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[email protected] david.dartley@gmail.com is offline
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Default Stereo receievers: THD of .04 vs. .08

Thanks all for the advice on B Stock merchandise.

Okay, I'm scared to mention non-high-end or non-scientific stuff here
because of the flaming I once took from a forger, but here goes:

I think I've decided on buying a pair of Infinity Beta 50 speakers.

I'm among two receivers--a Yamaha 497 (75w per ch) and an Onkyo TX
8522 (100w per ch).

One salient difference is that the Yamaha claims a 0.04 THD, and the
Onkyo a 0.08.
I THINK I have a pretty discerning ear. Do you think that difference
in THD would make much of a difference between those two receivers,
using that one pair of speakers?

Thanks.
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Richard Crowley Richard Crowley is offline
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Default Stereo receievers: THD of .04 vs. .08

wrote ...
Thanks all for the advice on B Stock merchandise.

Okay, I'm scared to mention non-high-end or non-scientific stuff here
because of the flaming I once took from a forger, but here goes:


Just ignore the forgers, the idiots, and the psychopaths.

I think I've decided on buying a pair of Infinity Beta 50 speakers.

I'm among two receivers--a Yamaha 497 (75w per ch) and an Onkyo TX
8522 (100w per ch).

One salient difference is that the Yamaha claims a 0.04 THD, and the
Onkyo a 0.08.
I THINK I have a pretty discerning ear. Do you think that difference
in THD would make much of a difference between those two receivers,
using that one pair of speakers?


Considering that you will be listening through speakers with
10x or maybe even 100x more distortion, dunno how you
would tell the difference?

(That applies to ANY speakers, not just the ones you mentioned.)


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Default Stereo receievers: THD of .04 vs. .08

On Jan 9, 4:29*pm, "Richard Crowley" wrote:
wrote ...

Thanks all for the advice on B Stock merchandise.


Okay, I'm scared to mention non-high-end or non-scientific stuff here
because of the flaming I once took from a forger, but here goes:


Just ignore the forgers, the idiots, and the psychopaths.

I think I've decided on buying a pair of Infinity Beta 50 speakers.


I'm among two receivers--a Yamaha 497 (75w per ch) and an Onkyo TX
8522 (100w per ch).


One salient difference is that the Yamaha claims a 0.04 THD, and the
Onkyo a 0.08.
I THINK I have a pretty discerning ear. *Do you think that difference
in THD would make much of a difference between those two receivers,
using that one pair of speakers?


Considering that you will be listening through speakers with
10x or maybe even 100x more distortion, dunno how you
would tell the difference?

(That applies to ANY speakers, not just the ones you mentioned.)


Thanks. So the 10x to 100x part is what applies to any speakers?

I really didn't know that, nor did I, obviously, know what speaker
spec to look at to find out how much distortion a speaker provides.
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Richard Crowley Richard Crowley is offline
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Default Stereo receievers: THD of .04 vs. .08

wrote ...
"Richard Crowley" wrote:
Considering that you will be listening through speakers with
10x or maybe even 100x more distortion, dunno how you
would tell the difference?

(That applies to ANY speakers, not just the ones you mentioned.)


Thanks. So the 10x to 100x part is what applies to any speakers?

I really didn't know that, nor did I, obviously, know what speaker
spec to look at to find out how much distortion a speaker provides.
THD


They don't generally even quote THD (or IM, or phase, or group
or any other kind of distortion) specs for speakers at all. But the
ones I remember seeing were much greater than 1% (and typically
greater than 10%, even). Note that Infinity doesn't even mention
distortion on the web page that describes your speakers. Very few
(if any?) speaker makers do.

That is why the general consensus is that you will hear a MUCH
greater difference between transducers (microphones & speakers)
and acoustics than you will between similar pieces of electronics.
I would not base a decision on 0.04 vs 0.08% THD in the power
amp.




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Default Stereo receievers: THD of .04 vs. .08

On Jan 9, 4:10 pm, wrote:
One salient difference is that the Yamaha claims a 0.04 THD, and the
Onkyo a 0.08.
I THINK I have a pretty discerning ear. Do you think that difference
in THD would make much of a difference between those two receivers,
using that one pair of speakers?


These figure are specifications: they are written more as a legal
document than anything else, e.g., you might bitch about the
sound, but the manufacturer will put it on the test bench, measure
the THD, show you that it meets that spec, and you're on your own.

Further, THD is one of the LEAST useful measurements of
audio equipment.

Ignore it.

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Default Stereo receievers: THD of .04 vs. .08



Richard Crowley wrote:

wrote ...
Thanks all for the advice on B Stock merchandise.

Okay, I'm scared to mention non-high-end or non-scientific stuff here
because of the flaming I once took from a forger, but here goes:


Just ignore the forgers, the idiots, and the psychopaths.

I think I've decided on buying a pair of Infinity Beta 50 speakers.

I'm among two receivers--a Yamaha 497 (75w per ch) and an Onkyo TX
8522 (100w per ch).

One salient difference is that the Yamaha claims a 0.04 THD, and the
Onkyo a 0.08.
I THINK I have a pretty discerning ear. Do you think that difference
in THD would make much of a difference between those two receivers,
using that one pair of speakers?


Considering that you will be listening through speakers with
10x or maybe even 100x more distortion, dunno how you
would tell the difference?

(That applies to ANY speakers, not just the ones you mentioned.)


The character of speaker distortion is quite different to typical amplifier
distortion.

Graham


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Default Stereo receievers: THD of .04 vs. .08

Any ideas then on where I might get opinions on which of those two
receivers sound better, between the Onkyo and the Yamaha?

I don't think any of the stores convenient to me carry both, so I
don't know where I could check them out side-by-side.

Thanks.
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Default Stereo receievers: THD of .04 vs. .08



Richard Crowley wrote:

They don't generally even quote THD (or IM, or phase, or group
or any other kind of distortion) specs for speakers at all. But the
ones I remember seeing were much greater than 1% (and typically
greater than 10%, even).


At FULL power.

At low power it will be much less.

snip

I would not base a decision on 0.04 vs 0.08% THD in the power
amp.


0.08% is barely any better than the highly discredited 0.1% which was
once considered a benchmark figure (DIN 45510 ? etc) . Amplifiers with
full power THD ratings of ~ 0.1% are audibly defective IME at typical
listening levels.

Bear in mind that the 0.08% figure is a best case number measured at
full power (this suits amplifiers).. At around a watt of output (which
is where most listening is done) the THD is likely to have climbed to
nearly 1% if it's a typical Class AB bipolar output stage.

Graham


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Default Stereo receievers: THD of .04 vs. .08

wrote in message


I think I've decided on buying a pair of Infinity Beta 50
speakers.

I'm among two receivers--a Yamaha 497 (75w per ch) and an
Onkyo TX 8522 (100w per ch).


One salient difference is that the Yamaha claims a 0.04
THD, and the Onkyo a 0.08.


Not relevant. Besides what Richard said about the speakers having tons more
distortion, THD measurements like this can be fudged for marketing purposes,
while being perfectly honest.

A well made SS power amp usually has about 0.03% or less THD at all levels
up to maybe 3/4 of the power level at which the amp clips. The THD then
increases along a smooth curve to about 0.08% just below clipping, and
rapidly to 30% or more above that. This is a big generalization, and some
amps are either quite a bit better or quite a bit worse. For example, some
amps will have only 0.02% THD just below clipping, and others will have
0.2%. Furhtermore amps put out less power at clipping at the frequency
extremes. In fact a lot of receivers won't put out full rated power at 20
Hz. The good news is that a lot of receivers run their whole lives without
getting above 20 watts.

Just for grins but to make a point, lets say that Yamaha and Onkyo both have
their receivers made in the same plant in China, and that those crafty
Chinese put the identically same power amps into both receivers. The Onkyo
marketing department decides that power is what sells receivers, so they
rate their receivers for more power, which makes the distortion go up. The
Yamaha marketing department decides that low distortion is what sells
receivers, so they rate their receivers for a little less power, which makes
the distortion go down.

See my point? The actual distortion of the receiver at its rated power can
be manipulated by juggling the rated power. The difference in rated power
might be less than 10%, which has just about zero audible signficance.

I THINK I have a pretty discerning ear.


Let's stipulate that! ;-)

Do you think
that difference in THD would make much of a difference
between those two receivers, using that one pair of speakers?


Not a chance. I suspect that in a close AB test with levels matched and all
the rest, the power amp in either receiver functions like the proverbial
straight wire with gain.

BTW Richard flinched at giving real world distortion numbers for speakers,
but I won't. The distortion produced by a given speaker is strongly
influenced by power and frequency. All speaker drivers tend to produce
more distortion when operated at higher powers compared to their power
capacity, and they also tend to produce more distortion when operated at
lower frequencies compared to their low frequency limits. Sometimes drivers
will also produce more distortion under other conditions.

In the middle of its operational range, a good loudspeaker driver might have
0.1% distortion or a little less. At its lower limit but at moderate power
levels, the distortion may increase to 5-10%. At low frequencies and high
powers, the distortion can be truely large, on the order of 30% or more.

Surprisingly, 30% distortion at say 40 Hz can be surprisingly acceptable,
because musical instruments that operate in the bass range tend to produce a
lot of harmonics of their own that tend to mask the distortion added by the
speakers. Truely prodigious speakers can have as little as 10% distortion
at 20Hz at very high sound levels like 120 dB. Your typical large
floor-standing home speaker will probably have 10% THD by the time it is
putting out 100 dB at 50 Hz, and things grow worse rapidly below that.

Note that my estimated numbers for loudspeaker distortion tend to agree with
Richard's general point, which is that speakers distortion is so large that
it tends to wash out or mask the distortion in amplifiers. However, at
medium power levels and medium frequencies, a speaker driver's distortion
might be low enough that under ideal conditions, 0.1% THD might be audible.


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Default Stereo receievers: THD of .04 vs. .08

wrote in...
Any ideas then on where I might get opinions on which of those two
receivers sound better, between the Onkyo and the Yamaha?

I don't think any of the stores convenient to me carry both, so I
don't know where I could check them out side-by-side.


I would not expect to hear any difference between them.
I would make the choice based on features that are most
important to me within the price I'm willing to pay.

You are far more likely to hear a difference moving your
speakers or your listening chair a foot or two, than between
any two similar power amps.

But then this tends to be a more practical collection of people
than other newsgroups which are more obsessive and believe
they can actually hear a difference between 0.04 and 0.08%
They also believe in magic cables, wooden knobs, and $3000
power cords, etc. Most of us lack such remarkable heights
of faith.


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Default Stereo receievers: THD of .04 vs. .08



Arny Krueger wrote:

wrote

I think I've decided on buying a pair of Infinity Beta 50
speakers.

I'm among two receivers--a Yamaha 497 (75w per ch) and an
Onkyo TX 8522 (100w per ch).


One salient difference is that the Yamaha claims a 0.04
THD, and the Onkyo a 0.08.


Not relevant. Besides what Richard said about the speakers having tons more
distortion, THD measurements like this can be fudged for marketing purposes,
while being perfectly honest.

A well made SS power amp usually has about 0.03% or less THD at all levels
up to maybe 3/4 of the power level at which the amp clips.


THD specs are typically made 'just prior to clipping'.

The THD in the 100mW to 1W region will be significantly higher than the 'data
sheet figure' though for all typical Class AB bipolar output stages. This is why
amps that only make say 0.08% on the spec sheet ARE audibly inferior to their
betters.

My own benchmark of suitability for good quality audio is a 'spec sheet' figure
of 0.01% which is likely to translate to ~ 0.1% at lower wattages.

Look at this (page 9 "THD + N vs Output Power") for an example of what I mean.
http://www.national.com/ds.cgi/LM/LM3875.pdf
The LM3875 was popularly adopted as the 'Gainclone' in some circles some years
back.

Graham





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Default Stereo receievers: THD of .04 vs. .08

On Jan 9, 6:17 pm, Eeyore
wrote:
Arny Krueger wrote:
wrote


I think I've decided on buying a pair of Infinity Beta 50
speakers.


I'm among two receivers--a Yamaha 497 (75w per ch) and an
Onkyo TX 8522 (100w per ch).


One salient difference is that the Yamaha claims a 0.04
THD, and the Onkyo a 0.08.


Not relevant. Besides what Richard said about the speakers having tons more
distortion, THD measurements like this can be fudged for marketing purposes,
while being perfectly honest.


A well made SS power amp usually has about 0.03% or less THD at all levels
up to maybe 3/4 of the power level at which the amp clips.


THD specs are typically made 'just prior to clipping'.

The THD in the 100mW to 1W region will be significantly higher than the 'data
sheet figure' though for all typical Class AB bipolar output stages. This is why
amps that only make say 0.08% on the spec sheet ARE audibly inferior to their
betters.

My own benchmark of suitability for good quality audio is a 'spec sheet' figure
of 0.01% which is likely to translate to ~ 0.1% at lower wattages.

Look at this (page 9 "THD + N vs Output Power") for an example of what I mean.http://www.national.com/ds.cgi/LM/LM3875.pdf
The LM3875 was popularly adopted as the 'Gainclone' in some circles some years
back.


GIven the way THD is measured, an amplifier will
have a THD spec which goes as the reciprocal of power,
simply because THD is a broadband measurement and
can't distinguish noise from harmonics. This is why the
correct designation is THD+N.

Thus, with a constant noise floor, for every halving of power,
the THD+N figure will rise by about 40%.

Secondly, THD as a measure of audibility has been pretty
much shown to be useless, regardless of the claims
seen here and elsewhere. These claims simply ignore
significant factors such as masking.

If you're claiming on reliably and repeatedly hearing
duifferences at the levels of distortion you're claiming,
look somewhere else, it ain't THD.
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Default Stereo receievers: THD of .04 vs. .08


wrote in message
...
Thanks all for the advice on B Stock merchandise.

Okay, I'm scared to mention non-high-end or non-scientific stuff here
because of the flaming I once took from a forger, but here goes:

I think I've decided on buying a pair of Infinity Beta 50 speakers.

I'm among two receivers--a Yamaha 497 (75w per ch) and an Onkyo TX
8522 (100w per ch).

One salient difference is that the Yamaha claims a 0.04 THD, and the
Onkyo a 0.08.
I THINK I have a pretty discerning ear. Do you think that difference
in THD would make much of a difference between those two receivers,
using that one pair of speakers?

Thanks.


Yamaha's quality is a mite better than Onkyo's - that would be MY criteria.

Mark Z.


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wrote in message


GIven the way THD is measured, an amplifier will
have a THD spec which goes as the reciprocal of power,
simply because THD is a broadband measurement and
can't distinguish noise from harmonics. This is why the
correct designation is THD+N.


Thus, with a constant noise floor, for every halving of
power, the THD+N figure will rise by about 40%.


Secondly, THD as a measure of audibility has been pretty
much shown to be useless, regardless of the claims
seen here and elsewhere. These claims simply ignore
significant factors such as masking.


If you're claiming on reliably and repeatedly hearing
duifferences at the levels of distortion you're claiming,
look somewhere else, it ain't THD.


Agreed. THD|N measurements often raise unecessary concerns by presenting
data that might in the worst case result from low-level distortion like
crossover distortion.

With FFT-based measurement software, ignoring almost all of the noise floor,
and just measuring the actual harmonics is both feasible and often
implemented.

AFAIK this is done by first detecting the frequency of the fundamental. Only
power that is in the FFT buckets that correspond to integer multiples of the
fundamental are included in the final summary.

Similar techniques can be implemented for IM measurements.

When techniques like these are utilized, it is often found that SS
amplifiers have negligable crossover distortion.


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Chris Hornbeck Chris Hornbeck is offline
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On Wed, 9 Jan 2008 16:49:12 -0800 (PST),
wrote:

On Jan 9, 6:17 pm, Eeyore
wrote:


The THD in the 100mW to 1W region will be significantly higher than the 'data
sheet figure' though for all typical Class AB bipolar output stages. This is why
amps that only make say 0.08% on the spec sheet ARE audibly inferior to their
betters.



GIven the way THD is measured, an amplifier will
have a THD spec which goes as the reciprocal of power,
simply because THD is a broadband measurement and
can't distinguish noise from harmonics. This is why the
correct designation is THD+N.

Thus, with a constant noise floor, for every halving of power,
the THD+N figure will rise by about 40%.


And for a perfectly monotonic amplifier, this would
completely describe the case. Modern amplifiers, built as
Graham specified, are non-monotonic in amounts that
matter to the discussion. Several distortion mechanisms
*increase* at lower signal level, and dominate.


Secondly, THD as a measure of audibility has been pretty
much shown to be useless, regardless of the claims
seen here and elsewhere. These claims simply ignore
significant factors such as masking.


Certainly the classic "THD+N" number is hopelessly
outdated. And the classical method of measurement, sending
a sine wave through the amplifier, removing it from
the output, and counting up what's left, leaves a
lot of room for improvement.

But is there any other easy "black box" method to measure
non-linearity? Circuit analysis tells us where to look,
but that's not "black box".


look somewhere else, it ain't THD.


We know that there are significant monotonicity errors
in modern amplifiers and that classical "THD" measurements
mask them in broadband, rather than critical band ways.

My personal pet peeve is that amplifiers should be
specified in conjunction with intended use. Loudspeaker
sensitivity and number, room conditions, etc. define
an amplifier per-channel output level for 85dB SPL,
another for 25dB SPL, and another for 105dB SPL, at
intended listening position.

The first two numbers really matter for (too loud for me!)
critical listening in a very quiet room; the third much less
so (within reason).


Just some thoughts. Much thanks, as always,

Chris Hornbeck

"There's little that's impossible, but it becomes more complicated if
you move between different systems." - Mike Rivers, in another context
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wrote:

Eeyore wrote:
Arny Krueger wrote:
wrote


I think I've decided on buying a pair of Infinity Beta 50
speakers.


I'm among two receivers--a Yamaha 497 (75w per ch) and an
Onkyo TX 8522 (100w per ch).


One salient difference is that the Yamaha claims a 0.04
THD, and the Onkyo a 0.08.


Not relevant. Besides what Richard said about the speakers having tons more
distortion, THD measurements like this can be fudged for marketing purposes,
while being perfectly honest.


A well made SS power amp usually has about 0.03% or less THD at all levels
up to maybe 3/4 of the power level at which the amp clips.


THD specs are typically made 'just prior to clipping'.

The THD in the 100mW to 1W region will be significantly higher than the 'data
sheet figure' though for all typical Class AB bipolar output stages. This is why
amps that only make say 0.08% on the spec sheet ARE audibly inferior to their
betters.

My own benchmark of suitability for good quality audio is a 'spec sheet' figure
of 0.01% which is likely to translate to ~ 0.1% at lower wattages.

Look at this (page 9 "THD + N vs Output Power") for an example of what I mean.
http://www.national.com/ds.cgi/LM/LM3875.pdf
The LM3875 was popularly adopted as the 'Gainclone' in some circles some years
back.


GIven the way THD is measured, an amplifier will
have a THD spec which goes as the reciprocal of power,
simply because THD is a broadband measurement and
can't distinguish noise from harmonics. This is why the
correct designation is THD+N.

Thus, with a constant noise floor, for every halving of power,
the THD+N figure will rise by about 40%.


You're obfuscating.

Noise in a decently designed power amplifier is easily -100dB and WILL NOT dominate such measurements in the way you describe..

Anyone experienced in ampliifer design (or even repair an maintenance) will be familiar with seeing an increasing level of
harmonic products in the analyser output of a tradiotional THD test set as the power level is reduced.

The reason is simple. Distortion in the output stage arises primarily from variations in transconductance of the output devices.
At lower currents, this effect is most severe. It's a simple consequence of the physics.

Graham



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Arny Krueger wrote:

When techniques like these are utilized, it is often found that SS
amplifiers have negligable crossover distortion.


Pure nonsense. Crossover distortion remains the bete noire of conventional Class
AB bipolar designs.

Graham


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"Eeyore" wrote in
message
Arny Krueger wrote:

When techniques like these are utilized, it is often
found that SS amplifiers have negligable crossover
distortion.


Pure nonsense. Crossover distortion remains the bete
noire of conventional Class AB bipolar designs.


Please explain that in the context of the performance of this power
amplifier:

http://www.pcavtech.com/pwramp/macrot-5000VZ/index.htm

For example,

http://www.pcavtech.com/pwramp/macro...ex.htm#DR_001S

represents the following test conditions.

(1) 1 KHz was applied to the amp, and levels were set so that 1 watt was
delivered to an 8 ohm resistive load. This corresponds to FS in the graphic.

(2) The dynamic range test signal was applied. This test signal is composed
of a 1 KHz tone at 60 dB below the signal used in step 1.

(3) The graphic shows a spectral analysis of the output of the power
amplifier, referenced to the signals observed in step (1). We see the
following:

(3a) 60 Hz hum with harmonics, none worse than about 95 dB below the 1 watt
in step (1).

(3b) The 1 KHz test tone, 60 dB below the 1 watt in step (1)

(3c) All harmonics 120 or more dB below the 1 watt in step (1).

Normally, crossover distortion produces a series of harmonics of the low
level test signal. The test signal was about 85 dB below the amp's full
rated power. There are simply no observable harmonics.

Is it possible to have crossover distortion that generates no harmonics of
such a low level test signal?





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wrote in message
...
Thanks all for the advice on B Stock merchandise.

Okay, I'm scared to mention non-high-end or non-scientific stuff here
because of the flaming I once took from a forger, but here goes:

I think I've decided on buying a pair of Infinity Beta 50 speakers.

I'm among two receivers--a Yamaha 497 (75w per ch) and an Onkyo TX
8522 (100w per ch).

One salient difference is that the Yamaha claims a 0.04 THD, and the
Onkyo a 0.08.
I THINK I have a pretty discerning ear. Do you think that difference
in THD would make much of a difference between those two receivers,
using that one pair of speakers?


**Not per se. The bottom line is this:

Amplifiers (and speakers, for that matter) exhibit a large number of
characteristics. THD (at one power level and frequency) is just one
specification which may be meaningful for you and your speakers. Unless you
have a fair depth of technical knowledge, it is virtually impossible to
predict which amp will perform better on a given speaker system (if at all).

Think of it this way:

Which car accelerates and corners better: A 4.6 Litre V8 powered car, or a
1.8Litre 4 cyl one?

Answer: It depends on the cars. In the above test, I chose a Ford Mustang
and a Lotus Elise. The Lotus easily outperforms the Mustang. In every area.
The Lotus handles better, will easily out accelerate a Mustang (or pretty
much anything else on the road) and do it with far less power.

Same deal with amplifiers and speakers. Without examining several pages of
data (for both amps and speakers) it is virtually impossible to predict
which will work best.

Listen to both amps, through your choice of speakers and choose either
whichever sounds best, or, if there is not sound difference (highly likely),
choose whichever one you like the look of/better warranty/better
features/etc.

Trevor Wilson



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Arny Krueger wrote:

"Eeyore" wrote
Arny Krueger wrote:

When techniques like these are utilized, it is often
found that SS amplifiers have negligable crossover
distortion.


Pure nonsense. Crossover distortion remains the bete
noire of conventional Class AB bipolar designs.


Please explain that in the context of the performance of this power
amplifier:

http://www.pcavtech.com/pwramp/macrot-5000VZ/index.htm


Is it a "conventional Class AB bipolar design" ?

I suspect not.

Graham



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JANA JANA is offline
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Default Stereo receievers: THD of .04 vs. .08

With the distortion you mentioned, there will be no difference that you can
hear. Even at 0.1% THD distortion, you cannot hear that.

Check to see the power level that the distortion was measured at. At lower
volume levels, the distortion should be less. With efficient speakers, most
likely you will never exceed an average RMS power of about 10 Watts when
using high levels of sound. Normal listening levels would most likely be
less than 1 to 2 Watts of average power.

I would go for the higher power rating to be able to handle the peaks in the
sound. This is especially with the bass frequencies if in the event you
decide to sometimes use the amplifier on the loud side.

To hear the THD distortion defects, a very hearing acute person cannot hear
and THD distortion below about 2%. This is considered very high distortion
for any audio device. There are some very high end amplifiers that have THD
ratings in the 0.2% to 0.4% range.

The bottom line is to listen to the different amplifier and speaker
combinations. Then choose what sounds the best for your taste.

--

JANA
_____


wrote in message
...
Thanks all for the advice on B Stock merchandise.

Okay, I'm scared to mention non-high-end or non-scientific stuff here
because of the flaming I once took from a forger, but here goes:

I think I've decided on buying a pair of Infinity Beta 50 speakers.

I'm among two receivers--a Yamaha 497 (75w per ch) and an Onkyo TX
8522 (100w per ch).

One salient difference is that the Yamaha claims a 0.04 THD, and the
Onkyo a 0.08.
I THINK I have a pretty discerning ear. Do you think that difference
in THD would make much of a difference between those two receivers,
using that one pair of speakers?

Thanks.



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"Eeyore" wrote in
message
Arny Krueger wrote:

"Eeyore" wrote
Arny Krueger wrote:

When techniques like these are utilized, it is often
found that SS amplifiers have negligable crossover
distortion.


Pure nonsense. Crossover distortion remains the bete
noire of conventional Class AB bipolar designs.


Please explain that in the context of the performance of
this power amplifier:


http://www.pcavtech.com/pwramp/macrot-5000VZ/index.htm


Is it a "conventional Class AB bipolar design" ?


I suspect not.


It is class AB, and it is bipolar.

It is Crown, so probably part or all of the output stage was turned on its
head or split down the middle. ;-)

It has a linear power supply.

I should fetch up the measurements I made on the same day of a USA 850. Not
easy, but on a hard drive someplace.

Not as good, but not as bad as you seem to expect.

Remember, 5532s are class AB and bipolar. ;-)


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JANA wrote:

With the distortion you mentioned, there will be no difference that you can
hear. Even at 0.1% THD distortion, you cannot hear that.


The distortion spec is measured at close to full power.

The real distortion at lower powers where most of the listening is done may be
as much as TEN times higher with typical Class AB bipolar transistor designs.

I once imagined what you said above to be true, that was back in the late 70s in
fact. Until I listed to a top-notch 0.1% THD spec pro amplifier against a newer
design using more advanced circuitry that had THD nearly ten times lower.

The difference WAS NOT SUBTLE.

Graham





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Arny Krueger wrote:

"Eeyore" wrote in
message
Arny Krueger wrote:

"Eeyore" wrote
Arny Krueger wrote:

When techniques like these are utilized, it is often
found that SS amplifiers have negligable crossover
distortion.


Pure nonsense. Crossover distortion remains the bete
noire of conventional Class AB bipolar designs.


Please explain that in the context of the performance of
this power amplifier:


http://www.pcavtech.com/pwramp/macrot-5000VZ/index.htm


Is it a "conventional Class AB bipolar design" ?


I suspect not.


It is class AB, and it is bipolar.


It's not conventional.


It is Crown, so probably part or all of the output stage was turned on its
head or split down the middle. ;-)

It has a linear power supply.

I should fetch up the measurements I made on the same day of a USA 850. Not
easy, but on a hard drive someplace.

Not as good, but not as bad as you seem to expect.

Remember, 5532s are class AB and bipolar. ;-)


And the bias current in the output stage is a far larger fraction of the maximum
load current. It may operate entirely in Class A with many or even most loads.
Not many people are using 600 ohm working.

Graham


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"Eeyore" wrote in
message
JANA wrote:

With the distortion you mentioned, there will be no
difference that you can hear. Even at 0.1% THD
distortion, you cannot hear that.


The distortion spec is measured at close to full power.


The real distortion at lower powers where most of the
listening is done may be as much as TEN times higher with
typical Class AB bipolar transistor designs.


No way with modern amps. Any big rises at low levels that may be shown in
published tests is due to noise. The truth outs if someone actually
publishes a spectral analysis.

For one thing, modern output transistors have Ft up in the megahertz range.
Back in the 70s people were still struggling with output devices with Ft in
the KHz range.

But even so, the crossover spikes that remained were relatively small and
outside the audio range.

I once imagined what you said above to be true, that was
back in the late 70s in fact. Until I listed to a
top-notch 0.1% THD spec pro amplifier against a newer
design using more advanced circuitry that had THD nearly
ten times lower.


The difference WAS NOT SUBTLE.


That was like 30-odd years ago.

Time for a modern level set, Graham! ;-)

BTW Graham, why is it that when we get into discussions like this, its
always me that does the lab work?


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Arny Krueger wrote:

"Eeyore" wrote
JANA wrote:

With the distortion you mentioned, there will be no
difference that you can hear. Even at 0.1% THD
distortion, you cannot hear that.


The distortion spec is measured at close to full power.


The real distortion at lower powers where most of the
listening is done may be as much as TEN times higher with
typical Class AB bipolar transistor designs.


No way with modern amps.


YES Arny. The age of the amplifier is irrelevant.

It's simple semiconductor physics as applied to the classic complementary
emitter follower output stage. You can't change the physics of how
semiconductors work !

The one thing you CAN do is to use cleverer designs that reduce the impact of
the rapid change in device transconductance at lower currents. However very few
designs actually do this. Naturally mine do of course but even they do still
exhibit slightly higher THD at low power levels than at max output but by
somewhat less than ten to one.

This should be readily modellable with the best modern circuit simulation
packages now btw.

Graham

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Arny Krueger wrote:

For one thing, modern output transistors have Ft up in the megahertz range.
Back in the 70s people were still struggling with output devices with Ft in
the KHz range.


Has no influence on the change in transconductance of output devices with load
current.

Stop talking irrelevant nonsense.

How many amplifiers have YOU designed btw ? When you can illustrate you
actually know something relevant about the subject you'll be qualified to talk
about it. Until then all you're doing is repeating popular myths and
misapplying them. No better than the nitwits in r.a.t actually.

I AM right about this point Arny ! (as I usually am - nothing beats hands-on
design experience backed up by a solid understanding of the underlying physics
)

Graham

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JANA wrote:

With the distortion you mentioned, there will be no difference that you can
hear. Even at 0.1% THD distortion, you cannot hear that.


0.1% distortion that's 2nd harmonic or say seventh harmonic ?

You simply cannot make such broad statements. A serious limitation of THD
measurements is that the *total* tells you very little about how audible it is.

Graham



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Eeyore wrote:

Remember, 5532s are class AB and bipolar. ;-)


And the bias current in the output stage is a far larger fraction of
the maximum load current. It may operate entirely in Class A with
many or even most loads. Not many people are using 600 ohm working.


Let that apply for the poweramp too ... not at an unrealistic concept for
home use ... and there is NO issue.

Graham



Kind regards

Peter Larsen


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"Peter Larsen" wrote in message

Eeyore wrote:

Remember, 5532s are class AB and bipolar. ;-)


And the bias current in the output stage is a far larger
fraction of the maximum load current. It may operate
entirely in Class A with many or even most loads. Not
many people are using 600 ohm working.


Let that apply for the poweramp too ... not at an
unrealistic concept for home use ... and there is NO
issue.


IME, most home systems spend much of their time running at very low levels
where neither side of the output stage is ever cut off.


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"Eeyore" wrote in
message
Arny Krueger wrote:


For one thing, modern output transistors have Ft up in
the megahertz range. Back in the 70s people were still
struggling with output devices with Ft in the KHz range.


Has no influence on the change in transconductance of
output devices with load current.


But it does have something to do with the shape of such transients as show
up when you there is some crossover distortion.

But thanks for bringing up the issue of change in transconductance of the
output devices, particularly at low current levels. That's another issue
that modern devices sometimes do better at.

Stop talking irrelevant nonsense.


Lighten up, Graham. So seem to forget about all the truely weird nonsense
that we see on Usenet. How long has it been since you were on AAPLS?

How many amplifiers have YOU designed btw ?


More than I'd care to admit here. The experience made me a believer in
commercial amps. :-(



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Peter Larsen wrote:

Eeyore wrote:

Remember, 5532s are class AB and bipolar. ;-)


And the bias current in the output stage is a far larger fraction of
the maximum load current. It may operate entirely in Class A with
many or even most loads. Not many people are using 600 ohm working.


Let that apply for the poweramp too ... not at an unrealistic concept for
home use ... and there is NO issue.


Would you seriously suggest an amp or so of quiescent current would be
acceptable ? It certainly WILL fix the problem of course.

Graham

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Arny Krueger wrote:

"Peter Larsen" wrote
Eeyore wrote:

Remember, 5532s are class AB and bipolar. ;-)


And the bias current in the output stage is a far larger
fraction of the maximum load current. It may operate
entirely in Class A with many or even most loads. Not
many people are using 600 ohm working.


Let that apply for the poweramp too ... not at an
unrealistic concept for home use ... and there is NO
issue.


IME, most home systems spend much of their time running at very low levels
where neither side of the output stage is ever cut off.


It's not the cutting off per se that causes the distortion. Just modulating
the collector current of an emitter follower output stage by any significant
fraction of the quiescent value will cause distortion due to the change in
transconductance of the output devices. Transconductance changes with current
you see. This is semiconductor physics and its effect is most pronounced in
this situation. A change in transconductance results in an unwanted voltage
that adds to the signal and thereby causing the distortion.

Graham


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