PISS OFF - TV TECH MORON
 

"Keith G" wrote in message
...

"Arfa Daily" wrote


snip phaecal phlood


I actually lost interest in your crass and ridiculous rantings several
posts ago, but since you won't leave it alone, here is the bottom line.
You are not clever. You are not funny. Your wit is about as sharp as a
kangaroo's arse. Do you really not understand that the whole world
reading this thread, is laughing at you ? Lets be clear on this. That's
laughing AT you, not laughing WITH you ...

Your descent into the foul gutter language that always happens when
anyone sees fit to challenge you, merely shows you to be an ignorant
fool, and highlights your dubious heritage.

Now understand this. You can call me, and anyone else on here, anything
you like - I don't care. You don't offend me. I just pity your poor sad
existence. We have a saying over here. It goes " When the hole you're
digging gets so deep that you can't get out on your own - stop ".

And now I really don't have any further interest in you, or anything you
have to say.

And I don't mend televisions.



Swim is a Psychology MA and had to visit loony bins in the course of her
studies. (Handy for a career in IT....??)

She said the first thing they were told was 'not to try and reason with
the loonies'...??? :-)




Oh, I wouldn't call it trying to reason, Keith ...

Arfa

Measuring audio power ...
 

"tony sayer" wrote in message
...
In article , Arfa Daily
writes
Ok, so who knows a bit about measuring audio power ? Setting aside any
furious arguments about peak power, rms power, average power, backpeddling
average peak music power on any given friday in March etc, does an audio
power meter sum the power in both half cycles to arrive at a reading, or
just one.

I guess what I'm asking is half wave reccy ahead of the meter, or full
wave
bridge ?

Arfa



Is this the arfa daily who's a service tech?..


FWIW if its just the output of an audio amp I just use two bloody great
8 ohm resistors on a large heatsink with stout cables to reduce ohmic
losses, and connect that to the amp and use me trusty Fluke bench DMM to
measure the AC power developed when running a sine wave with the Hewlett
Packard distortion analyser keeping note of the distortion level to see
when its going into clip.

Measure that at a few different frequencies and square the AC measured
volts and divide by the 8 'ommes and thats the RMS power.

Sufficient and accurate and IMHO a good indication of what the amp will
develop.....

**Yep. Good enough for day-to-day stuff. I use the following:

http://uk.farnell.com/jsp/endecaSear...=9508180&N=401

A bunch of those nice, aluminium clad, 50 Watt resistors from Farnell.
They're bolted to a chunk of extruded aluminium rectangular tube. There's a
fan on one end and a thermal switch on the other. When it gets hot, the fan
switches on and cools the assembly (and warms the workshop, on these cold
Winter mornings). I have a bloody big old switch, so I can choose 8 Ohms, 4
Ohms or 2 Ohms for testing. Additional to that, but less often used, I have
a 0.1uF and a 2uF cap to switch across the load to test for stability. I
also use, less frequently, a dummy load, like this one:

http://stereophile.com/reference/60/

Mine has impedance minima to around 3 Ohms and there are other differences,
but this one is pretty good. As PA has indicated, such a test shows up many,
otherwise exemplary, amplifiers as being rather bad at operating into real
loudspeakers. All monitored by a 'scope and a wideband millivoltmeter. For a
long time I used a real power meter, using an analogue multiplier IC. It was
nice and convenient.


--
Trevor Wilson
www.rageaudio.com.au



--
Posted via a free Usenet account from http://www.teranews.com

Measuring audio power ...
 

"Trevor Wilson" wrote in message
...

"tony sayer" wrote in message
...
In article , Arfa Daily
writes
Ok, so who knows a bit about measuring audio power ? Setting aside any
furious arguments about peak power, rms power, average power,
backpeddling
average peak music power on any given friday in March etc, does an audio
power meter sum the power in both half cycles to arrive at a reading, or
just one.

I guess what I'm asking is half wave reccy ahead of the meter, or full
wave
bridge ?

Arfa



Is this the arfa daily who's a service tech?..


FWIW if its just the output of an audio amp I just use two bloody great
8 ohm resistors on a large heatsink with stout cables to reduce ohmic
losses, and connect that to the amp and use me trusty Fluke bench DMM to
measure the AC power developed when running a sine wave with the Hewlett
Packard distortion analyser keeping note of the distortion level to see
when its going into clip.

Measure that at a few different frequencies and square the AC measured
volts and divide by the 8 'ommes and thats the RMS power.

Sufficient and accurate and IMHO a good indication of what the amp will
develop.....

**Yep. Good enough for day-to-day stuff. I use the following:

http://uk.farnell.com/jsp/endecaSear...=9508180&N=401

A bunch of those nice, aluminium clad, 50 Watt resistors from Farnell.
They're bolted to a chunk of extruded aluminium rectangular tube. There's
a fan on one end and a thermal switch on the other. When it gets hot, the
fan switches on and cools the assembly (and warms the workshop, on these
cold Winter mornings). I have a bloody big old switch, so I can choose 8
Ohms, 4 Ohms or 2 Ohms for testing. Additional to that, but less often
used, I have a 0.1uF and a 2uF cap to switch across the load to test for
stability. I also use, less frequently, a dummy load, like this one:

http://stereophile.com/reference/60/

Mine has impedance minima to around 3 Ohms and there are other
differences, but this one is pretty good. As PA has indicated, such a test
shows up many, otherwise exemplary, amplifiers as being rather bad at
operating into real loudspeakers. All monitored by a 'scope and a wideband
millivoltmeter. For a long time I used a real power meter, using an
analogue multiplier IC. It was nice and convenient.


--
Trevor Wilson
www.rageaudio.com.au


Hi Trevor

Yep, those are the exact same resistors as I am using, but in the 100 watt
flavour. Heatsink the size of the Titanic with a matching fan bolted to the
end, but mine runs all the time. Has proved very useful for repair of high
power PA amps, where the owner complains of things like " cuts out half way
through the second set ". I can now leave the amp thrashing away into this
load, with the scope hung on the socket I've provided.

Arfa

Measuring audio power ...
 

" Keith the Gutless Pommy Wonder "


Moving on to more serious/interesting* subjects - we're toying with the
idea of a steam train in the garden.


** Gaaawd !!!

Now the pommy audiophool idiot turns out to be toy train freak as well.

Bet he even dresses up in a fake uniform and blows his whistle like mad !!

ROTFLMAO !!




........ Phil

Measuring audio power ...
 

"Arfa Con Man Daily"

TW

as PA has indicated,

**See: http://sound.westhost.com/vi.htm

Sorts out the "serious" ones.



Yep, those are the exact same resistors as I am using, but in the 100 watt
flavour. Heatsink the size of the Titanic with a matching fan bolted to
the end, but mine runs all the time. Has proved very useful for repair of
high power PA amps, where the owner complains of things like " cuts out
half way through the second set ". I can now leave the amp thrashing away
into this load, with the scope hung on the socket I've provided.


** If all you want is to heat up a power amp and see when it shuts down -
no heat generating dummy load is needed.

An air cored, 5 mH inductor load driven at 200 Hz does the job FAST !.

Impedance = 6.3 ohms.

Phase angle = 90 degrees.




........ Phil ;-)

PISS OFF - TV TECH MORON
 

"Arfa Daily" wrote in message
...

"Keith G" wrote in message
...

"Arfa Daily" wrote


snip phaecal phlood


I actually lost interest in your crass and ridiculous rantings several
posts ago, but since you won't leave it alone, here is the bottom line.
You are not clever. You are not funny. Your wit is about as sharp as a
kangaroo's arse. Do you really not understand that the whole world
reading this thread, is laughing at you ? Lets be clear on this. That's
laughing AT you, not laughing WITH you ...

Your descent into the foul gutter language that always happens when
anyone sees fit to challenge you, merely shows you to be an ignorant
fool, and highlights your dubious heritage.

Now understand this. You can call me, and anyone else on here, anything
you like - I don't care. You don't offend me. I just pity your poor sad
existence. We have a saying over here. It goes " When the hole you're
digging gets so deep that you can't get out on your own - stop ".

And now I really don't have any further interest in you, or anything you
have to say.

And I don't mend televisions.



Swim is a Psychology MA and had to visit loony bins in the course of her
studies. (Handy for a career in IT....??)

She said the first thing they were told was 'not to try and reason with
the loonies'...??? :-)




Oh, I wouldn't call it trying to reason, Keith ...


Anything less than 'phuck off' would be too resonable for him, but like I
say elsewhere, he's all over and done with. (Yesterday's big event in
ukra....)

PISS OFF - TV TECH MORON
 

"Keith Gutless Wonder Audiophool ****head "



** YOU are ****ed on this NG - Keith.

**** OFF COCK PULLER !!





........ Phil

Measuring audio power ...
 

I
tp://uk.farnell.com/jsp/endecaSearch/partDetail.jsp?SKU=9508180&N=401

A bunch of those nice, aluminium clad, 50 Watt resistors from Farnell.
They're bolted to a chunk of extruded aluminium rectangular tube. There's
a fan on one end and a thermal switch on the other. When it gets hot, the
fan switches on and cools the assembly (and warms the workshop, on these
cold Winter mornings). I have a bloody big old switch, so I can choose 8
Ohms, 4 Ohms or 2 Ohms for testing. Additional to that, but less often
used, I have a 0.1uF and a 2uF cap to switch across the load to test for
stability. I also use, less frequently, a dummy load, like this one:

http://stereophile.com/reference/60/

Mine has impedance minima to around 3 Ohms and there are other
differences, but this one is pretty good. As PA has indicated, such a test
shows up many, otherwise exemplary, amplifiers as being rather bad at
operating into real loudspeakers. All monitored by a 'scope and a wideband
millivoltmeter. For a long time I used a real power meter, using an
analogue multiplier IC. It was nice and convenient.


--
Trevor Wilson
www.rageaudio.com.au


Hi Trevor

Yep, those are the exact same resistors as I am using, but in the 100 watt
flavour.

Yep same ones he)

Heatsink the size of the Titanic with a matching fan bolted to the
end, but mine runs all the time. Has proved very useful for repair of high
power PA amps, where the owner complains of things like " cuts out half way
through the second set ". I can now leave the amp thrashing away into this
load, with the scope hung on the socket I've provided.

Arfa



--
Tony Sayer

Measuring audio power ...
 

tony sayer wrote:

Thought it was. The above power test was much the same whilst at Neve,
Audix, Audiolab, and SCPD.. AKA the BBC...;-))

You were at Neve too ? When was that ? I was there 1985-88 ( project leader -
custom dept - or 'operations' as it was otherwise known ! )

Graham

Measuring audio power ...
 

Serge Auckland wrote:

I use a Levell millivoltmeter

I truly hate those with a vengeance although I still have one ! They were great
in 1973.

Graham