In article , Huge
wrote:
On 2011-03-05, Dave Plowman (News) wrote:
Oh - building valve equipment is actually more difficult than
transistor stuff.
Maybe, but the magic smoke doesn't escape from valves as easily as it
does from transistors.
Can't say that has been much of a problem in my experience. But I agree
with your point that the problem isn't 'building' as such, but having some
understanding of what you are doing, and knowing how to test, take care,
etc. However if people are essentially just following fairly simple
standardised designs this shouldn't be difficult for either choice of
device type. I suspect the snag is that people see others building simple
valve designs and don't see simple transistor equivalents.
My own experience is that I did start off playing with valves and crystal
sets. For me a pest with valve designs in power amps was the tendency for
the performance to end up depending on the o/p transformer. So unless you
learned how to wind your own and became able to do a better job than the
'usual suppliers' the results ended up being limited by a factor outside
your control.
Of course you could go down the OTL route. But that never really seemed to
me a route that enthiusiasts with no real understanding of electronics
would find easy - unless again simply copying an existing design in all its
details. It also tends to remove the o/p transformer providing some
protection against trashing the valves (and speakers) when something is
wrong. 8-]
What I do find curious is that despite people eagerly making valve amps,
they seem less interested in making, say, valve FM tuners. Despite the
praise some heap on old designs like the troughline. I wonder to what
extent this is simply because you can buy o/p tranformers for power amps,
but I've not seen any suppliers of suitable IF transformers, etc.
So what people can easily make does, to me, seem conditioned by what
components you can find easily in few-off quantities. I've repeatedly
looked in recent years for someone who will sell a small quantity of 'Toko'
LPF blocks. These used to be easy to get a decade or two ago. But not now,
it seems. Of course you can DIY them. But it requires quite careful
selection of the precise LCR values.
Slainte,
Jim
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