hi, ive recently tried to add 2 x record decks to my 4mx setup (both omnitronic dd-2250s).
if there is just one deck connected - then it works fine - but if i have two connected - then i get a lot of background / signal noise on souce 2... i get the same effect if i swap the decks around so i dont think that it is caused by the deck itsef.
if i use a pre-amp and lower the source 2 input to line - then it seems to fix the problem but that means i need to use a pre-amp so that is not a great solution - id prefer to know if anyone has encountered this issue and how you resolved it?
edit - am using virtual dj 7
thanks,
dan
Hello DJTayla,
1) I don't know DD-2250, but in the manual of close DD models, I see a phono/line switch. If you have a phono/line switch on your DD-2250 units, please let me know if setting both DD-2250 in line level, and 4-Mx audio inputs in line level, you still get this noise on source 2?
2) Can you check if both turntables are powered on the same power outlet?
If they have 2 different power supply, can you check if you still hear the same noise when powering both on the same power outlet as the computer?
I wonder if you hear a ground loop when connecting both grounds, with both turntables generating a different ground level.
Thanks Maxdjack...
1) No pre-amp in the DD-2250s so no phono/line switch.. IF I use a seperate Pre-amp and select Line level on Inputs 3/4 then the Noise goes away (but this means I need to carry a pre-amp with me as well)
2) Yes both Turntables were plugged ibnto same 4-way - and I've tried isolating them and using a third (very different) turntable deck and no joy - still get te noise. In my opinion it is not a Ground hum (thats a warm noise(hum) whereas what I am getting is a very harsh white noise type interference - almost like to sound of machinery... ). The computer I am using is a laptop and I've tried with the Power source connected and disconnected - but same noise...
If I connect just one deck into 3/4 (and have nothing in 1/2) then the noise is not there.. but when TWO decks are connected and set at Phono - then the noise is there on Source 2 - (inputs 3/4).
It seems to me that there is a problem with the amplification circuit for inputs 3/4... I am not sure if that is something that can be fixed - or if I have to accept my 4mx is partially broken ?
Hello DJTayla,
Please confirm
a) on DJ Console 4-Mx control panel that the input channel on both inputs (1-2 and 3-4) is set on Phono.
b) on DJ Console 4-Mx rear panel that the ground cables of both turntables are connected between 4-Mx ground screw and the turntables.
It does not look like an amplification issue, but as if the 2 turntables have no ground (or do not share the same ground, which may occur with floating grounds).
Hi..
a) yes - both inputs are set to Phono
b) yes both decks are connected to the Ground screw.
If I remove from ground screw - then I get the familiar ground hum.. reconnecting and this goes away and left with the white noise/interference on Source 2...
grr !!
Hello DJTayla,
I suspect the issue comes from a ground difference of potential between both turntables.
To check if the issue comes from the ground can you try to the following process
1) connect the ground cable on 1 of the 2 turntables to another ground:
a- either with an ESD grounding plug, as this type of plug
b- or to a metal pipe for water, going to a basin or to a heater (as water pipes are grounded),
c- or to a convector heater (as electric covector heaters are ground).
2) and check the audio quality of hearing both devices in the 4-Mx once 1 turntable is grounded to the 4-Mx ground screw and the other is grounded to an external ground.
Hi - so been away from the internet over Christmas - but have tried to use my 4MX a number of times.... Keep on getting the Noise even with different setups at different locations..
Am trying to source a proper Grounding Plug - will keep this thread updated.
d
DJTAYLA,
Just a thought, are you using a surge protector or are you using a power conditioner?
TheSpinDoctor...
"If Music Be The Food Of Gods, Play On"
-Billy Shakespear
Hi Sorry - been offline for a while...
No - not using a Surge protector or conditioner.. (were you suggesting this might Cause - or fix the issue ?)
So this was a Second hand device... I am tending to think now that the original owner might have connected a Line level device whilst configured as Phono ? might a surge have caused damage ?
Hello,
1) Phono pre-amps are not that fragile: playing a line level signal in a phono input is a highly common mistake, so of course it makes a bad sound while playing at the wrong level, but it does not damage anything.
Moreover, if anything was damaged, the audio would be bad whether you connect 1 or 2 sources.
2) Have you tried adding a USB hub with a power adapter between your computer and your 4-Mx?
I think the issue may come from a noise in your computer power supply.
Thanks for the response.. I'll see if I can get hold of a Powered USB Hub....
I've also posted another issue here http://www.herculesdjmixroom.com/en-gb/forum/en-hardware/028064/ with the Phono inputs... not sure if they are connected at all or not...
If I can get a hub - I'll give it a try and let you know,
ta.
Hello,
Any News?
not managed to get a powered hub from anyone... and dont want to buy one as I am not convinced this is the issue..