I have a Gemini PT-2000 with a Linn after market cartridge -
yes, I paid a lot more for the cartridge than I did for the turntable
I have the Gemini 3 prong power cord plugged into the 3 prong wall outlet.
The audio lead is a 3 wire cable with a ground eyelet
That is plugged in to an inexpensive BBE Phono pre-amp with ground eyelet attached to the ground on the pre
The Phono Pre is plugged into its 2 prong wall wart (9?12?volt) then a grounded APS UPC on the same breaker as the turntable
that is, the turntable is grounded to both the wall and the pre-amp
The BBE out goes into a pair of line level ins on a Presonus FIreBox then firewire into the PC
No Hum!
using Cubase 5 to convert my old LPs
works great
plus it is oh so steam punk to sit at my state of the art PC and listen to Vinyl instead of ugh CDs or eww mp3s
Alright, this is based on 30 year old memories, but take it as you will.
Most turntables had a ground wire specifically meant to be attached to your pre-amp or an integrated amp. Most pre-amps/integrated amps had a terminal dedicated for this ground connection. The problem you are having is 60Hz finding ground through your audio connection between the turntable and amplifier. Lifting grounds won’t help. The chassis of your turntable and amplifier need to be at the same potential, otherwise a ground loop will occur.
Grounding separately through the ground prong of a 3 prong AC power connector is not ideal, especially if you don’t have a solid ground through the electrical outlet. Note that the longer the ground wire, and what ever it may inductively couple with along the way, will adversely affect what you are trying to accomplish.
Don’t let wires/cables that pass audio or your ground wire couple inductively with AC power - go for 90 degrees if they must pass in close proximity or figure-8 loops if you have to bundle audio cables.
If the turntable has a 2 prong connection, this is especially important. Verify, if you can, that you have a solid ground connection between the turntable and amp with a DMM - sometimes it can be flaky, either from oxidation or bad design.
Unless the TT has a fault in it, I’m thinking this must be due to the fact that the audio cables are surrounded by various EM-emitting sources – various power cords, CRT monitors, the computer itself (which is a rackmount and the TT is sitting on top of it)
My soundcard has some on-board DSP and I inserted an EQ with a bit of cut right at 60Hz which helped immensely and as far as I can tell isn’t really ruining music playback
Both ends are hooked up to their respective ground posts
As I wrote earlier, I bought a couple new TT’s that also had terrible hum, but I concluded that this was because they 1. were cheap 2. didn’t even have any ground wire 3. had built-in amplification 4. were designed primarily for USB audio ripping, and the audio section was a cheaply designed afterthought.
So I found this Gemini – it’s a reputable TT and cost about $350 new, so I hesitate to believe it’s poorly designed and either something is buggered inside it OR I’ve got an accumulation of hum from all the various EM sources nearby (which is a BIG ASSumption on my part, because I don’t even know if that’s a possible culprit, given my lack of knowledge about such things)
Like I said, I have a Gemini PT-2000. Got it at a music store’s going out of business sale 10 years ago for 200. It’s a good turntable and should not be noisy.
You are using a phono pre? I found out the hard way that just trying to emulate the RIAA curve in Cubase EQ is not good enough. The phono pre also provides the load so that moving magnet in the cartridge works correctly.
Pre-amp prices can go through the roof. The BBE I picked up at Guitar Center was only 50 and sounds as good as the pre in the Onkyo integrated I have in the living room.
Whoops – this turntable has a 2-prong connection – I’m sorry I incorrectly reported that. So I bought a hum eliminator – $104 – and I’m STILL getting hum, same volume
Does the TT have headphone output? If so, did you try that and eliminate the rest of the system from the scenario?
If not, try driving a headphone amp maybe and see what happens?
Do you have dimmers on your lighting? Turn them off if so.
Is it a 60hz HUM or BUZZ? That is pretty important.
I could look around and see if I have some isolation transformers that may work and send them to you wired up… Will take a bit of time to look. I have bins and bins of stuff in the basement from various electronic conceptions and I was digging for something a few weeks ago and kinda remember seeing some transformers in the mix.
Not sure, Doug. It depends on the type. It this eliminator on the electric or do you run the signal through it?
I would have to look at it. Most hum eliminators I have used are actually transformers used to decouple the signal from one unit to another. I have used other ones on electric side which were essentially a 1:1 transformer used to take the electric noise out (spikes on a sinewave). What did you buy?
I checked and I can’t find the transformers I thought I saw in the basement…
If I was in your shoes, I would simplify things and start from square one with the turn table and just plug it into a headphone amp if you have one. You need to determine where the noise is coming from… Sometimes UPS battery backups can cause issues. I’ve seen them filter the electric but the output was a modified/distorted sinewave some were actually square wave. They can generate noise as well. Not sure it the noise will back-feed into an electrical system…
Shooting in the dark here…
Perhaps you have a stereo that you could plug the turn table into to see if the hum persists? There’s something screwy going on here. There is probably something small being missed. This shouldn’t be this hard of an issue to solve. The fact that the other tables had similar noise (if I remember reading that correctly) leads me to think something else is going on and we are focusing too much on the table.
I’m Hearing Alot Of Hum!
This is the most common problem encountered with phono playback systems. And it can be puzzling sometimes to track down. First, you must isolate the source. Is it :
The Stereo
The Phono Preamp
The Turntable Wiring
The Phono Cartridge
The Stereo
Switch the stereo to CD or AUX, and with nothing playing, turn the volume up to your normal listening position. If there is no hum now, then we can eliminate the stereo. If there is a hum, powersupply service is probably indicated.
The Phono Preamp
This will require one accessory, a shorting plug. You need to get a couple of standard RCA plugs from Radio Shack for instance, and you need to short the center pin to the outside ground. Now, in place of the turntable, plug the shorting plugs into the phono input. Now, set the stereo to phono and turn the volume up to your normal listening position. If there is no hum now, then we can eliminate the phono preamp or phono stage. If there is a hum, phono stage service is indicated.
The Turntable Wiring
This will require one accessory. a pair of alligator clips. You can also get these at RS. You need to clip together, I.E. short out the left and right cartridge pins. Do this on the back of the cartridge. You needn’t remove the cartridge connections. Just connect one pair of clips between the red and green pins and another between the white and blue pins. Now, set the stereo to phono and turn the volume up to your normal listening position. If the hum is gone now, then we can eliminate the turntable wiring. If there is a hum, something is amiss with the turntable wiring. either a bad connection. or perhaps someone has changed the factory wires for some “fancy” wires that do not give sufficient shielding.
The Phono Cartridge
If you’ve come this far, then the problem must be the phono cartridge.
Most cartridges use hi permeability steel shells to protect the coils from electrical fields that can cause hum. However, not all companies use this system. As such , there are some cartridge brands that are sensitive to external electric fields and will hum. The only solution you have is to replace the offending cartridge. Or, if you love the sound and want to keep it, you will have to play with the location of the turntable and try to minimize hum. Sources of hum fields are power transformers in equipment, wiring in the walls, certain turntable drive motors. Experiment by listening to the hum while you move the tonearm through its arc(cued up!!) and see if you can find a null location that will give you the best results.
Did you buy just a stylus or the whole cartridge? A $15 stylus might be okay, depending on the cartridge. I spent a good bit more on the cartridge than for my turn-table.
Once you’ve exhausted the DIY options, which might be right-about-now, maybe take it to a tech to repair?
