Turntable Hum

[mikemorrow]

I have got a hum coming from my turntable. I have takin off my ground and the hum gets worse. I have relocated ground, same. Takin off cartrage, same. Replaced cart, same. What in the world is causing this?

[dingus]

when did this start and was it preceded by a change in you systems physical configuration? also, what are you using for power protection / conditioning?

[mikemorrow]

I have not moved anything in 2 years. But...but I did get a new cart (Grado) that is when I heard the hum for the first time. I put back on the old cart and the hum is still there. But it hum with out a cart allso.

[dingus]

possibly a connection that jiggled loose when you first added the Grado? since the hum wasnt there before, i would say it has something to do with the cart change.

[mikemorrow]

Ok, I have had alittle time on my hands today. I have eliminated the hum from the turn table and the cartridge head. But as soon as I connect any of the four wires I get hum. Could I have damaged all 4 of them?

[dingus]

i doubt all 4 were damaged. is anything loose, crimped or shorted?

[Rich-n-Texas]

My guess would be a ground loop. Don't know what you mean when you say you relocated ground though. Do you have all components plugged into a power strip? Have you plugged the power strip into another wall outlet? Also, adding another component can cause ground loops to occur.

Just some thoughts.

[basite]

hum most of the time indicates a grounding problem, maybe your ground cable got loose...

[mikemorrow]

My guess would be a ground loop. Don't know what you mean when you say you relocated ground though. Do you have all components plugged into a power strip? Have you plugged the power strip into another wall outlet? Also, adding another component can cause ground loops to occur.

Just some thoughts.


I just moved my ground to dif grounded areas, when that didnt work, I put it back. The power strip is the same. So my guess would be a ground loop.
??? Just what is a ground loop???

[mikemorrow]

Ok, I just got off the tele with my old stereo expert (took a long time to track that old man down). He asked me some questions. It is indeed my leads. I'm going down there to see him friday. He is an hour away from me now, so I better take the turntable with me. I'm alittle puzeled by all this, becouse I resoldered those connections. But my eyesight and hands arnt what they use to be. LOL

[Woochifer]

The Grados are known for picking up hum with specific turntable models (the Duals and ARs generally don't work well with Grado carts). This might be the case that you need to try yet another cartridge.

Another potential issue is the grounding strap on the cartridge itself. (this is usually a small foil strip attached to one of the terminals on the back of the cartridge) Some turntables work better if you remove the grounding strap, and recommend doing so prior to installing the cartridge.

With turntables, another way of removing hum is to reverse the polarity of the power cord (provided that you don't have a grounded or polarized plug).

Ground loop issues have a lot of variables in play, and these are some of the simpler things to try out first before going to more drastic measures. If the hum is in the lower frequencies (i.e., the 60 Hz frequency used in AC current), then it's probably a ground loop issue. If the interference is in the higher frequencies, then it's likelier that you have some interference that the cartridge or tonearm is picking up from the turntable motor (or perhaps the amplifier if it's close to the turntable).

[mikemorrow]

Well I found the little bugger. RCA cords are often over looked. I'm back to recording!!
:biggrin5: :23: :23: :23: :23: :biggrin5:

[Les Adams]

I recently had a similar hum problem with my Garrard 401 / SME 3009S2imp / Shure V15Vxmr / Trichord Dino phono Stage.

The cure was to replace the audio cable from the base of the arm to the phono stage and from the output of the phono stage to the main system preamp. I used Van Den Hul 102 III cable throughout and not only did the hum vanish, but a marked improvement in sound quality was evident.

I replaced the mains cable to the 401 with 3-core Supra mains cable (screened), connecting the mains earth to the turntable chassis. I then took a link from there to the SME screening can to which I also connected a wire down to the earth pole on the Trichord phono stage. The result was a totally hum-free phono system!

You might also check nearby potential sources of hum, such as mains cables and power supplies / transformers / TV set etc. Try moving things around.