Stewart Pinkerton wrote:

*All* amps use feedback, but some don't use *global* feedback, leading
to a common claim about 'zero feedback' valve amps.

Been thinking about this, where is the feedback in a triode, with a
NiCad between its cathode and ground ?

I use this in my phono stage, and I can't for the life of me, see any
feedback.

--
Nick

In message , Nick Gorham
writes
Stewart Pinkerton wrote:

*All* amps use feedback, but some don't use *global* feedback, leading
to a common claim about 'zero feedback' valve amps.

Been thinking about this, where is the feedback in a triode, with a
NiCad between its cathode and ground ?

I use this in my phono stage, and I can't for the life of me, see any
feedback.

--
Nick


The low internal impedance in a triode is because of the internal
feedback between the anode and the grid. Although the feedback
mechanism is obvious at high frequencies (Miller effect) the varying
voltage on the anode couples to the grid as an NFB mechanism even at LF.

Thinking of directly heated triodes, I see the pair of DA100s that I'm
selling on Ebay are up to 186 pounds.
--
Chris Morriss

A certain Andy Evans, of uk.rec.audio "fame", writes :

If it were, why do stereo LP’s made 40 years ago, amplified with 65-year-old
direct-heated triodes, sound so much better than today’s digital sound played
through 0.001% THD mass-fi rack stereos?

At one fell swoop, the author totally destroys his own credibility.

--

"Jokes mentioning ducks were considered particularly funny." - cnn.com

A certain RJH, of uk.rec.audio "fame", writes :

My 'reference' recordings are an old Louis Armstrong LP (50s I think) and an
original of Let it Bleed (66?). The quality (as well as the music let's not
forget!) is superb. Much of the late beatles stuff is pretty hq IMHO (cd and
LP). I bought a few remastered Hendrix cds a couple of years ago and the
quality compared to the record is diabolical - compressed and flat. They
must have got something right 40 years ago after all, at least to my mind.

No they didn't, because the cutting master tapes used to produce LPs
were all compressed and heavily EQ'd versions of the original recorded
masters. Unfortunately a lot of CDs use those original cutting master
tapes, and they reveal this compression well. This is not the fault of
CD, it is caused by poor quality source material.

Some of the vinyl enthusiasts on this group will tell you that vinyl
sounds just fine even after it has been digitally recorded. This
suggests several things, (1) CD/digital can record source material
sufficiently well to be almost completely transparent; (2) to repeat (1)
in a different way - the act of recording the vinyl onto CD doesn't
remove the so-called "warmth"; and (3) the "warmth" that people refer to
is a characteristic of vinyl, caused mostly by distortion, compression
and other imperfections.

--

"Jokes mentioning ducks were considered particularly funny." - cnn.com

Been thinking about this, where is the feedback in a triode, with a
NiCad between its cathode and ground ?

That's what I was wondering.

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

In article ,
Chesney Christ wrote:

A certain RJH, of uk.rec.audio "fame", writes :

My 'reference' recordings are an old Louis Armstrong LP (50s I think) and an
original of Let it Bleed (66?). The quality (as well as the music let's not
forget!) is superb. Much of the late beatles stuff is pretty hq IMHO (cd and
LP). I bought a few remastered Hendrix cds a couple of years ago and the
quality compared to the record is diabolical - compressed and flat. They
must have got something right 40 years ago after all, at least to my mind.

No they didn't, because the cutting master tapes used to produce LPs
were all compressed and heavily EQ'd versions of the original recorded
masters...

Are you still going on about lp production masters? First of all, not
all lp masters are compressed and/or heavily eq'd. Second, some eq is
meant to be complementary to the natural frequency response of the
medium. In other words, an lp master that *isn't* eq'd might be
considered 'broken', as would be an lp master without the RIAA curve.

You are also comparing the apples of the original lp issue (the good
sounding one) with the oranges of the cd issue (flat, compressed).

Stephen

On Tue, 22 Jul 2003 20:36:09 +0100, Nick Gorham
wrote:

Stewart Pinkerton wrote:

*All* amps use feedback, but some don't use *global* feedback, leading
to a common claim about 'zero feedback' valve amps.

Been thinking about this, where is the feedback in a triode, with a
NiCad between its cathode and ground ?

I use this in my phono stage, and I can't for the life of me, see any
feedback.

It's in the total impedance to ground, including the internal
resistances of the NiCad and the triode cathode, also the internal
feedback from anode to grid. That's why the pentode was developed, to
reduce this internal feedback and thereby increase gain.

To be fair, this is certainly about as low a feedback value as you can
get from a triode, with the NiCad bias!
--

Stewart Pinkerton | Music is Art - Audio is Engineering

"MiNe 109" wrote in message

In article ,
Chesney Christ wrote:

A certain RJH, of uk.rec.audio "fame", writes :

My 'reference' recordings are an old Louis Armstrong LP (50s I
think) and an original of Let it Bleed (66?). The quality (as well
as the music let's not forget!) is superb. Much of the late beatles
stuff is pretty hq IMHO (cd and LP). I bought a few remastered
Hendrix cds a couple of years ago and the quality compared to the
record is diabolical - compressed and flat. They must have got
something right 40 years ago after all, at least to my mind.

No they didn't, because the cutting master tapes used to produce LPs
were all compressed and heavily EQ'd versions of the original
recorded masters...

Are you still going on about lp production masters? First of all, not
all lp masters are compressed and/or heavily eq'd.

The compression is a variable, the equalization is pretty much a given.

Second, some eq is
meant to be complementary to the natural frequency response of the
medium. In other words, an lp master that *isn't* eq'd might be
considered 'broken', as would be an lp master without the RIAA curve.

The problem with this wild-add theory is that the natural frequency response
of the LP medium varies tremendously from playback system to playback
system.

You are also comparing the apples of the original lp issue (the good
sounding one) with the oranges of the cd issue (flat, compressed).

Since no reliable independent standard has been cited for "good sounding",
you're talking out the back of your neck.

A certain MiNe 109, of uk.rec.audio "fame", writes :
No they didn't, because the cutting master tapes used to produce LPs
were all compressed and heavily EQ'd versions of the original recorded
masters...

Are you still going on about lp production masters? First of all, not
all lp masters are compressed and/or heavily eq'd.

Pick an LP at random in a music shop, it probably is. A tiny fraction of
LPs manufactured in the early-mid 80s are less so. I'll wager at least
90% of LPs out there are heavily doctored.

Second, some eq is
meant to be complementary to the natural frequency response of the
medium.

Complete and total hogwash! The final recorded work as the artist
intends is on the final master tape (that is why it is called the
"master"), and all mixing and EQing to extract the correct sound will
have been done during the production of that master. From that point
forth, mass production is singularly concerned with reproducing that
master tape as closely as possible.

It is possible to further alter it as required for the target audience,
and this is often done for pop music, but it is incorrect to say that
this is "necessary" and it is bunkum to talk about it being
"complimentary" to anything. Digital's natural frequency response, when
properly aligned and set up, is ruler flat so no EQ is necessary. It
will reproduce the recorded work *exactly* if it is required to do so,
as is frequently the case with classical recordings and on any music
intended to be listened to by serious musophiles.

EQ and compression *are* necessary on vinyl, as the various
imperfections of the medium would ghost much of the sound, and for
practical reasons due to the inherently mechanical nature of the cutting
and playback processes. If you told the engineer this silly
"complimentary" theory of yours, he'd laugh in your face. Engineers used
as little EQ and compression as they could get away with. Unfortunately
that was still a lot.

In other words, an lp master that *isn't* eq'd might be
considered 'broken',

It certainly would be broken - without extensive EQ and compression the
resulting LP would be unplayable, and the cutting lathe could be
seriously damaged (notwithstanding technological developments in the 80s
which enhanced this situation - albeit too late). These are PRACTICAL
CONSIDERATIONS, and are absolutely nothing to do with making the music
more enjoyable. They are necessary for the music to be playable in the
first place. It's that simple.

as would be an lp master without the RIAA curve.

Another nasty idiosyncrasy, completely unnecessary with the advent of
digital.

You are also comparing the apples of the original lp issue (the good
sounding one) with the oranges of the cd issue (flat, compressed).

As we all know, the process of playing back vinyl is what adds all the
warmth (read : distortion). The CD will be a fairly authentic
reproduction of the LP cutting master - ie flat and crap. That's what is
going onto your vinyl, baby.

To get the best out of the CD you need to go back to the master tape and
do a direct cut, straight over to the digital. Then you'll be in a
position to hear all the bits that they had to remove from the LP.


--

"Jokes mentioning ducks were considered particularly funny." - cnn.com

Chris Morriss wrote:

In message , Nick Gorham
writes

Stewart Pinkerton wrote:

*All* amps use feedback, but some don't use *global* feedback, leading
to a common claim about 'zero feedback' valve amps.


Been thinking about this, where is the feedback in a triode, with a
NiCad between its cathode and ground ?

I use this in my phono stage, and I can't for the life of me, see any
feedback.

--
Nick


The low internal impedance in a triode is because of the internal
feedback between the anode and the grid. Although the feedback
mechanism is obvious at high frequencies (Miller effect) the varying
voltage on the anode couples to the grid as an NFB mechanism even at LF.

Yes I can see that, didn't think of it a feedback, but you are right.
Don't quite see how that leads to Miller, but thats probably my lack of
understanding. Should be able to fix that given time :-)

--
Nick