The things you see when ya go lookin'......
 

"Iain Churches" wrote in message
...

"Serge Auckland" wrote in message
...

One oddity I've noticed. On the SILK attenuator pages, they say of
conventional resistor attenuators "That's why at high attenuation level
(low signal out, low listening level) the bandwidth of such volume
control is very poor and the bandwidth is not constant over any switch
position."

This is only relevant if using very long high-capacitance cables. If
using cables of normal capacitance, and of normal domestic lengths, it
has no relevance as the bandwidth is already well in excess of the audio
bandwidth. Although I think a multi-tapped transformer as an attenuator
is a bit of overkill, it is a theoretically sound solution as the output
impedance will reduce as the attenuation increases. Pity they couldn't
have 23 separate secondaries, and keep the whole thing balanced input to
output. Now that *would* have given them a winding challenge!´

Serge. I have just built a passive preamp to *exactly* the specification
you quote above - multiple secondaries -balanced line throughout.

It's brilliant:-)

Iain

Interesting! Did you wind your own transformer? What secondary load are
you driving? I presume it's 10k bridging rather than 600 ohm terminating.

S.

The things you see when ya go lookin'......
 

"Serge Auckland" wrote in message
...

"Iain Churches" wrote in message
...

"Serge Auckland" wrote in message
...

One oddity I've noticed. On the SILK attenuator pages, they say of
conventional resistor attenuators "That's why at high attenuation level
(low signal out, low listening level) the bandwidth of such volume
control is very poor and the bandwidth is not constant over any switch
position."

This is only relevant if using very long high-capacitance cables. If
using cables of normal capacitance, and of normal domestic lengths, it
has no relevance as the bandwidth is already well in excess of the audio
bandwidth. Although I think a multi-tapped transformer as an attenuator
is a bit of overkill, it is a theoretically sound solution as the output
impedance will reduce as the attenuation increases. Pity they couldn't
have 23 separate secondaries, and keep the whole thing balanced input to
output. Now that *would* have given them a winding challenge!´

Serge. I have just built a passive preamp to *exactly* the specification
you quote above - multiple secondaries -balanced line throughout.

It's brilliant:-)

Iain

Interesting! Did you wind your own transformer? What secondary load are
you driving? I presume it's 10k bridging rather than 600 ohm terminating.



Wound for me at a local broadcast engineering workshop.
(I have friends in low places:-)

Nominal impedance 10k.
48dB attentuation in 2dB steps.
Inductance 80H.

Iain

The things you see when ya go lookin'......
 

"Andy Evans" wrote in message
oups.com...
OK, but I gotta say my (possible) future amp plans would probably be
more along the lines of a top-flight 300B with '****-off' iron.....

This is what I'm saying - you're thinking the end of the chain rather
than the start - everything goes through the input! You're amp is
ultimately never going to be better than the first two stages - put
ECC**s in it and its an ECC** amp.



Andy, I've got nothing against miniatures other than I think they look weedy
in the same chassis as 300Bs - see my cheepy chinky #01:

http://www.apah69.dsl.pipex.com/bez/Bez047.JPG

- one thing I like about it is has nice fat little 'knobber' valves in the
front line up. Another thing I like about is that I have just swapped it in
on my new speakers and it ****es over the Dynavox I had on them beforehand!
It's simple for me - if it's 'horns', it IS triodes (*end of*)....!!

(One thing I have noticed btw, is swapping mulitary Millards for the Chinee
CF2s on the Dynavox brought forth *no* discernable improvement...??!!)

On that subject....

Out with the old:

http://www.apah69.dsl.pipex.com/show/L1070646.JPG

and in with the new:

http://www.apah69.dsl.pipex.com/show/L1070649.JPG

:-)

Staggering performance now (the Visatons **** on the Fostex in these
cabinets) and my door frame is once again *thrumming* to the end of Blade
Runner, Track 1 as I type!! (Not too ****e for 4 inch drivers!! :-))

I'm hoping 'one here' will be a very happy bunny when he hears these!! (Or
I've got another pair I will be very happy to keep!! :-)

But I digress...

Back to your exhortations - fear ye not Andy, I have a pair of brand new
Sovtek 6SN7GTs (you know - the ones with the wonky glass) that have been
waiting very patiently for the last couple of years to have the right amp
slid underneath them!!

;-)

The things you see when ya go lookin'......
 

"Keith G" wrote in message
...

"Andy Evans" wrote in message
oups.com...
OK, but I gotta say my (possible) future amp plans would probably be
more along the lines of a top-flight 300B with '****-off' iron.....

This is what I'm saying - you're thinking the end of the chain rather
than the start - everything goes through the input! You're amp is
ultimately never going to be better than the first two stages - put
ECC**s in it and its an ECC** amp.



Andy, I've got nothing against miniatures other than I think they look
weedy in the same chassis as 300Bs - see my cheepy chinky #01:

http://www.apah69.dsl.pipex.com/bez/Bez047.JPG


Agreed. Miniatures are fine with EL84s or even EL34's but when
you get up to KT88s or 300B size, then only octals look right:-)

Back to your exhortations - fear ye not Andy, I have a pair of brand new
Sovtek 6SN7GTs (you know - the ones with the wonky glass) that have been
waiting very patiently for the last couple of years to have the right amp
slid underneath them!!

Now your're tallking:-)

Iain

The things you see when ya go lookin'......
 

"Iain Churches" wrote in message
...

"Andy Evans" wrote in message
oups.com...
OK, but I gotta say my (possible) future amp plans would probably be
more along the lines of a top-flight 300B with '****-off' iron.....

This is what I'm saying - you're thinking the end of the chain rather
than the start - everything goes through the input! You're amp is
ultimately never going to be better than the first two stages - put
ECC**s in it and its an ECC** amp.


Andy. I must agree with you that "octals have the magic"
but good results can be obtained with miniature nin-pin valves too.
I believe it is the topology that is most important.

People rattle on about "the dreadful high-gain minature pentode"
but seem to forget that both Peter Walker and Arthur Radford
understood its use in amplifiers which still perform exceptionally
well to this day.

I would think that when Keith begins to think about his top-flight
300B amp, miniature triodes will be conspicuous in their
absence:-)



Yes - see my reply to Andy. From the POV of physical 'size' and
'aesthetics', if nothing else!!

With the cost of a 'superamp project' in my mind there, my thoughts
immediately went to the recent robbery of 25 million quid mentioned on the
news just now. Apparently the Police are watching the airports for people
trying to move large amounts of cash abroad!!??

Larf? - I nearly lost me lunch!!

(It's gets fekkin' *sillier* every single day......!!!!)

:-))

The things you see when ya go lookin'......
 

Keith G wrote:
OK, but I gotta say my (possible) future amp plans would probably be more
along the lines of a top-flight 300B with '****-off' iron.....

(Not only is that on the back burner, but the cooker ain't even switched
on!!)

Keith:

Given on the assumption that by "'****-off' iron" you mean the very
best transformers, regardless of price:

Ever hear of the concept in economics of marginality? Technically it is
used to determine at which price per unit a perfect market clears. But
on the ground, and in core theory, it depends on the perception of
individuals about which products are worth more money because they give
greater satisfaction than the possession of the money. A corollary is
that greater and greater amounts of money at each step buy lesser and
lesser *increases* in satisfaction.

Your dream on the backburner is on the face of it not a bad idea. For
instance, many of us own absolutely better tube amps than you do, and
in a large number of cases we can afford them only because we built
them ourselves. We consider the expenditure worthwhile, and the
pleasure of something of (often) our own design and construction adds
to the value perceived. However, you should not fall into the trap of
thinking that the difference between your cheap Chinese and our cheap
DIY at several times the price of cheap Chinese is a gulf the size of
the Grand Canyon. It is a marginal, incremental difference. Think about
it: you have already arrived in the top one half of one percent of
hi-fi; at this level of hi-fi, all margins are minutely incremental and
very expensive.

We would find it a hardship to listen to your cheap chinese rather than
our cheap DIY. That is because we are used to what we have now and,
important this, have paid for it already and justified the cost to
ourselves.

You, having accustomed yourself to the cheap Chinese, and justified it
many times over, may be disappointed after paying several times the
cost of the cheap Chinese to discover that for so much money you have
gained only a small improvement in your sound.

At that, you will be in a better position than someone who has to lash
out ten times the price of the cheap Chinese to buy a good European or
American or Japanese tube amp on the open market. The difference will
come not only from the saved money but from the intrinsic DIY
satisfaction, which shines through your posts.

None of this will stop you if you really intend to go ahead.

*****

When you do go ahead, here's a tip. If you really want "****-you iron",
give the boutique hypesters a miss and buy your iron by the pound.
Literally. I mean it. The best transformer designers and builders earn
most of their basic bread, and a good bit of their jam, from the
national broadcasters. In essence, they give you their expertise for
free because the broadcasters have paid for skill development and
product development.

As an extreme example of buying transformers by the pound, hire one of
the poorer tranny designers (Patrick Turner is good and agreable if you
stroke him right) to run up a specification for you, take it to your
local generator rewinders, and let them do the job to save the
carriage. Or buy the designs of famous audio transformer designers off
the shelf. Amplimo and Plitron sell the designs of Menno van der Veen,
the best audio transformer designer now alive. Or Simon Shilton (who
may look like a boutique to the uninformed but whose transformer
designs are on many commercial amps with big names) sells a few of his
designs to the public at reasonable prices for what are essentially
custom designs (I can also recommend his DIY amp designs for which the
transformers are intended). But the best price/performance ratio is
without a doubt the Cut C-Core transformers made by Lundahl of Sweden.
In blind listening tests we ran they were chosen over the elite
Japanese transformers at many times the price. The Lundahls are only
one or two steps above the bottom rung in price, they're
ultra-adaptable, and they measure and sound as good as the very best.
The downside is that they look like what they are (industrial
artififacts from the hidden end of the broadcast industry) but what the
hell, Lundahl will sell you a can to pot them in if you insist on
having your transformers on display. Many of the highest-profile DIY
tube amp designers in the world swear by Lundahl transformers.

HTH.

Andre Jute
Visit Jute on Amps at http://members.lycos.co.uk/fiultra/
"wonderfully well written and reasoned information
for the tube audio constructor"
John Broskie TubeCAD & GlassWare
"an unbelievably comprehensive web site
containing vital gems of wisdom"
Stuart Perry Hi-Fi News & Record Review

The things you see when ya go lookin'......
 

"Iain Churches" wrote in message
...

"Keith G" wrote

Valves or SS, the better legacy 'names' are commanding big money
everywhere (as your dealer is telling you and as the two Sugdens I was
watching on eBay told me) and I suspect you could easily sell empty
cardboard boxes with the names Tannoy or Lowther on them these days!

:-) Indeed. I am happy to have a workshop full of worthless
old retro crap:-))


:-)


But I hesitate to suggest why there is great interest in SE - obviously
it
could be a 'sound quality' thing (as it is for me) but there's no
escaping
the increased publicity and much easier availability of SET amps will
have
some effect?

It seems that people find SET pleasing in a musical way.


Yes, this is fundamental. A better, more *pleasing* sound is what it's all
about AFAIAC....

It needs to be clearly stated that not everyone will like the SET/Horn
combination - I do, but then then I'm not overly endowed with the *technical
knowledge* that makes this 'difficult' for some people...!! ;-)



However, I am not sure if the Chinese presence is a good or a bad
thing. These amps do perhaps give people an "entry level" perspective
into thermionic audio, but at the same time the modest performance
may give the wrong impression of what a valve amp can do.


If valve amps are simply too expensive for impoverished/curious types, they
will never join the growing legions of 'thermionophiles'. I'm fairly sure,
that once they have got their feet wet, they will be curious about 'better
amps' and, now that valves are almost parallel with SS stuff on prices, a
clear upgrade path becomes visible presenting some interesting options. This
is where you come in - as a specialist builder in Europe, you have a hundred
quid advantage over Far Eastern competition on shipping costs alone. (It's
not for nothing that current 'modern' audio gear from the East weighs
*ounces*...)

(Not so in the 'Podes, though - poor old Pat "Lend Us A Shag 'Til I Get
Paid" Turner is stoked. Over there they are buying dirt girt Chinese valve
amps with big squidgy feet for the sole purpose of flattening out out their
warped vinyl, I gather!! ;-)

Either way, valve amp builders will have to do more to convince the buying
public that they are offering superior quality now that they are up against
stiff competition - it's possibly harsh and will probably weed out out a few
of the weaker players, but it's for the good of all, ultimately!!

(Luckily, even a modest valve amp has little or no trouble seeing off
similarly-priced SS competition, from what I can see/hear of it! ;-)


Few valve amps from Asia are sold through dealers, and so have
very questionable warranty rights. The component and build quality
is not too good at the moment (it will take them a while to get it right)
so failures within the first year are commom. This too creates a negative
impression.


Warranties from Chinese dealers (eBay) are *worthless* - when my volume pot
went tits up the dealer (Edmund Lam, aka 'Zagger1' on Fleabay) promised a
replacement - it never arrived. When I pointed this out to him after some
weeks, he promised to put another in the post - guess what....??

I have always said that people who can't fettle a valve amp shouldn't risk
the more exotic examples from the Far East. IME, European valve amps (very
likely *made* in China) like the (bullet proof?) Dynavox are a much safer
'entry option'....



I think it's all very healthy - a number of the people I 'speak to' who
are getting (or have just got) valve amps are quite young, so it's not a
'nostalgia thing' for them and, if it is simply a question of free choice
falling in favour of valves, then all I can safely say is 'Well, it ain't
just me!'!!

There was a whole generation that missed out on thermionic audio.


I almost did. Obviously, radios and record players (stereograms) were valves
when I wuz a kid, but I wasn't taking much notice. Maybe I have/had
deep-seated/ingrained memories of the sound quality and was trying
unsuccessfully to find it with SS gear??


The members of the music appreciation group to which I belong
(now twenty two strong) have thirteen valve power amps between
them. These people are very serious listeners, so a thermionic
presence well in excess of 50% speaks for itself.


AFAIAC, disregarding the excellent little Sony AV amp on the telly setup,
with my own amps currently running at 100% valve, it most certainly *does*
speak for itself!!

;-)

The things you see when ya go lookin'......
 

Iain Churches wrote:
"Andy Evans" wrote in message
oups.com...
OK, but I gotta say my (possible) future amp plans would probably be
more along the lines of a top-flight 300B with '****-off' iron.....

This is what I'm saying - you're thinking the end of the chain rather
than the start - everything goes through the input! You're amp is
ultimately never going to be better than the first two stages - put
ECC**s in it and its an ECC** amp.


Andy. I must agree with you that "octals have the magic"
but good results can be obtained with miniature nin-pin valves too.
I believe it is the topology that is most important.

People rattle on about "the dreadful high-gain minature pentode"
but seem to forget that both Peter Walker and Arthur Radford
understood its use in amplifiers which still perform exceptionally
well to this day.

I would think that when Keith begins to think about his top-flight
300B amp, miniature triodes will be conspicuous in their
absence:-)

Regards to all
--
Iain
www.kolumbus.fi/iain.churches

The things you see when ya go lookin'......
 

Iain Churches wrote:
"Andy Evans" wrote in message
oups.com...
OK, but I gotta say my (possible) future amp plans would probably be
more along the lines of a top-flight 300B with '****-off' iron.....

This is what I'm saying - you're thinking the end of the chain rather
than the start - everything goes through the input! You're amp is
ultimately never going to be better than the first two stages - put
ECC**s in it and its an ECC** amp.


Andy. I must agree with you that "octals have the magic"

Nothing more linear than a 6SN7, nothing more agreeable to the ear than
a 6SL7, and in combination unbeatably balanced. Check out Steve Bench's
site where he shows a bunch of driver topologies with measurements.

but good results can be obtained with miniature nin-pin valves too.
I believe it is the topology that is most important.

I like two of the miniatures, if by miniatures we mean 9-pin tubes.

My alltime fave driver is the WE417A, also made as the 5842 by many
others, including Ericson of Sweden, so generally available cheaply. Mu
over 40, up to 24mA, a Miller-capacitance killeer par excellence.



People rattle on about "the dreadful high-gain minature pentode"

....And for a CCS made with tubes rather than transistors, the EL84 is a
super tube.

but seem to forget that both Peter Walker and Arthur Radford
understood its use in amplifiers which still perform exceptionally
well to this day.

The EF86 is as often misapplied as it is maligned, and usually the
former precedes the latter!

I would think that when Keith begins to think about his top-flight
300B amp, miniature triodes will be conspicuous in their
absence:-)

If you're spending top dollar anyway, you may as well get an NOS double
digit triode for your driver. Andy has a list about which he has been
going on for a while, and a visit to Jim de Kort's VT52 site is
instructive. I drive SV572-3 and -10 and other kilovolt class tubes
with a 300B which is itself driven by a 417A which is driven via a pot
direct from the CD player: three stages total.

A sweet tube that is often overlooked (in these parts -- it has a
certain vogue in Japanese ultrafi circles) as a driver for a DHT is a
trioded EL34.

Regards to all
--
Iain
www.kolumbus.fi/iain.churches

HTH.

Andre Jute
Visit Jute on Amps at http://members.lycos.co.uk/fiultra/
"wonderfully well written and reasoned information
for the tube audio constructor"
John Broskie TubeCAD & GlassWare
"an unbelievably comprehensive web site
containing vital gems of wisdom"
Stuart Perry Hi-Fi News & Record Review

The things you see when ya go lookin'......
 

On Thu, 23 Feb 2006 14:25:01 -0000, "Keith G"
wrote:

I'm hoping 'one here' will be a very happy bunny when he hears these!!

slurps loudly ...

Cessna172