Feedback

[top gun]

Hi, So I set up my new Grace 707gii on my Kenwood 550, I picked one of my favorite carts an ADC xlm mkii improved sounds real nice, except I get feedback and the louder I turn it up the worse it gets, so I traded it out with my other ADC xlm and the same thing, so now I put on an Ortofon om20, no feedback but I like the ADC much better, what the heck could be going on, the Adc has a new stylus even. Please feedback would be welcome in this case. Thanks:sigh:

 

[gadget73]

How is your turntable placed? And more importantly, where is it relative to the speakers?

Turntables in a perfect world are as far from the speakers as possible, and mounted to the most stable thing you can come up with. Wall mounts actually work pretty good for this if you can fix the brackets to the studs. Failing that, what you really need is a good solid mounting surface that is ideally somewhat isolated from vibrations. There are a lot of expensive ways to do this, but a cheap and easy one might be a stout piece of wood big enough to fit under the table, and use some racketballs or similar cut in half to go between the board and whatever it sits on to help isolate it from vibration. Also, if possible, remove the lid while playing. It works as a sound board and does a nice job of transmitting sound into the table. If thats not practical, make sure its shut at least.

 

[majick47]

Another thing I'v seen is bookshelf speakers on bare wood floors without stands or anything to isolate them from the floor magnifying the low bass from the speaker. A subwoofer would also possibly cause the same thing feeding back to your turntable. Where ever you place the turntable on make sure it is solid and preferably heavy, also don't put it on top of a receiver or amplifier. As suggested a wall shelf is one of the best solutions to isolating a turntable from feedback.

 

[top gun]

Thanks for your replies, actually it even has feedback when it's not spinning and only when the stylus is touching the record, the turntable is mounted on a marble slab and is quite a distance from my speakers, never experienced this before I installed the Grace arm.

 

[Pio1980]

What type of mat is on the platter?

 

[elcoholic]

Feedback without playing a record? Hum perhaps? Clean the DIN plug connections yet?

 

[gadget73]

probably not feedback if you hear it with the stylus not on the record. Hum would also be my guess. Wiring issues perhaps.

 

[top gun]

No, the feedback happens only when the stylus is touching the record, spinning or not, do you think this may be a cartridge loading issue? Definitly not hum from grounding issues.

 

[Catcher10]

Really all you can do is try to isolate where the hum is coming from...start with the easy ones like your phono cables, make sure they are well shielded and ground wire connected. Try removing the ground......If that does not work then move to the cartridge wiring makeing sure its all good clean connections.

Based on your comment above, make sure no cart wires are touching. Also I see on vinylengine the ADC has a high output of 6.05mV, the OM20 is only 4.0mV......Do you hear the same with the OM20 but at a higher volume level?

 

[top gun]

Isolate was the answer, If I carefully lift up on the deck the rumble would subside so just a matter of isolation, thanks for your help.