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

In article , Stewart
Pinkerton wrote:
On Fri, 19 Nov 2004 09:30:57 +1100, Tat Chan
wrote:
and rich Asians (oh, all right, since this is a UK newsgroup, I meant
Orientals) ... apparently Hong Kong has an unbelievable number of Rolex
dealers for a place that small. Perhaps the worlds largest ratio of
square kilometres to Rolex dealers?

True, I'd forgotten good old Nathan Street! :-)

The last time I walked down Nathan Street (8 years ago) the overt fake
vendors probably outnumbered the genuine ones. Periodically I got
accosted by the ambulatory street vendors with the question "copywatch?"

The "Crocodile" shops (blue signage, mirror image croc.) sat happily
next to the "Lacoste" shops (green signage, standard croc.).

I ate in a restaurant on Lantau Island called "the Hilton" (no connection,
you understand).

I also remember the medical shops in Nathan Street whose windows displayed
jars containing items a wise man would not enquire about.

--
John Phillips

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

On Thu, 18 Nov 2004 18:51:40 +0000, Keith G wrote:

snip

But the competition is extremely hot for all electronics made outside
asian
sweat shops.


That's something I'm wondering about - I suppose the new wave of cheap
Chinese amps just *has* to be made in sweatshops. Still beter to buy them
than not I suspect.....

snip

I'm not so sure. From the photos they appear to be much better built than
I personally would associate with sweatshop work. There is obviously a lot
*more* work going into them than super-cheap labourers usually do - even
if there is an occasional rattling screw! No sign of pcbs held in by
soft self-tappers into plastic pillars, even though that could
probably be done in a valve amp by fitting a preformed plastic plate
under the chassis. It is quite possible that we are seeing an "economies
of scale" if these things are selling fast enough within China itself. If
all the different-appearing versions just happen to use the same
transformer set it would give a clue!

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

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

It is quite possible that we are seeing an "economies of scale" if these things
are selling fast enough within China itself.

Interesting point - I wonder how well they sell internally. And I wonder what
the motivation is to buy them inside China - the sound, or the 'retro' look and
style becoming a new chic (as it has in those parts)? If it's the sound, the
sales should endure. If it's the retro-chic, it may be a passing fancy and in
time may go.

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

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

In article , Patrick Turner
wrote:


Jim Lesurf wrote:



I would also point out that some/many(?) of the waveforms produced by
musical instruments are asymmetric and have a high peak/rms crest
factor even with sustained waveforms (see one of my websites for
examples). This means that how the nonlinearity varies with signal
level may be quite important, and a single sinewave THD value does not
indicate this.

Its IMD that you speak of.

Well, I would avoid calling it IMD as it might be misleading. I would
say the effect I am trying to describe is the way the distortion level
changes with the signal level. In particular, how it may start to rise
abruptly above a given signal level. Hence the implications for musical
waveforms which have high peak/rms factors and/or are asymmetric.

Old radios have a real "valve sound", and often not a happy one, if the
output tube is a pentode, so its current drive, and often not a stitch
of NFB, and so its 4% thd evem listening to the cricket.

The HF reception of AM is so bad, those sets need every bit of thd they
can muster to replace the real HF content of the programme, hence those
radios swindled your ears from what you should be hearing.

I'd personally prefer *not* to use distortion to 'substitute' for what has
been removed. That said, I don't really listen to AM.



I must say I have not witnessed much 7h in anything I have tested,
unless the level was taken to the brink of clipping, when by that
time the the mix of harmonics has mushroomed, as opposed to am amp
working at 1/10 of its maximum power, where the mix of harmonic
products is less complex, and also the imd mix is less complex.

My experience (mostly with SS amps) is similar. Indeed, my experience
even 20+ years ago was that this was often less of a problem than many
people assumed.

Perhaps the dynamic IMD action going on in what are essentially class B
amps is the main reason for concern with SS.

Most of the amps I've use or designed have been AB, not B. In most cases
I'm aware of the distortion tends to rise slowly with level.[1] The problem,
though, is that most magazine reviews and tests do not really illuminate
this area at all well.

[1] Until clipping.

The crossover distortion is one thing, it may not be serious, and the
IMD another.

But Bryston manage to do OK; they use both pnp and npn each side of the
rail, so the turn on turn off transfer curve is identical, so their
design inherently addresses the wide current gain differences between p
amd n devices. Most amps have p and n devices in the output stage, and
the differences are equivalent to using a 6L6 and an EL34 in the same PP
tube amp circuit.

FWIW when desiging amps about 20 years ago I did not find this to be a
problem, so I'd be surprised to find that it is nowdays. My memory may
be unreliable, but I think it used to be possible to buy complimentary
devices in gain matched band batches. Although I don't really recall
this area being a problem.

Can't comment on your saying it is "equivalent" to the valve situation
you mention as there seem to be a number of implied differences to
me, but I don't know enough about the 'valve' side of what you are
trying to compare.


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 , Don Pearce
wrote:
On Thu, 18 Nov 2004 09:04:38 +0000 (GMT), Jim Lesurf
wrote:


I am not quite sure how:

A) multiple field emitters, polotrons, and various other vacuum-state
devices.

B) high mobility / ballistic or quantum well/dot or multiple barried SS
devices.

fit into the above picture. My understanding is that they have been
developed during the last couple of decades, and in some cases required
new understanding of the relevant physics and/or novel fabrication
methods.

Don't know if any of them have been used in audio, though. :-)

I think that last sentence sums up the position of valves in the
mainstream. And are your B) devices products of valve research or solid
state research?

Vaguely speaking, A = valves, B = solid state.

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
 

"Dave Plowman (News)" wrote in message
...
In article ,
Mike Gilmour wrote:
My Avo valve characteristic meter MkII is as old as the hills so not
much to boast about..as it came in on a Zimmer frame ;-)..... but it
does work very well if calibrated from time to time..and I picked it up
for next to nothing.

You're lucky. Have you seen what they go for on Ebay?

--
*Thank you. We're all refreshed and challenged by your unique point of
view

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

Nope..ball park how much?

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

"Andy Evans" wrote in message
...
it does work very well if calibrated from time to time..and I picked it up
for
next to nothing.

You're lucky. Have you seen what they go for on Ebay?

who calibrates it? I got an AVO4 on ebay - haven't switched it on yet.

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

Comprehensive calibration instructions included in the technical manual and
its straightforward, especially with todays test gear :-)

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

"mick" wrote

That's something I'm wondering about - I suppose the new wave of cheap
Chinese amps just *has* to be made in sweatshops. Still beter to buy them
than not I suspect.....

snip

I'm not so sure. From the photos they appear to be much better built than
I personally would associate with sweatshop work. There is obviously a lot
*more* work going into them than super-cheap labourers usually do - even
if there is an occasional rattling screw!


The curious thing is that all the other screws holding the trannie housing
on had a blob of red 'inspectors' paint on them - see two of them just
clipping the edge of the circuit board in this pic:

http://www.apah69.dsl.pipex.com/keit...econdamp14.JPG

None of them were 'overtight' by any means. Note the proliferation of reb
blobs over most of the solder joints and all the other fixings! - It's not
as though someone hasn't been over them, but does smack a little of 'going
through the motions' QC-wise...


No sign of pcbs held in by
soft self-tappers into plastic pillars, even though that could
probably be done in a valve amp by fitting a preformed plastic plate
under the chassis.


Hmm, didn't get that far in this time round. Take it that it all feels firm
enough - I gave everything a good poke and prod!


It is quite possible that we are seeing an "economies
of scale" if these things are selling fast enough within China itself. If
all the different-appearing versions just happen to use the same
transformer set it would give a clue!


Somehow, based on absolutely bugger-all (?), I seem to have good instincts
when it comes to this sort of thing. When these amps came up on eBay there
was summat 'plain and simple' + 'ludicrousVFM' about them which is what
tempted me to give one a go. I was already pretty confident, having seen
that Fleetie's amp seemed to be the biz and has got some nice touches
construction-wise.

When the amp arrived it presented no surprises whatsoever - appeared to be
exactly what it said on the 'eBay box'. The worst I expected that might have
to be done would be to push a set of decent trannies into it and replace the
odd resistor if and when they burn out. But, I hafta say, there's no
indication the (agricultural-looking) trannies aren't up to the job - the
amps sound nice and the slam and bass (into a pair of DM2As that I spank
mercilessly) is well up to snuff. (I have an Atomic Kitten MP3 that starts
with a hell of a bang and has had one or two listeners literally jumping
with surprise with the volume at the 11 o' clock mark!! :-)

As to the rest of the components, all I can say is 'so far, so good??' - I
ran the first amp for 15 hours solid, straight out of the box and it it
didn't falter. Since then it goes on and stays on all day long doing
radio/MP3/CD work and doesn't bat an eyelid!

Build quality is a tad better than 'home grown' (to be entirely honest,
dammit :-) with some nice cable-tidying touches and is generally equal to
the Arion Acoustics I had a while back. The PCB tracks are especially nice -
good and wide.

What more can you do? :-)

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

"Andy Evans" wrote in message
...
It is quite possible that we are seeing an "economies of scale" if these
things
are selling fast enough within China itself.

Interesting point - I wonder how well they sell internally. And I wonder
what
the motivation is to buy them inside China - the sound, or the 'retro'
look and
style becoming a new chic (as it has in those parts)? If it's the sound,
the
sales should endure. If it's the retro-chic, it may be a passing fancy and
in
time may go.



Reading the comix gives me the impression that the Chinese home market (big
on AV and buying Yamaha kit by the boatload, apparently) likes 'valves with
everything' when it comes to audio gear....???? :-)


Two screen captures from 'Infernal Affairs' (a Kung Foo movie??):

http://www.apah69.dsl.pipex.com/keit...laffairs01.jpg

http://www.apah69.dsl.pipex.com/keit...laffairs02.jpg


(Says it all really!! ;-)

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

In article ,
Mike Gilmour wrote:
You're lucky. Have you seen what they go for on Ebay?

Nope..ball park how much?

200 quid plus.
More for one in good condition with manuals etc. Much more if as new and
with current calibration certificate.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&category=1502&item=57330374 57

--
*If a turtle doesn't have a shell, is he homeless or naked?

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