[Alex Pogossov]

Who is that "professional radio engineer", living not far from Canberra and
selling dodgy tube amps?
http://www.ebay.com.au/itm/110991918... 4.m1423.l2649

Patrick would know...

Spray painting the whoile transformer is a dodgy job. Laminates should be
painted black, while the covers -- different colour or crome.

And besides, "professionals" do not use 6.3mm jacks for the speaker
connectors, unless the contacts are gold plated. With nickel plated steel,
contact resistance is unstable within a few milliohms which is no-no for any
decent audiophil!

Regards,
Alex

[Phil Allison[_3_]]

"Alex Pogossov"


And besides, "professionals" do not use 6.3mm jacks for the speaker
connectors, unless the contacts are gold plated. With nickel plated steel,
contact resistance is unstable within a few milliohms which is no-no for
any decent audiophil!


** You must be thinking of "audiophools" not audiophiles.

Nickel plated *brass* 1/4 inch jacks and plugs are fine for speakers,
millions of instrument amps have used them for decades. Removal and
insertion plus occasional cleaning is all that is needed.

Gold plating is only for small signals.



.... Phil

[Alex Pogossov]

"Phil Allison" wrote in message
...

"Alex Pogossov"


And besides, "professionals" do not use 6.3mm jacks for the speaker
connectors, unless the contacts are gold plated. With nickel plated
steel, contact resistance is unstable within a few milliohms which is
no-no for any decent audiophil!


** You must be thinking of "audiophools" not audiophiles.

Nickel plated *brass* 1/4 inch jacks and plugs are fine for speakers,
millions of instrument amps have used them for decades. Removal and
insertion plus occasional cleaning is all that is needed.

Gold plating is only for small signals.

Ah, was kidding...
For the instrument amps, perhaps a jack is OK, but audiophools shall use
enormous gold plated terminals, and a special litz speaker wire of perhaps
2000 insulated 0.07mm strands each, so that ohmic loss is small and constant
from DC to 1MHz..Otherwise you lose transparency of the highs!

[flipper]

On Fri, 21 Dec 2012 16:20:27 +1100, "Alex Pogossov"
wrote:


"Phil Allison" wrote in message
...

"Alex Pogossov"


And besides, "professionals" do not use 6.3mm jacks for the speaker
connectors, unless the contacts are gold plated. With nickel plated
steel, contact resistance is unstable within a few milliohms which is
no-no for any decent audiophil!


** You must be thinking of "audiophools" not audiophiles.

Nickel plated *brass* 1/4 inch jacks and plugs are fine for speakers,
millions of instrument amps have used them for decades. Removal and
insertion plus occasional cleaning is all that is needed.

Gold plating is only for small signals.

Ah, was kidding...
For the instrument amps, perhaps a jack is OK, but audiophools shall use
enormous gold plated terminals, and a special litz speaker wire of perhaps
2000 insulated 0.07mm strands each, so that ohmic loss is small and constant
from DC to 1MHz..Otherwise you lose transparency of the highs!


I saw one site selling multi-thousand dollar speaker cables with the
'feature' that in THEIRS the signal traveled at 90% the speed of
light. Which, of course, is critical when sending audio 10 feet.

[Alex Pogossov]

"flipper" wrote in message
...
On Fri, 21 Dec 2012 16:20:27 +1100, "Alex Pogossov"
wrote:


"Phil Allison" wrote in message
...

"Alex Pogossov"


And besides, "professionals" do not use 6.3mm jacks for the speaker
connectors, unless the contacts are gold plated. With nickel plated
steel, contact resistance is unstable within a few milliohms which is
no-no for any decent audiophil!


** You must be thinking of "audiophools" not audiophiles.

Nickel plated *brass* 1/4 inch jacks and plugs are fine for speakers,
millions of instrument amps have used them for decades. Removal and
insertion plus occasional cleaning is all that is needed.

Gold plating is only for small signals.

Ah, was kidding...
For the instrument amps, perhaps a jack is OK, but audiophools shall use
enormous gold plated terminals, and a special litz speaker wire of perhaps
2000 insulated 0.07mm strands each, so that ohmic loss is small and
constant
from DC to 1MHz..Otherwise you lose transparency of the highs!


I saw one site selling multi-thousand dollar speaker cables with the
'feature' that in THEIRS the signal traveled at 90% the speed of
light. Which, of course, is critical when sending audio 10 feet.

A brilliant idea came to me. We need to start manufacturing special
audiophoolish coaxial cables with Z=4ohm impedance, Z=8ohm impedance and
Z=16ohm impedance. Using such coax as a speaker cable an audiophool can
achieve perfect matching of the speakers to the amp in the widest frequency
range. Group delay will be constant within picoseconds! They will line up to
buy such a cable. It will be very thick though as the inner diameter shall
be very close to the outer diameter to have low characteristic impedance.

Those audiophools who use Cyclotron amps, of course can not use unbalanced
coax in a fully balanced system. For those we will manufacture multilayer
ribbon cables with the same standard impedances! (Ordinary twisted pair is
unsuitable -- it has far too high characteristic impedance.) Perhaps as an
alternative a special twisted Litz can be used with half of the strands in
parall serving as conductor A, the other half -- conductor B. Most likely it
shall be impregnated by some high epsilon goop -- for higher capacitance and
hence lower impedance.

How does this sound?

[Phil Allison[_3_]]

"Alex Pogossov"


A brilliant idea came to me. We need to start manufacturing special
audiophoolish coaxial cables with Z=4ohm impedance, Z=8ohm impedance and
Z=16ohm impedance.


** Been around since the 1970s.

Using such coax as a speaker cable an audiophool can achieve perfect
matching of the speakers to the amp in the widest frequency range.


** Shame how loudspeakers do not have simple impedances over the audio band,
let alone beyond it.

While it is possible to add passive networks in parallel with a speaker ( ie
zobels) to fix this, nobody ever wants to.

Exceptions:

Some Magneplaner models and the KEF 104AB were close to resistive over the
audio band.


..... Phil

[flipper]

On Sun, 23 Dec 2012 12:03:45 +1100, "Alex Pogossov"
wrote:


"flipper" wrote in message
.. .
On Fri, 21 Dec 2012 16:20:27 +1100, "Alex Pogossov"
wrote:


"Phil Allison" wrote in message
...

"Alex Pogossov"


And besides, "professionals" do not use 6.3mm jacks for the speaker
connectors, unless the contacts are gold plated. With nickel plated
steel, contact resistance is unstable within a few milliohms which is
no-no for any decent audiophil!


** You must be thinking of "audiophools" not audiophiles.

Nickel plated *brass* 1/4 inch jacks and plugs are fine for speakers,
millions of instrument amps have used them for decades. Removal and
insertion plus occasional cleaning is all that is needed.

Gold plating is only for small signals.

Ah, was kidding...
For the instrument amps, perhaps a jack is OK, but audiophools shall use
enormous gold plated terminals, and a special litz speaker wire of perhaps
2000 insulated 0.07mm strands each, so that ohmic loss is small and
constant
from DC to 1MHz..Otherwise you lose transparency of the highs!


I saw one site selling multi-thousand dollar speaker cables with the
'feature' that in THEIRS the signal traveled at 90% the speed of
light. Which, of course, is critical when sending audio 10 feet.

A brilliant idea came to me. We need to start manufacturing special
audiophoolish coaxial cables with Z=4ohm impedance, Z=8ohm impedance and
Z=16ohm impedance. Using such coax as a speaker cable an audiophool can
achieve perfect matching of the speakers to the amp in the widest frequency
range. Group delay will be constant within picoseconds! They will line up to
buy such a cable. It will be very thick though as the inner diameter shall
be very close to the outer diameter to have low characteristic impedance.

Those audiophools who use Cyclotron amps, of course can not use unbalanced
coax in a fully balanced system. For those we will manufacture multilayer
ribbon cables with the same standard impedances! (Ordinary twisted pair is
unsuitable -- it has far too high characteristic impedance.) Perhaps as an
alternative a special twisted Litz can be used with half of the strands in
parall serving as conductor A, the other half -- conductor B. Most likely it
shall be impregnated by some high epsilon goop -- for higher capacitance and
hence lower impedance.

How does this sound?


Well, I suppose we just wouldn't mention that to be a transmission
line at audio frequencies the cable would have to be miles long.

[patrick-turner]

On Friday, 21 December 2012 13:07:28 UTC+11, Alex Pogossov wrote:
Who is that "professional radio engineer", living not far from Canberra and selling dodgy tube amps? http://www.ebay.com.au/itm/110991918... 4.m1423.l2649 Patrick would know... Spray painting the whoile transformer is a dodgy job. Laminates should be painted black, while the covers -- different colour or crome. And besides, "professionals" do not use 6.3mm jacks for the speaker connectors, unless the contacts are gold plated. With nickel plated steel, contact resistance is unstable within a few milliohms which is no-no for any decent audiophil! Regards, Alex

Why on earth would I know a so called "professional radio engineer" not far from Canberra?

The Ebay amateur guy you refer to is selling a POS ancient Mullard amp that has been painted grey all over, and he is located in a small country town called Bungendore, about 35km away from where I am in central Canberra cbd, and on road between here and Batemans Bay on sth Coast. The population of Canberra plus 50km radius is about 380,000 ppl, and i guess there are many ppl with Old Krappe amps who I don't know, and many of them don't know me, or know about me, or wouldn't want to ever know me if they ever did get to know my unbending opinions about Olde Junke that they have dressed up to sell by painting grey, while perhaps describing themselves as professionals while not being able to support that claim, or show any sign of any professionalism, or tradesmen like worthiness or honesty in any way. While the seller fails to show he is reputable, he doesn NOT show he is disreputable, and he only wants a low price which I am sure he will get, maybe $100 even, and even if it doesn't work, maybe another $100 worth of second hand parts and some labour might fix it.

The mono amp being sold seems to be just ONE, not a matching pair, and seems to have an old Leak OPT at one end of the chassis. Other parts on chassis look very generic old stuff, and R&C underchassis are combination of cheap 1W carbon film garbage quality R, with variety of some newish C plus mostly very old C parts from 1960s. So, underchassis has Real Crap that has not been re-engineered properly. 6mm jack at back is fine if in good condition, for low power, and the amp should suit somebody who wanted a low power mono system. There is room to put in a source switch and volume control to allow use of modern sources like CD, AM-FM tuner etc, or else the amp could be used for a low power musician's amp.