"Dave Plowman (News)" wrote in message
...
In article ,
Keith G wrote:
Even if true, the fact that there are *any* sales of valve amps is
enough to say they have not yet met their end, 'natural' or not.

I know you are incapable of understanding simple English, but my
comment was about developing such things - not sales.

Perhaps you'd educate us about the developments in SET design?


Developments? What are you going on about?

I'd suggest you read my posts before replying, then. The usual way when
trying to hold any kind of discussion.

- The design for my superb
little SET is from 1927!

Would go well with those carbon mics, I'd guess.

(No ****ing idea, have you? ;-)

I've an idea things have moved on audio wise in the thick end of 100
years. One day you might catch up.



One day you might grow up.

"Iain Churches" wrote in message
...

"David Looser" wrote in message


My most recent audio project has been a device to pick-off 5.1 or 7.1
LPCM
audio from the HDMI output of a Bluray player and send it as 4 AES/EBU
streams to a cinema audio processor. Try doing *that* with valves!

That's a good project. Do you have a picture?

I'm afraid not, and it's no longer here to photograph. But it's not much to
look at, just a plain aluminium box with a couple of PCBs inside. One PCB,
which was "borrowed" from a commercial HDMI repeater includes an SII9135
HDMI decoder chip, whilst the other PCB has the 4 AES/EBU transmitter chips
(Crystal CS8404) and a couple of standard CMOS logic chips on it. The
hardest bit was picking off the four I2S signals and their three related
clocks from the miniscule tracks on the repeater board. It took a
fine-pointed soldering iron, a magnifying glass and a steady hand ;-).

I have a project on the back burner to build a
pair of log meter amplifiers with valves to drive a
pair of Decca type Ernest Turner PPMs

http://www.kolumbus.fi/iain.churches...tTurnerPPM.jpg

Can't see the point myself since you can get PPM driver cards so easily, but
each to their own :-)


If the principal concern is price, you shouldn't even
think about building valve equipment. But if you
are looking to do something that will give you
weeks of building enjoyment and years of listening
pleasure then there is nothing better


I long ago ceased to find pleasure in building stuff simply for the sake of
building something. I've hade a lifetime of electronic construction, either
for myself, my employer or other people. It's the problem solving that I
enjoy, finding a solution to a particular requirement that cannot be met
satisfactorily or economically using off-the-shelf equipment. That's the
sort of thing I like doing, not building yet another HiFi amp. But as we've
both said before, each to their own.

David.

In article , David Looser
scribeth thus
"tony sayer" wrote

Did that have interlocked A and B keys like the UHF 2 and 77 series made
by Pye TvT?..

Not entirely sure what you mean by "A and B keys". It's a CG1 manufactured
by STC. Originally there were interlock keys intended to stop anyone opening
the rear doors without turning ofdf the power first. But if the doors aren't
even in place?

Yes thats the idea. All the B keys had to be back in a holder gubbins
before the A key could be pulled out which was in essence the master
power switch so no one could access the HV circuits whilst in operation.

Course duplicated A keys -did- happen..

One of our customers out in the wilds of Malaysia had a field engineer
who had a fair old few very remote sites to look after. It wasn't
unusual for no one to hear from him for a few days as mobiles weren't
yet invented and landlines didn't exist and comms radio links were rare.

Anyway they eventually found him at a main site, well what was left of
him. He'd received a fatal belt and his remains had been picked clean by
the jungle scavengers looking for a warmed up meal;!!.....


Mind you that was 15 kV on the Klystron's;!!

Is that B1 TX part of some 405 line revival that might be taking to the
Airwaves I believe from Ally Pally?..
--
Well, that's the plan...


Sounds like fun. Pity you couldn't rig the original aerial
installation..

What are you doing about the receivers tho?. Surely your not Tx ing in
625 line neg mod?...

Or is there a way of standard conversion thats freely available?..
--
Tony Sayer

In article ,
Keith G wrote:
Keith - I'll still call him that for the moment - thinks it adds to
his arguments giving people names. But positively hates it when others
do the same to him.


Oh, you missed where I recently got called Iain's 'running dog' then?
Like I've said a million times, chum: I pay back in the same coin I am
paid in. OK?

You can say it as often as you like, but it's you who starts off the name
calling.

As to 'positively hates it' - where TF *do* you get all that ********
from? More makey-up stuff inside your head?

No - from your posts. Very easy to see when you get annoyed.

Knock yourself out - like I give a toss! :-)

It would be hard to find one who more seeks approval from others.

--
*Don't byte off more than you can view *

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

"Jim Lesurf" wrote in message

In article
, Arny
Krueger
wrote:
"Jim Lesurf" wrote in message

In article ,
Iain Churches


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 THD 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.?

http://www.sowter.co.uk/push-pull-ou...ansformers.php

U701

http://www.sowter.co.uk/specs/u071.htm

It is spec'd at 0.05 THD @ 1 KHz at full power, but at
20 Hz? No spec. No way it would do 0.1 % THD at 20 Hz
without lots of loop feedback.

The secondary is speced at 0.9 ohms DCR which is as low
as its source impedance can possibly get without loop
feedback.

And also presumably excludes the transformed primary
resistance contribution as well as those of the core and
field losses.

Exactly. Then there is the source impedance of the tubes that drive the
transformer. Very much non-zero and definately positive.

Interesting question - could you get 20 dB feedback with
good stability?

Answers?

Price = £272.85

It clearly doesn't meet the sec I asked for. However I'm
happy to accept that a transformer to meet my spec
*could* be made. Although I hate to think how much it
would cost, or if anyone would take on the task of
selling you the first one-off at the same price as for
routine production. I wonder what "no extra cost" would
mean... :-)

History shows that despite all of the focus on rolling tubes, power amp
quality was mostly defined by output transfomers.


I just have my doubts about how often anyone making a DIY
audio power amp would even think of asking for one and
making a design that would as a total design also meet
the spec I set. My impression is that the bulk of DIY
valve enthuisiasts go for a rather less technically
demanding performance and the kinds of circuit topologies
that are 'old friends'.

The intersting part is where the DIY valve enthusiasts diefy less
technically demanding performance.

Also, my personal view is that valve power amps tend to
get into a 'tail wags dog' situation so far as the
designer/builder is concerned. i.e. the performance of
the overall design tends to become determined
by the transformer you can buy. For an engineer that
tends to mean that the real interest and skill may be in the design and
manufacture of the opt.

History bears that out. Dyna thrived by building low-cost relatively high
performance OPTs. McIntosh thrived with a very complicated and expensive
OPT.

From my POV that takes much of the interest
out of 'designing' the rest of the amp when the most
significant part is something you
have to pay someone else a lot of money to design and
build for you.
In effect, it becomes their design, not yours, and you no
longer really are in the driving seat - unless that
simply means the one who is
opening their wallet and saying "help yourself". :-)

It is clear that if you count your change after the transaction, you're not
in the market for a tube amp on the grounds of price performance.

As I said, there is nothing wrong in this if it's what
the builder wants to make. Just not really my cup of tea
as an activity when I was really into designing amps.

My view is that power amplifiers are no longer worth my time to fool with
the guts. I've mvoed on to system integration and actual hands-on technical
artistry - mixing and editing.

"Dave Plowman (News)" wrote in message
...
In article ,
Keith G wrote:
Keith - I'll still call him that for the moment - thinks it adds to
his arguments giving people names. But positively hates it when others
do the same to him.


Oh, you missed where I recently got called Iain's 'running dog' then?
Like I've said a million times, chum: I pay back in the same coin I am
paid in. OK?

You can say it as often as you like, but it's you who starts off the name
calling.


I can see it suits your twisted thinking to say that even in the face of the
recent example I quoted above.



As to 'positively hates it' - where TF *do* you get all that ********
from? More makey-up stuff inside your head?

No - from your posts. Very easy to see when you get annoyed.


Wishful thinking, old son.



Knock yourself out - like I give a toss! :-)

It would be hard to find one who more seeks approval from others.


You ever seen me get *approval* in here? You need to wipe the sleep from
your eyes....

In article ,
Keith G wrote:
Oh, you missed where I recently got called Iain's 'running dog' then?
Like I've said a million times, chum: I pay back in the same coin I
am paid in. OK?

You can say it as often as you like, but it's you who starts off the
name calling.


I can see it suits your twisted thinking to say that even in the face of
the recent example I quoted above.

Chicken and egg? Most have longer memories than your 'recent example'.

But you'd be in denial about that too, like so much else.

As to 'positively hates it' - where TF *do* you get all that ********
from? More makey-up stuff inside your head?

No - from your posts. Very easy to see when you get annoyed.


Wishful thinking, old son.

Shrug. You wouldn't be the first to be unaware of how your posts come
over.



Knock yourself out - like I give a toss! :-)

It would be hard to find one who more seeks approval from others.


You ever seen me get *approval* in here? You need to wipe the sleep from
your eyes....

Now let me see. All those friends who rave about your home made system(s).
The closed email group of sycophants you've referred to. None of which
have any bearing on what's discussed here. So what conclusion would one
draw?

--
*Re-elect nobody

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

In article , Arny
Krueger
wrote:
"Jim Lesurf" wrote in message



Interesting question - could you get 20 dB feedback with good
stability?

Answers?

None from me on that point. Don't have the knowledge or experience and
haven't spent time on it.


As I said, there is nothing wrong in this if it's what the builder
wants to make. Just not really my cup of tea as an activity when I was
really into designing amps.

My view is that power amplifiers are no longer worth my time to fool
with the guts.

Must admit that if I took serious interest these days it would be to learn
more about 'digital' sic amps. i.e. the various switching types. After
some decades of experiment they do seem to have reached the point where
they are worth considering. But for personal DIY 'messing about' I'd just
make amps of the sort I'm more familiar with.

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

"Dave Plowman (News)" wrote in message
...
In article ,
Keith G wrote:


You ever seen me get *approval* in here? You need to wipe the sleep from
your eyes....

Now let me see. All those friends who rave about your home made system(s).
The closed email group of sycophants you've referred to. None of which
have any bearing on what's discussed here. So what conclusion would one
draw?


See how you go: "rave'', "sycophants", "closed email group"...!!

I suspect you get yourself all worked up into a tizzy when you read my
posts!

:-)

"tony sayer" wrote in message
...
In article , David Looser
scribeth thus
"tony sayer" wrote

Did that have interlocked A and B keys like the UHF 2 and 77 series made
by Pye TvT?..

Not entirely sure what you mean by "A and B keys". It's a CG1 manufactured
by STC. Originally there were interlock keys intended to stop anyone
opening
the rear doors without turning ofdf the power first. But if the doors
aren't
even in place?

Yes thats the idea. All the B keys had to be back in a holder gubbins
before the A key could be pulled out which was in essence the master
power switch so no one could access the HV circuits whilst in operation.

Slightly different on the CG1 as the same key (of a type called a "Castell
key") is used for both. Normally it's in place on the power distribution
panel. If you remove it to open the rear doors then the power is immediately
disconnected. At least that's the theory, but it's a pain if you need to
make adjustments or measurements on the working TX, hence the "no doors"
option ;-)

Course duplicated A keys -did- happen..

One of our customers out in the wilds of Malaysia had a field engineer
who had a fair old few very remote sites to look after. It wasn't
unusual for no one to hear from him for a few days as mobiles weren't
yet invented and landlines didn't exist and comms radio links were rare.

Anyway they eventually found him at a main site, well what was left of
him. He'd received a fatal belt and his remains had been picked clean by
the jungle scavengers looking for a warmed up meal;!!.....


Nasty! At least that can't happen to us ;-)


What are you doing about the receivers tho?. Surely your not Tx ing in
625 line neg mod?...

The idea is to radiate 405-line system A. +ve mod, AM sound, the lot. Ofcom
permitting.

Or is there a way of standard conversion thats freely available?..
--
The are still a fair few 405-line or dual-standard receivers around.

David.