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

Andy Evans wrote:
Andre - I don't know if you are interested but I have five new SV811-10
which I don't know what to do with.

Thanks for the offer, Andy, but I doubt I'll be building more kilovolt
amps -- not scared, just wondering if I want to risk my back to pick up
an amp which weights nearly as much as I do. On the other hand, whoever
buys or inherits my Millennium will probably have to use 811s in the
place of the unobtanium SV-572-xx...

But these two digit DHTs - they really are DIFFERENT! Yes, a 6SN7
sounds good, but only until you try a 2C22/7193.

Was ist das?

Then the 1626 is a
real rock and roll tube - great bass dynamics and boogie factor -

I think Bob Danielak built a car amp with them. Can't remember the
details now, but it fitted on a shelf behind seat of his Fiat X1/9 or
124 Spyder, something like that. I remember he said the difficult thing
was the power supply design and construction.

I
still regret taking it out of my line stage. But the 26 has so much to
offer, it's on another level of sophistication altogether. All this
leaves the 9 pins in the dust. I ahven't tried the single triodes like
Andre says - stuff like the 5842, though I have some. The two small
tubes I like are the ECC40 and E80CC bit these are eclipsed by octals
and in particular the UX bases.

Andre Jute

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

Andy Evans wrote:
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.

Have you tried O-netics, as used by Gary Pimm, Lynn Olsen, and
incidentally me!

Don't even know what they are. It is years since I last bought any
trannies except Lundahls. I have some others here that I must use
first, and too many amps, so I should really break one down and recycle
the trannies every time I build another amp.

Where did you get the O-netics, were they expensive, what is good about
them?

Lynn was one of the first guys into Lundahl, not too long after me,
when they were a truly obscure Scandinavian brand.

Andre Jute

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

"Keith G" wrote in message
...

"Iain Churches" wrote in message
...


Keith has a good alternative to Lundahl, and practically on his doorstep.
- AE Sowter Ltd.


Yes. A definite contender for a *killer amp*....

None better I would say:-)

Keith. When the big days comes, before you make contact with them,
send me an e-mail. I shall be able to save you copious amounts of the
"elusive spondoolicks" :-)

Iain

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

"Andre Jute" wrote


I think Bob Danielak built a car amp with them. Can't remember the
details now, but it fitted on a shelf behind seat of his Fiat X1/9 or
124 Spyder, something like that. I remember he said the difficult thing
was the power supply design and construction.


http://www.geocities.com/TimesSquare/1965/caramp.html

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

"Iain Churches" wrote in message
...

"Keith G" wrote in message
...

"Iain Churches" wrote in message
...


Keith has a good alternative to Lundahl, and practically on his
doorstep.
- AE Sowter Ltd.


Yes. A definite contender for a *killer amp*....

None better I would say:-)

Keith. When the big days comes, before you make contact with them,
send me an e-mail. I shall be able to save you copious amounts of the
"elusive spondoolicks" :-)


OK, will do! ;-)

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

In article , Iain Churches
wrote:

"Serge Auckland" wrote in message
...

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.

Since I am unfamiliar with the use of such transformers for audio, I'll
risk asking a few simple questions. :-)

Can you explain what you mean by "10k bridging" in the above? Does it refer
to the input load/arrangement?

Under what conditions of use does the system present (?) 10kOhms?

What would be the levels of series resistances, shunt capacitances, etc,
for the above device? You quote '80H' for an inductance, but don't
distinguish the coupled (mutual) value from the uncoupled values.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

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

In article , Serge Auckland
wrote:

[snip]

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."

Can you give the URL for the page? I'm puzzled as I'd expect the maximum
output resistance of a conventional attenuator to occur at about the -6dB
setting, and fall as the output level is reduced below that. i.e. not have
a "poor bandwidth" at low settings, but at relatively high ones.

Is there some reason why the transformer referred to *doesn't* also have a
bandwidth that "is not constant" as the attenuation is altered? If nothing
else, I'd assume that the inductances, capacitances, and resistances, would
all tend to change, and affect the bandwidth...

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.

Will the input impedance not also tend to change as the o/p tap is changed?

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

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

But these two digit DHTs - they really are DIFFERENT! Yes, a 6SN7
sounds good, but only until you try a 2C22/7193.

Was ist das?

It's 'half' a 6SN7 - a 6J5GT substitute but with two top caps - grid
and anode. It sounds better than any 6SN7, 6J5 type, even better than a
6P5GT which is very nice or a CV1932. cheap - mostly JAN. Terrific
valve - others have remarked the same thing - smokes 6SN7s.

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

Where did you get the O-netics, were they expensive, what is good about

them?

Good value - my 6.6K PP level one were $98 each. Very detailed refined
sound - Lynn Olsen specifically says he preferred them to Lundahl. Made
by Bud Purvine,



Andy

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

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

"Serge Auckland" wrote in message
...

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.

Since I am unfamiliar with the use of such transformers for audio, I'll
risk asking a few simple questions. :-)

Can you explain what you mean by "10k bridging" in the above? Does it
refer
to the input load/arrangement?

For many years now, pro-audio has abandoned the old 600 ohms terminating
(that is, 600 ohms sending impedance, 600 ohms receiving) for the more
modern very low sending impedance (typically less than 50 ohms) into a high
receiving impedance (typically 10kohms) The 10k impedance is referred to as
"bridging" as it can be put across (bridge) a 600 ohm load without
materially affecting the level. The use of the terms is now something of an
anachronism, but is still retained to indicate a high load impedance, and to
distinguish it from the now rarely used 600 ohm terminating imedance. Before
I get lots of replies from professionals pointing out that 600 ohms is still
used, I agree, it is still used, but exceptionally, when terminating very
long lines. In studio use, it is never (almost never?) used.


Under what conditions of use does the system present (?) 10kOhms?

If a transformer is designed for 10k use, it needs to be presented with a
high load impedance on the secondary. A 10k transformer presented with a
600ohm load will distort at a much lower level than with a 10k load, as the
core saturates.

Conversely, if a transformer is designed for 600 ohm use is used with a 10k
load, it won't saturate or distort, but it could have an undesirable peak in
the treble response, although with a well-designed transformer, this won't
be too serious a problem. Nevertheless, the cousel of perfection is to
terminate transforers with their design impedance.


What would be the levels of series resistances, shunt capacitances, etc,
for the above device? You quote '80H' for an inductance, but don't
distinguish the coupled (mutual) value from the uncoupled values.

This will depend on the specific transformer, so I can't answer this....
Iain?

S.