I recently bought a used Gemini turntable. The stylus on it was broken so I ordered a new one. It sounds okay except it has the typical 60Hz hum – while music is playing back at moderate levels I can easily hear the hum. What’s funny is the RCA/phono cables that came with it have grounds at both ends – which I connected. I haven’t opened this thing up yet – what should I be looking for? Am I screwed?
Does the turntable have a grounded a.c. cord?
If it does, you can get a cheap adaptor which will ‘lift’ the ground.
This ‘lifting’ some times stops 60Hz hum.
Also make sure the stylus is properly ‘seated’ in the tone arm.
My new TT would sometimes buzz because of this.
Till I figured it out.
Get one or two of these. It will eliminate annoying noise.
It is a 3-prong power cord. By adapter I assume you mean the typical little 3-to-2 adapter thingy – I’ll try that.
Regarding the stylus – it was a bit weird how this stylus “fit” onto to tonearm/cartridge – didn’t seem quite right. But it’s playing music back, and it Is on there snugly
Thanks for the tips
60 cycle hum is likely a ground loop. Regarding the RCA cables with grounds at both ends … I’ve never seen/heard of such a thing … however … those cables/connections are not balanced. Therefore the ground connections on them should only be connected to ground on one side. Not both. Then idea is the shielding on the cable will collect RF/stray noise and conduct it to ground. If both ends of the cable connect to ground, that defeats the scheme and can create another path to ground … thus, a ground loop.
Try lifting one end of those cable(s) from ground.
Also, often turntables have a ground lead that connects to the turntable preamp (which preps the very low-level signal before injection into the receiver/integrated-amp/whatever. Is that intact? Does your hi-fi set have dedicated preamp input with a ground lug?
I discourage lifting electrical ground from any circuit … whether by removing the ground prong on the cable end … or using an “adapter”. I especially discourage such practice in the context of some gear of unknown disposition acquired second hand at a garage sale or similar. You just don’t know what someone has done tinkering with it. Some equipment, like tube powered gear, hold enough power inside to kill you even months after disconnected from the wall power. Gots to be careful out there.
Move Europe and enjoy 50Hz hum
I disconnected one of the two ground eyelets, but I’m still getting the hum.
This TT is actually connected to my soundcard’s breakout box, which believe it or not has phono inputs with the RIAA EQ and pre-amplification.
This is really irritating. I ordered two NEW turntables online and neither had a ground wire and hummed terribly. I sent them back… and then came across this Gemini in a pawnshop. Gemini’s are supposed to be nice, DJ-oriented tables – the one I bought retails for about $350 new.
What I don’t get is, the ground eyelet is part of the RCA cables that came with the unit – it does NOT come out of the TT itself like all my old TT’s did. Does that make any difference?
EDIT: Duh – I just realized something – there’s ground eyelets on both ends of the RCA cables BECAUSE there isn’t any ground wire coming out of the unit itself… having them at both ends essentially serves the same purpose as a built-in ground wire
One important thing to remember is that to help avoid ground loops you should ideally have a single-point earth connection. Earth loops are created when you have multiple ground points in a system.
looks like a bit of fault finding is needed.
Some things to try, does the hum change if you bring your hand close to the cartridge? make doubly sure you wired the four cartridge wires to the correct pins. is the arm earthed properly? have you placed the turntable away from any strong electromagnetic fields eg not on top of another unit with a mains transformer in it or near a CTR.
Suspicious that there is no separate earth connection from turntable to preamp! Now you should not disconnect the mains earth but for testing it is OK to lift the turntable mains earth and see if that improves things, then reconnect it immediately after.
Plug everything into the same multiway, turntable, interface, computer.
Are you sure there is no separate earth tag on the turntable?
I notice you say the supplied leads have a separate earth wire, try a different set of phono leads, and wire a separate earth from the turntables earth tag to the interface.
Wish someone had told me this about 20 years ago, was trying to figure out what was wrong with an Amp head,
stuck my hand in, touched a cap…and MAN did that give me a pelt! Not even viagra could make me that stiff!
From the Gemini FAQ page:
Q: What causes the loud hum coming through my system when the turntable is connected?
A: Be sure the ground terminal from your turntable is connected to your mixer ground terminal. If it is connected, there may be a break between the ground wire and the terminal.
One, or more, of the “special” cables may be defective, or have a break in the ground wire?
If the hi-fi doesn’t hum on its’ own (sans TT) then the problem must be with the TT and/or cabling.
Try checking all the TT associated cables for continuity with your multimeter.
my soundcard, oddly enough, has dedicated phono inputs for a turntable, complete with pre-amp and RIAA EQ built-in… plus the ground post
my interpretation of the layout of this TT was that the post on the TT was NOT a ground, just a connector to the internal circuitry of the unit… IOW, not a case of a ground loop
when I detach the eyelet from the post on the TT, the hum goes WAY up in volume
the stylus is attached to the cartridge quite snugly… if I jiggle it, the hum remains the same
the source of hum is not the soundcard, because if I try plugging the TT into 1/4" inputs, I still get hum, and if I plug for example a cassette deck into the phono inputs there isn’t any hum but IT SURE IS F***ING LOUD (due to pre-amp)
although the TT is located far away, the connectors, incl the ground eyelet, are within inches of my CRT monitor. If I turn the monitor off (or unplug it), hum still exists
This sounds (audibly that is) like classic turntable tonearm hum. Oh, wait – if I mess with the wires on the cartridge, the hum attenuates a great deal – still there but perhaps livable. Still, I’d like to eliminate it
Thank you all for help in this OT issue
DON’T disconnect em…
The amp and yout TT has to have the same ground-connection…
Especially the TT has to be grounded…
You got to have a pre-amp…otherwise it wont work…but…
maybe you run a “Moving-Coil” Systems…if your tt has one of these…
in that case me thinks you dont need to have a pre-amp-----
Maybe someone can clear it up…
PS: What kind (brand) of turntable…???
It works … I have an EMU card, too! 8)
RIAA equalisation is actually recorded onto the record, in effect it knocks the low end off the recording so they can cut the record without over cutting, as the lowend would cause the cutting head to move too extremely. It also allows closer grooves thus more time and louder cutting.
Thus regardless of moving coil or moving magnet the playback has to go through the opposite EQ to restore the bottom end as laid down by the RIAA.
A better explanation can be found here> http://en.wikipedia.org/wiki/RIAA_equalization
Ce n’est pas un EMU
Yup…have read it !!!
Btw: I own a “big knob” it has such inputs, too !!
But i’ve never really tried it…
If i’ve got the time i’ll try it to digitize some of my LP’s
Yeah, I thought the same and I haven’t listened to vinyl records for a while I realize. Popped a record on the player and … WTF! They is waaaaay too wobly and slow. Turns out that the RUBBER BAND that turns the thing around is way old and dry so it’s just stretched out of shape. I might as well buy a new one and that won’t happen this year. It’s back to Ramen noodles, the ultimate student fodder for the rest of the year … But it’s cool and maybe I’ll even learn something?
Then I’ll get rich and buy … a vinyl player??? Has time starting to go backwards lately?
Noo…i’ve “overworked” my old Dual…and it’s sounding =>
Theres nothing about the dynamic of an old turntable…
PS: I have found a site at the i-net with anything about TTs…manuals…and anything you want to…
But it’s lost somewher in my “favorites”…gimme a lil bit time and i’ll post it…
Sounds like “vinylgeaks.com” or slt…