Turntable Hum

[Keiko]

Hopefully someone can help me with this. It's not very bad, but I noticed a 60hz. hum from my turntable last night through the headphones with the volume up a bit. I only noticed after the side of the Lp. had stopped and I returned the tone arm to it's rest. This an Audio-Technica PL120 TT and I've noted from reviews online that this is an issue with these tables, but I couldn't find a solution. It has a built-in phono preamp which I don't use and leave off since it's connected to my receiver's phono stage. I tried flipping that on to check the effect and it made it buzz even louder (not surprising). I think the noise is getting in through the crappy IC's which are hard wired inside. Evidently, the motor has it's own power supply in these and it doesn't have the traditional ground wire to connect to a chassis. I went to Rat Shack today and bought an inline noise isolator which also only made it worse. Every component in my rig is plugged into a Belkin PF30 power conditioner and plugged into the same 15amp wall plug. I doubt a cheater plug is going to help. Any suggestions?

Thanks,

Mike

[hearingimpared]

Is there a ground wire running parellel to the hardwired ICs from the tonearm to the pre? Typically there is a ground wire that connects to a preamp grounding post.

[Keiko]

Is there a ground wire running parellel to the hardwired ICs from the tonearm to the pre? Typically there is a ground wire that connects to a preamp grounding post.

The IC's are pretty cheesy on this Joe. No external ground wire. It's probably got some internal ground inside the unit, but I don't think I'm inclined enough to open it up and start pokin' around inside. I may have to just live with it. It's not noticeable through my speakers. I only caught this last night when I was monitoring through the phones. Were you able to detect any hum on those CD's I did for you? They were transferred from this table.

[hearingimpared]

The IC's are pretty cheesy on this Joe. No external ground wire. It's probably got some internal ground inside the unit, but I don't think I'm inclined enough to open it up and start pokin' around inside. I may have to just live with it. It's not noticeable through my speakers. I only caught this last night when I was monitoring through the phones. Were you able to detect any hum on those CD's I did for you? They were transferred from this table.

No hum whatsoever just some big foot hairs.:D;)

[Keiko]

From Aunt Bunny's mustache. I gotta shave that b*tch Gus! :p
Bunny's so hairy, when she gives birth, the little Bigfoot's get 3rd degree rug burns.

I'll just live with this. It's not that bad really and I only noticed it with the volume pumped way up on the phones. Hangin' out here has made me fussy. But that's a good thing. I got an excuse now to upgrade. :D

[danger boy]

any decent built turntable will have a grounding wire. maybe yours was cut off by a previous owner if you're not the first owner of that turntable.

I don't know exactly where a grounding wire would attach to the inside of a turntable.. but if you could find out. it would be worth it I would think to make a new grounding wire.

[Keiko]

It's the way the AT-PL120's are designed Al. All of em' are the same. No ground wire to connect to a chassis. I noticed this right away when I first bought the player. These units are built fairly solid. Ripoff of the Technics SL 1200's. They look identicle, but on the inside I'm sure there's a lot of difference. The 1200's cost anywhere between 400.00 - 600.00. The average cost of these clones is around 200.00. Pretty good bang for the buck IMO, but it's not the real deal.

[danger boy]

you might want to try one of those three prong cheater plugs for the wall unit. not saying this will solve the hum, but it might help. It has helped in other instances of buzz/hum before.

[Keiko]

I'll pick up one tomorrow and try it. They're only a couple bucks, but I have my doubts that it will help.

BTW...Hope your doing better. :)

[gdb]

You might try to make sure that no AC power cords are close to your TTs I/Cs and I know some people have wrapped aluminum foil around the I/Cs for additional shielding.:)

[rayslifecycle]

Keiko - I got it.

You are not using the phono stage in the TT - but you are plugging it into the Phono Stage in your reciever, and that input usually has a ground.

Try using the phonostage in the TT and plug the interconnects into a different input on your receiver - I'm sure the hum will go away.
They built the unit to connect this way because so many new receivers never bother to put a phonostage in anymore.....

To use the phono stage on the Reciever - replace the ground that would normally be there -

Let me know if that works

Good luck

[Keiko]

That was worth the try clark...I switched to a line level on the receiver and turned on the tables pre. No change. Actually, It seemed a little louder. I'm pretty sure it's picking up some sort of EMI/RFI through the interconnects. LOL...I may try the tin foil thing next. :D

Thanks for the suggestions gents. I may just have to fly Ben out here so he can solder in a pair of his silvers for me. ;)

[rayslifecycle]

oh man

I thought that would do it...........
Is there a three prong plug on the power cord?

[Keiko]

No, 2 prong, but the table itself is plugged into a power conditioner. They designed it with a nice, heavy detachable power cord, but hard wired in those crappy, generic interconnects. : P

[bikezappa]

Have you tried moving and or rotating the turntable to see if the hum level changes?

Does moving your hand near the cartrage change the hum?

I assume you have tried moving the interconnects to no effect.

[Keiko]

I jiggled the cables and that had a slight effect. Having my hand near the tonearm and cart didn't appear to. I swapped out the cart and headshell and the noise is still present.

I'm almost certain it's the IC's. I think I've found a shop that can help me and maybe replace them with something better. They offer turntable service on their site and they're located right down the road from me. It's still early here on the rock. I'll be calling these folks in a bit.

http://www.creativesoundhawaii.com/

[rayslifecycle]

What - they don't sell Polk:D

[Fongolio]

Now Mike if it were me I'd have the bottom off that table and solder a ground lead for external use on it in a flash but if you aren't comfortable taking stuff apart and modding I understand. I just swapped out the rca's in my bedroom rig Dual TT this morning. The old ones were skinny and didn't have gold plating. Difference is subtle but noticable. I don't think I've ever owned a piece of equipment I didn't take the cover off of just to see what makes it tick. I usually wait until the warranty's are expired though. Good luck.

[Keiko]

Yeah, I'm just afraid if I popped the hood on it Fongo and started messing around with connections, I'd short something out. Like I said, I can live with it because it's only noticeable on a high volume. I've done a few vinyl transfers with the new cart and haven't noticed hum on any of the CD's. They sound pretty darn good as a matter of fact. The DL-160 is a very definite improvement.

[Keiko]

I'm such a dumbass. Because I should have known. I have a cooling fan on top of my receiver. On a hunch, I unplugged it. And sure enough, the hum magically disappeared. Two things learned here, besides the obvious. There is such a thing as Audio Enthusiast head space. :o

[Fongolio]

Excellent, Glad it worked out for you Mike. And at zero dollars spent too. Cool.

[Keiko]

Excellent, Glad it worked out for you Mike. And at zero dollars spent too. Cool.

Yep! I was prepared to take it down to and have the IC changed. Still a cheesy little interconnect. When I talked to the guy today, he quoted me 60.00 to solder another one in. It's working fine now, so think I'll save that charge to my cc. I'm broke enough already since I've spent on upgrades the past couple weeks. Gotta love it though. ;)

[rayslifecycle]

Mike

Good news!!!!
.......happy listenning.

Ray

[Keiko]

Mike

Good news!!!!
.......happy listenning.

Ray

You to bro. :)

[hearingimpared]

Duh . . . lot's of times the problems are just staring us in the face. I'm glad you got rid of that hum. Now if I can get rid of mine which is a lot more complicated.

[Keiko]

Wow Joe, seriously? I don't have near the experience, but with your VPI and all those goodies for it? That would make me sick. :(