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Peter Wieck Peter Wieck is offline
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Default No Interconnect is the Best

On Jan 19, 8:17*pm, Eeyore
wrote:
Peter Wieck wrote:
My take on such things based on my experience is that Euro makers such
as Revox or Tandberg (B&O not so much) use very high-quality pots and
switches


And what audio products do Tandberg make ?

What Revox products use pots (or switches carrying audio) ?

They USED to use the likes of Preh parts IIRC which are reasonable but not
anything special.

Graham


Vintage, not current... was that not obvious?

Peter Wieck
Wyncote, PA
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"flipper" wrote in message
...
On Sun, 20 Jan 2008 14:35:35 +0200, "Iain Churches"
wrote:


"Eeyore" wrote in message
...


Bret Ludwig wrote:

Complete agreement. No preamp, no interconnect.

What's wrong with either of those exactly ?


Surely, these days the preamp is superfluous.
A CD player can give you 2V.


That depends on the player but you should be aware that the rating is
FS (full scale), the maximum voltage it can produce, and not nominal
line level which, if the CD was recorded in conformance with the
original specifications, would be 17dB-20dB under that level.

True. Many classical CDs these days peak at -10dB. Many
pop CDs are clipped at +0dBFS

Iain



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"flipper" wrote in message
...
On Sun, 20 Jan 2008 20:59:31 +0200, "Iain Churches"
wrote:


"flipper" wrote in message
. ..
On Sun, 20 Jan 2008 14:35:35 +0200, "Iain Churches"
wrote:


"Eeyore" wrote in message
...


Bret Ludwig wrote:

Complete agreement. No preamp, no interconnect.

What's wrong with either of those exactly ?


Surely, these days the preamp is superfluous.
A CD player can give you 2V.

That depends on the player but you should be aware that the rating is
FS (full scale), the maximum voltage it can produce, and not nominal
line level which, if the CD was recorded in conformance with the
original specifications, would be 17dB-20dB under that level.

True. Many classical CDs these days peak at -10dB. Many
pop CDs are clipped at +0dBFS

Iain


The problem is neither of those numbers tell you what nominal program
level is so you can't estimate how 'loud' it will sound, I.E. what
your nominal output power will be.



Yes. That's why I use a 100k DACT on the input of the power amp,
which has an input sensitivity if 1V for full power. I use no preamp.
It works well.

Iain


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Eeyore Eeyore is offline
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Peter Wieck wrote:

Eeyore wrote:
Peter Wieck wrote:


My take on such things based on my experience is that Euro makers such
as Revox or Tandberg (B&O not so much) use very high-quality pots and
switches


And what audio products do Tandberg make ?

What Revox products use pots (or switches carrying audio) ?

They USED to use the likes of Preh parts IIRC which are reasonable but not
anything special.

Graham


Vintage, not current... was that not obvious?


Not from the tense of the verb 'to use'.

Graham

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Default No Interconnect is the Best



Iain Churches wrote:

"flipper" wrote
"Iain Churches" wrote:

Surely, these days the preamp is superfluous.
A CD player can give you 2V.


That depends on the player but you should be aware that the rating is
FS (full scale), the maximum voltage it can produce, and not nominal
line level which, if the CD was recorded in conformance with the
original specifications, would be 17dB-20dB under that level.


Why do you think that ?

I don't recall any part of the Red Book spec that requires a specific
average or peak level.


True. Many classical CDs these days peak at -10dB.


In which case they're simply badly mastered and throwing away performance.
I suspect what you say isn't true actually.

Graham



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flipper wrote:

The problem is neither of those numbers tell you what nominal program
level is so you can't estimate how 'loud' it will sound, I.E. what
your nominal output power will be.


Define 'nominal program level'. You made it up didn't you ?

Graham


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On Jan 20, 7:13*pm, Eeyore
wrote:
Peter Wieck wrote:
Eeyore wrote:
Peter Wieck wrote:


My take on such things based on my experience is that Euro makers such
as Revox or Tandberg (B&O not so much) use very high-quality pots and
switches


And what audio products do Tandberg make ?


What Revox products use pots (or switches carrying audio) ?


They USED to use the likes of Preh parts IIRC which are reasonable but not
anything special.


Graham


Vintage, not current... was that not obvious?


Not from the tense of the verb 'to use'.

Graham- Hide quoted text -

- Show quoted text -


Active use, present day....

The equipment is operating as I write - that would be active, present
tense. Further - when have I _EVER_ posted on anything of commercial
manufacture also of significance less than ten (10) years old?

Peter Wieck
Wyncote, PA
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flipper wrote:

On Mon, 21 Jan 2008 00:15:43 +0000, Eeyore
wrote:



Iain Churches wrote:

"flipper" wrote
"Iain Churches" wrote:

Surely, these days the preamp is superfluous.
A CD player can give you 2V.

That depends on the player but you should be aware that the rating is
FS (full scale), the maximum voltage it can produce, and not nominal
line level which, if the CD was recorded in conformance with the
original specifications, would be 17dB-20dB under that level.


Why do you think that ?


Basically, because it's true.


I don't believe you.


I don't recall any part of the Red Book spec that requires a specific
average or peak level.


It doesn't spec output voltage either. So?


Output voltage isn't related to the CD. It's related to the hardware. The CD
merely carries data.

Graham

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flipper wrote:

Eeyore wrote:
flipper wrote:

The problem is neither of those numbers tell you what nominal program
level is so you can't estimate how 'loud' it will sound, I.E. what
your nominal output power will be.


Define 'nominal program level'. You made it up didn't you ?


You really don't know or did you figure it would be a good candidate
for one of your word games?


Provide a reference to 'nominal program level' in the Red Book spec or shut
the **** up.

Graham

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"Iain Churches" wrote in message
ti.fi...

"West" wrote in message
news:3iukj.9316$8A4.7230@trnddc02...

"Iain Churches" wrote in message
ti.fi...

"West" wrote in message

news:CMhkj.975$hk4.885@trnddc03...
I think that I have come to a conclusion that the best interconnects

are
no
interconnects. In my amp I have installed a 100k stereo (L-type) step
Ladder
attenuator with a 4 way stereo select switch. The amp now looks like

an
integrated amp but the preamp part, is of course, passive.
Has any one else used these step attenuators with good results? I'm
wondering if some of the real hi-end "botique" resistors really make

an
improvement. You have to use a bunch of them. I'm using Dale

resistors
for
now. At least I know that the sound outclasses any of my

interconnects.
That's why I opened this post with the best is nothing. Any

improvement
I
can make?
All constructive replies are most welcomed. Thank you.



Hi West. Your thinking follows on from the comment made by
Morgan Jones that "no preamp is better than any preamp" but then
you have to have a gain control. Fitting this to the power amp is
an excellent solution. I use DACT (Danish Audio Connectors)
stepped attenuators 100k stereo.They are 24 position.

http://www.dact.com/html/attenuators.html


If you insist on finer resolution then there is TKD P65CS
available with up to 60 steps. There is a considerable difference
in the price.

http://www.tkd-corp.com/02_products/p_04variable_a.html


For a stand alone stepped attenuator, I have been experimenting
with a 1:1 audio transformer with a multi-tapped secondary.

Best regards
Iain

Thanks Iain for the informing and kind words. At this point I am not
really
interested in mathematically precise attenuation, but more an analog
purist
approach in keeping the signal, let's say unadulterated. Thus I would
endeavor to know if certain type resistors are superior than others in
passing a signal. Thanks as always.



Yes I understand your point of view. In my own experience,
building an accurate attenuator (regardless of the quality of the

resistors
used) is a pretty time consuming business. A DACT stereo can be
had for probably less than the cost of parts and the cost of
labour to construct something similar but inferior.

The mathematical accuracy is necessary during attenuation
(moving stop to stop) you wish to keep the centre image
rock steady.


Thanks again my friend. You made me aware of something that I have never
considered. The tracking between the 2 attenuators is very important for a
solid center image. This is going to change my approach because I now
realize that mathematical precision is not just nice to have but essential.
I think I will go for the DACT. I suppose that a ladder configuration is
also important vs. a serial one. I have one from a Chinese company that I
use is a passive preamp. It has 4 rows of 1/4 W resistors. I bought another
one cheap from a different Chinese vendor and it also claims to be a stereo
ladder type but has only 2 rows of resistors. I don't understand that one.
To reiterate, thanks for the heads up. We are fortunate to have you involved
with RAT.
(see my other question at the bottom)

As to the boutique resistors, you must decide for yourself
if you can see or hear any benefit in their use. A Japanese
company recently sent me their catalogue of "superior
non.magnetic resistors" I could find no-one who could
think of a tube amp audio application in which they
could be proved to be superior.

However, on the otherhand, I do know a couple of bespoke
guitar amp builders who use the old style carbon resistors
(cracked carbon, I think they were called) in certain places
in their amplifiers for their particular sound.

Best regards
Iain

Iain, don't you need a lot of tube power to drive your Maggies? Also have

you ever compared your Maggies (in the normal stereo configuration. 2
speakers) with the ESL 63 and the Martin Logans? I'm curious for your
opinions in this regard and anyone else who would like to chime in. (see
above for my other response to mathematical tracking)

west





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Eeyore Eeyore is offline
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Default No Interconnect is the Best



flipper wrote:

Eeyore wrote:

Provide a reference to 'nominal program level' in the Red Book spec


Doesn't have a thing to do with 'red book' nor did I mention 'red
book'. That's your straw man, not mine.

or shut the **** up.


Which word is it you don't understand? Nominal, program, or level?


It's apparent you haven't a clue about any of them.

Graham

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Eeyore Eeyore is offline
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Default No Interconnect is the Best



flipper wrote:

The CD format, however, wasn't created in a vacuum nor was it randomly
picked from thin air. It was specified in light of what it was to
'replace' and be, at least as the proponents said, 'better' than, I.E.
analog. And the normal analog process (U.S.) was 20dB headroom over
nominal. I believe it was 18dB in the U.K.


Pure nonsense. Pre-digital recording, peak audio levels went right to the very
edge of tape saturation for one.

Graham

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Patrick Turner Patrick Turner is offline
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Default No Interconnect is the Best, attenuator guidlines.



West wrote:

"Iain Churches" wrote in message
ti.fi...

"West" wrote in message
news:3iukj.9316$8A4.7230@trnddc02...

"Iain Churches" wrote in message
ti.fi...

"West" wrote in message
news:CMhkj.975$hk4.885@trnddc03...
I think that I have come to a conclusion that the best interconnects

are
no
interconnects. In my amp I have installed a 100k stereo (L-type) step
Ladder
attenuator with a 4 way stereo select switch. The amp now looks like

an
integrated amp but the preamp part, is of course, passive.
Has any one else used these step attenuators with good results? I'm
wondering if some of the real hi-end "botique" resistors really make

an
improvement. You have to use a bunch of them. I'm using Dale

resistors
for
now. At least I know that the sound outclasses any of my

interconnects.
That's why I opened this post with the best is nothing. Any

improvement
I
can make?
All constructive replies are most welcomed. Thank you.



Hi West. Your thinking follows on from the comment made by
Morgan Jones that "no preamp is better than any preamp" but then
you have to have a gain control. Fitting this to the power amp is
an excellent solution. I use DACT (Danish Audio Connectors)
stepped attenuators 100k stereo.They are 24 position.

http://www.dact.com/html/attenuators.html


If you insist on finer resolution then there is TKD P65CS
available with up to 60 steps. There is a considerable difference
in the price.

http://www.tkd-corp.com/02_products/p_04variable_a.html


For a stand alone stepped attenuator, I have been experimenting
with a 1:1 audio transformer with a multi-tapped secondary.

Best regards
Iain

Thanks Iain for the informing and kind words. At this point I am not
really
interested in mathematically precise attenuation, but more an analog
purist
approach in keeping the signal, let's say unadulterated. Thus I would
endeavor to know if certain type resistors are superior than others in
passing a signal. Thanks as always.



Yes I understand your point of view. In my own experience,
building an accurate attenuator (regardless of the quality of the

resistors
used) is a pretty time consuming business. A DACT stereo can be
had for probably less than the cost of parts and the cost of
labour to construct something similar but inferior.

The mathematical accuracy is necessary during attenuation
(moving stop to stop) you wish to keep the centre image
rock steady.


Thanks again my friend. You made me aware of something that I have never
considered. The tracking between the 2 attenuators is very important for a
solid center image. This is going to change my approach because I now
realize that mathematical precision is not just nice to have but essential.
I think I will go for the DACT. I suppose that a ladder configuration is
also important vs. a serial one. I have one from a Chinese company that I
use is a passive preamp. It has 4 rows of 1/4 W resistors. I bought another
one cheap from a different Chinese vendor and it also claims to be a stereo
ladder type but has only 2 rows of resistors. I don't understand that one.
To reiterate, thanks for the heads up. We are fortunate to have you involved
with RAT.
(see my other question at the bottom)


West, you don't need anything to be more complex than it has to be.

This is particularly true of audio circuitry, but you mustn't have
anything
simpler than it must be to achieve a flawless result beyond which any
extra complexity
has a countering effect.

So, the DACT is a fine solution where simple single ended signal
transfer is wanted,
and there isn't any need to keep output resistance from the attenuator
constant.
SE circuitry is simply having a ground to ground connection via a
shielded coax cable
which is an extension of the OV rails of ther amps and one live signal
inner wire whose
voltage goes +ve and -ve above and below the OV level.

The Rin and Rout of the attenuator is important.
for tube amps, 50k is minimum if the attenuator is driven off the anode
circuit
of a low-µ triode. The DC to that anode should be via CCS.
So the only load seen by that anode is the cap coupled 50k.
1/2 12AU7 is fine, and has Ra = 13k at about Ia = 4mA. So RL = 4 x Ra.

The music will survive.

The Rout of the attenuator is only a problem if it becomes too high a
resistance
which then allows roll off of the HF due to following cable C, following
tube Miller C, stray C
or low input resistance to the next stage.
So assuming we'd never use less than a 50k pot or attenuator,
the maximum Rout from the wiper is nearly at the -6dB position
where resistance is equal above and below wiper point.
So with 50k pot, plus 13k Rout of driving tube there is 63k.
Half way down 63k is 31.5k, and the two halves are in parallel and hence
Rout
max is simply 15.75k.

If there is a short interconnect to a power amp with 100pF and
say 100pF power amp input C, then the -3dB with a total of 200pF is at
50kHz.

if a 100k pot/attenuator was used with 200pF, the -3dB point would
become too close
to the audio band.

If the pot was feeding a cathode follower buffer, the Cin of the CF
would only be perhaps
20pF and the BW would remain fine.

But a pot or attenuator is rarely ever used at the -6dB position unless
the source signal was indeed feeble.
More likely the 12 o clock position is used and the Rout of the pot
becomes 1/10 of the pot value in parallel
with the rest of the R above the wiper, and in this case with a 50k pot
the R below wiper is 5k and we can ignore the
remaining R of over 50k.
Rout at the 12 o'clock position or -20dB spot is thus approx 5k and HF
-3dB point becomes 150kHz with 200pF
and way above that with a cathode follower.

Its all very well asking questions about whether or not you are to use
an interconnect,
or an attenuator, or the darn brandname of this important thingemebob
but without thinking about
how and where and what impedance / resistances are involved everywhere,
you are ****ing into the wind.

Its the numbers that deliver the best sound, not the choice of
brandname,
or whether in fact you have an interconnect or not, or what type of
interconnect it is.
Some folks line a twisted pair made of very fine wire with a third wire
included in the twist up which is connected to 0V at the preamp end
only.
One of the pair carries the signal with the other being the 0V line.
It is a fine but fragile interconnect which is prone to noise pick up
more so than a coax cable I have found, but routed away from noisy
things like speaker wires
and mains cables the twisted pair is a very easy and cheap audiophile
doable solution.
Cat 5 wires can be used for the actual wires being twisted.





As to the boutique resistors, you must decide for yourself
if you can see or hear any benefit in their use. A Japanese
company recently sent me their catalogue of "superior
non.magnetic resistors" I could find no-one who could
think of a tube amp audio application in which they
could be proved to be superior.

However, on the otherhand, I do know a couple of bespoke
guitar amp builders who use the old style carbon resistors
(cracked carbon, I think they were called) in certain places
in their amplifiers for their particular sound.

Best regards
Iain

Iain, don't you need a lot of tube power to drive your Maggies? Also have

you ever compared your Maggies (in the normal stereo configuration. 2
speakers) with the ESL 63 and the Martin Logans? I'm curious for your
opinions in this regard and anyone else who would like to chime in. (see
above for my other response to mathematical tracking)


Maggies I tested here did like some power because they were relatively
insensitive to many other speakers.
50 watts seemed fine, so any tube amp with 4 x EL34 or bigger will be
OK.
Same goes for ESL63.
Martin Logan impedance curves are not to be seen anywhere and I think
the ML company
feels embarassed about their Z curves probably because there is a huge
amount of capacitance.
So 4 x KT88/KT90 are more appropriate.

Something SE with such speakers needs to have good grunt ability so
forget a lone 300B.
But a quad of KT88 in parallel and in beam tetrode with CFB could give
48 watts, and be rather blameless....

Patrick Turner.



west

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"Iain Churches" wrote in message
ti.fi

Yes. That's why I use a 100k DACT on the input of the
power amp, which has an input sensitivity if 1V for full
power. I use no preamp. It works well.


It has been reported to me that 100K pots have enough resistance to cause
excess thermal noise when used with truely clean (e.g. SS) power amps. As a
rule, SS power amps have either 5 or 10 K ohm input level controls.


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"Eeyore" wrote in
message

Iain Churches wrote:



True. Many classical CDs these days peak at -10dB.


In which case they're simply badly mastered and throwing
away performance. I suspect what you say isn't true
actually.


It is not unusual to see classical CDs that peak out in the 2-3 dB range,
but never as much as 10 dB. I suspect that Iain has been mislead by looking
at old-fashioned analog meters with their usually fairly gross needle
dynamics.




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"Eeyore" wrote in
message
flipper wrote:

The CD format, however, wasn't created in a vacuum nor
was it randomly picked from thin air. It was specified
in light of what it was to 'replace' and be, at least as
the proponents said, 'better' than, I.E. analog. And the
normal analog process (U.S.) was 20dB headroom over
nominal. I believe it was 18dB in the U.K.


While 20 dB headroom may be used for live recording, 2-4 dB is condsidered
to be plenty of headroom for a recording being distributed to consumers.

Pure nonsense. Pre-digital recording, peak audio levels
went right to the very edge of tape saturation for one.


....and beyond.


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"Eeyore" wrote in
message
West wrote:

I just checked a DACT dealer (http://diycable.com) and
they want $180 for a CT2, stereo step attenuator. What
do you think of that cost effectiveness?


A COMPLETE waste of money.


Agreed. A good regular potentiometer is more to the point, far more
cost-effective, and has a very large number of steps. A good example would
be the volume control on my Conrad-Johnston and Apt preamps.

The one step-type attenuator that I use frequently with great pleasure are
those on my 02R96. The steps are controlled by a shaft encoder's large knob
with a nice dimple for twirling with my forefinger, and read out very
nicely on a tastefully illuminated LCD display.


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"flipper" wrote in message

On Mon, 21 Jan 2008 10:25:10 -0500, "Arny Krueger"
wrote:

"Eeyore" wrote
in
message
flipper wrote:

The CD format, however, wasn't created in a vacuum nor
was it randomly picked from thin air. It was specified
in light of what it was to 'replace' and be, at least
as the proponents said, 'better' than, I.E. analog.
And the normal analog process (U.S.) was 20dB headroom
over nominal. I believe it was 18dB in the U.K.


While 20 dB headroom may be used for live recording, 2-4
dB is condsidered to be plenty of headroom for a
recording being distributed to consumers.


http://www.ebu.ch/CMSimages/en/tec_t..._tcm6-4669.pdf


"The EBU recommends
that, in digital audio equipment, its Members should use
coding levels for digital audio signals which
correspond to an alignment level which is 18 dB2 below
the maximum possible coding level of the digital
system, irrespective of the total number of bits
available."


IOW, if you're going to align the machine, use a test signal that is 18.2 dB
below FS. That's for setting up them machine. It is not a statement of the
maximum levels to record program material at.

Earlier in the standard, there's a clear statement that alignment level and
permitted maximum level are two different things that are defined separately
in the same document:

"
(the terms "alignment level" and "permitted maximum level" are defined in
ITU-R Recommendation BS.645 [2];"




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flipper wrote:

Eeyore wrote:
flipper wrote:

The CD format, however, wasn't created in a vacuum nor was it randomly
picked from thin air. It was specified in light of what it was to
'replace' and be, at least as the proponents said, 'better' than, I.E.
analog. And the normal analog process (U.S.) was 20dB headroom over
nominal. I believe it was 18dB in the U.K.


Pure nonsense.


You'd be able to figure it out if you'd put one or two brain cells to
work.

http://www.ebu.ch/CMSimages/en/tec_t..._tcm6-4669.pdf

"The EBU recommends
that, in digital audio equipment, its Members should use coding levels
for digital audio signals which correspond to an alignment level which
is 18 dB below the maximum possible coding level of the digital
system, irrespective of the total number of bits available."


That headroom IS NOT transferred to the **CD** you blithering IDIOT.

That's typical practice in the mixing console which has wider dynamic range
than a CD.

The amount of stuff you only 'half know' is astonishing.

Graham

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"Arny Krueger" wrote in message
. ..
"Eeyore" wrote in
message

Iain Churches wrote:



True. Many classical CDs these days peak at -10dB.


In which case they're simply badly mastered and throwing
away performance. I suspect what you say isn't true
actually.


It is not unusual to see classical CDs that peak out in the 2-3 dB range,
but never as much as 10 dB. I suspect that Iain has been mislead by
looking at old-fashioned analog meters with their usually fairly gross
needle dynamics.



Arny. See my post of yesterday. I picked out 2 CDs at random,
and checked their peak level on an HHB.

Iain





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"Arny Krueger" wrote in message
...
"Iain Churches" wrote in message
ti.fi

Yes. That's why I use a 100k DACT on the input of the
power amp, which has an input sensitivity if 1V for full
power. I use no preamp. It works well.


It has been reported to me that 100K pots have enough resistance to cause
excess thermal noise when used with truely clean (e.g. SS) power amps. As
a rule, SS power amps have either 5 or 10 K ohm input level controls.


The tube amp to which I refer has a SNR of 102dB, and 0.1% THD at
50W I think you will agree that is pretty "clean" The stepped attenuators
replace the grid resistor. 100k is a good value.

Regards
Iain



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"Eeyore" wrote in message
...


True. Many classical CDs these days peak at -10dB.


In which case they're simply badly mastered and throwing away performance.


There are no commercial recordings existing that have
a dynamic of even 80dB, so mastering to peak level
is not required, except for pop music in an attempt to make it sound
louder than the competition.

I suspect what you say isn't true actually.


I have just picked out two CDs at random: Thomas Arne,
"Six overtures" and "Polish Symphonies". The first peaks at
-10dB FS, the second at -9dB FS, according to the meter
on my HHB CD recorder. Some tracks, in order to preserve
the dynamic marked by the composer, peak at a considerably
lower level.

Best regards
Iain







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"flipper" wrote in message
...
On Sun, 20 Jan 2008 21:36:49 +0200, "Iain Churches"
wrote:


Yes. That's why I use a 100k DACT on the input of the power amp,


That only goes 'down', not up.

which has an input sensitivity if 1V for full power. I use no preamp.
It works well.


Very well might. It depends a lot on what you listen to and what that
"full power" value is at 1V.

My main tube amp is a 50W push pull parallel hombrew.
It can fill my fairly large listening room with music at a fairly
serious level, with the attenuator at 1 o'clock.

http://www.kolumbus.fi/iain.churches...-30%20SA01.jpg



Regards
Iain



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"West" wrote in message
news:%fWkj.23865$8A4.18841@trnddc02...



Iain, don't you need a lot of tube power to drive your Maggies? Also have

you ever compared your Maggies (in the normal stereo configuration. 2
speakers) with the ESL 63 and the Martin Logans? I'm curious for your
opinions in this regard and anyone else who would like to chime in. (see
above for my other response to mathematical tracking)

West, You must be confusing me with someone else, as
unfortunately, I don't own a pair of Maggies. A pal of mine
who has them has talked about critical placing, and about
lack if sentivity. It's a very long time since I have heard a
pair of ESLs too. They are not really to my taste.

Regarding the tracking accuracy of the DACT, they promise
0.05dB error, as I recall.

Best regards
Iain



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Default No Interconnect is the Best, attenuation and source switch options.


..
"Patrick Turner" wrote in message
...

But what I said was that even with the very nicest selection of parts,
and amp not optimally set up cannot be as good as one that has been set
up better.


Yes indeed. People seem sometimes so concerned about silver wire
between the input connectors and the selector switch that they tend to
overlook that their amp has poorly matched or low emission tubes,
with the bias set all over the place.

IF they only were to sacrifice some maximum power.
But no, marketing cowboys who now guide the design process
scream "Watts, more Watts!!!!" at the apprentice engineers.


Strange how the power bandwidth of tube power amps
used to be quoted at 0.1% THD after Harold Leak reached
this fig. Now, 1% is often used, just to add a watt or two to
the power spec.

When we come to SET amps, appalling loading mistakes are very common in
both output stages AND driver stages.
The apprentices sometimes have appalling basic knowledge of anything!

The 845 amp I have just got running has exemplary measured performance
for an SET amp. I gave the OPT two ways of arrangeing the secondaries in
a no-waste
constant current density manner with a section of either 4 ohms or 6.6
ohms.


Patrick Do you have a schematic of this amp on your website? I very
much want to build a good pair of SET monoblocs in the not-too-distant
future.

Iain






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"Iain Churches" wrote in message
ti.fi
"Arny Krueger" wrote in message
...
"Iain Churches" wrote in message
ti.fi

Yes. That's why I use a 100k DACT on the input of the
power amp, which has an input sensitivity if 1V for full
power. I use no preamp. It works well.


It has been reported to me that 100K pots have enough
resistance to cause excess thermal noise when used with
truely clean (e.g. SS) power amps. As a rule, SS power
amps have either 5 or 10 K ohm input level controls.


The tube amp to which I refer has a SNR of 102dB, and
0.1% THD at 50W I think you will agree that is pretty
"clean" The stepped attenuators replace the grid
resistor. 100k is a good value.


I'll bet money that the SNR given was made with the input gain turned all
the way up, and connected to the output of a signal generator that had an
output impedance of 600 ohms.

Redo the measurement with the control at its electrical center.


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"flipper" wrote in message

On Mon, 21 Jan 2008 14:24:55 -0500, "Arny Krueger"
wrote:

"flipper" wrote in message

On Mon, 21 Jan 2008 10:25:10 -0500, "Arny Krueger"
wrote:

"Eeyore" wrote
in
message
flipper wrote:

The CD format, however, wasn't created in a vacuum
nor was it randomly picked from thin air. It was
specified in light of what it was to 'replace' and
be, at least as the proponents said, 'better' than,
I.E. analog. And the normal analog process (U.S.)
was 20dB headroom over nominal. I believe it was
18dB in the U.K.

While 20 dB headroom may be used for live recording,
2-4 dB is condsidered to be plenty of headroom for a
recording being distributed to consumers.

http://www.ebu.ch/CMSimages/en/tec_t..._tcm6-4669.pdf


"The EBU recommends
that, in digital audio equipment, its Members should use
coding levels for digital audio signals which
correspond to an alignment level which is 18 dB2 below
the maximum possible coding level of the digital
system, irrespective of the total number of bits
available."


IOW, if you're going to align the machine, use a test
signal that is 18.2 dB below FS. That's for setting up
them machine. It is not a statement of the maximum
levels to record program material at.


Actually, it is because the avoidance of full scale
clipping, as well as standardization, is the reason for
it.


OK Flipper, you can't read technical documents and reach reasonable
conclusions. I can live with that.


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"Iain Churches" wrote in message
i.fi
"Arny Krueger" wrote in message
. ..
"Eeyore" wrote
in message

Iain Churches wrote:


True. Many classical CDs these days peak at -10dB.


In which case they're simply badly mastered and throwing
away performance. I suspect what you say isn't true
actually.


It is not unusual to see classical CDs that peak out in
the 2-3 dB range, but never as much as 10 dB. I suspect
that Iain has been mislead by looking at old-fashioned
analog meters with their usually fairly gross needle
dynamics.


Arny. See my post of yesterday. I picked out 2 CDs at
random, and checked their peak level on an HHB.


Iain, I've looked at several 100 commerical CDs using DAW software, over a
period of over a decade. 2 CD's? Why I laugh?


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"Iain Churches" wrote in message
ti.fi
"Eeyore" wrote
in message ...


True. Many classical CDs these days peak at -10dB.


In which case they're simply badly mastered and throwing
away performance.


There are no commercial recordings existing that have
a dynamic of even 80dB,


So far so good. But I've got at least one or two that come close.

so mastering to peak level
is not required, except for pop music in an attempt to
make it sound louder than the competition.


Peak levels on classical CDs pretty typically max out in the -1 to -4 dB
range.

I've looked at 100s of classical CDs over a period of about 12 years. My
methodology is ripping with a PC and looking at the resulting .wav file with
a digital editor.


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Iain Churches wrote:

"Eeyore" wrote

True. Many classical CDs these days peak at -10dB.


In which case they're simply badly mastered and throwing away performance.


There are no commercial recordings existing that have
a dynamic of even 80dB, so mastering to peak level
is not required, except for pop music in an attempt to make it sound
louder than the competition.


Mastering at a lower level than necessary will simply reveal flaws in the
'replay' system. The 'bottom bits' are less accurate.


I suspect what you say isn't true actually.



I have just picked out two CDs at random: Thomas Arne,
"Six overtures" and "Polish Symphonies". The first peaks at
-10dB FS, the second at -9dB FS, according to the meter
on my HHB CD recorder. Some tracks, in order to preserve
the dynamic marked by the composer, peak at a considerably
lower level.


I'd be slightly suspicious of that meter in that case.

How about transferring to your PC and examining the file with a wave editor ?

Graham



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"Eeyore" wrote in message
...


I'd be slightly suspicious of that meter in that case.

How about transferring to your PC and examining the file with a wave
editor ?


Whatever for?
The output of the CD recorder is routed via AES/EBU to the LO1
position and meters on the Lewo console. It corresponds exactly
with the level indicated by the HHB CD recorder.

Iain



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"Iain Churches" wrote in message
i.fi

"Eeyore" wrote
in message ...


I'd be slightly suspicious of that meter in that case.

How about transferring to your PC and examining the file
with a wave editor ?


Whatever for?


To get a quick, accurate answer.

CD transfers take place in 1/7 real time or less. A 1 hour piece thus takes
a fairly predictable 9 minutes to load, with no attention required other
than to start the operation. Loading a 1 hour file into a digital editor for
analysis usually takes 1 minute or two. Actually scanning the whole file for
a complete statistics report takes another minute or two. About 12 minutes
of which at least 8 minutes can be multitasked, to get an incredibly precise
report on the peak, RMS, and average maximums and minimums, and the precise
points in the file where they occurred.

The output of the CD recorder is routed via AES/EBU to
the LO1 position and meters on the Lewo console.


So you sit and watch the meters for the duration of the recording? What if
you blink your eyes?

That's cruel and unusual punishment for people with lives to live.

It corresponds exactly with the level indicated by the HHB
CD recorder.


Got one of those, and no way would I trust the information about levels that
I get from it for a question such as the one at hand. Such information as it
provides is designed for setting levels, which one does with a goodly amount
of headroom because the metering is so imprecise and recording levels are so
unpredictable.



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On Jan 20, 1:27*pm, "Iain Churches" wrote:
"GerryE123" wrote in message

...



My SE 45 amp has a pair of built-in Goldpoint attenuators. *Of course this
allows me to run my digital source directly into it. *Goldpoint and DACT
are the two most popular high-quality attenuators. *Here's a link to a
photo of the underside of my amp (the Goldpoints can be seen at the top):


http://i27.photobucket.com/albums/c1...123/set45c.jpg


Nice amp, Gerry. *Can we see a pic of the top also?
Your impressions of SET, and why you chose to build
one, would be of interest.

best regards
Iain


Hi Iain:

I purchased the amp from a friend who had it custom built by James
Burgess in California. James is a Jeweler by trade and does
meticulous work. Here's some links to photos of the top of the amp
and also a schematic (the schematic will be hard to read, but could be
downloaded and enlarged):

http://i27.photobucket.com/albums/c1...23/blue45a.jpg

http://i27.photobucket.com/albums/c1...23/blue45b.jpg

http://i27.photobucket.com/albums/c1.../blueschem.jpg

My impression of the amp is that it's super transparent and "natural"
sounding. I find the 45 to be a bit "modern" sounding. More
"neutral" sounding than "warm" (like a 300B). Of course I'm using
modern 45s, but I find the same thing even with old-stock 45s.

I have a SET amp because I have totally bought into the "simple-is-
best" concept. Both at the system and component level. My system
consists of a high quality digital source, SE 45 amp and simple, high
quality open baffle speakers.

Gerry
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"Arny Krueger" wrote in message
. ..
"Iain Churches" wrote in message
ti.fi
"Eeyore" wrote
in message ...



There are no commercial recordings existing that have
a dynamic of even 80dB,


So far so good. But I've got at least one or two that come close.


Sorry. Close is not good enough. The statement statement
stands, and comes from an article published by the BPI.
It even includes info from Russian labels such as Origen.


Both at Decca and RCA the two companies of which
I have considerable knowledge, production discs were
mastered to peak at approx 10dB above ref. of -18dBFS.
You can work out the rest, Arny.

I am not stating by any means that other labels may not follow
different criteria. There are non-confirmists in other walks of
life than just religion.

I have lost count of the number of commercial CD
mastering sessions in which I have taken part.
Again, these may or may not be typical from a
world's eye view, but -8dBFS is commonly used for
classical music and pop material allowed to peak
to -1dBFS. I have also (sadly) seen pop material
driven badly into clippping.

Regards
Iain










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"flipper" wrote in message
...
On Tue, 22 Jan 2008 07:29:52 -0500, "Arny Krueger"
wrote:

"flipper" wrote in message
m
On Mon, 21 Jan 2008 14:24:55 -0500, "Arny Krueger"
wrote:

"flipper" wrote in message

On Mon, 21 Jan 2008 10:25:10 -0500, "Arny Krueger"
wrote:

"Eeyore" wrote
in
message
flipper wrote:

The CD format, however, wasn't created in a vacuum
nor was it randomly picked from thin air. It was
specified in light of what it was to 'replace' and
be, at least as the proponents said, 'better' than,
I.E. analog. And the normal analog process (U.S.)
was 20dB headroom over nominal. I believe it was
18dB in the U.K.

While 20 dB headroom may be used for live recording,
2-4 dB is condsidered to be plenty of headroom for a
recording being distributed to consumers.

http://www.ebu.ch/CMSimages/en/tec_t..._tcm6-4669.pdf

"The EBU recommends
that, in digital audio equipment, its Members should use
coding levels for digital audio signals which
correspond to an alignment level which is 18 dB2 below
the maximum possible coding level of the digital
system, irrespective of the total number of bits
available."

IOW, if you're going to align the machine, use a test
signal that is 18.2 dB below FS. That's for setting up
them machine. It is not a statement of the maximum
levels to record program material at.

Actually, it is because the avoidance of full scale
clipping, as well as standardization, is the reason for
it.


OK Flipper, you can't read technical documents and reach reasonable
conclusions. I can live with that.


That's an amusing fantasy but even if it were true it would still
leave me light years ahead of your three monkeys, head in sand, snip
of inconvenient evidence. You're the one with a 'reading problem'.

But rather than repeat it, how about some professional mastering
companies?

http://www.chicagomasteringservice.com/loudness.html

"In studios with both types of metering present, a point on the
negative dBFS scale would be correlated with a point on the dBVU
scale. Typically this is something like -20 dBFS = 0 dBVU, so that "0
dB" on a VU meter would leave approximately 20dB of headroom for
signal peaks on the dBFS scale."


Hi Flipper. Interesting you should mention the VU. The mastering
facility where I work often has digital PPMs, a pair of analogue
PPMs and VUs also. The resident engineer told me that he finds the
VUs extremely useful for their indication of a close approximation
of the "perceived loudness" with compressed material. This is
something considered important in the domain of popular
"louder is better" CD mastering.



http://www.cdmasteringservices.com/dynamicrange.htm

"CDs produced in 1985 had an average (RMS) level of -18dB."

He's willing to "compromise" with the loudness wars at -14dB but
states "For the record, I personally prefer -18db."


That's pretty standard, but perhaps not universal,
and the situation is *not* improving:-(

Regards to all
Iain






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Iain Churches wrote:

"flipper" wrote in message

"In studios with both types of metering present, a point on the
negative dBFS scale would be correlated with a point on the dBVU
scale. Typically this is something like -20 dBFS = 0 dBVU, so that "0
dB" on a VU meter would leave approximately 20dB of headroom for
signal peaks on the dBFS scale."


All of which seems to go right over your silly little head.


Hi Flipper. Interesting you should mention the VU. The mastering
facility where I work often has digital PPMs, a pair of analogue
PPMs and VUs also. The resident engineer told me that he finds the
VUs extremely useful for their indication of a close approximation
of the "perceived loudness" with compressed material. This is
something considered important in the domain of popular
"louder is better" CD mastering.


What the hell is the point of monitoring 'perceived loudness'. Have these
people not got EARS to do that ? Measureing 'loudness' with a meter makesa
bout as much sense as giving a fish a bicycle and has always struck me as
being about the lamest excuse you could imagine for using a backward,
technically flawed method !

The metering needs to tell you something useful such as whether you're
clipping and VUs most certainly haven't a hope in hell of doing that. Nor
do PPMs exactly either. They're based on metering what is believed not to
sound likes it's clipping, and a PPM won't register momentary clips either.

To avoid 'digital clips' it's necessary to use a 'digital meter' that
registers the exact amplitude of every sample.

Graham

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"flipper" wrote in message
...

Out of curiosity, got any, say circa 1985, CDs?


Last night, after sauna, I was looking at some British remastered pop
CD's from that era. Jethro Tull in particular. They all seemed average
around -18dBFS. In contrast, much current pop material peaks at,
or close to, clipping.

Regards to all
Iain







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wrote in message
...
On Jan 20, 1:27 pm, "Iain Churches" wrote:
"GerryE123" wrote in message

...



My SE 45 amp has a pair of built-in Goldpoint attenuators. Of course
this
allows me to run my digital source directly into it. Goldpoint and DACT
are the two most popular high-quality attenuators. Here's a link to a
photo of the underside of my amp (the Goldpoints can be seen at the
top):


http://i27.photobucket.com/albums/c1...123/set45c.jpg


Nice amp, Gerry. Can we see a pic of the top also?
Your impressions of SET, and why you chose to build
one, would be of interest.



I purchased the amp from a friend who had it custom built by James
Burgess in California. James is a Jeweler by trade and does
meticulous work. Here's some links to photos of the top of the amp
and also a schematic (the schematic will be hard to read, but could be
downloaded and enlarged):



http://i27.photobucket.com/albums/c1...23/blue45a.jpg

http://i27.photobucket.com/albums/c1...23/blue45b.jpg

http://i27.photobucket.com/albums/c1.../blueschem.jpg


Hi Gerry.

Thanks for those. JB has made a very good job - you must be a
proud owner:-)

My impression of the amp is that it's super transparent
and "natural" sounding. I find the 45 to be a bit "modern"
sounding. More "neutral" sounding than "warm" (like a 300B).
Of course I'm using modern 45s, but I find the same thing
even with old-stock 45s.


It's difficult to put listening impressions into words. What do
you mean by "modern" ?

I have a SET amp because I have totally bought into
the "simple-is-best" concept. Both at the system and
component level.


There is perhaps something to be said for a low parts
count, as Morgan Jones says, "components that are
not there cannot fail". But then SET amps traditionally
have little or no NFB and so are inherently stable, not
requiring step circuits to prevent them from turning into
oscillators:-) Achieving unconditional stability in a PP
amp is something of a stumbling block for many hombrew
builders, and this may well be the reason that they choose
SET for a project amp.


My system consists of a high quality
digital source, SE 45 amp and simple, high
quality open baffle speakers.


Thanks for the info - most interesting:

I am thinking about doing a small survey of people
who choose, use and enjoy SET systems. I am
particularly interested to know what type of music
they enjoy and what they think works best on their
own system. I forgot to ask you this question.

Best regards
Iain




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"Arny Krueger" wrote in message
. ..

The output of the CD recorder is routed via AES/EBU to
the LO1 position and meters on the Lewo console.


So you sit and watch the meters for the duration of the recording? What
if you blink your eyes?


:-)))

The meter has a peak level marker, which stays in place until you
cancel it, plus the possibility to assign 98 other levels into memory.

It corresponds exactly with the level indicated by the HHB
CD recorder.


Got one of those, and no way would I trust the information about levels
that I get from it for a question such as the one at hand.


I knew you had. That's why I mentioned it.
What you don't have is the Lewo post-production desk:-)

Iain





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Iain Churches wrote:

"flipper" wrote

Out of curiosity, got any, say circa 1985, CDs?


Last night, after sauna, I was looking at some British remastered pop
CD's from that era. Jethro Tull in particular. They all seemed average
around -18dBFS. In contrast, much current pop material peaks at,
or close to, clipping.


Yes, that's 'modern' music production for you. Go to rec.audio.pro for a
discussion of it every week or two.

Graham

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