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BIG WHOOPS! I wrote that in a rush.If your equipment is designed for balanced operation it's quite
likely the unbalanced connections are an afterthought and the
screen connected to mains ground.
This is common. It is not generally considered poor design.
Don't forget about capacitive coupling between the windings in theAnd assuming it has the normal transformer supplying the DC - I'm not
sure why reversing the mains lead should have any effect - given an
isolating transformer of this type removes any reference from the supply -
even when one leg of the supply is grounded as in the UK.
Who said anything about gain? I said electronics. Usually done with justWell they can't be 'better' since you're introducing extra electronics
to balance and unbalance the signal -- not many devices are balanced
internally.
This is not correct. Changing the circuit from an unbalanced input or
output to a balanced input or output does not add a gain stage.
Makes no difference in principle if both the tuner and amps are separateYou also have a balanced output radio tuner? Record deck? Etc?
The tuner does, but I use the unbalanced outputs. We were talking about
power amplifier connections, anyway.
It is if you want to avoid hum loops. ;-)If your equipment is designed for balanced operation it's quite likely
the unbalanced connections are an afterthought and the screen
connected to mains ground.
This is common. It is not generally considered poor design.
Not much point in using a balanced line if you're going to 'unbalance' itIf your equipment is designed for balanced operation it's quite
likely the unbalanced connections are an afterthought and the
screen connected to mains ground.
This is common. It is not generally considered poor design.
BIG WHOOPS! I wrote that in a rush.
Balanced inputs are commonly converted to unbalanced by grounding one
side -- to the SIGNAL ground (that is, zero volts in an amplifier with a
balanced power supply), NOT the mains ground.
Could be - although I've not come across this in practice. Of course in"Dave Plowman (News)" <dave@davenoise.co.uk> wrote:
And assuming it has the normal transformer supplying the DC - I'm not
sure why reversing the mains lead should have any effect - given an
isolating transformer of this type removes any reference from the
supply - even when one leg of the supply is grounded as in the UK.
Don't forget about capacitive coupling between the windings in the
mains transformer. Depending on transformer geometry, the coupling might
be stronger to one mains lead than to the other. So it is advantageous
to make the stronger coupled one ground.
bang... bang... bang... bang... [sound of William Sommerwerck banging hisWell they can't be 'better' since you're introducing extra electronics
to balance and unbalance the signal -- not many devices are balanced
internally.
This is not correct. Changing the circuit from an unbalanced input
or output to a balanced input or output does not add a gain stage.
Who said anything about gain? I said electronics.
So to you all electronics add gain? Talk about two peoples separated by aWell they can't be 'better' since you're introducing extra
electronics to balance and unbalance the signal -- not many devices
are balanced internally.
This is not correct. Changing the circuit from an unbalanced input
or output to a balanced input or output does not add a gain stage.
Who said anything about gain? I said electronics.
bang... bang... bang... bang... [sound of William Sommerwerck banging his
head against a concrete wall] bang... bang... bang... bang...
bang... bang... bang... bang... [repeated sounds of head banging againstIn article <h0qna0$74s$1@news.eternal-september.org>,
William Sommerwerck <grizzledgeezer@comcast.net> wrote:
You also have a balanced output radio tuner? Record deck? Etc?
The tuner does, but I use the unbalanced outputs. We were talking
about power amplifier connections, anyway.
Makes no difference in principle if both the tuner and amps are separate
from the pre-amp. Unless you feel there is some magic length where
balanced suddenly becomes essential?
[More loud and anguished head-banging from yrs. truly.]Balanced inputs are commonly converted to unbalanced by grounding
one side -- to the SIGNAL ground (that is, zero volts in an amplifier
with a balanced power supply), NOT the mains ground.
Not much point in using a balanced line if you're going to 'unbalance' it
in this way. Use a transformer to do the job properly.
I've already given you chapter and verse which you choose not toBalanced inputs are commonly converted to unbalanced by grounding
one side -- to the SIGNAL ground (that is, zero volts in an amplifier
with a balanced power supply), NOT the mains ground.
Not much point in using a balanced line if you're going to 'unbalance'
it in this way. Use a transformer to do the job properly.
[More loud and anguished head-banging from yrs. truly.]
I "know people". I'm going to find someone who's a legitimate expert on
audio grounding, and try to get some sort of definitive answer.
Almost everything you've said goes against what I believe to be correct --In article <h0r47v$7bi$1@news.eternal-september.org>,
William Sommerwerck <grizzledgeezer@comcast.net> wrote:
Balanced inputs are commonly converted to unbalanced by grounding
one side -- to the SIGNAL ground (that is, zero volts in an amplifier
with a balanced power supply), NOT the mains ground.
Not much point in using a balanced line if you're going to 'unbalance'
it in this way. Use a transformer to do the job properly.
[More loud and anguished head-banging from yrs. truly.]
I "know people". I'm going to find someone who's a legitimate expert
on audio grounding, and try to get some sort of definitive answer.
I've already given you chapter and verse which you choose not to
understand. You could try re-reading it more carefully.
Please quote those parts. If I have given wrong information I'd like toI've already given you chapter and verse which you choose not to
understand. You could try re-reading it more carefully.
Almost everything you've said goes against what I believe to be correct
-- and some of it is unquestionably wrong.
Have you checked your power amps with a DVM set to continuity to see ifI have not had any "Aha!" moments of
sudden clarity.
Well, pretty well all of the advice you've been given suggests checkingI've already asked two people for advice. I'm going to do some more
research on this, and eventually get back to the group. Case closed, for
the time being.
I dunno US electrics, but can't see why that would matter. As far as
audio - or video - is concerned there should be only one ground. And
that doesn't really matter what mains circuit things are fed from as
there will be an isolating transformer between it and the DC. Unless
it's some crappy design where it has to be grounded for safety reasons.
Do you routinely have different phases running audio equipment in the sameThe Apollo 11 landing was almost aborted by such an issue.
The LM guidance computer was fielding all kinds of high priority data
from the landing radar and control inputs. It was also, unbeknownst to
the crew, also looking at the rendezvous radar as well. [This so an
immediate Abort to Orbit could be accomplished; if the landing was
abandoned.]
If the 2nd radar saw nothing, great, no data. BUT as it happens, it ran
off a different phase of the LM power system, and the little big of
noise between it and the landing radar was enough to be noticed. As a
result, the computer started spitting out 1201 alarms, which was palnned
for & acceptable, but disconcerting to everyone involved.
I'm not quite ready to put everything on one circuit. So I'm going to
call both Parasound and Pioneer to see what insights, if any, they have
to offer.
I dunno US electrics, but can't see why that would matter. As far as audio
- or video - is concerned there should be only one ground. And that
doesn't really matter what mains circuit things are fed from as there will
be an isolating transformer between it and the DC. Unless it's some crappy
design where it has to be grounded for safety reasons.
No, but you can have 180 degree in phase situatuionIn article <h0rc0r$8vr$1@reader1.panix.com>,
David Lesher <wb8foz@panix.com> wrote:
I dunno US electrics, but can't see why that would matter. As far as
audio - or video - is concerned there should be only one ground. And
that doesn't really matter what mains circuit things are fed from as
there will be an isolating transformer between it and the DC. Unless
it's some crappy design where it has to be grounded for safety reasons.
The Apollo 11 landing was almost aborted by such an issue.
The LM guidance computer was fielding all kinds of high priority data
from the landing radar and control inputs. It was also, unbeknownst to
the crew, also looking at the rendezvous radar as well. [This so an
immediate Abort to Orbit could be accomplished; if the landing was
abandoned.]
If the 2nd radar saw nothing, great, no data. BUT as it happens, it ran
off a different phase of the LM power system, and the little big of
noise between it and the landing radar was enough to be noticed. As a
result, the computer started spitting out 1201 alarms, which was palnned
for & acceptable, but disconcerting to everyone involved.
Do you routinely have different phases running audio equipment in the same
room in a house in the US? This smacks to me of bad practice and isn't
allowed in the UK. Nor would it happen in a pro audio installation in say
a TV etc studio - all the relevant equipment would be on the same phase -
leaving the others for power hungry devices like air con and lighting.
Of course a power hungry large computer system might well be different -
but the pitfalls of this are surely well known?
Really, if you feed two equipment from a separateIn article <5069d9c439dave@davenoise.co.uk>, "Dave Plowman (News)"
dave@davenoise.co.uk> wrote:
In article <h0rc0r$8vr$1@reader1.panix.com>,
David Lesher <wb8foz@panix.com> wrote:
I dunno US electrics, but can't see why that would matter. As far as
audio - or video - is concerned there should be only one ground. And
that doesn't really matter what mains circuit things are fed from as
there will be an isolating transformer between it and the DC. Unless
it's some crappy design where it has to be grounded for safety reasons.
The Apollo 11 landing was almost aborted by such an issue.
The LM guidance computer was fielding all kinds of high priority data
from the landing radar and control inputs. It was also, unbeknownst to
the crew, also looking at the rendezvous radar as well. [This so an
immediate Abort to Orbit could be accomplished; if the landing was
abandoned.]
If the 2nd radar saw nothing, great, no data. BUT as it happens, it ran
off a different phase of the LM power system, and the little big of
noise between it and the landing radar was enough to be noticed. As a
result, the computer started spitting out 1201 alarms, which was palnned
for & acceptable, but disconcerting to everyone involved.
Do you routinely have different phases running audio equipment in the same
room in a house in the US? This smacks to me of bad practice and isn't
allowed in the UK. Nor would it happen in a pro audio installation in say
a TV etc studio - all the relevant equipment would be on the same phase -
leaving the others for power hungry devices like air con and lighting.
Of course a power hungry large computer system might well be different -
but the pitfalls of this are surely well known?
No, but you can have 180 degree in phase situatuion
between the split 240 transformer, and have 240 volts potential going
to the audio setup. I always like to use only
one leg of the transformer split out on the pole or one breaker. In my opinion
there is a chance of more problems using both sides of the transformer
allthough some audio installations use a split transformer to
reduce posible noise. So its all in how you look at it.
Not different as in 3 phase but split phase. It is very common to haveDo you routinely have different phases running audio equipment in
the same
room in a house in the US? This smacks to me of bad practice and
isn't
allowed in the UK. Nor would it happen in a pro audio installation
in say
a TV etc studio - all the relevant equipment would be on the same
phase -
leaving the others for power hungry devices like air con and
lighting.
Of course a power hungry large computer system might well be
different -
but the pitfalls of this are surely well known?
--
*The modem is the message *
Dave Plowman d...@davenoise.co.uk London SW
To e-mail, change noise into sound.
I don't know of any modern piece of equipment that ties the neutral to theOn Jun 11, 11:10 am, "Dave Plowman (News)" <d...@davenoise.co.uk
wrote:
Do you routinely have different phases running audio equipment in the
same room in a house in the US? This smacks to me of bad practice and
isn't allowed in the UK. Nor would it happen in a pro audio
installation in say a TV etc studio - all the relevant equipment would
be on the same phase - leaving the others for power hungry devices
like air con and lighting.
Of course a power hungry large computer system might well be
different -
but the pitfalls of this are surely well known?
Not different as in 3 phase but split phase. It is very common to have
240 Volt service into the house from a center tapped transformer. The
high power devices like ovens, A/C, water heaters, clothes dryers get
the full 240 volts fromt the 2 outer feeds. The rest of the house gets
the center tap 'neutral' and one of the 2 outer feeds via a circuit
breaker. Because the loads may not be balanced across 2 'phases', the
neutral will not be the same between various outlets.There is your
'ground loop' when you plug in devices that tie the neutral to the
chassis.
In most town situations, one transformer covers a large area - but that isNow tell me how the mains wiring is done in a typical UK residence. Do
you get 480 center tapped? My guess is 'no' but I have no certainty.
Do you get just 2 wires from the transformer. Is one end of the 240V
feed tied to earth? Does that earth lead build up voltage drops in the
building giving you essentially the same problem we have in the US ?
--
If there are indeed three phases, would not the phase toIn article
0110bd8a-c72d-4a02-8f6a-5a1e1aa883d1@i6g2000yqj.googlegroups.com>,
stratus46@yahoo.com> wrote:
On Jun 11, 11:10 am, "Dave Plowman (News)"
d...@davenoise.co.uk
Now tell me how the mains wiring is done in a typical UK
residence. Do
you get 480 center tapped? My guess is 'no' but I have no
certainty.
Do you get just 2 wires from the transformer. Is one end
of the 240V
feed tied to earth? Does that earth lead build up voltage
drops in the
building giving you essentially the same problem we have
in the US ?
In most town situations, one transformer covers a large
area - but that is
to step down the high distribution voltage to the 240
volts. This produces
three phases - all 240v - and neutral is ground. Between
phases you get
440 volts. This three phase plus neutral (ground) is fed
along the street,
and only one phase (usually 100 amp max) is fed to a
house. Alternate
phases are use to other houses to balance the load. A very
large house may
have a second phase - but electric heating isn't common in
the UK due to
cost so up to 100 amps (25kW) is more than enough for
most.
(snip)
Dave Plowman dave@davenoise.co.uk
London SW
To e-mail, change noise into sound.