And another one!
 

"David Looser" wrote in message
...
"Iain Churches" wrote in message
...


Whilst PCBs were widely used for mass-produced valve equipment, especially
TVs, in the 1960s they were not without problems. The heat conducted
through
the valve pins, or through the lead-outs of high-wattage resistors, caused
localised over-heating and charring of the (invariably SRBP) board. This
lead to the need to use things such as long-pinned valveholders which are
likely no longer available.

Makers of quality valve amps these days, bolt the
board with standoffs to a metal plate of the same
size to which the valve bases are mounted, so that
the heat is dissipated via the plate and into the chassis
and not the board.

Iain

And another one!
 

"Dave Plowman (News)" wrote in message
...
In article ,
Keith G wrote:
As I said, doing the layout manually is part of the fun. PC board
design programmes not. And I have my own equipment for producing them.
Not a 'room' though. Sounds like you've never actually made such a
thing. ;-)


Sounds like you are calling Iain a *liar* with almost every response you
make to his posts without actually using the word...??

You feel that too?

Not surprising given how much he contradicts himself.

Retirement doesn't suit you, Dave. Your comprehension
skills are deteriorating fast. Get out of that rocking chair,
and build yourself a valve amp, there is no better therapy.
I am sure we could organise a wip round to get you a
turntable. It could be the start of a new life:-)


Iain

And another one!
 

"Dave Plowman (News)" wrote in message
...
In article ,
Iain Churches wrote:
Making your own PCBs is part of the fun. And doing the layout manually
- not computer generated. That you think the only option is vero board
says you've not done much one off construction.

I have a PC board design programme and access to a
UV box/etching room.

As I said, doing the layout manually is part of the fun.

Depends on your idea of fun:-)

PC board design programmes not.

The software can pick up errors, and design you a good
board, double or multi layer if required, in a much more
efficient manner.

It can also produce the masks or whatever it is you
call them in English and of course perhaps the greatest
advantage of all over hand design is that the programme
can export the the code for the CNC drilling machine..

Do you use transparencies, black tape, and
drill with a pin vice?

And I have my own equipment for producing them.

Good for you, sunshine:-)

Iain

And another one!
 

"Keith G" wrote

Sharp? in what sense?


The PJ lamp is burning, I've no time to get into an 'in depth' here -
sharp in the most obvious sense that a normal person would understand.

Not a very useful answer! I no more know what *you* think a "normal" person
means by it than I know what you think it does. I know what *I* think the
word means when applied to a person, but you keep saying "don't guess - ask"
so I asked. Since you applied the word to yourself I guess it's not the
meaning I had in mind.


Yes, yes, yes - all that is obvious and easy to blow out the window by
setting a careful inviation to listen.

On the contrary, it's near impossible to "blow that out of the window". You
either didn't understand what I said, or have simply chosen to ignore it.


See above about how my friends would tell me to take a hike if I tried to
treat them in the patronising manner you describe!


I'm not expecting you to do so, I'm simply pointing out that your friends
comments don't tell us anything useful about the quality of your
loudspeakers.


Well yours are nothing to write home about, not if your posting style
here
is anything to go by.....


Said it a million times already (where were you - in the toilets?) - I pay
back in the coin I am paid in. ;-)

Since you were already posting in that style when I joined this group I
doubt that ;-)

David.

And another one!
 

"Keith G" wrote in message
...


I think the highest reading I have had on my meter was 525 volts - it's
funny how quiet and slow everything goes while you are holding the probe!
:-)


Morning Keith,

That's a serious voltage!

I have a Solartron (valve) bench psu that can manage
600VDC at 500mA. People get used to the routine
of working with valves - switching off the DC from
the bench PSU, and switching on the discharge box
wired across the reservoir caps of the amp becomes
second nature.

An open valve amp chassis commands a lot of respect:-)


Iain

And another one!
 

In article , Iain Churches
wrote:

"Jim Lesurf" wrote in message
...
In article , Iain Churches
wrote:

"Dave Plowman (News)" wrote in message
...

Oh - building valve equipment is actually more difficult than
transistor stuff.

But building with valves is a lot more fun:-) I've done plenty of
both over the years.

I have also done both.[1] But have much preferred designing and
building 'transistor stuff'.

I can understand that - each to his own:-)

Indeed.

Maybe this is because I prefer to develop my own designs in my own
ways.

You can do that with valves too, and even modify the performance in a
subtle way by substituting a Mullard for say a Westinghouse valve. They
do sound different.

The problem is that your "and even" isn't the same thing as genuinely doing
you own design.

Not feel pushed into doing something based on an old design and aimed
at what I can get o/p transformers for.

You can get OPTs for anything and everything valve related. Sowter,
Hammond, Welter and many others have a huge selection, and will also
custom design/build at no extra cost.

How much do they charge for opts that deliver 200w 10Hz-100kHz into 8 Ohms
at TDH well below 0.1%, and 400w ditto into 4 Ohms wilst giving you an
across the band output impedance below 0.1 Ohm? Response flat to 0.2dB
20Hz to 20kHz with low-order falls outwith that. Oh, and at least 30A peak
with no limiting on continuous sinewave into loads below 4 Ohms. With, of
course, no need to have freedback from the secondary, and all from the same
output - i.e. no taps to meet the specs for different impedance loads.?

I appreciate that for a cost, etc, almost anything might be built. I've
been involved in using some quite impressive HV transformers - just not for
audio. :-)

But the problem I was referring to is that I doubt most home DIY people
would ever think of asking for designs like those that are way out of the
usual run for valve audio amps. Most DIY makers will simply either choose
an established design and transformers - then do as you mention and fiddle
with the choice of valves. Or will come up with a design that stays within
a limited envelope of performance.

There is nothing inherently 'wrong' in that. But as I said, it does seem to
be conditioned by what they have already seen made and used. It can also
mean a lot of cost for a transformer you can simply take out of the design
if you use transistors instead. Significant if you are seriously developing
a new design as you then probably would keep wanting a 'slightly different'
transformer as you changed the design. Fortunately not a problem if you are
just choosing a stock familiar item for what is basically a stock familiar
design.

And by 'design' I don't just mean changing the maker's label on the choice
of valve type or trying out PTFE caps from someone. I mean more than that.
As I assume you will understand if you have genuinely developed your own
design ideas rather than tweaked something. Again, that does not mean that
such tweaking and modding isn't often significant. But I am trying to
distinguish different types of activity where the difference will be
evident to you if you have done both.

BTW When I spoke to one of the above about another 'unusual' transformer
requirement they were helpful. But the meaning and context of 'no extra
cost' wasn't quite what someone might assume from the above. Not quite as
easy as what you say seems to suggest. This is understandable, though, as
they are running commercial businesses, not amateur charities.

On 08 Mar in uk.rec.audio, Iain Churches wrote:


I take a pride in the finished result. On many occasions people have
asked me to "build one for them"

http://www.kolumbus.fi/iain.churches...em/C50_007.jpg

In the above case, twelve times!

Afraid I can't compete with that. No records exist any more of the
Armstrong sales, alas. The numbers would be in the thousands per year, but
no idea now what they are. I confess I didn't build them all myself,
though. :-)

Most of what I designed during my 'academic' work wasn't audio amplifiers.
Since then I've not built anything for anyone other than myself. But like
yourself I do feel some pleasure that what I've built works well, and seems
durable. I'm still using a pair of 700 systems that we built nearly 30
years ago. Haven't felt any need to change despite occasionally trying
something else. (FWIW Still also use a couple of 600s.)

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

And another one!
 

"Jim Lesurf" wrote in message
...

I must admit I have recently become more and more puzzled by the way he
keeps misinterpreting/misrepresenting some of the things I've said - even
when both here and in emails between us I've pointed out what I actually
wrote and meant are not in accord with what he then presents as my
meaning.

In the case of the clarinet maker, he read your posts
on the subject and needed no interpretation from me
or anyone else.

Audio (especially when one includes music)
is such a broad field that no one person can
be an expert in all areas. In the he case of
musical instrument design I am more interested
in the information that can be supplied by someone
who really is an expert in that field, with both
theoretical and practical experience, and I was
very pleased when such a person took the
trouble to contact me, and also introduced
me to others in the field. I am trying to gain
admission to a specialist (closed) group
to learn more.

Regarding the Bosendorfer discussion, I
am still waiting for an answer from them to my
enquiry sent more than a month ago.

The describing of other, very competent professional
people as witless and incompetent also goes against the
grain somewhat, I must admit:-)

Iain.

And another one!
 

In article ,
Iain Churches wrote:
There's all that metal-bashing needed with valves that, frankly, I can do
without.

It does take some effort it's true. But it is part of
the project. There are many options.

One can buy a ready punched chassis, for say a
25 amp (2x EL34) plus driver/phase inverter,
and input stage. One can also by good blank
chassis from companies such as Hammond, or have
one made locally. I use a small local firm who can
make me a very professional loking chasssis in
stainless steel or copper, pre punched for about
E50.They can work from even a drawing made in
Word, but prefer an AutoCad file.

I am sure there are dozens of good firms in the UK
who can do this kind of work, for probably much
less than I pay.

Seems to be there's less and less of these things you want to do yourself
(talking about a hobby).

Making the chassis is part of the fun. And doesn't require expensive
equipment.

--
*Everyone has a photographic memory. Some just don't have film*

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

And another one!
 

In article ,
Iain Churches wrote:
Of course. Fiddling with all of those will likely make them sound worse
than when correctly set up.


Typical meaningless (and erroneous) ****y response noted.

Thanks for showing yet again you have no concept of decent sound
reproduction.

Probably not your intention, Dave but you are
sounding more and more like Arny:-)

I doubt he fiddles with a correctly set up record playing deck in a vain
attempt to 'improve' it.

Is there any truth in the rumour that, now you
are retired with even more time on your hands,
Arnold is giving you recording lessons via Skype?

Heh heh. This from the one who thinks a ribbon mic is a hyper cardiod. One
of the first things you learn about microphones.

--
*Virtual reality is its own reward *

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

And another one!
 

In article ,
Iain Churches wrote:
Oh indeed. The laws of physics are quite specific as to LF response
in a horn.

But there is no denying that with certain types
of music, ( i.e. small string ensembles) a SET
amp and horns give the most wonderful lifelike
musical experience.

You mean something with no bottom end?

I am reminded of the first time I heard the
Resnekov SET with a pair of Lowthers
(Prokofiev String Quartet) as a guest at the home
of the gentleman who had played the cello on
that performance. It was so realistic, I felt I could
shut my eyes, reach out and touch the cello.

And you find that experience so remarkable you have to mention it?
I'd suggest you get some decent speakers and amps for general use. And
make sure the listening room is decently treated...

--
*Women like silent men; they think they're listening.

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