On Oct 21, 7:48 am, "Iain Churches" wrote:
"Andre Jute" wrote in message

oups.com...
On Oct 19, 12:11 am, "Iain Churches" wrote:

The noise floor was exceptionally low. Later, a quick
look on the bench revealed the noise floor to be 100µV, so a
SNR of 105dB and at 96W, the THD was only 0.1%

It depends on your outlook whether you view the Velleman K40x0 as that
rare thing, a perfect all-round amp --

It's all opinion. Some opinions are informed by relevant experience
and therefore more valuable. Some opinions are informed by nothing but
street corner gossip or personal animosity and are therefore
worthless.

Oh,. I don't think it is anywhere near that!
I regard it as a good-sounding DIY project, no more.
The fact that the tube sockets are mounted on the PCB
really put me off.

I have a Radford STA 100. So no contest.

And I have a Quad II. No contest, to my mind at least; it depends what
you want to measure and hear. Except that the Quad II doesn't put out
100W. Let's compare apples with apples, not with gilded plums, mmm?

I could compare the Velleman K4000 100W with a bunch of other kits I
have built and used extensively: Arion Adonis PP 5581 20W, Audio
Innovations Classic Stereo 25 PP EL34 25W, Triode Supply Japan Miyabe
300B SEPP 16W, etc, etc, and in no instance would it be comparing
apples with apples, for the good and simple reason that none of them
have 100W. In that the Velleman K40*0 stands alone, and gives the
beginner versatility to use the most grossly insensitive bookshelf
speakers to get real oomph on any music whatsoever. I could have
chosen any of the amps listed, or any of the other kits I have built,
including some I don't list because they have less than 10W, and said
they're fine on some aspect (or even the best) but, while all of them
have served me very well indeed, none of them can be put up against
the Velleman without admitting some handicap in some perfectly common
everyday use for an identifiable group of users.

I might add that my favourite among that lot is the AI, which is a
gentleman's amp, never intrusive; an amp you can play 14 hours every
day and never find fault with. I find the Velleman far too analytical
for my taste but that is because it is so accurate, a characteristic
many value. But, to illustrate once more that all this is relative to
usage and opinion, I play mainly chamber music at low volume;
symphonic or other "big" music played on insensitive speakers
*requires* a big amp. If I were into heavy metal or whatever the
current fave of the loud set is called, I wouldn't touch any of my
favourite amps for chamber music -- they'd all be less than convincing
-- I'd go straight to the Velleman and acoustic overload heaven.

By the way, the Velleman K40*0 is eminently tweakable. On my old
netsite I had an entire big section devoted to altering the factory
spec to make it sound like anything you wanted it to sound like. The
"harshness" Jon Yaeger objects to, for instance, was just a matter of
swapping out a ceramic (! now that's an excess of engineering...) cap
for a film cap; you would of course sacrifice a little of the
excellent noise spec (which was why the designer put it in there) but
might consider the loss worthwhile to gain precisely the sound you
want. I'm amazed that Yaeger doesn't know that.

As for the snobbery of demanding point to point wiring on kits, go
right ahead: you'll be helping to kill the hobby off faster than is
necessary. In my experience eliminating the PCB, or insisting on
sockets mounted to the chassis, just about triples the price of the
kit, and ensures that the successful assembly rate is halved.
(Suppliers who give a completion guarantee, or who provide a
handholding service, keep very good records of these matters! Or you
can read between the lines in the instructions and on the sites of
those who sell PTP kits how fed up they are with seeing time and
profits dribble away in support to eejits who cannot follow simple
instructions.)

If you insist on hardwiring, nothing stops you buying a Velleman K40*0
kit, or any other kit with a chassis, to get the design and all the
parts, and simply drilling the cover to hold sockets for the tubes and
then fitting the components to tag strips you supply. Nor is there any
secret to designing a PCB construction properly for heat management:
either ascertain that the kit has ceramic standoffs for power tubes
and resistors as standard, or add them yourself. I'm really amazed at
discovering DIYers who brag about their craftsmanship, then complain
about an amp because it is designed to be built on a PCB: if you don't
like it, change it!

Iain

For those who need or want a 100W and prefer tubes, the Velleman K40x0
is unique, zero competition that I know about.

I don't see much point in nitpicking commercial amps against
irrelevant self-proclaimed "standards"; the test is whether the thing
works in the hands of owners, and the K40*0 worked fine for a decade
and more in my hands. We've already had a bunch of clowns in this
thread condemning one of the most succesful commercial amps in the
world *without ever seeing one or hearing it*. That sort of street
corner gossip repeated as gospel is what trashes the reputation of
RAT, not putting down the thieves of intellectual rights or netbullies
and netstalkers -- on the contrary, it is toleration and protection of
such people that trashes our reputation.

Andre Jute
Visit Jute on Amps at http://members.lycos.co.uk/fiultra/
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