In article , Nick Gorham
wrote:
Wally wrote:


Does that mean that the specifics of the lay-up aren't too critical?


As far as I know, based on talking to someone who does wind his own,
everything is critical. And until you have built it, you just don't know
how it will work out. The commercial makers have years of experience
behind them, that lets them know with good accuracy what its going to
end up like.

I suspect that the optimum design is a nightmare of 'trade offs' and
'experience'. I'm certainly no expert on power amp audio transformers, but
I think one of the problems is the inter-winding capacitances.

The interleaving helps reduce the shunt capacitance across seen across each
secondary or primary, but tends to increase the link capacitance between
primary and secondary. These all affect the impedance of the transformer at
HF, so can have a serious influence on HF power delivery or amplifier
stability.

I think you can also trade-off 'sectioning' the transformer with
intervleaving. This means effectively using sets of windings that are 'in
series' magnetically on the same core. You also have to worry about things
like heating, risk of flashover at the ends of the windings or through the
insulation, etc, etc.

At the other (frequency) end, of course, you get problems with saturation
non-linearity and finite winding coupling, leakage, etc.

Personally, I was always quite happy to work on SS designs and avoid the
above nightmares. :-)

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

Part, if not most, of the reason a lot of people are wandering back to
valves is because they are getting fed up with the mushy/grey/boring sound
of a lot of the SS equipment that's floating about these days. To buy a
valve amp is not to seek more of the same but to get something which is
totally different and hopefully a lot more satisfying. This may take a while
to grow on you (or indeed it may not), I do hope you'll give it a fair
chance to prove it's worth.....

Oh, I shall, have no fear. It'll be my _baby_!

Also, I had the chance recently to hear Nick Gorham's ****-me-SET!
Whoah, that sounded nice! Quiet, but nice!


Martin
--
M.A.Poyser Tel.: 07967 110890
Manchester, U.K. http://www.fleetie.demon.co.uk

In article , Trevor Wilson
writes

"tony sayer" wrote in message
...
Hole punches for transformers? Like, big square shapes?


No, but nothing to stop you using them for 'starter holes' is there???

Tell you what is useful for odd shaped and even regular shaped holes in
ally is using a router designed for wood use!. I have a cheap trend one
for some 30 quid and some cheap bits for same. There is a very small dia
bit that has lasted very well cutting all manner of shapes in 16 SWG
ally sheet. Even if you waste a few, their quite cheap from the DIY
sheds and do work very well...

**I'd never thought of using a router for aluminium, but, given that I
regularly cut aluminium with my TCT blade compound mitre saw, I guess it
should be OK. I would suggest that some lubricant might be a smart idea
though. Aluminium tends to stick to blades.



Oh yes, I do, squirt a drop of oil on it but it spins so bloody fast I
think the oil doesn't get a chance. I believe your supposed to do it
slower but like drilling in masonry the faster the drill the better it
seems to work. TCT blades do cut ally very well and jigsaws with the
RIGHT blade in them are very good too.

Theres a maintenance works down the road who are due to close before
long. I've got first refusal of their Edward's Trucut guillotine and
bending/folding machine!..

Better start thinking about making a valve amp
--
Tony Sayer

"Glenn Booth" wrote in message
...
In message , Wally
writes
Keith G wrote:

The way I see it, it's a two-stage thing:

1) Get a dot on the screen

2) Get it to move about a bit.....

3) Try and show something useful.

4) Realise you haven't a clue what you're looking at and play with
Lissajous (sp?) figures for a while 'cos it looks cool.

--
Regards,
Glenn Booth


Thats what I like about old Sci-Fi films, the lab usually has a few scopes
dotted around displaying Lissajous figures - essential for world
domination. )

4) Realise you haven't a clue what you're looking at and play with
Lissajous (sp?) figures for a while 'cos it looks cool.

Yes, I used to connect left to X and right to Y and observe!

Can be quite interesting when you "get into it"! Bass especially is mainly
shared so everything seems to be a variation of movement around a line
at 45 degrees, bottom-left to top-right. Sometimes you get a nice
circle or ellipse when some fairly pure tone is out of phase by the
right amount.

How sad was I when I was 16?! Oh well!


Martin
--
M.A.Poyser Tel.: 07967 110890
Manchester, U.K. http://www.fleetie.demon.co.uk

In article , Keith G
wrote:


I see an opportunity here for 'refinishers' - someone to buy Chinese
amps in bulk (it's the delivery charges that bump the prices up) and
swap, say, the OPTs (and possibly power trannies) to enhance their
performance much the same way as a certain Cambridge firm 'rebuilds'
brand new Indian Enfield motorcycles into a much better machine
(rebore/hone, new pistons and electronic ignition for example).

Fark sight quicker to do that and end up with summat that certainly
looks the part than bugger about paying silly UK prices for fancy
fascias and gold knobs......

I have my doubts about how 'quick' the above might be if you actually want
an improvement for the expense and effort. I'd suspect that the electrical
properties of the output transformer of a valve power amp would be an
integral part of the overall design, particularly if there is any feedback
from the secondary or a primary tap. Changing to a 'better' output
transformer might then mean a number of other changes to the design to
ensure stability, etc.

The performance of an amplifier comes from the way all the components work
in conjunction. Just replacing one item with a 'better' one might simply
make the performance worse...

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 , Mike Gilmour
wrote:


Thats what I like about old Sci-Fi films, the lab usually has a few
scopes dotted around displaying Lissajous figures - essential for world
domination. )

I quite like films like "When Worlds Collide" and they cut to "the
computer" and show lots of whirling rods and cams. :-)

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

"Jim Lesurf" wrote in message
...
In article , Keith G
wrote:


I see an opportunity here for 'refinishers' - someone to buy Chinese
amps in bulk (it's the delivery charges that bump the prices up) and
swap, say, the OPTs (and possibly power trannies) to enhance their
performance much the same way as a certain Cambridge firm 'rebuilds'
brand new Indian Enfield motorcycles into a much better machine
(rebore/hone, new pistons and electronic ignition for example).

Fark sight quicker to do that and end up with summat that certainly
looks the part than bugger about paying silly UK prices for fancy
fascias and gold knobs......

I have my doubts about how 'quick' the above might be if you actually want
an improvement for the expense and effort. I'd suspect that the electrical
properties of the output transformer of a valve power amp would be an
integral part of the overall design, particularly if there is any feedback
from the secondary or a primary tap. Changing to a 'better' output
transformer might then mean a number of other changes to the design to
ensure stability, etc.

The performance of an amplifier comes from the way all the components work
in conjunction. Just replacing one item with a 'better' one might simply
make the performance worse...


Indeed, 'upset the balance', as it were. In which case one would need to
reverse the changes or move onto different components, which I guess is
pretty much how valve amplifier designs are finalised anyway.

Part of the appeal of valve kit to some people is that it can be 'tweaked'
in a comparatively easy way, making the amplifier a more significant
contributor to the overall sound characteristics of a 'hi-fi' system. Not
that everybody thinks that is necessarily a good thing - I've been so
pleased with the sound I get using my own kit amp, I've never been tempted
to fiddle with it......

"Jim Lesurf" wrote in message
...
In article , Mike Gilmour
wrote:


Thats what I like about old Sci-Fi films, the lab usually has a few
scopes dotted around displaying Lissajous figures - essential for world
domination. )

I quite like films like "When Worlds Collide" and they cut to "the
computer" and show lots of whirling rods and cams. :-)


....... being operated by a mechanical Olivetti adding machine with the
handle ripped off, like in The Prisoner rerun, a day or two ago!

:-)

Part of the appeal of valve kit to some people is that it can be 'tweaked'
in a comparatively easy way

Which is what I just said.

But apparently I'm ostracised for buying a cheap Chinese (not "Chinky" please)
valve amp.

I'm SO sorry.

No, I'm not.

Jeez, it comes down to something when a guy buys a valve amp and gets
dissed to **** cos it's a cheapie Chinese one cos he can't afford
the proper TdP kit.

Where's Trots these days, anyway?


Martin
--
M.A.Poyser Tel.: 07967 110890
Manchester, U.K. http://www.fleetie.demon.co.uk