"Arny Krueger" wrote in message
...

"Eiron" wrote in message
...
Browsing some amp specs, I find that one old Rotel amp has ten
times the distortion of the others in the range.
Is this a typo or was the RA-960 specially designed for people
who like valve (tube) sound?

Compare http://www.rotel.com/content/manuals/ra960bx_eng.pdf
with http://www.rotel.com/content/manuals/ra980bx_eng.pdf
(and the same for rb... power amps)

Most good SS amps can be speced for 0.03%, 0.3%, 3%, or 10%
THD by means of adjusting the rated power. Same amp.




You also need to remember that the majority of valve amps produce
predominately second harmonic distortion to which the ear is very
tolerant, whereas SS amps are usually third and odd harmonics
which the ear doesn't like at all.



--
Woody

harrogate three at ntlworld dot com

On Mon, 30 Jan 2012 21:16:09 -0000, "Woody"
wrote:

"Arny Krueger" wrote in message
m...

"Eiron" wrote in message
...
Browsing some amp specs, I find that one old Rotel amp has ten
times the distortion of the others in the range.
Is this a typo or was the RA-960 specially designed for people
who like valve (tube) sound?

Compare http://www.rotel.com/content/manuals/ra960bx_eng.pdf
with http://www.rotel.com/content/manuals/ra980bx_eng.pdf
(and the same for rb... power amps)

Most good SS amps can be speced for 0.03%, 0.3%, 3%, or 10%
THD by means of adjusting the rated power. Same amp.




You also need to remember that the majority of valve amps produce
predominately second harmonic distortion to which the ear is very
tolerant, whereas SS amps are usually third and odd harmonics
which the ear doesn't like at all.

But do bear in mind two things.

First, small valve amps generally produce an awful lot of second
harmonics, while solid state amps produce bugger all of any kind of
harmonics.

Second, harmonics are never the problem while listening to music.
Intermod is the problem because it is generally unrelated musically to
any of the wanted notes. For the production of intermods, it makes no
difference whether the amp's distortion is predominantly odd or even.

d

"Don Pearce" wrote in message
...
On Mon, 30 Jan 2012 21:16:09 -0000, "Woody"
wrote:

"Arny Krueger" wrote in message
om...

"Eiron" wrote in message
...
Browsing some amp specs, I find that one old Rotel amp has
ten
times the distortion of the others in the range.
Is this a typo or was the RA-960 specially designed for
people
who like valve (tube) sound?

Compare http://www.rotel.com/content/manuals/ra960bx_eng.pdf
with http://www.rotel.com/content/manuals/ra980bx_eng.pdf
(and the same for rb... power amps)

Most good SS amps can be speced for 0.03%, 0.3%, 3%, or 10%
THD by means of adjusting the rated power. Same amp.




You also need to remember that the majority of valve amps
produce
predominately second harmonic distortion to which the ear is
very
tolerant, whereas SS amps are usually third and odd harmonics
which the ear doesn't like at all.

But do bear in mind two things.

First, small valve amps generally produce an awful lot of
second
harmonics, while solid state amps produce bugger all of any
kind of
harmonics.

Second, harmonics are never the problem while listening to
music.
Intermod is the problem because it is generally unrelated
musically to
any of the wanted notes. For the production of intermods, it
makes no
difference whether the amp's distortion is predominantly odd or
even.

d



The point was that the ear is very tolerant of second harmonic
distortion so you can have what appears to be a high level of
distortion on a valve amp on paper - measured by figures in front
of the decimal point - but the brain doesn't object. Agreed SS
amps produce little or no distortion at any harmonic but what
they do produce is mainly odd harmonics which the ear finds
objectionable so it is easy to see why valves (or Class A SS
amps) somehow sound 'right.'

I seem to remember that the late great JLH (or was it Doug Self?)
did some testing many years ago to try to find out why SS amps
just don't sound the same as valves. What came out was that the
ear was not unhappy at as high as 1-2% or more second harmonic
distortion, but it could detect odd harmonic many times lower
that that - and I'm talking well less than 0.1% here. I'll have
to have a dig and see if I've still got the original somewhere -
I'm sure I kept it.


--
Woody

harrogate three at ntlworld dot com

"Woody"

The point was that the ear is very tolerant of second harmonic distortion
so you can have what appears to be a high level of distortion on a valve
amp on paper - measured by figures in front of the decimal point - but the
brain doesn't object.

** Not true with music programme.

Maybe true with pure tones and with 2nd harmonic content less than 1% by
voltage - but the term "object" is subjective not factual.



I seem to remember

** Yawnnnnnnnnn...

Folk remember what they feel like remembering.


.... Phil

On Mon, 30 Jan 2012 23:20:16 -0000, "Woody"
wrote:

"Don Pearce" wrote in message
...
On Mon, 30 Jan 2012 21:16:09 -0000, "Woody"
wrote:

"Arny Krueger" wrote in message
news:lI6dneSVc7XUVbvSnZ2dnUVZ5jadnZ2d@giganews. com...

"Eiron" wrote in message
...
Browsing some amp specs, I find that one old Rotel amp has
ten
times the distortion of the others in the range.
Is this a typo or was the RA-960 specially designed for
people
who like valve (tube) sound?

Compare http://www.rotel.com/content/manuals/ra960bx_eng.pdf
with http://www.rotel.com/content/manuals/ra980bx_eng.pdf
(and the same for rb... power amps)

Most good SS amps can be speced for 0.03%, 0.3%, 3%, or 10%
THD by means of adjusting the rated power. Same amp.




You also need to remember that the majority of valve amps
produce
predominately second harmonic distortion to which the ear is
very
tolerant, whereas SS amps are usually third and odd harmonics
which the ear doesn't like at all.

But do bear in mind two things.

First, small valve amps generally produce an awful lot of
second
harmonics, while solid state amps produce bugger all of any
kind of
harmonics.

Second, harmonics are never the problem while listening to
music.
Intermod is the problem because it is generally unrelated
musically to
any of the wanted notes. For the production of intermods, it
makes no
difference whether the amp's distortion is predominantly odd or
even.

d



The point was that the ear is very tolerant of second harmonic
distortion so you can have what appears to be a high level of
distortion on a valve amp on paper - measured by figures in front
of the decimal point - but the brain doesn't object. Agreed SS
amps produce little or no distortion at any harmonic but what
they do produce is mainly odd harmonics which the ear finds
objectionable so it is easy to see why valves (or Class A SS
amps) somehow sound 'right.'

I seem to remember that the late great JLH (or was it Doug Self?)
did some testing many years ago to try to find out why SS amps
just don't sound the same as valves. What came out was that the
ear was not unhappy at as high as 1-2% or more second harmonic
distortion, but it could detect odd harmonic many times lower
that that - and I'm talking well less than 0.1% here. I'll have
to have a dig and see if I've still got the original somewhere -
I'm sure I kept it.

Another thing to remember is that while valve amps (single ended ones,
that is) produce predominantly second, or even harmonics, the amount
of third harmonic they produce is also far in excess of that from an
SS amp.

Self's work, if I remember right, was really about crossover
distortion which was not understood terribly well in the early days.
Now anybody with a computer and sound card can analyse it fully and
deal with it. It took a while for designers to understand the
mechanisms and design properly. Since then there is no audible
difference between competent amplifiers of any class.

d

Somewhere on teh intarwebs Don Pearce wrote:
[snip]
Self's work, if I remember right, was really about crossover
distortion which was not understood terribly well in the early days.
Now anybody with a computer and sound card can analyse it fully and
deal with it.

I'd be very grateful if you were to give me some pointers. I'm about to
start building my own speakers from the best drivers out of maybe five older
pairs (bit of a mix'n'match) and would love to know more about sussing out
T/SPs and XO building using the computer.

TIA,
--
Shaun.

"Humans will have advanced a long, long, way when religious belief has a
cozy little classification in the DSM."
David Melville (in r.a.s.f1)

On Sat, 4 Feb 2012 23:50:24 +1300, "~misfit~"
wrote:

Somewhere on teh intarwebs Don Pearce wrote:
[snip]
Self's work, if I remember right, was really about crossover
distortion which was not understood terribly well in the early days.
Now anybody with a computer and sound card can analyse it fully and
deal with it.

I'd be very grateful if you were to give me some pointers. I'm about to
start building my own speakers from the best drivers out of maybe five older
pairs (bit of a mix'n'match) and would love to know more about sussing out
T/SPs and XO building using the computer.

TIA,

Get hold of Vance Dickason's "Loudspeaker Design cookbook". You can
download a PDF of it readily enough, then if it suits, buy the real
thing.

Thiel-Small parameters are covered quite well. You can put the
equations into a spreadsheet to make them easy to use.Crossovers are
covered there too.

Read and understand before you start cutting MDF, though.

d

"Don Pearce" wrote in message
...
On Sat, 4 Feb 2012 23:50:24 +1300, "~misfit~"
wrote:

Somewhere on teh intarwebs Don Pearce wrote:
[snip]
Self's work, if I remember right, was really about crossover
distortion which was not understood terribly well in the early days.
Now anybody with a computer and sound card can analyse it fully and
deal with it.

I'd be very grateful if you were to give me some pointers. I'm about to
start building my own speakers from the best drivers out of maybe five
older
pairs (bit of a mix'n'match) and would love to know more about sussing out
T/SPs and XO building using the computer.

TIA,

Get hold of Vance Dickason's "Loudspeaker Design cookbook". You can
download a PDF of it readily enough,

Really?

"Woody" wrote in message
...
"Don Pearce" wrote in message
...

Second, harmonics are never the problem while listening to music.
Intermod is the problem because it is generally unrelated musically to
any of the wanted notes. For the production of intermods, it makes no
difference whether the amp's distortion is predominantly odd or even.

The point was that the ear is very tolerant of second harmonic distortion
so you can have what appears to be a high level of distortion on a valve
amp on paper - measured by figures in front of the decimal point - but the
brain doesn't object.

First off Woody, you are obviously obfuscating the fact that you were wrong
and that Mr. Pearce provided you with a much-needed correction. If you were
a man, you'd start out by admitting that you were wrong.

You've also still totally missed the point, Woody.

Any amplfier that produces *any* order of nonlinear distortion is going to
produce IM when concurrently reproducing multiple tones, such as with real
world music and speech.

Some kinds of harmonic distortion can be either masked or even thought to be
euphonic because they are related to the tone structure of the music signal
that is already there.

Now here is the critical point: IM distortion is rarely if ever similar to
the tone structure of the music. It is generally aharmonic. IOW, it sticks
out like a sore thumb.

Read my lips, Woody: There is *no* known way to produce harmonic distortion
without also producing IM with any real world musical or voice signal. Low
order harmonic distortion may sneak by the ear, but the IM that *must* be
produced at the same time won't.

"Woody"


You also need to remember that the majority of valve amps produce
predominately second harmonic distortion


** This is a very silly myth.

A correctly operating, push-pull tube output stage produces mainly 3rd
harmonic distortion.

So does a SS one - but about 100 times less.




.... Phil