Attaching ground wire to Junction Box question...

Attaching ground wire to Junction Box question...

Postby philipmarlowe » Fri May 11, 2018 6:35 pm

Hello. New here, and apologies if this has been discussed multiple times. Please just redirect me to the proper place if so.

Anyway, I just got my first new "pre-owned" turntable in the other night. Scout 1.1. w/jmw 9. It's gorgeous, and I'm extremely pleased.

So, I was going through the process of setting the table up last night, first time doing this btw, and all was going "ok" until i got ready to plug in the rca cables and the ground wire to the junction box. I noticed that there is already a ground wire from the bottom of the table into the junction box. so my question is, do I just connect my ground wire that i'm running to the pre-amp groun, on top of the other ground wire within the junction box? so they would be using the same post and touching, is this an issue? i hope that makes sense. as it stands right now, i just don't have a ground wire running from the table to the pre-amp.

Also, a couple other question/observations i noticed upon setting it up. Does my specific jmw 9 tonearm not have adjustable azimuth screws on each side of the arm? i've seen other setup videos online where others have adjust azimuth by twisting either the right or left screw in or out to set level. I attempted to screw mine in and out with zero movement. lol. also, i noticed a slight "whirring" noise coming from the very top of the motor/pulley. it wasn't noticeable from my listening distance, but right above the table it was. any ideas on fixing this?

I'm hoping this table provides me with years of enjoyable service. Thanks for your time!



Not my specific table, but this is the model i have and what my tonearm looks like. i've noticed some are all silver, mine is the one with that black cap.
Image
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Re: Attaching ground wire to Junction Box question...

Postby seamonster » Fri May 11, 2018 7:12 pm

Try it as is, first, then try the other possibilities to see which affords you the least hum. You won't harm anything by using the single grounding post at your junction box for all ground wires simultaneously.
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Re: Attaching ground wire to Junction Box question...

Postby philipmarlowe » Fri May 11, 2018 9:57 pm

You won't harm anything by using the single grounding post at your junction box for all ground wires simultaneously.


Thank you so much. Exactly what I was looking for.

The result.... Before I added the ground wire, with just the two RCAs,I could turn the amp up to about 43% vol. level before you started to hear that electric hum in the speakers. Now with the ground wire it’s not until like 58%, and that’s much higher than I’d ever listen to anything. So thank you!
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Re: Attaching ground wire to Junction Box question...

Postby Stringreen » Sat May 12, 2018 6:13 pm

You shouldn't hear any hum....I would continue your search
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Re: Attaching ground wire to Junction Box question...

Postby elader » Mon May 14, 2018 9:20 am

the ground wire already attached to the box - going to the nut on the bottom of the bearing housing?

Its hard to predict what causes/fixes hum. Keep any gear with transformers away from the table, use shielded cables, and play with what gets grounded to what.
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Re: Attaching ground wire to Junction Box question...

Postby philipmarlowe » Wed May 16, 2018 3:56 pm

Stringreen wrote:You shouldn't hear any hum....I would continue your search



interesting. i just always assumed, since i've always experienced this in the past on all other equipment, that once you turned your amplifier high enough when on the phono stage you would hear that electro hum once you reached a certain point.

so you're saying that i should hear nothing, for example, like i do when i'm on the input with the bluesound node 2?

as for my current setup i have the table up on a platform shelf i built and attached to the studs in the wall. approx. 1.5 feet above the integrated amp. all power cords are plugged into a furman power strip/conditioner. And i currently have a set of cheapo $6 fospower rca cords going from the turntable to the integrated amp, with a ground wire also. Oh, and the ground wire from a bottom screw under the tonearm running to the junction box ground (shared by both the turntable ground wire & int. amp ground wire). Any ideas on simple fixes? as of right now it sounds pretty great, since the hum doesn't kick in until the power is cranked much higher than i'd ever listen to any of my records. also, i'm probably about to purchase decent Acoustic Zen Wow interconnects to replace the cheap fospower RCAs.

Thanks again all for the feedback.
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Re: Attaching ground wire to Junction Box question...

Postby Orchids1 » Thu May 17, 2018 10:01 am

I never ran a ground wire from the junction box to the underside of the table on my Scout or my Avenger. Instead, I ran two grounds from the junction box: one to the ground on the line pre and the other to the ground on the phono pre. Both tables were dead silent. If this grounding arrangement doesn’t work for you, then you have to eliminate other potential sources of hum, for example, unshielded phono interconnects, phono cartridge located close to transformer, interconnects touching power cables, and EMI interference from external sources. Rich
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Re: Attaching ground wire to Junction Box question...

Postby pscm » Mon May 21, 2018 8:35 pm

I think maybe older jmw9's did not have adjustable side weights. Azimuth is adjusted with tonarm counterweight.
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Re: Attaching ground wire to Junction Box question...

Postby philipmarlowe » Sat May 26, 2018 12:47 am

pscm wrote:I think maybe older jmw9's did not have adjustable side weights. Azimuth is adjusted with tonarm counterweight.


Ahhh, thank you. I’m going to go with that, because I just installed a new cartridge and I was unable to get them to move at all. :lol:

Speaking of a new cartridge, I installed a dynavector 10x5 and that resulted in me being able to turn the power up even further (to about 75%) before hearing some electric hum. The old cartridge I had was an AT m1e I believe, and I was using that until I decided on what new cartridge to buy. So, it appears I’m moving in the right direction, and I have new cables arriving tomorrow that I’m hoping will help even further.

But I just wanted to thank everyone for the knowledge. I’m sure it won’t be the last time I come to the board for advice.
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