Audio, hi-fi and car audio

Audio Banter (https://www.audiobanter.co.uk/forum.php)

- uk.rec.audio (General Audio and Hi-Fi) (https://www.audiobanter.co.uk/uk-rec-audio-general-audio/)

- - Slam (https://www.audiobanter.co.uk/uk-rec-audio-general-audio/533-slam.html)

In article , Andy Evans
wrote:
I am uncertain about the above for two reasons; 1) That you are
essentially telling us that 'slam' is an 'artificial effect', but then
only tell us what it does *not* mean,

I assume the above is quoted from myself, although the quoting is not
clear...

If it's an artificial effect, does it need to be defined, or indeed can
it be defined?

Well, if you use a word without giving me a definition, how can I know what
you mean by it? If thr word has no definable meaning, can it be expected to
convey any information from the speaker to the listener?

Your description seemed to be equivalent to saying "a koala bear is not a
kangeroo". This may tell me something, but does not really help me to
recognise a koala bear when I see one, nor know what you recognise as one.

If you said a "a koala bear is a small type of bear" this might be of some
use if I am aware of what some other bears look like. This would not be a
precise definition - allowing an unambiguous recognition - but would
perhaps be helpful. Unfortunately, giving an example of what something is
not may not tell me much at all.

2) I still have the feeling that various people are using the term for
*different* things

Agreed

the kind of problem that can arise when magazines, etc, use a term
without giving a clear and unambiguous definition.

Agreed. I don't use the term (and many others) for that reason. I do use
words like 'timbre' which are easier to check between the original
acoustic source and the reproduction of it. I'd welcome the day when
reviewers attempt to define useful terms rather than trying to invent
undefinable terms.

It would also be nice if Martin Colloms were able to give a meaningful
definition of his 'points system' for rating the 'sound' of items. So far
as I can tell, this, along with many other comments in reviews, seem to
mean no more than the reviewer saying "I felt I liked A more than B'. Fine
for him, but perhaps not much use to the rest of us! :-/

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

In article , Wally wrote:
Stimpy wrote:

Sit on the floor in front of a kick drum when someone kicks it hard...
That's slam :-)

A kick drum was exactly what I was thinking while reading John's comments.
You get it in band rehearsal rooms - feel it in the guts.

I guess I get to the wrong type of concert :-)

--
John Phillips

"Kurt Hamster" wrote in message
...
On Wed, 01 Oct 2003 17:04:10 +0100, Don Pearce used
to say...

Handwaving were ne'er so lyrical. Unfortunately we are still no nearer
to a clue as to what Slam is...

Do you know what a slammed door sounds like?

IME just about all doors sound different. Which specific door are you
referring to?

Your description seemed to be equivalent to saying "a koala bear is not a
kangeroo".

More like saying "why should I define what a flying pig is"

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

On Fri, 03 Oct 2003 16:09:47 +0100, Jim Lesurf
wrote:

In article , Stewart Pinkerton
wrote:
On Thu, 02 Oct 2003 19:56:27 +0100, Laurence Payne
wrote:

Any really good amplifier will be able to handle full power
more-or-less continuously - certainly for several minutes - without a
problem.

And wouldn't object to being asked to deliver considerably more if
momentarily demanded? You seem to be arguing against transient
headroom :-)

Anyone who knows anything about amps *does* argue against 'transient
headroom', which is just another word for a cheap power supply.

In that case, I'm afraid I don't know much about amplifiers. :-)

Oh, come now, that can't be true! :-)

My own view/experience is that it can be quite useful in the context of
reproducing musical signals to arrange for the amp/PSU to have a short-term
power ability that is well above the sustained power ability. The reasons
for this in my view are;

1) Most music tends to include relatively brief musical transient events
which reach short-term levels well above the mean level.

Fair comment, *but* 'relatively brief' is generally (a lot) more than
20 milliseconds, so that it's still necessary for the power supply to
be fully recharged by the mains.

2) Allowing the rail voltages to fall under sustained demand helps reduce
the power dissipation in the output devices compared with what you get if
you try to maintain the same rail levels as existed for short-term high
power bursts. This keeps the device tempeatures down, etc, which can be
useful.

That's true, but also leads to bias changes in many amps, meaning that
the sound can have a different character after loud passages. Note
that I'm referring to pretty poor amps here - but then you've pretty
much confined the field to such amps, with your pre-qualification of
extremely saggy power supplies. I take it that we're not dealing with
Class G multi-rail amps here?

The main disadvantages are in my view:

1) The sustained mean power levels measured in a review tend to be
under-reading the actual ability (e.g. the 700 I designed only rated at
200Wpcs 'rms' sic both channels sinewave driven, but could actually
deliver around 300Wpc mean per channel for a tenth of a second or so. (This
is not the peak 'instananeous' transient value, which I'd agree is
misleading.) Thus in terms of actual use the 200Wpc perhaps didn't really
indicate how much the amp could provide with music.

2) You have to ensure the amp does not produce distortion or become upset
in some way when the rails fluctuate. This seems sensible, anyway, to me,
as it avoids things like distortion crosstalk between channels.

I'm interested in the logistics of an amp with such a disparity
between its 'toneburst' and continuous ratings. Was this a PSU
problem, or just thermal dissipation in the output stage?

I should say that for myself, I much prefer a 'stiff' power supply,
with all that means in terms of coping with tough loudspeaker loads.
This may be overkill for many systems, but it gives me confidence that
thew sound of the amp won't change under any conditions of load or
musical dynamics.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

On Sat, 4 Oct 2003 08:33:02 +0100, Chris Morriss
wrote:

In message , Stewart Pinkerton
writes
On 03 Oct 2003 07:08:40 GMT, John Phillips
wrote:

"Slam" is an effect I have never actually felt in the concert hall even
with big bass percussion so it may only be an artificial effect which
occurs in "small" listening rooms. It happens in mine on all kinds
of music. Perhaps it is an effect which gets created at large rock
concerts but I only listen to rock at home.

It is certainly used as reviewer jargon and as a marketing term. The
differences of opinion here belie statements to the effect that it is
a well understood term.

It's commonly associated with a noticeable hump in the bass response
around 60-80 Hz. Check out any dance club, you'll find a fair bit of
EQ in this band, probably combined with speakers which drop off fast
below 50Hz. This gives bass which is commonly described as 'tight' and
'fast', with plenty of 'slam'.

Since a hump in that part of the bass spectrum and a fast roll-off below
that is exactly what I hate (I like well-damped bass that continues
slowly dropping off as the frequency drops. One of the reasons I still
can't agree with you about reflex boxes) then I'll avoid any speakers
that people say have 'Slam'.

It should be noted that whether a speaker is a sealed box or a reflex
design says *nothing* about how well-damped is its bass response.
That's purely a function of system 'Q'. Listen to the bigger ATC
designs for top-class examples of well-damped reflex sytstems which
will thump your chest cavity with ease on loud kick-drum (now that's
what *I* call 'slam'!), but have no lumpiness or 'one note' quality
about their bass response. Since they're flat down to 20-25Hz, how
fast they drop off *below* that frequency is hardly relevant to music
listening.
--

Stewart Pinkerton | Music is Art - Audio is Engineering