BUZZ sound

niranjanjaveri · Post by **niranjanjaveri** » Sat Oct 31, 2009 3:34 pm

When I route my Pa800 through Presonus fire box say, just for amplication it gives buzz sound. I also had routed triton le through INput 1,2 but that doest cause any buzz.I also interchanged the connections and chords on the two boards. The buzz is just continues evn if the keyboard is swtich off but connected to the electric switch surprisingly. I checked with a head phone individually -the heapphone out, Audio out LEFt and right and there is no buzz through head phone.
Can anyone help me know what can be the cause.
Regards,
Niranjan

karmathanever · Post by **karmathanever** » Sat Oct 31, 2009 3:48 pm

You may already know all of this but just in case....

The L/R and 1/2 and line-in ports are balanced so I recommend that you buy and use balanced cables.
I had this problem and it completely went away when I started using balanced (TRS 1/4") cables.
They look like stereo jacks (but are not!!).

Hope this solves your problem.

Pete

niranjanjaveri · Post by **niranjanjaveri** » Sat Oct 31, 2009 4:03 pm

Thanks Pete....
I will try to get those.
Just a question
So incase I am playing live, routiing through the mixer and not Presonus then I can use my regular Mono chords right?
Thank you once again for posting the Pics too.. highly appreciated..

Regards,
Niranjan

niranjanjaveri · Post by **niranjanjaveri** » Sat Oct 31, 2009 4:08 pm

Just found a cheaper balanced chord on Guitar center will that work...here is the link.

http://www.guitarcenter.com/Live-Wire-T ... 1168096.gc

regards,
Niranjan

BruceG · Post by **BruceG** » Sat Oct 31, 2009 4:14 pm

Hi Pete

I route mono left and right leads from L and R outputs into the left and right stereo inputs in my Yamaha Stagepas amp/mixer. Should I be using balanced leads? I don't get interference but I'm wondering if I would improve the sound quality by doing so.

Kind regards

Bruce

Rob Sherratt · Post by **Rob Sherratt** » Sat Oct 31, 2009 5:44 pm

Pa800 has balanced/unbalanced ins and unbalanced outs. Pa2x ins and outs are balanced/unbalanced. What Pete says is correct for Pa2x only.

A balanced/unbalanced socket will operate in balanced mode if a TRS plug is inserted, and will operate in unbalanced mode if a TS plug is inserted.

Regards,
Rob

niranjanjaveri · Post by **niranjanjaveri** » Sat Oct 31, 2009 7:46 pm

Rob then what can be the cause of that buzz sound.
Regards,
Niranjan

niranjanjaveri · Post by **niranjanjaveri** » Sun Nov 01, 2009 4:40 am

Rob ,
I Just read this on one of your older post in April.

You mentioned---
I just wanted to add a note here for any other Pa500 owners, that because the Pa500 does not use balanced outputs, it is very important to use a MONO jack lead if you are connecting it to anything like powered speakers or a mixer whose inputs can accept balanced or unbalanced. If you plug a STEREO/TRS plug in, then the input circuit is switched from unbalanced to balanced mode.

If you connect using a STEREO/TRS jack lead, then the input at the powered speakers or mixer desk will be expecting to see a balanced signal. When it sees only the unbalanced signal from the Pa500, then you loose more than 50% of the signal and there is an impedance mismatch that causes distortion and unwanted resonance to the sound.

With unbalanced cables you should keep the lead length to less than 3 meters, and the leads must be kept far away from any mains cables or power supplies, otherwise you will get hum pickup.

Best regards,
Rob

So is that the issue with me too..just feeling depressed.. my LE doesnt have any interference issues but the keyboard costing double the Price is giving me probs.Do I need to buy the DI box to convert the unbalance to balance signal.Just curious what outputs does triton Le has.
Regards,
Niranjan

Rob Sherratt · Post by **Rob Sherratt** » Sun Nov 01, 2009 6:16 am

Hi Niranjan,

Unbalanced leads should be less than 3m or you can pick up a lot of mains buzz. An unbalanced lead should not be plugged in to a mixer desk or power speaker socket that only expects to see a balanced input. Some are dual mode and they are OK.

A Behringer Dual DI D120 box is only $30, so give it a try if you are using long leads or connecting to a balanced input somewhere else.

http://www.solotechnic.co.uk/behringer- ... 28187.html

I would use a pair of 0.5m jumper leads from Pa800 or Pa500 to a dual DI Box tied with cable ties to my keyboard stand, then I would use Microphone leads with XLR connectors from the DI Box to a mixer or powered speakers. The XLR inputs on a mixer desk must be set to line level with no +48v phantom power or you'll blow the DI box up.

If you still get hum, then operate the "earth lift" switch on the Behringer Dual DI D120 box.

Best regards,
Rob

karmathanever · Post by **karmathanever** » Sun Nov 01, 2009 9:44 am

Rob S wrote:Pa800 has unbalanced ins and outs. Pa2x ins and outs are balanced. What Pete says is correct for Pa2x only.

Thanks Rob - had not realised the spec difference there in the PA800...

I ask myself:- was there a world shortage of balanced connectors at the time of the PA800 birth?

I cannot believe that Korg would not include balanced connectors on the PA800 output - particularly as they have gone to the trouble of putting balanced connectors for the line-in on the PA800 ????????????????????????????????????????

Hmmmm ... same for the PA588 !!!

Pete

hitman · Post by **hitman** » Sun Nov 01, 2009 4:43 pm

niranjanjaveri,

why don't you try to plug your PA800 into a different power outlet!

Another thing to do would be to check if the mono-TRS cables are OK.

Finally, are you using a LapTop with your Presonus(some are not grounded through the power supply and will cause noises)? If a laptop is being used, try running it just of battery power and see if the noise is still there.
If am not mistaking, the presonus should have a ground screw in the back, which you can connect with a cable to one of the chasis screws of the PA800 (to eliminate ground issues).

Rob Sherratt · Post by **Rob Sherratt** » Sun Nov 01, 2009 4:56 pm

mono/unbalanced cables == TS plugs
stereo/balanced cables == TRS or XLR plugs

Sam CA · Post by **Sam CA** » Mon Nov 02, 2009 3:53 am

I remember my Console Theory teacher saying that a Cable is just a Cable. A cable can not be balanced or unbalanced on its own. It's the circuit that is balanced or unbalanced. According to him, If we have 2 balanced devices ,we need to have a 3 conductor cable (TRS , XLR or whatever) to keep them balanced. Since, it's more expensive to make Balanced devices, most home stereos, or consumer level audio devices are unbalanced. Pro level studio gears are mostly balanced. If a balanced device is connected to an unbalanced device,the whole thing becomes unbalanced. That's why in Pro studios they try to use balanced devices as much as possible,because unbalanced devices are generally noisier. If a device is balanced, we have to use a 3 conductor cable, because a 2 conductor cable will unbalance the device. (we could still connect balanced devices with a 2 conductor cable,but it ruins the whole thing we paid the extra money for ). He basically said that although some manufacturer do call these cables balanced or unbalanced, but it's really not true because the cable can only be balanced with what you plug it into.Rob, does this make sense?

niranjanjaveri · Post by **niranjanjaveri** » Mon Nov 02, 2009 5:29 am

hitman wrote:niranjanjaveri,

why don't you try to plug your PA800 into a different power outlet!

Another thing to do would be to check if the mono-TRS cables are OK.

Finally, are you using a LapTop with your Presonus(some are not grounded through the power supply and will cause noises)? If a laptop is being used, try running it just of battery power and see if the noise is still there.
If am not mistaking, the presonus should have a ground screw in the back, which you can connect with a cable to one of the chasis screws of the PA800 (to eliminate ground issues).

Thank you hitman,
YES I had my Laptop very close to Presonus yesterday and also as Rob mentioned the Mono cables were very close to power cables,,,,,,,,,,,,,,WOWW.

Today when I reconnected I took care that the audio cables were separated from power ones and kept the laptop far away from the cables, magically the whole BUZZ vanished . it turned into a slight HISSSH sound but that was when I turned the output knob on presonus to almost Max.

Thank you Rob,Sam, hitman and Karmathanever for sharing your knowledge,
I have also looked into the behringer D120.Will get one soon.

AS I always tell my friends this forum is full of genius people and ocean of knowledge.

Regards

Rob Sherratt · Post by **Rob Sherratt** » Mon Nov 02, 2009 7:17 am

Assyrianpianist wrote:He basically said that although some manufacturer do call these cables balanced or unbalanced, but it's really not true because the cable can only be balanced with what you plug it into.Rob, does this make sense?

Hi Sam,

It makes sense. A balanced line driver (as implemented by most studio microphones and by telephone exchanges) sends the signal both in phase and anti-phase simultaneously on the Hot (+Signal) and Cold (-Signal) wires with respect to screen (Ground). During transmission along long leads, a mains voltage and other noise is normally induced to the same extent in both conductors with respect to Ground, so at the receiver you have:

Hot = +Signal +Noise
Cold = -Signal +Noise

The balanced receiver does a subtraction which cancels out the noise:

(Hot - Cold) = (+Signal +Noise) - (-Signal + Noise) = 2 * Signal

Most studio MICs implement a balanced line driver, so the noise signal will cancel out when the receiver does the subtraction.

Best regards,
Rob