After several years with the same physical setup, I have a new hum in my
systm. I have a dual monitor PC with LCD screens placed between a pair of
Tannoys. The Tannoys are driven by the CRM outs on a Soundcraft Ghost.
The system has been very quiet. Last Friday, as I was powering up the
system for a Nuendo mix session, I had a hard drive problem. After
repairing the PC, and finally getting everything going on Saturday, I have
a hum.

The hum only occurs when 1) The LCD's are on and receiving a signal from
the PC and 2) when Bus A is being sent to the Tannoys. If I turn off the
LCD's (or the PC) the hum goes away. If I switch to bus b, 2trk A or 2trk
B, there's no hum. All of the tape ins/outs/inserts go to a patch bay,
where it's lined up with a pair of Tascam 24 tracks. I first brought the
bus A gain all the way down, with no effect, then I panned every channel
left, with no effect (hum is from both speakers), I then pulled every cable
except power and speaker cables from the Ghost with no effect.

So it seems that my bus A got screwed somehow. My Question is: is there
anything I can pull apart and look at? I am not an electronics wiz - I can
solder my own cables (and do). I'd rather not take the time (and money) to
get it to the local repair shop, and if I did, I don't know that the
problem would be reproducible without sticking the same PC in place.

With low expectations, but still hoping,
Greg

Sounds to me like you probably put a new cable in for the hard drive, which
is faulty, but not faulty enough to fail, just be noisy.

So my bet is you replace the cable, correct?

--


Roger W. Norman
SirMusic Studio

"Greg Bryant" wrote in message
9.11...
After several years with the same physical setup, I have a new hum in my
systm. I have a dual monitor PC with LCD screens placed between a pair of
Tannoys. The Tannoys are driven by the CRM outs on a Soundcraft Ghost.
The system has been very quiet. Last Friday, as I was powering up the
system for a Nuendo mix session, I had a hard drive problem. After
repairing the PC, and finally getting everything going on Saturday, I have
a hum.

The hum only occurs when 1) The LCD's are on and receiving a signal from
the PC and 2) when Bus A is being sent to the Tannoys. If I turn off the
LCD's (or the PC) the hum goes away. If I switch to bus b, 2trk A or 2trk
B, there's no hum. All of the tape ins/outs/inserts go to a patch bay,
where it's lined up with a pair of Tascam 24 tracks. I first brought the
bus A gain all the way down, with no effect, then I panned every channel
left, with no effect (hum is from both speakers), I then pulled every
cable
except power and speaker cables from the Ghost with no effect.

So it seems that my bus A got screwed somehow. My Question is: is there
anything I can pull apart and look at? I am not an electronics wiz - I
can
solder my own cables (and do). I'd rather not take the time (and money)
to
get it to the local repair shop, and if I did, I don't know that the
problem would be reproducible without sticking the same PC in place.

With low expectations, but still hoping,
Greg

"Roger W. Norman" wrote in
:

Sounds to me like you probably put a new cable in for the hard drive,
which is faulty, but not faulty enough to fail, just be noisy.

So my bet is you replace the cable, correct?


Hmm, no, I didn't, but I can give that a shot. The PC uses a pair of
SATA drives, and I think I have a spare set of cables. I just tried
moving the power cable from the Ghost's PSU, as it ran next to the LCD
cables and fiddled with (read "organized") a bunch of cables running past
the PC from patchbay to rack, but no change. All I did for the XP
problem was a software repair - that's what's bugging me. Normally a new
hum would have an obvious hardware change, but this one I just don't get.
The good news is that no one has yet to say, "Oh, yeah, Ghosts tend to do
that if you . . ." .

The PC and console are both on different UPS's, so I wouldn't expect a
surge to get through, and I have a web dev server sitting off in a
different corner with just a surge protector that's been running fine, so
I don't think a surge could have gotten through.

I have a center channel speaker I've been meaning to put under the LCDs,
but haven't because it will raise them up a bit more than I like, but I
think I'll try that next. That will get the LCDs just a little more
distance from the Tannoys, which may help if it's a shielding problem. I
don't think so, as the hum is on the mix out as well as the control room
out, though. Maybe I'll rip the PC out and re-run all of its cables
first.

Thanks for the suggestion,
Greg

Won't make any difference with SATA devices. If it were 40 or 80 pair IDE
cables or moreso SCSI cables you sometimes have the same symptoms.

--


Roger W. Norman
SirMusic Studio

"Greg Bryant" wrote in message
9.11...
"Roger W. Norman" wrote in
:

Sounds to me like you probably put a new cable in for the hard drive,
which is faulty, but not faulty enough to fail, just be noisy.

So my bet is you replace the cable, correct?


Hmm, no, I didn't, but I can give that a shot. The PC uses a pair of
SATA drives, and I think I have a spare set of cables. I just tried
moving the power cable from the Ghost's PSU, as it ran next to the LCD
cables and fiddled with (read "organized") a bunch of cables running past
the PC from patchbay to rack, but no change. All I did for the XP
problem was a software repair - that's what's bugging me. Normally a new
hum would have an obvious hardware change, but this one I just don't get.
The good news is that no one has yet to say, "Oh, yeah, Ghosts tend to do
that if you . . ." .

The PC and console are both on different UPS's, so I wouldn't expect a
surge to get through, and I have a web dev server sitting off in a
different corner with just a surge protector that's been running fine, so
I don't think a surge could have gotten through.

I have a center channel speaker I've been meaning to put under the LCDs,
but haven't because it will raise them up a bit more than I like, but I
think I'll try that next. That will get the LCDs just a little more
distance from the Tannoys, which may help if it's a shielding problem. I
don't think so, as the hum is on the mix out as well as the control room
out, though. Maybe I'll rip the PC out and re-run all of its cables
first.

Thanks for the suggestion,
Greg

"Roger W. Norman" wrote in message
...
Sounds to me like you probably put a new cable in for the hard drive,
which
is faulty, but not faulty enough to fail, just be noisy.



I don't know about that. Seems to me that if it was noise radiated from
the computer he'd hear it all the time. The fact that the noise is only
on one buss, and exists even with all the signal lines disconnected from
the console, suggests to me that the problem is in the board.

--
"It CAN'T be too loud... some of the red lights aren't even on yet!"
- Lorin David Schultz
in the control room
making even bad news sound good

(Remove spamblock to reply)

"Lorin David Schultz" wrote in news:7he9d.39438
$223.25963@edtnps89:

"Roger W. Norman" wrote in message
...
Sounds to me like you probably put a new cable in for the hard drive,
which
is faulty, but not faulty enough to fail, just be noisy.



I don't know about that. Seems to me that if it was noise radiated from
the computer he'd hear it all the time. The fact that the noise is only
on one buss, and exists even with all the signal lines disconnected from
the console, suggests to me that the problem is in the board.


I'm still not sure what it was, but it's gone. I did the "rip a bunch of
wires out that grew organically" and organize them. Not anything I'd
expect to change a hum, like the monitor cable had gotten wrapped around
the lightpipe cables (yeah, lots of rfi with lightpipe . I hate not
knowing what it was, but I like not having it. At least that area looks a
whole lot cleaner.

Thanks for your suggestions,
Greg

Greg Bryant wrote:

I'm still not sure what it was, but it's gone. I did the "rip a bunch of
wires out that grew organically" and organize them. Not anything I'd
expect to change a hum, like the monitor cable had gotten wrapped around
the lightpipe cables (yeah, lots of rfi with lightpipe . I hate not
knowing what it was, but I like not having it. At least that area looks a
whole lot cleaner.

See if you can make it come back, then.

Is there a lighting dimmer or a touch lamp somewhere in the building?
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."