Yes would get another power strip with some surge protection, maybe even conditioning to protect equipment.

Yes would also use same circuit but plug into a wall outlet the TT. First without adapter, and then with.

Not encouraging that when using old TT quiet. And by amp thinking your int. Rotel which you are familiar with.

 

Would take a break and think about calling the seller to let know.

Thanks!

Edited by billybob
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On 3/11/2022 at 10:01 AM, Harleywood said:

Thanks for the reply. I haven't checked the cables yet. I read the manual and am having a hard time believing that I have to use the provided interconnects and ground. I did however remove the headshell and cart and when I powered up without them installed on the arm the hum was gone and it's dead quiet everywhere. I figure if it was an interconnect issue it would still hum without headshell installed. What's your thought on that? Headshell wires look good. No contacts or bare wire touching headshell but the leads do rest against it. Any suggestions on what/how to troubleshoot this? Thanks!

 

New interconnects can be defective.  If there’s no hum with the “came-in-the-box” cables, use them for now, and when you want to use better cables, be sure you can return them if they cause issues.  Years ago, I bought a premium brand subwoofer interconnect for my new-to-me sub.  Not only did it cause a hum that wouldn’t go away, it kept the sub from turning off, even when the AVR had been turned off overnight.  In the morning, the sub was still awake and still humming.

 

I returned the subwoofer interconnect, and the sales rep was amazed, saying he’d never heard of a problem like that.  That was the same reply that I got from a sales rep at another shop, when I returned the Monster Cable speaker wires that made my system sound so bad that I didn’t want to listen to it.  When I reinstalled the cheap interconnect, the hum went away and the sub would turn on and off automatically, just like it was supposed to.  I got a better interconnect later, and I’m still using it, now connected to my new sub that I bought in 2020.

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I have the buzz almost gone. When I first powered up with the new 1200gr with a brand new AT VM 750sh cartridge the buzz was loud in both channels with the volume at 20. Turn it up to listening level and it overpowered the music. Now the buzz is only in the right channel (left channel dead quiet) and only noticeable in dead wax at volumes over 45 which 42 to 55 is my normal listening level. I've tried with the ground wire and without. With out ground wire buzz is gone but replaced by 60hz hum at volumes of 60 or higher. I've tried cheater plug on TT power cord with the  ground wire attached and still get the right channel only buzz. I'm not settling for a 60hz hum without ground wire attached and I'm not settling for this right channel only buzz. Still searching for answers.... ugh. 

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try backing the power cord out just a hair from the receptacle in the back of the turntable (not the plug going into the wall - the other end). I  Recall reading somewhere that somebody solved a hum issue by doing just that. Hard to fathom why that should matter.  I actually read that tip before setting up my GAE, so when I plugged the cord into the back of my table I did exactly that; I Pushed it all the way in then backed it out about a 16th of an inch.   It still fits quite snug.  And no hum until I turn my 200 W Mac Integrated amp to about 65%. And I only hear it then when I hold my ear to the Tweeter horn.

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It really sounds like it’s time to speak to the turntable dealer.  You shouldn’t have to go through all this to make a new turntable operate properly.

 

Okay, one last thing:  the turntable ground definitely has to go the the preamp/receiver, not to mains/wall socket ground.  It’s meant to match any slight voltage differences between each component, not to provide a path to actual ground.  I ran into something similar when setting up my bi-amped speakers.  The hum could not be eliminated until I ran a ground wire from the TT to the AVR to one power amp, then to the second power amp.  That got it done!

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