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On 15/04/2019 10:11, charles wrote:
In article l.net,
Dave Liquorice wrote:
On Sun, 14 Apr 2019 08:00:12 +0100, Brian Gaff wrote:


its affected by proximity, sounds more like a parasitic oscillation of
some sort.


That's what I'd be looking for. Monitor the cuurent draw, does it
follow the buzz level? The buzz is a symptom of the PSU running out
of steam, do the driver chips/transistors get warm/hot?


As it takes a while to appear and does so slowly I'd guess that it's
only just unstable and requires a signal to kick it off.


as I said - check the power supply.

bad decoupling cap feeding high impedance source that picks up hum from
the body once the cap has stopped being a cap.

--
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the course of time they create for themselves a legal system that
authorizes it and a moral code that glorifies it.

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In article l.net,
Dave Liquorice wrote:
On Sun, 14 Apr 2019 08:00:12 +0100, Brian Gaff wrote:


its affected by proximity, sounds more like a parasitic oscillation of
some sort.


That's what I'd be looking for. Monitor the cuurent draw, does it
follow the buzz level? The buzz is a symptom of the PSU running out
of steam, do the driver chips/transistors get warm/hot?


The buzz is well below peak programme level. On a PPM. I'd guess at it
peaking 2 with the actual mod peaking 6. (At the levels I'm mostly driving
everything at) So it is sort of masked by anything continuously loud. But
very obvious on quiet bits. But if you wind up the drive to the speakers,
the buzz remains constant.

Not too keen on breaking into a brand new unit to measure current draw.

As it takes a while to appear and does so slowly I'd guess that it's
only just unstable and requires a signal to kick it off.


--
*Beauty is in the eye of the beer holder...

Dave Plowman London SW
To e-mail, change noise into sound.
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In article ,
The Natural Philosopher wrote:
On 15/04/2019 10:11, charles wrote:
In article l.net,
Dave Liquorice wrote:
On Sun, 14 Apr 2019 08:00:12 +0100, Brian Gaff wrote:


its affected by proximity, sounds more like a parasitic oscillation of
some sort.


That's what I'd be looking for. Monitor the cuurent draw, does it
follow the buzz level? The buzz is a symptom of the PSU running out
of steam, do the driver chips/transistors get warm/hot?


As it takes a while to appear and does so slowly I'd guess that it's
only just unstable and requires a signal to kick it off.


as I said - check the power supply.

bad decoupling cap feeding high impedance source that picks up hum from
the body once the cap has stopped being a cap.


Did you actually read my post? The buzz stops as you approach the device.
But perhaps your body is out of phase. ;-)

--
*Forget the Joneses, I keep us up with the Simpsons.

Dave Plowman London SW
To e-mail, change noise into sound.
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On Mon, 15 Apr 2019 13:48:21 +0100, Dave Plowman (News) wrote:

its affected by proximity, sounds more like a parasitic

oscillation of
some sort.


That's what I'd be looking for. Monitor the cuurent draw, does it
follow the buzz level? The buzz is a symptom of the PSU running

out
of steam, do the driver chips/transistors get warm/hot?


The buzz is well below peak programme level. On a PPM. I'd guess at it
peaking 2 with the actual mod peaking 6.


Buzz is a symptom possibly caused by the thing oscillating flat out
ultrasonically or in the low RF range... Bung a scope on the output?

Try shorter or different speaker leads? Though ISTR this is an actve
tri-amped speaker system?

But if you wind up the drive to the speakers, the buzz remains constant.


Which indicates it's not incoming to that amp.

Not too keen on breaking into a brand new unit to measure current draw.


Fair enough, scope? AC Volt meter? With no programme there shouldn't
be any "signal" from, DC to light, across the speakers. You should
be able to measure the buzz when present, if it happens with the
meter connected but fairly small not amp supply rails that I'd expect
with the thing "hooting". B-)

--
Cheers
Dave.



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In article l.net,
Dave Liquorice wrote:
On Mon, 15 Apr 2019 13:48:21 +0100, Dave Plowman (News) wrote:


its affected by proximity, sounds more like a parasitic

oscillation of
some sort.

That's what I'd be looking for. Monitor the cuurent draw, does it
follow the buzz level? The buzz is a symptom of the PSU running

out
of steam, do the driver chips/transistors get warm/hot?


The buzz is well below peak programme level. On a PPM. I'd guess at it
peaking 2 with the actual mod peaking 6.


Buzz is a symptom possibly caused by the thing oscillating flat out
ultrasonically or in the low RF range... Bung a scope on the output?


Try shorter or different speaker leads?


They are all of a foot long. ;-) Speakon 8 and car trailer multi core
cable.


Though ISTR this is an actve
tri-amped speaker system?


Yup. And didn't buzz with the previous X/O which is a direct replacement
Exactly the same physical size, and even the mains in and XLRs in roughly
the same place.

But if you wind up the drive to the speakers, the buzz remains
constant.


Which indicates it's not incoming to that amp.


Quite. Although it does seem to be started by the input signal. Unplug the
XLR to the X/O input, no buzz - at least for as long as I've tried it.
With signal starts in a couple of minutes after power up. And continues if
you then unplug the input.

Not too keen on breaking into a brand new unit to measure current draw.


Fair enough, scope? AC Volt meter? With no programme there shouldn't
be any "signal" from, DC to light, across the speakers. You should
be able to measure the buzz when present, if it happens with the
meter connected but fairly small not amp supply rails that I'd expect
with the thing "hooting". B-)


I thought I'd seen it all given how many bits of gear I'd plugged up at
work over the years. ;-)

If I unplug the X/O from the amp with the buzz going, the buzz stops.
That's not to say it isn't some form of interaction.

--
*I feel like I'm diagonally parked in a parallel universe*

Dave Plowman London SW
To e-mail, change noise into sound.


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Default Electronics funny.

In article , Dave Plowman (News)
scribeth thus
In article ,
The Natural Philosopher wrote:
On 15/04/2019 10:11, charles wrote:
In article l.net,
Dave Liquorice wrote:
On Sun, 14 Apr 2019 08:00:12 +0100, Brian Gaff wrote:

its affected by proximity, sounds more like a parasitic oscillation of
some sort.

That's what I'd be looking for. Monitor the cuurent draw, does it
follow the buzz level? The buzz is a symptom of the PSU running out
of steam, do the driver chips/transistors get warm/hot?

As it takes a while to appear and does so slowly I'd guess that it's
only just unstable and requires a signal to kick it off.

as I said - check the power supply.

bad decoupling cap feeding high impedance source that picks up hum from
the body once the cap has stopped being a cap.


Did you actually read my post? The buzz stops as you approach the device.
But perhaps your body is out of phase. ;-)


Now thats is odd., Assuming it used the THAT and SMM series of balanced
line receivers they should only see the input differential voltage
unless that differential system isn't working i.e. the common mode side
is up ****e creek.

Electronic balance is fine but it must be isolated from its supply limes
and other odd references around.

Maybe one input side is getting connected to the metal earthwork?.

Bring it up here Dave got the equipment to suss that one out;!.

--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.


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On Mon, 15 Apr 2019 16:41:45 +0100, Dave Plowman (News) wrote:

Buzz is a symptom possibly caused by the thing oscillating flat

out
ultrasonically or in the low RF range... Bung a scope on the

output?

Try shorter or different speaker leads?


They are all of a foot long. ;-) Speakon 8 and car trailer multi core
cable.

Though ISTR this is an actve tri-amped speaker system?


Yup. And didn't buzz with the previous X/O which is a direct replacement
Exactly the same physical size, and even the mains in and XLRs in
roughly the same place.


Behringer are "budget" and make down to a price, corners get cut.
Most of the time they get away with the cut corners but not always.
It's the silly little things like decoupling capacitors and the like
that get cut.

But if you wind up the drive to the speakers, the buzz remains
constant.


Which indicates it's not incoming to that amp.


Quite. Although it does seem to be started by the input signal. Unplug
the XLR to the X/O input, no buzz - at least for as long as I've tried
it. With signal starts in a couple of minutes after power up. And
continues if you then unplug the input.


So following the parasitic oscilation theory. Once kicked off it
carries on.

Not too keen on breaking into a brand new unit to measure current


draw.


Fair enough, scope? AC Volt meter?


Just re-read the thread and it's the crossover you are changing, the
power amps remain the same. Do that amps get hot/draw more with the
buzz present, it could be their power supply(s) that are suffering
the strain rather than the one in the cross over.

I thought I'd seen it all given how many bits of gear I'd plugged up at
work over the years. ;-)


Parasitic oscillation in "pro" audio kit doesn't happen very often. I
think I've only encountered once, maybe twice in 40+ years. Normally
shows itself by a PPM being end stopped but nothing audible.

If I unplug the X/O from the amp with the buzz going, the buzz stops.
That's not to say it isn't some form of interaction.


If the crossover is hooting, unplugging it from the amps disconnects
that signal, the amps stop drawing current and the amp PSUs can
return to normal, sans buzz.

--
Cheers
Dave.



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On 15/04/2019 23:17, Dave plow**** wrote:
Did you actually read my post? The buzz stops as you approach the device.
But perhaps your body is out of phase.;-)

No Dave, I never read your posts.

You've been killfiled for years


--
If I had all the money I've spent on drink...
...I'd spend it on drink.

Sir Henry (at Rawlinson's End)
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On 15/04/2019 23:17, tony sayer wrote:
In article , Dave Plowman (News)
scribeth thus
In article ,
The Natural Philosopher wrote:
On 15/04/2019 10:11, charles wrote:
In article l.net,
Dave Liquorice wrote:
On Sun, 14 Apr 2019 08:00:12 +0100, Brian Gaff wrote:

its affected by proximity, sounds more like a parasitic oscillation of
some sort.

That's what I'd be looking for. Monitor the cuurent draw, does it
follow the buzz level? The buzz is a symptom of the PSU running out
of steam, do the driver chips/transistors get warm/hot?

As it takes a while to appear and does so slowly I'd guess that it's
only just unstable and requires a signal to kick it off.

as I said - check the power supply.

bad decoupling cap feeding high impedance source that picks up hum from
the body once the cap has stopped being a cap.


Did you actually read my post? The buzz stops as you approach the device.
But perhaps your body is out of phase. ;-)


Now thats is odd., Assuming it used the THAT and SMM series of balanced
line receivers they should only see the input differential voltage
unless that differential system isn't working i.e. the common mode side
is up ****e creek.

Electronic balance is fine but it must be isolated from its supply limes
and other odd references around.

Maybe one input side is getting connected to the metal earthwork?.

Bring it up here Dave got the equipment to suss that one out;!.


I also think this is an earthing issue, exacerbated by the new unit's
switch mode power supply.

Hence my suggestion in an earlier post to use cable ferrite chokes that
help to eliminate HF earth and common mode issues.

However the behaviour of connecting an input that causes a 'buzz' that
remains after disconnecting the input does sound more sinister, such as
an instability. I looked up Behringer and their equipment gets mixed
reviews as well as being the wrong end of a few legal issues with
pirating designs.
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In article l.net,
Dave Liquorice scribeth thus
On Mon, 15 Apr 2019 16:41:45 +0100, Dave Plowman (News) wrote:

Buzz is a symptom possibly caused by the thing oscillating flat

out
ultrasonically or in the low RF range... Bung a scope on the

output?

Try shorter or different speaker leads?


They are all of a foot long. ;-) Speakon 8 and car trailer multi core
cable.

Though ISTR this is an actve tri-amped speaker system?


Yup. And didn't buzz with the previous X/O which is a direct replacement
Exactly the same physical size, and even the mains in and XLRs in
roughly the same place.


Behringer are "budget" and make down to a price, corners get cut.
Most of the time they get away with the cut corners but not always.
It's the silly little things like decoupling capacitors and the like
that get cut.

But if you wind up the drive to the speakers, the buzz remains
constant.

Which indicates it's not incoming to that amp.


Quite. Although it does seem to be started by the input signal. Unplug
the XLR to the X/O input, no buzz - at least for as long as I've tried
it. With signal starts in a couple of minutes after power up. And
continues if you then unplug the input.


So following the parasitic oscilation theory. Once kicked off it
carries on.

Not too keen on breaking into a brand new unit to measure current


draw.

Fair enough, scope? AC Volt meter?


Just re-read the thread and it's the crossover you are changing, the
power amps remain the same. Do that amps get hot/draw more with the
buzz present, it could be their power supply(s) that are suffering
the strain rather than the one in the cross over.

I thought I'd seen it all given how many bits of gear I'd plugged up at
work over the years. ;-)


Parasitic oscillation in "pro" audio kit doesn't happen very often. I
think I've only encountered once, maybe twice in 40+ years. Normally
shows itself by a PPM being end stopped but nothing audible.

If I unplug the X/O from the amp with the buzz going, the buzz stops.
That's not to say it isn't some form of interaction.


If the crossover is hooting, unplugging it from the amps disconnects
that signal, the amps stop drawing current and the amp PSUs can
return to normal, sans buzz.


On another group a poster there says he's used lots of these units
without any buzz or hum problems at all..
--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.




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In article , Fredxx
scribeth thus
On 15/04/2019 23:17, tony sayer wrote:
In article , Dave Plowman (News)
scribeth thus
In article ,
The Natural Philosopher wrote:
On 15/04/2019 10:11, charles wrote:
In article l.net,
Dave Liquorice wrote:
On Sun, 14 Apr 2019 08:00:12 +0100, Brian Gaff wrote:

its affected by proximity, sounds more like a parasitic oscillation of
some sort.

That's what I'd be looking for. Monitor the cuurent draw, does it
follow the buzz level? The buzz is a symptom of the PSU running out
of steam, do the driver chips/transistors get warm/hot?

As it takes a while to appear and does so slowly I'd guess that it's
only just unstable and requires a signal to kick it off.

as I said - check the power supply.

bad decoupling cap feeding high impedance source that picks up hum from
the body once the cap has stopped being a cap.

Did you actually read my post? The buzz stops as you approach the device.
But perhaps your body is out of phase. ;-)


Now thats is odd., Assuming it used the THAT and SMM series of balanced
line receivers they should only see the input differential voltage
unless that differential system isn't working i.e. the common mode side
is up ****e creek.

Electronic balance is fine but it must be isolated from its supply limes
and other odd references around.

Maybe one input side is getting connected to the metal earthwork?.

Bring it up here Dave got the equipment to suss that one out;!.


I also think this is an earthing issue, exacerbated by the new unit's
switch mode power supply.

Hence my suggestion in an earlier post to use cable ferrite chokes that
help to eliminate HF earth and common mode issues.

However the behaviour of connecting an input that causes a 'buzz' that
remains after disconnecting the input does sound more sinister, such as
an instability. I looked up Behringer and their equipment gets mixed
reviews as well as being the wrong end of a few legal issues with
pirating designs.


See the other post to Dave L re this,
--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.


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In article ,
tony sayer wrote:
Did you actually read my post? The buzz stops as you approach the device.
But perhaps your body is out of phase. ;-)


Now thats is odd., Assuming it used the THAT and SMM series of balanced
line receivers they should only see the input differential voltage
unless that differential system isn't working i.e. the common mode side
is up ****e creek.


Electronic balance is fine but it must be isolated from its supply limes
and other odd references around.


Maybe one input side is getting connected to the metal earthwork?.


Absolutly not.

But if it were a problem with the amp input side, why was the analogue X/O
clean?

--
*My luck is so bad that if I bought a cemetery, people would stop dying.

Dave Plowman London SW
To e-mail, change noise into sound.
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"charles" wrote in message
...
In article , Rod Speed
wrote:


"charles" wrote in message
...
In article l.net,
Dave Liquorice wrote:
On Sun, 14 Apr 2019 08:00:12 +0100, Brian Gaff wrote:

its affected by proximity, sounds more like a parasitic oscillation
of some sort.

That's what I'd be looking for. Monitor the cuurent draw, does it
follow the buzz level? The buzz is a symptom of the PSU running out of
steam, do the driver chips/transistors get warm/hot?

As it takes a while to appear and does so slowly I'd guess that it's
only just unstable and requires a signal to kick it off.

as I said - check the power supply.


Pointless with two new devices with a decent brand like that.


somebody in purchasing thought they could shave
?0.1 off the cost by buying cheaper compoents?


Doesn't happen with that brand and clearly now that it is clear
how to get rid of the buzz, it isnt a power supply problem.

The BBC once sent back a whole batch of AVO8s
because they were inaccurate. It does happen.


Different issue entirely.

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Default Lonely Psychopathic Senile Ozzie Troll Alert!

On Tue, 16 Apr 2019 19:36:08 +1000, cantankerous trolling geezer Rot Speed,
the auto-contradicting senile sociopath, blabbered, again:


somebody in purchasing thought they could shave
?0.1 off the cost by buying cheaper compoents?


Doesn't happen with that brand and clearly now that it is clear
how to get rid of the buzz, it isnt a power supply problem.

The BBC once sent back a whole batch of AVO8s
because they were inaccurate. It does happen.


Different issue entirely.


Yeah, the issue here is your pathological auto-contradicting issue, senile
pest!

--
The Natural Philosopher about senile Rot:
"Rod speed is not a Brexiteer. He is an Australian troll and arsehole."
Message-ID:
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"The Natural Philosopher" wrote in message
...
On 15/04/2019 10:11, charles wrote:
In article l.net,
Dave Liquorice wrote:
On Sun, 14 Apr 2019 08:00:12 +0100, Brian Gaff wrote:


its affected by proximity, sounds more like a parasitic oscillation of
some sort.


That's what I'd be looking for. Monitor the cuurent draw, does it
follow the buzz level? The buzz is a symptom of the PSU running out
of steam, do the driver chips/transistors get warm/hot?


As it takes a while to appear and does so slowly I'd guess that it's
only just unstable and requires a signal to kick it off.


as I said - check the power supply.

bad decoupling cap feeding high impedance source that picks up hum from
the body once the cap has stopped being a cap.


Can't be that given that two identical copies have the buzz problem.



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Default More Heavy Trolling by Senile Nym-Shifting Rot Speed!

On Wed, 17 Apr 2019 05:26:39 +1000, Jac Brown, better known as cantankerous
trolling senile geezer Rot Speed, wrote:


bad decoupling cap feeding high impedance source that picks up hum from
the body once the cap has stopped being a cap.


Can't be that given that two identical copies have the buzz problem.


The OP actually pointed already out where his error is, senile Rodent Speed!
Or did you simply feel the need to auto-contradict again, you pathological
auto-contradicting senile asshole? BG

--
Kerr-Mudd,John addressing senile Rot:
"Auto-contradictor Rod is back! (in the KF)"
MID:
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Default Electronics funny.

Found some Tufnol lying around, so made the new brackets. Absolutely no
difference. Seems it was the position between the two units causing the
buzz - not connection to the stand. Dropping the X/O out of its mounting
on to the top of the amp - only a couple of inches - sorted the buzz. Not
easy to reposition either of them.

So in desperation, removed the mains earth from the X/O. Result, clean as
a whistle with it back in its original position with the ally brackets too.

Looked inside. Mains earth is a short length of wire from the IEC inlet to
the chassis. Signal ground is the PCB bolted to the chassis. (I'd already
tried disconnecting the XLR screens without success.)

Amp is much the same. IEC in and IEC unswitched out are grounded to the
same point on the chassis. Signal grounds to a different point on the
chassis.

Ground loops (to me) are usually a hum rather than buzz, so still don't
know what is going on.

And still don't know why the old X/O which has the same grounding
arrangements was OK. As I said, the only real difference is the old had an
analogue PS, while the new a SMPS.

I'm happy to leave things with no mains earth to the X/O, and rely on the
XLR screens for a safety ground. It's not going to be unplugged etc when
in use.

--
*The problem with the world is that everyone is a few drinks behind *

Dave Plowman London SW
To e-mail, change noise into sound.
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In message , "Dave Plowman (News)"
writes
Ground loops (to me) are usually a hum rather than buzz, so still don't
know what is going on.

And still don't know why the old X/O which has the same grounding
arrangements was OK. As I said, the only real difference is the old had
an analogue PS, while the new a SMPS.


Based on my experience with SMPS powered laptops in a pro situation,
this always sounded to me like shash of one sort or another from the
power supply, possibly induced into an earth loop.

It ought really to be queried with Behringer.
--
Bill
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In article , Dave Plowman (News)
scribeth thus
Found some Tufnol lying around, so made the new brackets. Absolutely no
difference. Seems it was the position between the two units causing the
buzz - not connection to the stand. Dropping the X/O out of its mounting
on to the top of the amp - only a couple of inches - sorted the buzz. Not
easy to reposition either of them.

So in desperation, removed the mains earth from the X/O. Result, clean as
a whistle with it back in its original position with the ally brackets too.

Looked inside. Mains earth is a short length of wire from the IEC inlet to
the chassis. Signal ground is the PCB bolted to the chassis. (I'd already
tried disconnecting the XLR screens without success.)

Amp is much the same. IEC in and IEC unswitched out are grounded to the
same point on the chassis. Signal grounds to a different point on the
chassis.

Ground loops (to me) are usually a hum rather than buzz, so still don't
know what is going on.

And still don't know why the old X/O which has the same grounding
arrangements was OK. As I said, the only real difference is the old had an
analogue PS, while the new a SMPS.

I'm happy to leave things with no mains earth to the X/O, and rely on the
XLR screens for a safety ground. It's not going to be unplugged etc when
in use.


Dave, this just shouldn't be a problem with pro equipment least pro in
this sense being balanced in's and i presume out?.

We have a lot of pro audio gear over time and never have we had this
happen and that does inc some equipment from Behringer.

You shouldn't have to rely on the XLR screens as a safety ground their
not there for that the main safety earth is, least thats how it works
and has worked for many years in my past experience.

The metal chassis should be earthed and for safety reasons via the mains
provided earth the XLR cable screens should be connected to that as well
internally, Unless its a big mixing desk studio installation where a
separate "tech" earth is provided or called for to ground audio cables
and that will be to reduce the possibility of picked up noise.

I reckon it way well be that this unit is duff somewhere, it was a new
ones was it not and not a second-hand one where someone might have been
at the insides perhaps?...

--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.


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snip

The metal chassis should be earthed and for safety reasons via the mains
provided earth the XLR cable screens should be connected to that as well
internally...


I posted here a while back about a two core (ie unearthed) mains IEC C13
cable which I threw away. I found another one yesterday.

Cheers
--
Clive


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In article ,
tony sayer wrote:
I'm happy to leave things with no mains earth to the X/O, and rely on
the XLR screens for a safety ground. It's not going to be unplugged etc
when in use.


Dave, this just shouldn't be a problem with pro equipment least pro in
this sense being balanced in's and i presume out?.


Indeed. Hence me posting about it. ;-)

We have a lot of pro audio gear over time and never have we had this
happen and that does inc some equipment from Behringer.


Same here. When I worked for Thames, we'd buy the latest semi-pro gizmo
from the liked of Behringer just to assess it. Mainly outboards for use in
the music recording studio. Things like digital reverbs started out in
that sort of market before being available from the more respected pro
sources. And they all simply plugged in and worked.

You shouldn't have to rely on the XLR screens as a safety ground their
not there for that the main safety earth is, least thats how it works
and has worked for many years in my past experience.


Oh, indeed. But without knowing what else to try, I'm going to keep it as
is. The fuse in the Behringer is 1 amp, and the XLR screens and connectors
will handle that as a fault current quite happily. I'd not do it where
others were likely to have to fiddle with it.

The metal chassis should be earthed and for safety reasons via the mains
provided earth the XLR cable screens should be connected to that as well
internally, Unless its a big mixing desk studio installation where a
separate "tech" earth is provided or called for to ground audio cables
and that will be to reduce the possibility of picked up noise.


I reckon it way well be that this unit is duff somewhere, it was a new
ones was it not and not a second-hand one where someone might have been
at the insides perhaps?...


Thing is, it was the same with two units... But not the older Behringer
X/O. Which is what confused me, and the reason for this thread.

--
*Time is what keeps everything from happening at once.

Dave Plowman London SW
To e-mail, change noise into sound.
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On 17/04/2019 19:13, Dave Plowman (News) wrote:
Found some Tufnol lying around, so made the new brackets. Absolutely no
difference. Seems it was the position between the two units causing the
buzz - not connection to the stand. Dropping the X/O out of its mounting
on to the top of the amp - only a couple of inches - sorted the buzz. Not
easy to reposition either of them.

So in desperation, removed the mains earth from the X/O. Result, clean as
a whistle with it back in its original position with the ally brackets too.


Which is what I expected for the reasons stated, hence the suggestion of
placing a ferrite in the mains cable.

Running without an earth is not ideal. Perhaps use a low current RCD
might mitigate the danger.
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In message , "Dave Plowman (News)"
writes
In article ,
tony sayer wrote:

You shouldn't have to rely on the XLR screens as a safety ground their
not there for that the main safety earth is, least thats how it works
and has worked for many years in my past experience.


Oh, indeed. But without knowing what else to try, I'm going to keep it as
is. The fuse in the Behringer is 1 amp, and the XLR screens and connectors
will handle that as a fault current quite happily. I'd not do it where
others were likely to have to fiddle with it.

At the risk of sounding nannying, it should at least be reported to
Behringer. If two of these are faulty, it points at least to a bad
batch.

I'm sure it is safe in your use, but other, less experienced, people
will presumably buy these and who knows what earths will be left off to
cure the buzz.

--
Bill
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On 19/04/2019 16:47, Bill wrote:
In message , "Dave Plowman (News)"
writes
In article ,
Â* tony sayer wrote:

You shouldn't have to rely on the XLR screens as a safety ground their
not there for that the main safety earth is, least thats how it works
and has worked for many years in my past experience.


Oh, indeed. But without knowing what else to try, I'm going to keep it as
is. The fuse in the Behringer is 1 amp, and the XLR screens and
connectors
will handle that as a fault current quite happily. I'd not do it where
others were likely to have to fiddle with it.

At the risk of sounding nannying, it should at least be reported to
Behringer. If two of these are faulty, it points at least to a bad batch.


More likely a design flaw.

I'm sure it is safe in your use, but other, less experienced, people
will presumably buy these and who knows what earths will be left off to
cure the buzz.


We don't how the earth is connected internally. The earth inside could
be exceptionally quiet and the buzz caused from associated equipment and
it's associated earthing.

Earthing arrangement can be a nightmare with no obvious solution and the
inappropriate apportioning of blame.

I hate the idea of the removal of an earth. It reminds me of days when
some would leave the earth off an oscilloscope to improve noise
performance or to look/compare at signals at raised voltages.

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In message , Fredxx
writes
I hate the idea of the removal of an earth.


Very early in my "career" I was called on to make sure the Scottish
Variety Orchestra was "safe". The guitarist's amp had no earth, no
grommet where the remaining two cores went through the metalwork and the
outer sleeve was cut through. I was the only engineer on site.
We were not allowed to fix problems in musician's equipment and it was
before the days of safety isolating transformers.
The whole orchestra waited while he went home to fetch another amp.
I got a huge bollocking because of the cost, and just one small message
of praise and support.
--
Bill


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In article ,
Bill wrote:
Oh, indeed. But without knowing what else to try, I'm going to keep it as
is. The fuse in the Behringer is 1 amp, and the XLR screens and connectors
will handle that as a fault current quite happily. I'd not do it where
others were likely to have to fiddle with it.

At the risk of sounding nannying, it should at least be reported to
Behringer. If two of these are faulty, it points at least to a bad
batch.


I can't be certain the Behringer unit is faulty. The amplifiers are home
made, and it could be some interaction I've not fathomed out.

I'm sure it is safe in your use, but other, less experienced, people
will presumably buy these and who knows what earths will be left off to
cure the buzz.


It's not a common problem with this unit. Others seem to have found it
fine.

--
*How many roads must a man travel down before he admits he is lost?

Dave Plowman London SW
To e-mail, change noise into sound.
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Default Electronics funny.

In article ,
Fredxx wrote:
At the risk of sounding nannying, it should at least be reported to
Behringer. If two of these are faulty, it points at least to a bad batch.


More likely a design flaw.


I'm sure it is safe in your use, but other, less experienced, people
will presumably buy these and who knows what earths will be left off to
cure the buzz.


We don't how the earth is connected internally. The earth inside could
be exceptionally quiet and the buzz caused from associated equipment and
it's associated earthing.


Indeed - my problem. I do know how the earths are connected. In both the
X/O and amp they go straight to the chassis via just about the shortest
route.

Earthing arrangement can be a nightmare with no obvious solution and the
inappropriate apportioning of blame.


Tell me about it. ;-)

I hate the idea of the removal of an earth. It reminds me of days when
some would leave the earth off an oscilloscope to improve noise
performance or to look/compare at signals at raised voltages.


Yup.

--
*Many people quit looking for work when they find a job *

Dave Plowman London SW
To e-mail, change noise into sound.
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In article ,
Fredxx wrote:
I hate the idea of the removal of an earth.


Many years ago, a friend bought a reasonably expensive Pioneer separates
Hi-Fi system. Turntable, amp, tuner, cassette deck. With all the mains
going to the same 4 way trailing socket and all the phonos connected, it
hummed. making up phono leads with no screen connection at one end - and
trying every combination of connected and non connected ones didn't work.
Got rid of the hum, but ended up with buzz. Only answer was to remove all
the mains grounds except the amp one.

Quad at that time only grounded the pre-amp. Everything else had two
core mains leads. Using 110v mains plugs. ;-)

--
*42.7% of statistics are made up. Sorry, that should read 47.2% *

Dave Plowman London SW
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In article , Bill
scribeth thus
In message , Fredxx
writes
I hate the idea of the removal of an earth.


Very early in my "career" I was called on to make sure the Scottish
Variety Orchestra was "safe". The guitarist's amp had no earth, no
grommet where the remaining two cores went through the metalwork and the
outer sleeve was cut through. I was the only engineer on site.
We were not allowed to fix problems in musician's equipment and it was
before the days of safety isolating transformers.
The whole orchestra waited while he went home to fetch another amp.
I got a huge bollocking because of the cost, and just one small message
of praise and support.


Yes quite a few accounts over the years of the lead singer/guitarist
writhing around when he grabbed the mic stand...

Other had wrapped around his fretboard..

--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.


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In article , Dave Plowman (News)
scribeth thus
In article ,
Fredxx wrote:
I hate the idea of the removal of an earth.


Many years ago, a friend bought a reasonably expensive Pioneer separates
Hi-Fi system. Turntable, amp, tuner, cassette deck. With all the mains
going to the same 4 way trailing socket and all the phonos connected, it
hummed. making up phono leads with no screen connection at one end - and
trying every combination of connected and non connected ones didn't work.
Got rid of the hum, but ended up with buzz. Only answer was to remove all
the mains grounds except the amp one.

Quad at that time only grounded the pre-amp. Everything else had two
core mains leads. Using 110v mains plugs. ;-)


There is IIRC a 2.2 Ohm ressy in the quad to prevent that problem if a
three pin mains lead of the IEC type is used, and used they are in
"upgraded" QUAD 303's

Or a non standard quad mains via the bulgin


--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.




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Default Electronics funny.

In article , Dave Plowman (News)
scribeth thus
In article ,
Bill wrote:
Oh, indeed. But without knowing what else to try, I'm going to keep it as
is. The fuse in the Behringer is 1 amp, and the XLR screens and connectors
will handle that as a fault current quite happily. I'd not do it where
others were likely to have to fiddle with it.

At the risk of sounding nannying, it should at least be reported to
Behringer. If two of these are faulty, it points at least to a bad
batch.


I can't be certain the Behringer unit is faulty. The amplifiers are home
made, and it could be some interaction I've not fathomed out.



Right!, so the crossover then goes to some home-brew amps if so what are
they and are they bal or unbal inputs?..


I'm sure it is safe in your use, but other, less experienced, people
will presumably buy these and who knows what earths will be left off to
cure the buzz.


It's not a common problem with this unit. Others seem to have found it
fine.


--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.


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In article ,
tony sayer wrote:
Quad at that time only grounded the pre-amp. Everything else had two
core mains leads. Using 110v mains plugs. ;-)


There is IIRC a 2.2 Ohm ressy in the quad to prevent that problem if a
three pin mains lead of the IEC type is used


Can I ask where that 2.2 ohm resistor went?


, and used they are in
"upgraded" QUAD 303's


Or a non standard quad mains via the bulgin


Both the 33 and 303 came with 3 pin Bulgin. If you used the 303 stand
alone, you used a three core mains lead. If used with the 33, the 3 core
for the 33 only, and a supplied two core from the switched mains outlet on
the 33 to the 303.

Not quite sure what they did on the 405-2 series amps. That has an IEC
input and IEC output. Both earthed. But never had a 4 Series pre-amp or
tuner.

--
*Change is inevitable ... except from vending machines *

Dave Plowman London SW
To e-mail, change noise into sound.
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Default Electronics funny.

In article ,
tony sayer wrote:
I can't be certain the Behringer unit is faulty. The amplifiers are home
made, and it could be some interaction I've not fathomed out.



Right!, so the crossover then goes to some home-brew amps if so what are
they and are they bal or unbal inputs?..


Balanced. Using THAT1240 ICs. The whole idea being to avoid ground loop
problems...

--
*Drugs may lead to nowhere, but at least it's the scenic route *

Dave Plowman London SW
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On 21/04/2019 00:15, Dave Plowman (News) wrote:
In article ,
tony sayer wrote:
I can't be certain the Behringer unit is faulty. The amplifiers are home
made, and it could be some interaction I've not fathomed out.



Right!, so the crossover then goes to some home-brew amps if so what are
they and are they bal or unbal inputs?..


Balanced. Using THAT1240 ICs. The whole idea being to avoid ground loop
problems...


They have some serious CMRR.

I doubt the X/O has anything like that?
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In article ,
Fredxx wrote:
On 21/04/2019 00:15, Dave Plowman (News) wrote:
In article ,
tony sayer wrote:
I can't be certain the Behringer unit is faulty. The amplifiers are home
made, and it could be some interaction I've not fathomed out.



Right!, so the crossover then goes to some home-brew amps if so what are
they and are they bal or unbal inputs?..


Balanced. Using THAT1240 ICs. The whole idea being to avoid ground loop
problems...


They have some serious CMRR.


I doubt the X/O has anything like that?


I didn't recognise the number on the balance ICs in the X/O.

I have loads of SSM 2143 I could try, though, on the amp. But I've not had
problems with either before.

Because the cable run is so short, I've just used the most basic circuit
for the THAT1240.

But

--
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Dave Plowman London SW
To e-mail, change noise into sound.


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In article , Dave Plowman (News)
scribeth thus
In article ,
tony sayer wrote:
Quad at that time only grounded the pre-amp. Everything else had two
core mains leads. Using 110v mains plugs. ;-)


There is IIRC a 2.2 Ohm ressy in the quad to prevent that problem if a
three pin mains lead of the IEC type is used


Can I ask where that 2.2 ohm resistor went?


Apologies remembering wrong! Nothing out of the ordinary in that
circuit..



, and used they are in
"upgraded" QUAD 303's


Or a non standard quad mains via the bulgin


Both the 33 and 303 came with 3 pin Bulgin. If you used the 303 stand
alone, you used a three core mains lead. If used with the 33, the 3 core
for the 33 only, and a supplied two core from the switched mains outlet on
the 33 to the 303.

Not quite sure what they did on the 405-2 series amps. That has an IEC
input and IEC output. Both earthed. But never had a 4 Series pre-amp or
tuner.


Yes could have written that a bit/lot clearer the bulgin 3 Pin does have
an earth on it using a two core mains cable partnered with the 33 as
they probably couldn't get a Three pin outlet which does make the audio
screened lead earth the protective earth.

Not good engineering really on Quad's behalf..

--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.


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In article , Dave Plowman (News)
scribeth thus
In article ,
tony sayer wrote:
I can't be certain the Behringer unit is faulty. The amplifiers are home
made, and it could be some interaction I've not fathomed out.



Right!, so the crossover then goes to some home-brew amps if so what are
they and are they bal or unbal inputs?..


Balanced. Using THAT1240 ICs. The whole idea being to avoid ground loop
problems...


They fed by a + volt and a neg volt supply centre tapped or floating do
you know?..


http://www.thatcorp.com/1240-series_...iver_ICs.shtml


--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.


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In article , Fredxx
scribeth thus
On 21/04/2019 00:15, Dave Plowman (News) wrote:
In article ,
tony sayer wrote:
I can't be certain the Behringer unit is faulty. The amplifiers are home
made, and it could be some interaction I've not fathomed out.



Right!, so the crossover then goes to some home-brew amps if so what are
they and are they bal or unbal inputs?..


Balanced. Using THAT1240 ICs. The whole idea being to avoid ground loop
problems...


They have some serious CMRR.


What the THAT chips, if so how so?..


I doubt the X/O has anything like that?


--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.


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In article , Dave Plowman (News)
scribeth thus
In article ,
Fredxx wrote:
On 21/04/2019 00:15, Dave Plowman (News) wrote:
In article ,
tony sayer wrote:
I can't be certain the Behringer unit is faulty. The amplifiers are home
made, and it could be some interaction I've not fathomed out.


Right!, so the crossover then goes to some home-brew amps if so what are
they and are they bal or unbal inputs?..

Balanced. Using THAT1240 ICs. The whole idea being to avoid ground loop
problems...


They have some serious CMRR.


I doubt the X/O has anything like that?


I didn't recognise the number on the balance ICs in the X/O.

I have loads of SSM 2143 I could try, though, on the amp. But I've not had
problems with either before.



Wouldn't surprised if they were pin compatible!..

Because the cable run is so short, I've just used the most basic circuit
for the THAT1240.

But

It really shouldn't matter those sorts of chip can take balanced lines
up to miles long if need be!..


I've got/getting rather then theres something odd with the power supply
for these somewhere?..

Can you describe it in more detail?..

--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.


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In article ,
tony sayer wrote:
In article , Dave Plowman (News)
scribeth thus
In article ,
tony sayer wrote:
I can't be certain the Behringer unit is faulty. The amplifiers are
home made, and it could be some interaction I've not fathomed out.



Right!, so the crossover then goes to some home-brew amps if so what
are they and are they bal or unbal inputs?..


Balanced. Using THAT1240 ICs. The whole idea being to avoid ground loop
problems...


They fed by a + volt and a neg volt supply centre tapped or floating do
you know?..


Of course I know. I built them. ;-) +/-15v.


http://www.thatcorp.com/1240-series_...iver_ICs.shtml


--
*Why is the word abbreviation so long? *

Dave Plowman London SW
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