And need help getting rid of it. The hum exist through both the sub and the speakers.
I didn't think of checking to see if the hum was mechanical but I doubt that's the problem. It's picking up noise of the stack - I think. Any suggestion on how to shield the turntable better? I don't have much of an option for distance. He's got a lot of rare records - many are released only to radio stations during the 60s and 70s. The turntable is a Denon DP29. Yes I already suggested that he replace the TT with a nicer one but if I can't get rid on the noise it's immaterial. Also there are allot of digital devices that need to stay on Channel Plus video modulator, Comcast HD box with DVR and a satellite receiver. The shelves are about a foot apart the TT is on the fourth shelf with a cassette player above that.

cassette
shelf

turntable
shelf

modulator
DVD
Comcast HD box
shelf

Cable box
Denon AVR2105
shelf

Nuvo Concerto
Adcom GFA5400
base shelf

Marc

Make sure ground wire is properly connected, if still hum...then disconnect ground wire. have sold many of these TT with no prob(as well as millions of assorted brands over the last 32 yrs)..if no diff , check rca connections, check internal phono preamp is in off position if using phono input or in on position if going in on aux or line level input...awaiting results
tjg

This message was edited by TJG55 on 07/14/05 14:17 ET.

just a quick checklist that I'd go through...

1) disconnect cable feed from the comcast box and see if the hum goes away
2) ensure that the grounding lead from the turntable's chassis / tonearm is connected to an appropriate ground
3) turn off other non-used components one by one to see if they are inducing the hum
4) replace the MM (likely) cartridge
5) does the hum exist when the turntable motor is off? if no, if the turntable allows you to, can you manually rotate the platter without any hum?
6) last resort, place a line level isolation transformer between the turntable and the system

without knowing any other information, I'd place my bet on #1. CATV DC offset is the likely source of most audio hums, even if it is not the selected source.

Try putting some foam or other padding under the legs of the turntable. It could very well be vibration that your hearing.

If the hum turns out not to be electrical, try all the audiophile tweak remedies: platter mat, massive isolation shelf and/or suspended isolation shelf. Some cartridges are more susceptable to hum than others. I was listening to some LPs at a customers house the other day and it was quite enjoyable.

Basic sugestion, Maybe the denon dealer out there know. But Does the avr2105 have a phono input? If not you need a Phono preamp.

Yes the AVR2102 has a phono input and the turntable is grounded and the RIAA pre-amp that is built into the turntable is turned off.

Marc

Have you checked to see if the cartridge is installed properly? Is the turntable grounded to the actual chasis of the preamp?

I was going to suggest to check the manual to see if that table already had a RIAA EQ in it and outputted line level...

Marc beat me to it!!

Also, the cartridge may be picking up hum from stray noise coming from the other components.

A/V components are not as well shielded and isolated as they used to be. Installers that used the old RTI IRF-6 remember that getting that antenna even a couple feet away from a cable/sat box or DVD player made all the difference in range because otherwise the remote's signal was competing with the hash coming out of the components.

Unplug (do not just turn off) the cable boxes, DVD player, modulator, etc. to see which is the offending unit.

Then it's a matter of getting the table out on a shelf far enough away to keep the noise from being picked up.

The Target isolation shelf always worked great to keep the table from mistacking from bass or footsteps.

I started using turntables in the sixties, and have seen lots of ways of hooking them up. Your statement puzzles me.

If there is a phono preamp in the turntable and you turn it off, you should get no signal out of it. Or maybe just a little residual hum. Maybe even some tiny bit of audio might leak through.

The AVR102 has a phono input. If you are using that phono input, then it is equalizing the signal, basically boosting the crap out of the bass. Now, if what is coming out of the turntable with the preamp turned off is just maybe a bit of audio leaking through and a bit of hum -- -- -- then you will have bad hum.

You need to either use the built-in preamp and take its output into a line level input on the AVR102,
or
turn off the preamp and disconnect the cartridge from it, running cartridge leads to the phono input on the AVR102. You will have to extend them to do that, which can be its own noise situation.

You probably should just use the preamp built into the turntable.

In either case, the audio leads from the cartridge to whichever preamp you use are NOT the ground. If you use the internal preamp of the turntable, presumably the manufacturer will have connected the chassis of the tonearm and the turntable body to the chassis of the preamp, giving you no hum. If you are not using the phono preamp in the turntable, you will need to connect a wire from the ground of the turntable to the ground post nearest the phono input on the AVR102. Don't use any other ground connection on the AVR102, as this one will give you the lowest noise with the phono signal.

EBG....the switch UNDER THE PLATTER switches a built in phono preamp...when switched off, the output of the tt is standard PHONO out level....Simply... when inputting to a phono input --switch off....when inputting to a line level input---switch on...this works... have sold many of these with no problems, used both ways.
tjg

Still a valid troubleshooting test, however... Try it both ways, and see if it helps.

That's very cool. It would do for me if I ever need a replacement, if I can get it to play 78s...no lie....

Do you connect a ground wire to the A/V unit if the preamp is switched off, but not if it is switched on?

Last time I looked, Thorens was the only decent table you could still buy new that played 78 rpm.

I think that Rega also makes a 78 only deck as an option.