Emu XL-7 & MP-7 User's Group

I've got exactly the same problem, but only when my computer screen (a LCD Prophet View 720) is on. If i turn it off, the buzz in the main outs stops. Besides I don't have any buzz in the headphones.
Really strange ...

Varial

  ----- Original Message ----- 
  From: acopolis@... 
  To: xl7@yahoogroups.com 
  Sent: Monday, November 04, 2002 6:51 PM
  Subject: [xl7] Re: BUZZING SOUNDS


  Hello,

      I just got my MP7 and I love it! BUT when I hook it up to my amp from
  the main outs (or anny of the outs) and plug the unit in I get a buzzing
  sound and when I turn the unit on the sound gets louder. Has anyone else
  noticed a similar problem? Is this normal? It seems like it shouldnt do it ,
  none of my other gear makes this much noise!  Its not so bad that I can't
  use it but I wounder if it will pose a problem at clubs. The head phone jack
  seems to sound fine but I plan on adding rom soon and I am nervous about
  messing up the one place that doesn't buzz. Do you have to send it in to get
  the problem fixed. What should I do?

  peace, acopolis
  www.space380.com
  888-909-4380



        Yahoo! Groups Sponsor 
              ADVERTISEMENT
             
       
       

  To unsubscribe from this group, send an email to:
  xl7-unsubscribe@yahoogroups.com



  Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. 



[Non-text portions of this message have been removed]

Hello,

    I just got my MP7 and I love it! BUT when I hook it up to my amp from
the main outs (or anny of the outs) and plug the unit in I get a buzzing
sound and when I turn the unit on the sound gets louder. Has anyone else
noticed a similar problem? Is this normal? It seems like it shouldnt do it ,
none of my other gear makes this much noise!  Its not so bad that I can't
use it but I wounder if it will pose a problem at clubs. The head phone jack
seems to sound fine but I plan on adding rom soon and I am nervous about
messing up the one place that doesn't buzz. Do you have to send it in to get
the problem fixed. What should I do?

peace, acopolis
www.space380.com
888-909-4380

Before this gets too out of hand, I figured I'd offer some insights
into what causes hum.  The answer?  Just about everything.  =)  See the
last paragraph for an issue specific to the XL-7.

As with all gear, ground loops can be a problem.  If two devices are
plugged in to each other via audio cables and have different ground
references (i.e. plugged into different AC circuits), some of the AC
power "leaks" through the audio cables, causing 60 cycle (and possibly
harmonics) hum.  To solve this problem, search around the web for tips
on reducing ground loops.  I'm sure there are many more comprehensive
sites out there than what I can offer.

Second, most analog gear (especially mixers) is sensitive to
electromagnetic interference.  Particularly nasty culprits are computer
monitors, halogen lamps, computer cases, refrigerators, etc.  The only
solution here is to try and physically rearrange the interfering
devices.

Finally, the XL-7 has a requirement that the front panel be grounded to
the main chassis.  The symptom of this is buzzing from the HEADPHONE
JACK ONLY.  If you also have hum out of the mains or subs, go back and
reread the previous two paragraphs, because this is not your issue.  If
you must open up your unit (eeek, that didn't sound good) make sure to
check that all ribbon cables are snug, as they have a tendency to come
loose when you pull the two pieces apart.  Also, make sure to put all
the screws back in when you put it together again.  This should ensure
that grounding comes from the chassis rather than the headphone ribbon
cable (the littlest one).

Hope this helps,
  -Aaron

__________________________________________________
Do you Yahoo!?
HotJobs - Search new jobs daily now
http://hotjobs.yahoo.com/

Just one more thing to add...

MIDI can sometimes cause noise to be added to a synth, especially so-called
clock noise.  My spec a MIDI connector should only have its shield pin
connected to ground if it is a MIDI output jack (MIDI itself is a current
loop interface that is optically coupled so it does not need ground
connected between sender device and receiver device).  Unfortunately this
requirement is violated more times in my experience then it should be.  Some
computer interfaces are particularly prone to this mistake.

So if you have noise in your outputs be sure you try to disconnect all the
MIDI connections to the device (XX7 for example) and see if that causes the
noise to be eliminated.  If the MIDI cable connected to your device's output
is the cause then you have a MIDI device it is driving that has incorrect
wiring.  If the MIDI input on the device eliminates the noise then your
instrument is incorrectly wired.

How do you fix this?  Make a MIDI cable that does not have the middle pin
connected nor any shield wiring.  or if you have some flexibility in your
setup try different connection schemes.  Sometimes a THRU box can fix this
too.


drk

www.delora.com/music
www.mp3.com/zdrk
drk.iuma.com

On 11/4/02 1:14 PM, "Aaron Eppolito" <synthesis77@...> wrote:

> Before this gets too out of hand, I figured I'd offer some insights
> into what causes hum.  The answer?  Just about everything.  =)  See the
> last paragraph for an issue specific to the XL-7.
> 
> As with all gear, ground loops can be a problem.  If two devices are
> plugged in to each other via audio cables and have different ground
> references (i.e. plugged into different AC circuits), some of the AC
> power "leaks" through the audio cables, causing 60 cycle (and possibly
> harmonics) hum.  To solve this problem, search around the web for tips
> on reducing ground loops.  I'm sure there are many more comprehensive
> sites out there than what I can offer.
> 
> Second, most analog gear (especially mixers) is sensitive to
> electromagnetic interference.  Particularly nasty culprits are computer
> monitors, halogen lamps, computer cases, refrigerators, etc.  The only
> solution here is to try and physically rearrange the interfering
> devices.
> 
> Finally, the XL-7 has a requirement that the front panel be grounded to
> the main chassis.  The symptom of this is buzzing from the HEADPHONE
> JACK ONLY.  If you also have hum out of the mains or subs, go back and
> reread the previous two paragraphs, because this is not your issue.  If
> you must open up your unit (eeek, that didn't sound good) make sure to
> check that all ribbon cables are snug, as they have a tendency to come
> loose when you pull the two pieces apart.  Also, make sure to put all
> the screws back in when you put it together again.  This should ensure
> that grounding comes from the chassis rather than the headphone ribbon
> cable (the littlest one).
> 
> Hope this helps,
> -Aaron
>

--- drK <drk@...> wrote:
> MIDI can sometimes cause noise to be added to a synth

Very good observation.  I have a old IBM laptop that violates the MIDI
grounding thing and when it's plugged into *anything* that is in *any*
way connected to things that have audio outputs, the noise is
unbelievable.  I have to make sure to plug it into a MIDI box (like an
MTP-AV) instead of any audio gear...

__________________________________________________
Do you Yahoo!?
HotJobs - Search new jobs daily now
http://hotjobs.yahoo.com/

Ye it sucks I got same problem worst I did send to emu pure phatt 
shit rom and its missing THEY SUCK 
--- In xl7@y..., <acopolis@s...> wrote:
> Hello,
> 
>     I just got my MP7 and I love it! BUT when I hook it up to my 
amp from
> the main outs (or anny of the outs) and plug the unit in I get a 
buzzing
> sound and when I turn the unit on the sound gets louder. Has anyone 
else
> noticed a similar problem? Is this normal? It seems like it 
shouldnt do it ,
> none of my other gear makes this much noise!  Its not so bad that I 
can't
> use it but I wounder if it will pose a problem at clubs. The head 
phone jack
> seems to sound fine but I plan on adding rom soon and I am nervous 
about
> messing up the one place that doesn't buzz. Do you have to send it 
in to get

> the problem fixed. What should I do?
> 
> peace, acopolis
> www.space380.com
> 888-909-4380