My turntable produces feedback Turntables / CD Decks Discuss My turntable produces feedback in the DJ Equipment Forum forums; I have 2 Numark TTX USB decks a Numark dxm01 usb mixer and Ortofon concorde electro cartridges. I know that I should place my speakers away from the decks so ...

[clubber001]

I have 2 Numark TTX USB decks a Numark dxm01 usb mixer and Ortofon concorde electro cartridges. I know that I should place my speakers away from the decks so I placed them about 9 feet (3 meters), but the still produce feedback. And I wonder then how they do it on parties when the monitor is right next to the decks. PS: I'm using JBL JRX 125 speakers and crown xls 602 amp.
Any suggestions ?

[DTR]

Could you go into more detail? Is there a hum when you're not playing anything?

[clubber001]

If I turn the volume more than half way up, yes then the hum appearers when nothing is played, but if i kill thee bass from the mixer the hum disappears and if I'm playing a record the same thing. However if the volume is lower then no hum and everything is ok.

[DTR]

What happens if you unplug the deck from the mixer? It is not a feedback issue so don't worry about moving your speakers. How are the decks connected to the mixer?

[clubber001]

If I unplug the deck from the mixer the hum goes away the decks are connected through the phono input, but i also tired to switch the decks to line output (these have this option too) and to plug them into the line input but the same story. But as I was saying at a lower sound level there's no problem, but you can't party at a low sound level

[Chris Powell]

do you use cdjs? is it the same with them...?

also make sure the phono leads from the amp are going into the master output on the mixer NOT record output.

[tOM]

i am assuming you've earthed the decks properly??

[Marc_Watson]

I wondering that too!

Check your turntables and/or CDJs are earthed properly, that may do the trick!

[DTR]

If it happens on the Line output too then it's probably not a dodgy ground. Do those decks have a Ground Lift switch on the back? If so try switching that to the other position. How long have you had this problem?

[clubber001]

Well I don't use cdjs but I've plugged my mp3 walkman into the line output and no problem. These decks don't have a ground cable (neither ground lift switch) they are grounded through their power cable. The problem was there from the beginning.

[DTR]

It sounds like a design issue with the decks. Does the phono output still work if you switch off the power to the turntables? If not then the Line output or USB output circuitry is actively cut into the signal path.

As a precaution, make sure your phono cables from the turntables are seperated from any power cables. If you have to cross the cables, try to cross the power and phono cables at 90 degree angles to eachother.

It sounds like your signal is being corrupted by noise from a 50 / 60Hz supply. As the same thing happens with the Line Output I think it's unlikely to be something after the deck's output.

[clubber001]

Yes the phono output still works when I switch the turntable off, Hower I've resolved the problem. My decks where placed on a wooden table so the table amplified the speaker's vibrations. I placed a 5 cm thick foam under each deck and the completely isolate the vibrations. So party's on

[DTR]

Interesting, I wasn't expecting that...

Glad you got it fixed though