Question for Sylvia: Splitting AV output

[Trevor]

"Trevor Wilson" <trevor@SPAMBLOCKrageaudio.com.au> wrote in message
news:ave81eFl0qdU1@mid.individual.net...

Or this POS:

http://www.sakurasystems.com/products/47amp.html

Same output stage that you can find in a TV set. It'll set you back
several grand.

It won't set *me* back anything! I sure that buy that sort of crap.

Trevor.

 

[F Murtz]

Trevor wrote:

"felix_unger" <me@nothere.com> wrote in message
news:avdalvFf8spU1@mid.individual.net...
The tonal qualities of valve amps is legendary

Sure is, that's why everyone uses solid state now
Silly argument, everyone uses solid state because it is cheaper, easier

to transport etc, nothing to do with tonal qualities, the vast majority
do not carry on about little nuances of reproduction,extremely few carry
on like wine snobs in their field.

Trevor.

 

[Trevor]

"F Murtz" <haggisz@hotmail.com> wrote in message
news:kmstes$v25$1@dont-email.me...

Trevor wrote:
"felix_unger" <me@nothere.com> wrote in message
news:avdalvFf8spU1@mid.individual.net...
The tonal qualities of valve amps is legendary

Sure is, that's why everyone uses solid state now

Silly argument, everyone uses solid state because it is cheaper, easier to
transport etc,

Yep, and a dozen other benefits.

nothing to do with tonal qualities,

Yep, don't want to add any "tonal qualities"

the vast majority do not carry on about little nuances of
reproduction,extremely few carry on like wine snobs in their field.

Yep, happy to listen to the music, not (mass)debate endlessly about personal
preferences.

Trevor.

 

[Frank Slootweg]

yaputya <yaputya.leftlegin@gmail.com> wrote:

"felix_unger" <me@nothere.com> wrote in message news:avbu2sF5400U1@mid.individual.net...
On 13-May-2013 7:07 PM, Trevor wrote:

"felix_unger" <me@nothere.com> wrote in message
news:avbli5F392aU1@mid.individual.net...
So why then do the most fastidious audiophiles prefer valve amplifiers?
They're commonly known as audiophools. What people *prefer* does not have to
bear any relationship to absolute performance, just their personal notion of
it.
Valve amps are preferred by many electric guitarists for their distortion
qualities of course, something you may choose to *produce* a certain musical
"sound", but not a good choice for musical *reproduction* of that sound, and
certainly not when you don't want that distortion at all.

So let's see some distortion figures for Hi Fi valve amps vs transistor/mosfet amps then

Why would we? THD figures are rather meaningless. That they're easy to
measure and quote don't mean they're meaningfull.

from SC June 2008 Altitude 3500-SS Stereo Valve Amplifier (RRP $1899)
@32W THD < 0.63% at 1kHz

compare this to two of SCs power amp modules;
from SC January 2004 Studio 350 Audio Amplifier (transistor)
@180W THD < 0.002% at 1kHz

from SC August 2008 Ultra-LD Mk.2 200W Power Amplifier (transistor)
@100W THD < 0.001% at 1kHz

Also, valve amps have very poor damping factors which means the loudspeaker
cone excursions are not tightly controlled, especially in the 'piston' range
below about 500 Hz. (i.e. muddy bass).

 

[DavidW]

Trevor Wilson wrote:

* The use of loudspeakers whose impedance characteristic is such that
the vast majority of solid state amplifiers cannot deal with it. Like
this:
http://www.rageaudio.com.au/modules/gallery/view.php?a=Accustat&image=091027105452_accu.jpg

That's a craaazy-looking impedance graph.

 

[Trevor Wilson]

On 15/05/2013 8:13 AM, DavidW wrote:

Trevor Wilson wrote:
* The use of loudspeakers whose impedance characteristic is such that
the vast majority of solid state amplifiers cannot deal with it. Like
this:
http://www.rageaudio.com.au/modules/gallery/view.php?a=Accustat&image=091027105452_accu.jpg

That's a craaazy-looking impedance graph.

**It is pretty nasty, but certainly not unusual for many electrostatic
loudspeakers. The original Quad ESL57 possessed an impedance curve at
low frequencies that went extremely low indeed.


--
Trevor Wilson www.rageaudio.com.au

 

[Trevor Wilson]

On 15/05/2013 12:29 AM, Frank Slootweg wrote:

yaputya <yaputya.leftlegin@gmail.com> wrote:

"felix_unger" <me@nothere.com> wrote in message news:avbu2sF5400U1@mid.individual.net...
On 13-May-2013 7:07 PM, Trevor wrote:

"felix_unger" <me@nothere.com> wrote in message
news:avbli5F392aU1@mid.individual.net...
So why then do the most fastidious audiophiles prefer valve amplifiers?
They're commonly known as audiophools. What people *prefer* does not have to
bear any relationship to absolute performance, just their personal notion of
it.
Valve amps are preferred by many electric guitarists for their distortion
qualities of course, something you may choose to *produce* a certain musical
"sound", but not a good choice for musical *reproduction* of that sound, and
certainly not when you don't want that distortion at all.

So let's see some distortion figures for Hi Fi valve amps vs transistor/mosfet amps then

Why would we? THD figures are rather meaningless. That they're easy to
measure and quote don't mean they're meaningfull.

**Utterly and completely untrue. THD figures (comprehensives ones, which
include the spectrum of distortion components) can tell us a great deal
about an audio product. That said, it is also true that beyond certain
limits, further reductions in THD may not be useful for humans. Such
reductions may cause other problems, which can introduce other artefacts
which humans can respond negatively to.

Make no mistake: An amplifier which exhibits (say) 10% THD _IS_
introducing it's own signature into a system and is not acceptable for a
high fidelity reproduction system. An amplifier which exhibits less than
(say) 0.1% THD is not likely to be so compromised. An amplifier which
exhibits less than (say) 0.001% THD is unlikely to be differentiated
from the 0.1% example.



--
Trevor Wilson www.rageaudio.com.au

 

[yaputya]

"Trevor" <trevor@home.net> wrote in message news:kmsjqm$3uf$1@speranza.aioe.org...

"felix_unger" <me@nothere.com> wrote in message news:avbuafF5400U2@mid.individual.net...
On 13-May-2013 8:30 PM, Rod Speed wrote:

So why then do the most fastidious audiophiles prefer valve amplifiers?

Because they are brain dead fools that have never
had a fucking clue about anything at all, ever.

So you're willing to claim there's no difference between CD sound, and vinyl, or valve amp and transistor? You won't get many
HiFi enthusiasts to agree then.

Of course there is a difference, thankfully technology has improved greatly, and the problems with valve amps and vinyl records
are not something we have to put up with any more. That a minority still choose to do so is entirely their choice, and they are
welcome to it.

Trevor.

Too bloody true. These idiots who cling on to expensive antiquated technology seem to forget
all the other problems they have to put up with....if you are stupid enough to spend money
on such crap I guess you will convince yourself it sounds better, or you just have to admit
you are a gullible fool.....
-pops and clicks
-scratches and dust
-turntable noise, wow and flutter, rumble
-stylus wear
-microphonic valves
-valves wear out and lose emission

And despite poor damping factors indicating valve amp output impedances of several ohms,
I bet the fools are also paying for 'Monster Cable' too!!!!


etc. etc.

 

[Frank Slootweg]

Trevor Wilson <trevor@spamblockrageaudio.com.au> wrote:

On 15/05/2013 12:29 AM, Frank Slootweg wrote:
yaputya <yaputya.leftlegin@gmail.com> wrote:

"felix_unger" <me@nothere.com> wrote in message news:avbu2sF5400U1@mid.individual.net...
On 13-May-2013 7:07 PM, Trevor wrote:

"felix_unger" <me@nothere.com> wrote in message
news:avbli5F392aU1@mid.individual.net...
So why then do the most fastidious audiophiles prefer valve amplifiers?
They're commonly known as audiophools. What people *prefer* does not have to
bear any relationship to absolute performance, just their personal notion of
it.
Valve amps are preferred by many electric guitarists for their distortion
qualities of course, something you may choose to *produce* a certain musical
"sound", but not a good choice for musical *reproduction* of that sound, and
certainly not when you don't want that distortion at all.

So let's see some distortion figures for Hi Fi valve amps vs transistor/mosfet amps then

Why would we? THD figures are rather meaningless. That they're easy to
measure and quote don't mean they're meaningfull.

**Utterly and completely untrue. THD figures (comprehensives ones, which
include the spectrum of distortion components) can tell us a great deal
about an audio product.

I obviously refered to the *non*-comprehensive ones which yaputya
quoted (but you snipped), i.e. "@XXW THD < 0.YY% at 1kHz". By definition
the "T" in THD makes the THD meaningless if not accompied by a slew of
other relevant/related data. But I know that you know that.

But to be [f|F]rank, it was mainly flame-bait. Sorry that you we're
the one that bit / got hooked.

[...]

 

[yaputya]

"Frank Slootweg" <this@ddress.is.invalid> wrote in message news:avhgh5FctprU1@mid.individual.net...

Trevor Wilson <trevor@spamblockrageaudio.com.au> wrote:
On 15/05/2013 12:29 AM, Frank Slootweg wrote:
yaputya <yaputya.leftlegin@gmail.com> wrote:

"felix_unger" <me@nothere.com> wrote in message news:avbu2sF5400U1@mid.individual.net...
On 13-May-2013 7:07 PM, Trevor wrote:

"felix_unger" <me@nothere.com> wrote in message
news:avbli5F392aU1@mid.individual.net...
So why then do the most fastidious audiophiles prefer valve amplifiers?
They're commonly known as audiophools. What people *prefer* does not have to
bear any relationship to absolute performance, just their personal notion of
it.
Valve amps are preferred by many electric guitarists for their distortion
qualities of course, something you may choose to *produce* a certain musical
"sound", but not a good choice for musical *reproduction* of that sound, and
certainly not when you don't want that distortion at all.

So let's see some distortion figures for Hi Fi valve amps vs transistor/mosfet amps then

Why would we? THD figures are rather meaningless. That they're easy to
measure and quote don't mean they're meaningfull.

**Utterly and completely untrue. THD figures (comprehensives ones, which
include the spectrum of distortion components) can tell us a great deal
about an audio product.

I obviously refered to the *non*-comprehensive ones which yaputya
quoted (but you snipped), i.e. "@XXW THD < 0.YY% at 1kHz". By definition
the "T" in THD makes the THD meaningless if not accompied by a slew of
other relevant/related data. But I know that you know that.

But to be [f|F]rank, it was mainly flame-bait. Sorry that you we're
the one that bit / got hooked.

So you are a troll

[...]

 

[Frank Slootweg]

yaputya <yaputya.leftlegin@gmail.com> wrote:

"Frank Slootweg" <this@ddress.is.invalid> wrote in message news:avhgh5FctprU1@mid.individual.net...
Trevor Wilson <trevor@spamblockrageaudio.com.au> wrote:
On 15/05/2013 12:29 AM, Frank Slootweg wrote:
yaputya <yaputya.leftlegin@gmail.com> wrote:

"felix_unger" <me@nothere.com> wrote in message news:avbu2sF5400U1@mid.individual.net...
On 13-May-2013 7:07 PM, Trevor wrote:

"felix_unger" <me@nothere.com> wrote in message
news:avbli5F392aU1@mid.individual.net...
So why then do the most fastidious audiophiles prefer valve amplifiers?
They're commonly known as audiophools. What people *prefer* does not have to
bear any relationship to absolute performance, just their personal notion of
it.
Valve amps are preferred by many electric guitarists for their distortion
qualities of course, something you may choose to *produce* a certain musical
"sound", but not a good choice for musical *reproduction* of that sound, and
certainly not when you don't want that distortion at all.

So let's see some distortion figures for Hi Fi valve amps vs transistor/mosfet amps then

Why would we? THD figures are rather meaningless. That they're easy to
measure and quote don't mean they're meaningfull.

**Utterly and completely untrue. THD figures (comprehensives ones, which
include the spectrum of distortion components) can tell us a great deal
about an audio product.

I obviously refered to the *non*-comprehensive ones which yaputya
quoted (but you snipped), i.e. "@XXW THD < 0.YY% at 1kHz". By definition
the "T" in THD makes the THD meaningless if not accompied by a slew of
other relevant/related data. But I know that you know that.

But to be [f|F]rank, it was mainly flame-bait. Sorry that you we're
the one that bit / got hooked.

So you are a troll

Nope, it was a somewhat provocative response to a rather meaningless
specification. People who talk back to/at you aren't neccessarily
trolls. So why the ad Hominem? Don't you have a real argument?

BTW, do you think that a troll would have let Trevor Wilson get away
with his "**Utterly and completely untrue." statement?

 

[yaputya]

"Frank Slootweg" <this@ddress.is.invalid> wrote in message news:avkr5gF56oiU1@mid.individual.net...

yaputya <yaputya.leftlegin@gmail.com> wrote:

"Frank Slootweg" <this@ddress.is.invalid> wrote in message news:avhgh5FctprU1@mid.individual.net...
Trevor Wilson <trevor@spamblockrageaudio.com.au> wrote:
On 15/05/2013 12:29 AM, Frank Slootweg wrote:
yaputya <yaputya.leftlegin@gmail.com> wrote:

"felix_unger" <me@nothere.com> wrote in message news:avbu2sF5400U1@mid.individual.net...
On 13-May-2013 7:07 PM, Trevor wrote:

"felix_unger" <me@nothere.com> wrote in message
news:avbli5F392aU1@mid.individual.net...
So why then do the most fastidious audiophiles prefer valve amplifiers?
They're commonly known as audiophools. What people *prefer* does not have to
bear any relationship to absolute performance, just their personal notion of
it.
Valve amps are preferred by many electric guitarists for their distortion
qualities of course, something you may choose to *produce* a certain musical
"sound", but not a good choice for musical *reproduction* of that sound, and
certainly not when you don't want that distortion at all.

So let's see some distortion figures for Hi Fi valve amps vs transistor/mosfet amps then

Why would we? THD figures are rather meaningless. That they're easy to
measure and quote don't mean they're meaningfull.

**Utterly and completely untrue. THD figures (comprehensives ones, which
include the spectrum of distortion components) can tell us a great deal
about an audio product.

I obviously refered to the *non*-comprehensive ones which yaputya
quoted (but you snipped), i.e. "@XXW THD < 0.YY% at 1kHz". By definition
the "T" in THD makes the THD meaningless if not accompied by a slew of
other relevant/related data. But I know that you know that.

But to be [f|F]rank, it was mainly flame-bait. Sorry that you we're
the one that bit / got hooked.

So you are a troll

Nope, it was a somewhat provocative response to a rather meaningless
specification. People who talk back to/at you aren't neccessarily
trolls. So why the ad Hominem? Don't you have a real argument?

Amplifier manufacturers nearly always quote the THD at 1kHz, it is a
perfectly valid way to compare amps as the other distortion measurements
will reflect the quality of the 1kHz result.
The manufacturers of the Altitude amp I quoted do the same:
http://www.fountek.net/products.asp?id=114
Note that is the only distortion measuement they mention.

SC measured and plotted the THD vs power and THD vs frequency for
the Altitude and their 200W amp module. Since this is not a binary NG
I cannot post them here, but they clearyly show that the valve amp is
vastly inferior in distortion at all frequencies and powers.

BTW, do you think that a troll would have let Trevor Wilson get away
with his "**Utterly and completely untrue." statement?

What's the difference between a provocative response and a troll, then?

 

[felix_unger]

On 17-May-2013 9:12 PM, yaputya wrote:

"Frank Slootweg" <this@ddress.is.invalid> wrote in message news:avkr5gF56oiU1@mid.individual.net...
yaputya <yaputya.leftlegin@gmail.com> wrote:
"Frank Slootweg" <this@ddress.is.invalid> wrote in message news:avhgh5FctprU1@mid.individual.net...
Trevor Wilson <trevor@spamblockrageaudio.com.au> wrote:
On 15/05/2013 12:29 AM, Frank Slootweg wrote:
yaputya <yaputya.leftlegin@gmail.com> wrote:
"felix_unger" <me@nothere.com> wrote in message news:avbu2sF5400U1@mid.individual.net...
On 13-May-2013 7:07 PM, Trevor wrote:

"felix_unger" <me@nothere.com> wrote in message
news:avbli5F392aU1@mid.individual.net...
So why then do the most fastidious audiophiles prefer valve amplifiers?
They're commonly known as audiophools. What people *prefer* does not have to
bear any relationship to absolute performance, just their personal notion of
it.
Valve amps are preferred by many electric guitarists for their distortion
qualities of course, something you may choose to *produce* a certain musical
"sound", but not a good choice for musical *reproduction* of that sound, and
certainly not when you don't want that distortion at all.
So let's see some distortion figures for Hi Fi valve amps vs transistor/mosfet amps then
Why would we? THD figures are rather meaningless. That they're easy to
measure and quote don't mean they're meaningfull.
**Utterly and completely untrue. THD figures (comprehensives ones, which
include the spectrum of distortion components) can tell us a great deal
about an audio product.
I obviously refered to the *non*-comprehensive ones which yaputya
quoted (but you snipped), i.e. "@XXW THD < 0.YY% at 1kHz". By definition
the "T" in THD makes the THD meaningless if not accompied by a slew of
other relevant/related data. But I know that you know that.

But to be [f|F]rank, it was mainly flame-bait. Sorry that you we're
the one that bit / got hooked.
So you are a troll
Nope, it was a somewhat provocative response to a rather meaningless
specification. People who talk back to/at you aren't neccessarily
trolls. So why the ad Hominem? Don't you have a real argument?
Amplifier manufacturers nearly always quote the THD at 1kHz, it is a
perfectly valid way to compare amps as the other distortion measurements
will reflect the quality of the 1kHz result.
The manufacturers of the Altitude amp I quoted do the same:
http://www.fountek.net/products.asp?id=114
Note that is the only distortion measuement they mention.

SC measured and plotted the THD vs power and THD vs frequency for
the Altitude and their 200W amp module. Since this is not a binary NG
I cannot post them here, but they clearyly show that the valve amp is
vastly inferior in distortion at all frequencies and powers.

THD is only a reliable measure of amplifier quality and performance if
it is quoted as a maximum over the audio bandwidth at a reasonlble power
output level. eg. 0.01% max THD 20hz - 20Khs @ 40w RMS per channel both
channels driven

BTW, do you think that a troll would have let Trevor Wilson get away
with his "**Utterly and completely untrue." statement?
What's the difference between a provocative response and a troll, then?

--
rgds,

Pete
-------
"If Julia is the answer, then what was the stupid question!"

 

[Frank Slootweg]

yaputya <yaputya.leftlegin@gmail.com> wrote:

"Frank Slootweg" <this@ddress.is.invalid> wrote in message news:avkr5gF56oiU1@mid.individual.net...
yaputya <yaputya.leftlegin@gmail.com> wrote:

"Frank Slootweg" <this@ddress.is.invalid> wrote in message news:avhgh5FctprU1@mid.individual.net...
Trevor Wilson <trevor@spamblockrageaudio.com.au> wrote:
On 15/05/2013 12:29 AM, Frank Slootweg wrote:
yaputya <yaputya.leftlegin@gmail.com> wrote:

"felix_unger" <me@nothere.com> wrote in message news:avbu2sF5400U1@mid.individual.net...
On 13-May-2013 7:07 PM, Trevor wrote:

"felix_unger" <me@nothere.com> wrote in message
news:avbli5F392aU1@mid.individual.net...
So why then do the most fastidious audiophiles prefer
valve amplifiers?
They're commonly known as audiophools. What people *prefer*
does not have to bear any relationship to absolute
performance, just their personal notion of it.
Valve amps are preferred by many electric guitarists for
their distortion qualities of course, something you may
choose to *produce* a certain musical "sound", but not a
good choice for musical *reproduction* of that sound, and
certainly not when you don't want that distortion at all.

So let's see some distortion figures for Hi Fi valve amps vs
transistor/mosfet amps then

Why would we? THD figures are rather meaningless. That
they're easy to measure and quote don't mean they're
meaningfull.

**Utterly and completely untrue. THD figures (comprehensives
ones, which include the spectrum of distortion components) can
tell us a great deal about an audio product.

I obviously refered to the *non*-comprehensive ones which
yaputya quoted (but you snipped), i.e. "@XXW THD < 0.YY% at
1kHz". By definition the "T" in THD makes the THD meaningless if
not accompied by a slew of other relevant/related data. But I
know that you know that.

But to be [f|F]rank, it was mainly flame-bait. Sorry that you
we're the one that bit / got hooked.

So you are a troll

Nope, it was a somewhat provocative response to a rather
meaningless specification. People who talk back to/at you aren't
neccessarily trolls. So why the ad Hominem? Don't you have a real
argument?

Amplifier manufacturers nearly always quote the THD at 1kHz, it is a
perfectly valid way to compare amps as the other distortion
measurements will reflect the quality of the 1kHz result.

Yes, I do know what manufacturers quote, but, as I said, that does
not make them particularly useful.

*If* it's a very good amp, the 1kHz at XXW THD number will be
representative for other frequencies and power levels.

The point is that most amps are *not* "very good amps", so it's silly
to trust some non-representative single THD number.

The manufacturers of the Altitude amp I quoted do the same:
http://www.fountek.net/products.asp?id=114
Note that is the only distortion measuement they mention.

SC measured and plotted the THD vs power and THD vs frequency for
the Altitude and their 200W amp module.

*That* is the kind of distortion data I'm referring to, for the
complete frequency and power range.

And then we haven't even touched on crossover distortion and clipping
distortion, nor on the issue that the equal weighing of all harmonics in
THD is a matter of debate.

Since this is not a binary NG
I cannot post them here, but they clearyly show that the valve amp is
vastly inferior in distortion at all frequencies and powers.

BTW, do you think that a troll would have let Trevor Wilson get
away with his "**Utterly and completely untrue." statement?

What's the difference between a provocative response and a troll,
then?

(IMO (and in my case)) A provocative response is on-topic and intended
to trigger an on-topic response. A troll is just intended to trigger
heated responses, anger, etc., i.e. just the emotions matter, not the
content.

Thanks for your response.

 

[Trevor]

"Frank Slootweg" <this@ddress.is.invalid> wrote in message
news:avnbueFm207U1@mid.individual.net...

SC measured and plotted the THD vs power and THD vs frequency for
the Altitude and their 200W amp module.

*That* is the kind of distortion data I'm referring to, for the
complete frequency and power range.

And then we haven't even touched on crossover distortion

Crossover distortion will clearly be shown in THD specs at low power, and is
just as bad (or worse) for any Vacuum tube amp as solid state using the same
amplification class.
Easier and cheaper to build a decent class A solid state amp of the same (or
more) power as a similar VT one these days if low power distortion is your
prime consideration.

and clipping distortion,

No need to go anywhere near clipping with a modern solid state amp of
course, unlike low power VT amps, since you can get about ten times the
power output for less money.

nor on the issue that the equal weighing of all harmonics in
THD is a matter of debate.

If *ALL* harmonics (individually and in total) are below the threshold of
human hearing, as with any good modern solid state amp, (but not with VT
amps) what does it matter?
Why in hell put up with increased even order distortion, just so it makes
the odd order distortion figures look relatively lower, even when they are
actually far higher is absolute terms for example? Only nutbags think like
that. Plenty of those of course :-(
There are plenty of effects processors to digitally add even order
distortion these days if that is what you prefer to clean audio, no need to
buy a valve amp to do it any more.

Trevor.

 

[yaputya]

"felix_unger" <me@nothere.com> wrote in message news:avmm4iFh7reU1@mid.individual.net...

On 17-May-2013 9:12 PM, yaputya wrote:

"Frank Slootweg" <this@ddress.is.invalid> wrote in message news:avkr5gF56oiU1@mid.individual.net...
yaputya <yaputya.leftlegin@gmail.com> wrote:
"Frank Slootweg" <this@ddress.is.invalid> wrote in message news:avhgh5FctprU1@mid.individual.net...
Trevor Wilson <trevor@spamblockrageaudio.com.au> wrote:
On 15/05/2013 12:29 AM, Frank Slootweg wrote:
yaputya <yaputya.leftlegin@gmail.com> wrote:
"felix_unger" <me@nothere.com> wrote in message news:avbu2sF5400U1@mid.individual.net...
On 13-May-2013 7:07 PM, Trevor wrote:

"felix_unger" <me@nothere.com> wrote in message
news:avbli5F392aU1@mid.individual.net...
So why then do the most fastidious audiophiles prefer valve amplifiers?
They're commonly known as audiophools. What people *prefer* does not have to
bear any relationship to absolute performance, just their personal notion of
it.
Valve amps are preferred by many electric guitarists for their distortion
qualities of course, something you may choose to *produce* a certain musical
"sound", but not a good choice for musical *reproduction* of that sound, and
certainly not when you don't want that distortion at all.
So let's see some distortion figures for Hi Fi valve amps vs transistor/mosfet amps then
Why would we? THD figures are rather meaningless. That they're easy to
measure and quote don't mean they're meaningfull.
**Utterly and completely untrue. THD figures (comprehensives ones, which
include the spectrum of distortion components) can tell us a great deal
about an audio product.
I obviously refered to the *non*-comprehensive ones which yaputya
quoted (but you snipped), i.e. "@XXW THD < 0.YY% at 1kHz". By definition
the "T" in THD makes the THD meaningless if not accompied by a slew of
other relevant/related data. But I know that you know that.

But to be [f|F]rank, it was mainly flame-bait. Sorry that you we're
the one that bit / got hooked.
So you are a troll
Nope, it was a somewhat provocative response to a rather meaningless
specification. People who talk back to/at you aren't neccessarily
trolls. So why the ad Hominem? Don't you have a real argument?
Amplifier manufacturers nearly always quote the THD at 1kHz, it is a
perfectly valid way to compare amps as the other distortion measurements
will reflect the quality of the 1kHz result.
The manufacturers of the Altitude amp I quoted do the same:
http://www.fountek.net/products.asp?id=114
Note that is the only distortion measuement they mention.

SC measured and plotted the THD vs power and THD vs frequency for
the Altitude and their 200W amp module. Since this is not a binary NG
I cannot post them here, but they clearyly show that the valve amp is
vastly inferior in distortion at all frequencies and powers.

THD is only a reliable measure of amplifier quality and performance if it is quoted as a maximum over the audio bandwidth at a
reasonlble power output level. eg. 0.01% max THD 20hz - 20Khs @ 40w RMS per channel both channels driven

It is preferable to display the data as a graph which shows THD over the frequency range
for a given power, and THD over the power range for a given frequency, usually 1kHz.
Creating a 3-D plot showing all combinations would be even better, but would require automated testing.
AFAIK nobody does this, since the 2D plots are adequate.
..
SC published 2D graphs for both the Altitude valve amp and their 200W module.

 

[yaputya]

"Frank Slootweg" <this@ddress.is.invalid> wrote in message news:avnbueFm207U1@mid.individual.net...

yaputya <yaputya.leftlegin@gmail.com> wrote:
Amplifier manufacturers nearly always quote the THD at 1kHz, it is a
perfectly valid way to compare amps as the other distortion
measurements will reflect the quality of the 1kHz result.

Yes, I do know what manufacturers quote, but, as I said, that does
not make them particularly useful.

*If* it's a very good amp, the 1kHz at XXW THD number will be
representative for other frequencies and power levels.

The point is that most amps are *not* "very good amps", so it's silly
to trust some non-representative single THD number.

The manufacturers of the Altitude amp I quoted do the same:
http://www.fountek.net/products.asp?id=114
Note that is the only distortion measuement they mention.

SC measured and plotted the THD vs power and THD vs frequency for
the Altitude and their 200W amp module.

*That* is the kind of distortion data I'm referring to, for the
complete frequency and power range.

You should be able to see the SC measurements here (zoom in)
http://imageshack.us/a/img198/3375/distortionvalvevstransi.jpg

These are scanned from SC who hold all copyright etc.