turntable hum, how to eliminate

kprhok

I recently purchased a turntable and plugged the jacks into the phono inputs in my HK receiver. When I turned up the volume I distinct hum began and increased to a loud hum, even without any further volume increase. I moved the Polk bookshelf speaker at least 4 feet away but it still hummed when I turned up the volume.

The turntable has a built in pre-amp. Should I connect to an input other than the phono input on my receiver? I noticed one review said not to use phono inputs if you have a preamp on your turntable.

mhardy6647

Is the tt grounded to the preamp and/or is the preamp grounded to the receiver? Try with and without grounds between the components. If any of the components is old enough to have a two-prong, nonpolarized AC mains plug, try reversing it in the socket. One way could give less background hum than the other.

Polkersince85

There should be a switch somewhere to turn the preamp off and use the phono input. Otherwise, try the aux input. Make sure you have a ground wire from the table to the HK.

kprhok

It's a new Audio-Technica PL120 with built in preamp. There was no ground wire with the turntable. The hum is the type I used to get years ago when the ground wire failed with older turntables. Not sure why this turntable doesn't have a ground. I'll try switching the preamp switch off.

Thanks for the feedback!!

kprhok

Just checked the back of the turntable. The switch is for "line" or "phono", so there doesn't appear to be a switch for turning preamp on or off........I'll try moving the cables to an aux input......hope this works.

kprhok

I don't see inputs for aux but see several for Video 1, Video 2, etc. Would those work as "aux" lines? Thanks

Polkersince85

yes. they should work.

Make sure the wires at the back of the cartridge are not touching each other.

Move your interconnects around. But only do one change at a time to isolate the issue.

kprhok

Will do. - I really appreciate the advice.

Toolfan66

Is the table level??

hearingimpared

kprhok wrote: »

I recently purchased a turntable and plugged the jacks into the phono inputs in my HK receiver. When I turned up the volume I distinct hum began and increased to a loud hum, even without any further volume increase. I moved the Polk bookshelf speaker at least 4 feet away but it still hummed when I turned up the volume.

The turntable has a built in pre-amp. Should I connect to an input other than the phono input on my receiver? I noticed one review said not to use phono inputs if you have a preamp on your turntable.

Dude you plugged a phono preamp in your turntable which now has line level output. You then plugged the line level output to the phono input stage of your HK receiver. The phono stage cannot handle a line level signal not to mention all the RIAA eq and capacitive and resistive loading in the phono stage circuitry of the HK.

Just plug it into the AUX port and you will be good to go. Just make sure you ground the tonearm or the phono pre to the HK grounding post or a chasis screw (in most cases it is ground).

apphd

kprhok wrote: »

I don't see inputs for aux but see several for Video 1, Video 2, etc. Would those work as "aux" lines? Thanks

I don't think so. Those are probably "Video" inputs. I didn't catch what mod. HK you have, but I think I would try both, a line level R/L in with the TT set properly, and the phono in on the HK to see which one sounded best to me. Most stereo inputs would be Red and White color coded, video would be Yellow. If you go line level look for Aux. (which it looks like you do not have), tape/VCR, or CD anything but "Phono" in.

If you set the TT up to output through the Phono then you must use the Phono in on the HK. You may be able to wire your own ground from a case screw on the TT to the HK case.

hearingimpared

apphd wrote: »

I don't think so. Those are probably "Video" inputs. I didn't catch what mod. HK you have, but I think I would try both, a line level R/L in with the TT set properly, and the phono in on the HK to see which one sounded best to me. Most stereo inputs would be Red and White color coded, video would be Yellow. If you go line level look for Aux. (which it looks like you do not have), tape/VCR, or CD anything but "Phono" in.

If you set the TT up to output through the Phono then you must use the Phono in on the HK. You may be able to wire your own ground from a case screw on the TT to the HK case.

VCR audio line level input! Good info here ^^^^!

apphd wrote: »

If you set the TT up to output through the Phono then you must use the Phono in on the HK. You may be able to wire your own ground from a case screw on the TT to the HK case.

Just to clarify; if you bypass the built in phono pre in the TT then you must plug your TT into the phono jacks on the HK. You must use a ground wire in this case. With the phono pre engaged you may not have to.

hearingimpared

Keiko wrote: »

This particular table was designed without a ground wire, Joe. It may be grounded internally somehow, but I'm not sure. It's a Technics SL-1200 clone and for <200.00 it isn't a bad table, although it's not really in the same league as a genuine 12xx.

I enjoyed mine while I had it. Those Motown CDs I sent you were ripped from an AT-PL120, but since I upgraded to the SL-1210M5G I haven't looked back. I think you'd agree my latter rips have been far superior.

Well if he does get hum from lack of grounding, what always works is to attach a ground wire to the 5th ground pin or post on the underside of the tonearm and connect it to the HK ground post if he does bypass the built-in phono pre and that is if he can get to the underside of the tonearm.

I would think there would be a ground wire going from the 5th pin of the tonearm to the built-in phono pre.

kprhok

Thanks for all the input! The Problem was the opened dust cover capturing too much vibration inside a bookcase which I didn't discover until I touched it and noticed a slight vibration, even at low volumes..., and the hum went away.

jimmydep

kprhok wrote: »

...I continue to learn something new every time I return to this site.

Imagine how smart you'll be if you never leave..:)

kprhok

I was almost to embarrassed to post what I had discovered after all the troubleshooting everyone provided.

hearingimpared

kprhok wrote: »

Thanks for all the input! The Problem was the opened dust cover capturing too much vibration inside a bookcase which I didn't discover until I touched it and noticed a slight vibration, even at low volumes..., and the hum went away.

Get the hell out, no ****?:eek: I never ever use my TT with the cover down. In fact I've never heard of this problem before.

I don't like playing records with the cover down because, well, the best way to explain it is to imagine placing your head into the bottom of a drum and closing off the bottom and then turn your stereo up to the volume you normally listen to. You head will feel like it's going to explode with all the vibrations and various frequencies bouncing around.

This is what can happen to your tonearm, cartridge and stylus with you dust cover down.

IMHO, if the dust cover is removable, before playing a record remove it.

kprhok

To be sure I wasn't imagining it, I increased volume as high as I could stand it and still experienced no hum with the dust cover closed. When I lift the dust cover I have to cut volume down to about 20%, and you can easily feel the vibration resonating through the cover. Hold it firmly and the hum stops. I am fairly confident now that the problem was the sound from the port in the back of the Polk Lsi speaker which sits on the same bookshelf causing the dust cover to vibrate at modest volumes.

Polkersince85

Turntable 101: Don't put your table on the same stand as your speaker.

hearingimpared

Polkersince85 wrote: »

Turntable 101: Don't put your table on the same stand as your speaker.

And that too! ^^^^^^

inspiredsports

What kind of cartridge is mounted on the tonearm. The reason I ask is that I have found Grado's to hum more frequently than others.

hearingimpared

inspiredsports wrote: »

What kind of cartridge is mounted on the tonearm. The reason I ask is that I have found Grado's to hum more frequently than others.

There is no Grado on that TT. It a professional TT and comes stock with a Audio-Technica ATP-2 cartridge and a Audio-Technica ATP-N2 stylus which is removable. The output of the cartridge is 5.3 mV which probably makes it a MM type cartridge. The only thing I really knew about this TT before reading the manual is that it is a pro TT.

My experience with Grados are they tend to dance as well as having a hum problem but I'm pretty sure it only occurs on the less expensive Grados.

kprhok; Here's the owner's manual in-case you don't have one.

http://www.audio-technica.com/cms/resource_library/literature/9c88e62be89b0c74/p51612_01reva_at_pl120.pdf

I can't tell if the dust cover is removable but I would check and see. If I were you I would remove it before playing records.

ohskigod

selling the turntable on Ebay will fix the problem all kinds of fast


I Keed, I keed!