Valve amp (preferably DIY) to drive apair of Wharfedale Diamond II's
 

On Thu, 11 Nov 2004 15:25:00 +0000, Jim Lesurf wrote:

Most of this is rather "old hat" I suppose, but here goes anyway:-

snip

Frequency response - bottom end is limited by the volume of the room.

I am not sure why you say the above. I don't know of any research that
would support it as an unqualified statement. Indeed, if the room door is
closed it should be easier to generate sound pressures at LF in a room
than in the open with most forms of LF speaker (e.g. infinite baffle).


Not what I read originally, but this contains similar info:
http://aca.gr/paper23.htm




Output impedence of the amplifier - controlling the speaker damping - is
also inaudible to the majority of listeners unless it is *really* bad.

I am not sure what definitions you are using for phrases like " *really*
bad ". However the problem here is not usually one of "controlling
speaker damping". It is the amplifier o/p impedance and the i/p impedance
of a loudspeaker form a network which introduces a frequency-dependent
attenuation. Thus altering the frequency response.


A new search came up with this, which I find rather interesting. He
analyses the effect of the damping factor at the most critical frequency
- the speaker resonance:
http://www.audioholics.com/techtips/...pingfactor.php



THD is meanongless in the real world. It is a great method of producing
comparisons between amps, but there are so many other factors to be
taken into consideration that, below something like 5%, it is completely
inaudible.

That is not my experience. I have in the past heard distortion levels
below this. And my recollection is that the literature reports audibility
for distortions below 5%


Heavily biased (grin), but applicable to some degree:
http://www.audiocraftersguild.com/Aa...ojan_horse.htm

Sorry, I can't find the reference that I'm sure I saw to 5% THD. Research
appears to show that the minimum detectable THD is in the region of 1% to
3% for the majority of people when listening to music. Test tone THD is
generally detectable at lower levels. Detection still depends on the
harmonic content, frequency and variables like room acoustics though, so
IMHO an untrained listener may well not *notice* 5% THD even if it is
detectable by someone else.

http://www.targetpc.com/hardware/art...s/index2.shtml

Steve bench has some interesting oscillograms showing the same 8.7% THD as
both increasing and decreasing harmonics,but I can't comment on the
audibility of these! :-)

http://members.aol.com/sbench102/thd.html

--
Mick
(no M$ software on here... :-) )
Web: http://www.nascom.info

Valve amp (preferably DIY) to drive apair of Wharfedale Diamond II's
 

In article , John Phillips
wrote:
In article , Jim Lesurf wrote:
... my concerns a

1) That the consumer press at times misleads people and impedes
understanding, and hence may hold back further progress in producing
items that the consumers concerned might prefer in their own terms.

Yes, this is certain. However, this has been the case for the last 25
years at least and pregress is still made quietly behind the scenes.

Yes and no. :-) I agree that progress is often made. However my
impression is that this isn't always the case, and that the magazines are
often diverting attention or causing people to based their views and
judgements upon errors and misunderstandings.

This is less of a problem for 'professional' people who may already have
their own knowldge and access to more reliable sources. But for the
'consumers' or hobby/enthusiasts I fear that some of the nonsense that is
sometimes published may be a significant impedement at times. May cause
their to waste large amounts of their time and money which they might have
found to be better spent in other ways.

I recall abandoning Wireless World and HFNRR as a student in the late
seventies for their increasingly popularist approaches. And as for
Scientific American - can you imagine today being given detailed plans
for your own Zinc/Sulphur-powered rocket or plans for an X-ray machine
capable of photographing the bones of your own hand?

I'm not personally worried by the 'popular' motives. I can quite understand
magazines desiring to be widely and easily read. My concern is when what
they sacrifice is ensuring that what they say is reliable, or even has any
meaning at times! It is one thing to explain a topic clearly and simply. It
is something else to use writers whose knowldge is clearly flawed to write
nonsense that reads as 'cool' and which fosters ignorance or
misunderstandings.

[snip]


2) That I wish to understand the 'why' and 'how' of such matters.
Partly as a matter of personal curiousity. Partly as I'd like to be
able to help those who wish to make 'better' items - including ones
like valve amps for those who prefer them. ...

So would I. However I do not know where to go for this, short of a
subscription to JAES, except places like this where I drop in from time
to time between bouts of business travel to see who's arguing with whom,
and for the occasional nugget of value (value to me, that is).

My personal view is that the writings of a few authors - e.g. Keith Howard
and Barry Fox - for HFN are generally well worth reading. Even if you don't
always agree, they tend to be well thought out and based upon evidence
and/or a decent level of understanding of engineering, etc.

But that the output of many other magazine authors/editors needs treating
with caution at times - irrespective of some of them having established
themselves as 'names'. Can only comment on the UK consumer mags here,
though, as I've not read the USA ones for many years.

A particular dissapointement to me in this context is HFW magazine. I like
the fact that they develop and publish 'kits' for things like valve amps so
people can build things for themselves and enjoy the results. However I
dislike the way this is accompanied by repeated errors in other areas, and
only doing this in limited areas. Thus I would be much happer, for example,
if they also did SS kits, and not be so biassed in their approach.

However I'd agree that - short of joining a group like the AES - getting
more detailed and reliable info can be difficult if you are interested in
understanding these areas in a systematic and 'scientific' manner. The
difficulty is that there *is* good material around, but the
signal/(noise+distortion) ratio in magazines, and on the web, etc is
sometimes lower than might be desired. :-)

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

Valve amp (preferably DIY) to drive apair of Wharfedale Diamond II's
 

In article ,
Kurt Hamster wrote:
It's the total amount of gas consumed that matters - not what the boiler
is doing at any one time. It's true a condensing boiler is slightly more
efficient when running in condensing mode rather than flat out, but this
doesn't make up for keeping the house at the same high temperature 24
hours.

There you go again, making up statements/facts/points to suit your
argument. "High temperature"? Where did I say it was a high temperature,
in fact I recommended turning it down a few degrees. Whether you like it
or not the method I use works.

The same 'high' temperature relative to the outside one? If you really
don't understand what I mean, then just remove the high. Makes no
difference. You're saving fuel by reducing the temperature, and wasting
some by leaving it on 24 hours.

Did you think I was guessing?

Since you do about near everything else, why not this?

I rarely guess about something I care about.

FWIW, this isn't a matter of my opinion. Do some research if my word
isn't good enough. Which I'll expect you'll agree with.

This isn't a matter of my opinion. My gas bills tell me it works. I
choose them over you, natch!

You've made the classic mistake - so common on here - of advocating two
lines of action, reducing the overall temperture while running it 24
hours. And attributing the savings to the wrong one - running it 24 hours.

All so you can 'win' the point. ********, it works. My gas bills are
reducing.

Forgot for a minute you were one of those ******* who need to 'win'
everything and thought you might for once want to impart some sincere
advice. But of course I was mistaken.

Fit a programmable thermostat as I recommended and you'll get even
greater savings.

It would take a long while to recover the costs and I intend moving in
less than a year.

So you automatically think this applies to everyone?

BTW, I have heating for comfort. And I want it at a suitable temperature
for the time of day. I don't want the house as hot at night when I'm in
bed as in the evening when relaxing. And don't want it as hot during the
day when I'm more likely to be performing some active task.

--
*A closed mouth gathers no feet.*

Dave Plowman London SW
To e-mail, change noise into sound.

Valve amp (preferably DIY) to drive apair of Wharfedale Diamond II's
 

On Fri, 12 Nov 2004 09:56:49 +0000 (GMT), Jim Lesurf
wrote:



For that reason, it is a word best used sparingly and with care in this
context.

Slainte,

Jim

But what, exactly, do you mean by "best"?

;-)

d
Pearce Consulting
http://www.pearce.uk.com

Valve amp (preferably DIY) to drive apair of Wharfedale DiamondII's
 

Kurt Hamster wrote:
On Fri, 12 Nov 2004 10:14:44 +0000, Ian Molton used
to say...


Kurt Hamster wrote:


Which have **** all do do with anything as the converse is also true
given the relevant EQ etc etc etc...

What if the valve amps distortion has a non-reversible transfer
function? un-eq-ing distortion is not always possible.

What if, what if, what if...

You want me to make that more concrete?

Ok, you tell me how you would go about un-eq-ing a clipped waveform.

I await your response.

There is no response to your what-if, that's why you asked it. Your what
if didn't relate to the original point, it was just a what-if so you
could save face.

WTF?

I stated that a decent linear system was 'better' because it can be eq'd
to any particular taste.

you then said that "the converse is also true given the relevant EQ etc
etc etc..." (as quoted above).

when I point out the converse is NOT always true, you start obfuscating
and avoiding the issue.

****.

during summer the thing is only used for hot water (and one radiator
which we cant shut off due to stupid design of the system...)

I just leave it on all year round and let the thermostat decide. The
downside to living in a Victorian end terrace :(

What thermostat?

Valve amp (preferably DIY) to drive apair of Wharfedale Diamond II's
 

"Ian Molton" wrote in message

Arny Krueger wrote:
"Ian Molton" wrote in message


How big are the features on a typical mask used in photolithography
then?

At one time they were quite large. In some processes there is no
mask - the pattern is written directly on the wafer.

Interesting. when you say directly, howso? burnt by a laser and etched?

http://www.advantest.co.jp/products/...en-index.shtml


Indeed - but is the mask that fine or is the image focued through a
much bigger mask?

If a mask is used, its far larger than the finished product.

Out of curiostiy, how big?

I've seen masks for one chip that were wall-sized.

However, current technology seems to be smaller:

http://www.photoplotstore.com/pages/photomasks.html

Valve amp (preferably DIY) to drive apair of Wharfedale Diamond II's
 

"Nick Gorham" wrote in message

Tat Chan wrote:


To make a fine distinction, some people go for what they
*perceive* as being more accurate.


sure, but sometimes perception doesn't reflect what is actually
going on.

I am sure you will have studied physics, name me one case where
perception does reflect exactly what is actually going on ?

Consider the many well-known optical and audible illusions.

http://www.photoplotstore.com/pages/photomasks.html

http://www.brl.ntt.co.jp/IllusionFor...y/index-e.html

Valve amp (preferably DIY) to drive apair of Wharfedale Diamond II's
 

"Jim Lesurf" wrote in message
...
In article , Phil North
wrote:

Now if people buying valve gear would just say its because they
*prefer* the sound rather than saying the sound is *better* (how can
it be given SS systems can reproduce it), there would be no problems
:-)

Is it possible to prefer something and not think that it is better at
the same time?

For me, the key point here is that 'better' is a term that is defined in
different ways by different people.



Of course - nothing unusal about that, it happens with half the English
Language. Words like 'fast', 'tall', 'slow', 'wide' etc. have no meaning
until a common standard is accepted. Normally possible with the use of such
a standard ('mph' for example) but often still meaningless in a world that
has come to accept exaggeration and blatant misrepresentation as standard
practice.


Hence unless people first agree upon
the specific definition they are using, employing the word 'better' tends
to lead to arguments at cross-purposes.


That depends on the underlying motives of those who wilfully and routinely
choose to turn the casual use of such words into protracted acrimony.



For that reason, it is a word best used sparingly and with care in this
context.


Even that, however polite and innocent-seeming, is a form of censorship not
acceptable to me and one or two others in here.......

Valve amp (preferably DIY) to drive apair of Wharfedale DiamondII's
 

Arny Krueger wrote:

Interesting. when you say directly, howso? burnt by a laser and etched?

http://www.advantest.co.jp/products/...en-index.shtml

Thanks.

I've seen masks for one chip that were wall-sized.

what was the feature size on the mask ?

However, current technology seems to be smaller:

http://www.photoplotstore.com/pages/photomasks.html

:-)

Valve amp (preferably DIY) to drive apair of Wharfedale Diamond II's
 

"Ian Molton" wrote in message

Arny Krueger wrote:

I've seen masks for one chip that were wall-sized.

what was the feature size on the mask ?

A few times the width of an ordinary drafting pen.

I think that was the point - at the time they were just plotting these out
on standard drafting plotters.