Now, don't get all hot about it.
I have a dbx recorder or two here, and one can actually record bandwidth
limited squarewaves at higher levels. The one artefact you tend to see of
cours, is down to the finite time the processor takes to do things. You tend
to get level overshoots and undershoots and an obvious worsening of the
noise performance on louder recordings
I never really understood why everyone went toDolby, it was terrible if the
heads and eq were not exact, and was inherently non linear in an obvious
way. I would imagine if DBX had been adopted more widely, people would have
been a lot happier to have cassettes for home recording.

Brian

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"Phil Allison" wrote in message
...

"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

Brian Gaff wrote:
Now, don't get all hot about it.
I have a dbx recorder or two here, and one can actually record bandwidth
limited squarewaves at higher levels. The one artefact you tend to see of
cours, is down to the finite time the processor takes to do things. You tend
to get level overshoots and undershoots and an obvious worsening of the
noise performance on louder recordings
I never really understood why everyone went to Dolby,

I remember when Dolby B first started appearing on cheaper Japanese cassette
players. It solved the hiss problem by simply slicing off everything above 8k.
Of course these days that wouldn't bother me...unfortunately

"Brian Gaff" wrote

I never really understood why everyone went toDolby,

Well Dolby came first!

it was terrible if the heads and eq were not exact, and was inherently
non linear in an obvious way. I would imagine if DBX had been adopted more
widely,

I never liked DBX, noise modulation was far too apparent for my liking.

people would have been a lot happier to have cassettes for home recording.


I fail to see how cassettes could have been *more* popular for home
recording than they were! People, by and and large were very happy with it.

David.

"Brian is one big long Gaffe"

I have a dbx recorder or two here, and one can actually record bandwidth
limited squarewaves at higher levels.


** So ****ing what ?

**** off - you TOP POSTING

STUPID DAMN TROLL !!!!!!!!



..... Phil

Brian Gaff wrote:
Now, don't get all hot about it.
I have a dbx recorder or two here, and one can actually record
bandwidth limited squarewaves at higher levels. The one artefact you
tend to see of cours, is down to the finite time the processor takes
to do things. You tend to get level overshoots and undershoots and an
obvious worsening of the noise performance on louder recordings
I never really understood why everyone went toDolby, it was terrible
if the heads and eq were not exact, and was inherently non linear in
an obvious way. I would imagine if DBX had been adopted more widely,
people would have been a lot happier to have cassettes for home
recording.

**Actually, dbx is MUCH more difficult to get right than DolbyT.

[Anecdote]

When I went for an interview for my last job (ca. 1975), I was ushered into
the demo room for a major audio equipment importer into Australia. I was
left alone, with the instructions that I could listen to the equipment if I
wished, whilst I waited for the boss. I dutifully selected an LP, placed it
on the turntable, and gradually advanced the volume control, 'till I could
just hear the surface noise on the Marantz 1200b (100 Watts per channel) and
sat down to listen to the Klipsch Corner Horns.

The room exploded. I ran for the volume control and the sales-guy popped his
head into the room and said:

"I see you've found our stash of dbx encoded LPs."

I got the job. I spent 5 years working on the entire dbx range, all the way
from the humble 117 single ended stuff, to the mighty 301 processors. It
rapidly became apparent that dbx encode/decode systems magnify flaws in
recording equipment in a way that DolbyT does not (as much).


--
Trevor Wilson
www.rageaudio.com.au

Well, obviously, in the days I was talking about, digital recording was
still in the domain of the pro, and tended to sound very furry by comparison
to good analogue.

However I remember having a bit of a heated argument about the realism or
otherwise with some test luminary at a Heathrow Hotel show back then.
Pointing out that the dc coupled amp was a complete waste of time as
speakers could not really do constant air pressure unless you lived inside
an infinite baffle enclosure in any case.
I agree crossovers by their design had phase shift, after all they are
basically fillters.

I then got into some heated discussion about doppler with a lowther
enthusiast..

Brian

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"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.


--
Trevor Wilson
www.rageaudio.com.au

"Brian Gaff" wrote in message
m...

Well, obviously, in the days I was talking about, digital recording was
still in the domain of the pro, and tended to sound very furry by
comparison to good analogue.

When was that then?

However I remember having a bit of a heated argument about the realism or
otherwise with some test luminary at a Heathrow Hotel show back then.
Pointing out that the dc coupled amp was a complete waste of time as
speakers could not really do constant air pressure unless you lived
inside an infinite baffle enclosure in any case.

The point of dc coupled amps was never to get dc from the speakers! Anyway
living inside an infinite baffle enclosure would still not make a point to
it as there is an air path through the mouth to the back of the eardrum, so
our ears are not "dc coupled"

The point of dc coupling amplifiers was to reduce LF phase-shifts, thus
increasing LF stability within feedback loops, and to eliminate bulky and
expensive output capacitors.

David.

Brian Gaff wrote:
Well, obviously, in the days I was talking about, digital recording
was still in the domain of the pro, and tended to sound very furry by
comparison to good analogue.

**Huh?


However I remember having a bit of a heated argument about the
realism or otherwise with some test luminary at a Heathrow Hotel
show back then. Pointing out that the dc coupled amp was a complete
waste of time as speakers could not really do constant air pressure
unless you lived inside an infinite baffle enclosure in any case.

**Nonsense. It's all about phase shift.


I agree crossovers by their design had phase shift, after all they are
basically fillters.

I then got into some heated discussion about doppler with a lowther
enthusiast..

**No point. Lowther enthusiasts are either brain damaged or hearing
impaired. Either way, I don't waste my time with them.

Please consider NOT top posting. It is confusing and poor netiquette.




--
Trevor Wilson
www.rageaudio.com.au

On Mon, 11 Jan 2010 14:52:48 +1100, "Trevor Wilson"
wrote:

**Nonsense. It's all about phase shift.

Which of course speakers themselves don't have...

d

Actually, having read your piece, I suppose I should mention some other
things. Some of the edgy sounding amps in the 70s were often due to dodgy
filtering from what I could tell. Pioneer seems to suffer from this
problem.

I once had a Tandberg amp that really seemed able to drive almost anything,
and sounded crisp and nice. Problem was it picked up any RF going and
amplified it.. Not very practical.


Tape, as I said in another response here had problems as it was obviously
impossible to record DC to a tape, so the flat tops were not flat.

You did not cover this aspect, but when folk decided direct coupling was a
nice way to sell amplifiers, they used to show it with square waves of
course. However, in air, you do not get DC, unless you cont the wind as DC,
but I've yet to see any speaker capable of a sustained draft!

So, integration will occur, thus the square wave is an input that cannot be
output in any case.

Brian

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"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

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