Hi,

I've just put up a new web page at

http://www.audiomisc.co.uk/HFN/Squar...quareDeal.html

that looks at the use of squarewaves for assessing amplifiers, etc.

Prompted to do this by noticing squarewave results being used to present
ideas about speaker cables, and realising that the humble squarewave has
largely fallen into disuse.

I've also tweaked the site a bit, and hope to make a few other minor
improvements and alterations soon.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

We used to use squarewaves for the following.
To show how bad tape machines were...
To show the tone control effects

However, you need to look at the harmonics on a true square wave, which of
course cannot actually exist.

grin

Brian

--
Brian Gaff -
Note:- In order to reduce spam, any email without 'Brian Gaff'
in the display name may be lost.
Blind user, so no pictures please!
"Jim Lesurf" wrote in message
...
Hi,

I've just put up a new web page at

http://www.audiomisc.co.uk/HFN/Squar...quareDeal.html

that looks at the use of squarewaves for assessing amplifiers, etc.

Prompted to do this by noticing squarewave results being used to present
ideas about speaker cables, and realising that the humble squarewave has
largely fallen into disuse.

I've also tweaked the site a bit, and hope to make a few other minor
improvements and alterations soon.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics
http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

In article ,
Brian Gaff wrote:
We used to use squarewaves for the following.
To show how bad tape machines were...
To show the tone control effects

You can also use them to show up the lousy phase response of most
loudspeakers. :-) Although by the same token they also show the Quad ESLs
are rather good in this respect.

However, you need to look at the harmonics on a true square wave,

Not sure which purpose you have in mind. You can of course use either time
domain or frequency domain depending on what your specific purpose may
"need".

which of course cannot actually exist.

Yes, that is something I point out on the webpage, and explore the
practical implications. One being that tests with bench waveform generators
may give different results to normal domestic audio sources. :-)

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

"Brian Gaff" wrote in message
om...
We used to use squarewaves for the following.
To show how bad tape machines were...
To show the tone control effects

However, you need to look at the harmonics on a true square wave, which of
course cannot actually exist.

**If you REALLY want to laugh, look at a 7kHz square wave from a CD player
(even 5kHz is barely passable from most CD players). A good R-R or high end
vinyl playback can do a MUCH better job.


--
Trevor Wilson
www.rageaudio.com.au

"Trevor Wilson" wrote in message
...

"Brian Gaff" wrote in message
om...
We used to use squarewaves for the following.
To show how bad tape machines were...
To show the tone control effects

However, you need to look at the harmonics on a true square wave, which
of course cannot actually exist.

**If you REALLY want to laugh, look at a 7kHz square wave from a CD player
(even 5kHz is barely passable from most CD players). A good R-R or high
end vinyl playback can do a MUCH better job.

Bull****

David.

David Looser wrote:
"Trevor Wilson" wrote in message
...

"Brian Gaff" wrote in message
om...
We used to use squarewaves for the following.
To show how bad tape machines were...
To show the tone control effects

However, you need to look at the harmonics on a true square wave,
which of course cannot actually exist.

**If you REALLY want to laugh, look at a 7kHz square wave from a CD
player (even 5kHz is barely passable from most CD players). A good
R-R or high end vinyl playback can do a MUCH better job.

Bull****

**Red Book CD tops out at 22.05kHz. A decent RR can easily top 30kHz. A top
of the line vinyl rig can easily manage 60kHz. Do the math.


--
Trevor Wilson
www.rageaudio.com.au

"Trevor Wilson" wrote


**Red Book CD tops out at 22.05kHz. A decent RR can easily top 30kHz. A
top of the line vinyl rig can easily manage 60kHz. Do the math.


And what do your ears top-out at?

David.

"Trevor Wilson" wrote in message

David Looser wrote:
"Trevor Wilson" wrote in
message ...

"Brian Gaff" wrote in message
om...
We used to use squarewaves for the following.
To show how bad tape machines were...
To show the tone control effects

However, you need to look at the harmonics on a true
square wave, which of course cannot actually exist.

**If you REALLY want to laugh, look at a 7kHz square
wave from a CD player (even 5kHz is barely passable
from most CD players). A good R-R or high end vinyl
playback can do a MUCH better job.

Bull****

Agreed.

**Red Book CD tops out at 22.05kHz. A decent RR can
easily top 30kHz. A top of the line vinyl rig can easily
manage 60kHz. Do the math.

The math includes the phase response. If a system is linear phase or minumum
phase then there is a mathematical relationship between amplitude and phase.
In the general case, there is no such necessary relationship.

Modern D/A and A/D converters are generally generally based on phase linear
filters.

Both LP and analog tape playback is far from being either minimum phase or
linear phase because of their transfer function is based on both minimum
phase and non-minimum phase filtering. The minimum phase elements are
electronic, and the non-minimum phase elements are based on the fact that
they both involve moving media with mechanical and/or magnetic wavelength
effects.

Bottom line, it is not uncommon to have wide bandwidth, but with many
unpredictable phase changes. Well the phase changes are unpredictable until
you understand more details about how they work.

In general analog tape machines have far poorer square wave response than
their actual frequency response predicts because of wavelength effects
related to the head gaps.

This argument is exactly why square waves are no good unless you are trying
to track something specific down, for example a psu running out of steam
and going hummy on high powers into a reactive load.

Brian

--
Brian Gaff -
Note:- In order to reduce spam, any email without 'Brian Gaff'
in the display name may be lost.
Blind user, so no pictures please!
"David Looser" wrote in message
...
"Trevor Wilson" wrote in message
...

"Brian Gaff" wrote in message
om...
We used to use squarewaves for the following.
To show how bad tape machines were...
To show the tone control effects

However, you need to look at the harmonics on a true square wave, which
of course cannot actually exist.

**If you REALLY want to laugh, look at a 7kHz square wave from a CD
player (even 5kHz is barely passable from most CD players). A good R-R or
high end vinyl playback can do a MUCH better job.

Bull****

David.

"Trevor Wilson"

**If you REALLY want to laugh, look at a 7kHz square wave from a CD player
(even 5kHz is barely passable from most CD players). A good R-R or high
end vinyl playback can do a MUCH better job.


** Square waves output from a CD player (with a suitable test disk) are near
perfect examples of audio band limited square waves. The amplitude and
frequency are steady as a rock, harmonic phase relationships are near
perfect, channel matching is perfect and only inaudible harmonics are
missing.

OTOH, the square wave performance of typical hi-fi R-R and cassette decks is
utterly woeful. Amplitude is modulated all over the place, there is wow and
flutter, channel matching is woeful, there is obvious tape noise, harmonic
phase relationships are all out of wack, there is obvious ringing and still
the inaudible harmonics are missing.

In the cases of both LP and cassette, it is only possible to record a square
wave with low amplitude ( ie -20 dB or so) with any hope of just getting the
available bandwidth.

With CD, it makes no difference - full level ( ie 0dB) square waves are
routine.

TW is bereft of even a single clue.



..... Phil